From b218b9e47c9d1080d7762db66d1a7b9d7ce06b39 Mon Sep 17 00:00:00 2001
From: solidsnakedev <jona.ca.eng@gmail.com>
Date: Mon, 27 Oct 2025 13:01:50 -0600
Subject: [PATCH] feat: integrate TransactionBuilder into Client with
 signing/submission flow

- Add newTx() method to Client interfaces (ReadOnly, Signing)
- Implement SignBuilder and SubmitBuilder for transaction lifecycle
- Add generic type support (SignBuilder vs TransactionResultBase)
- Refactor protocol parameters resolution to 2-way (BuildOptions > Provider)
- Fix type inference with default generic in makeTxBuilder
- Update test files to use new protocol parameters pattern
---
 docs/content/docs/modules/core/Function.mdx   |    2 +-
 docs/content/docs/modules/core/Value.mdx      |   17 +
 docs/content/docs/modules/sdk/Credential.mdx  |    2 +-
 docs/content/docs/modules/sdk/Datum.mdx       |    2 +-
 docs/content/docs/modules/sdk/Delegation.mdx  |    2 +-
 .../docs/modules/sdk/Devnet/Devnet.mdx        |    2 +-
 .../docs/modules/sdk/Devnet/DevnetDefault.mdx |    2 +-
 .../content/docs/modules/sdk/EvalRedeemer.mdx |    2 +-
 docs/content/docs/modules/sdk/Label.mdx       |    2 +-
 docs/content/docs/modules/sdk/OutRef.mdx      |    2 +-
 docs/content/docs/modules/sdk/PolicyId.mdx    |    2 +-
 .../docs/modules/sdk/ProtocolParameters.mdx   |    2 +-
 .../docs/modules/sdk/RewardAddress.mdx        |    2 +-
 docs/content/docs/modules/sdk/Script.mdx      |    2 +-
 docs/content/docs/modules/sdk/Type.mdx        |    2 +-
 docs/content/docs/modules/sdk/UTxO.mdx        |    2 +-
 docs/content/docs/modules/sdk/Unit.mdx        |    2 +-
 .../docs/modules/sdk/builders/SignBuilder.mdx |   61 +-
 .../modules/sdk/builders/SignBuilderImpl.mdx  |   51 +
 .../modules/sdk/builders/SubmitBuilder.mdx    |   79 +
 .../sdk/builders/SubmitBuilderImpl.mdx        |   45 +
 .../sdk/builders/TransactionBuilder.mdx       |  231 +-
 .../sdk/builders/TransactionResult.mdx        |  160 +
 .../modules/sdk/builders/TxBuilderImpl.mdx    |    2 +-
 .../docs/modules/sdk/builders/Unfrack.mdx     |    2 +-
 .../docs/modules/sdk/client/Client.mdx        |  125 +-
 .../docs/modules/sdk/client/ClientImpl.mdx    |    6 +-
 .../docs/modules/sdk/provider/Blockfrost.mdx  |    2 +-
 .../docs/modules/sdk/provider/Koios.mdx       |    2 +-
 .../docs/modules/sdk/provider/Kupmios.mdx     |    2 +-
 .../docs/modules/sdk/provider/Maestro.mdx     |    2 +-
 .../docs/modules/sdk/provider/Provider.mdx    |    2 +-
 .../docs/modules/sdk/wallet/Derivation.mdx    |   14 +-
 .../docs/modules/sdk/wallet/Wallet.mdx        |    2 +-
 .../docs/modules/sdk/wallet/WalletNew.mdx     |    6 +-
 .../docs/modules/utils/FeeValidation.mdx      |    2 +-
 docs/content/docs/modules/utils/Hash.mdx      |    2 +-
 .../docs/modules/utils/effect-runtime.mdx     |   54 +
 docs/next-env.d.ts                            |    2 +-
 .../docs/modules/core/Function.ts.md          |    2 +-
 .../evolution/docs/modules/core/Value.ts.md   |   17 +
 .../docs/modules/sdk/Credential.ts.md         |    2 +-
 .../evolution/docs/modules/sdk/Datum.ts.md    |    2 +-
 .../docs/modules/sdk/Delegation.ts.md         |    2 +-
 .../docs/modules/sdk/Devnet/Devnet.ts.md      |    2 +-
 .../modules/sdk/Devnet/DevnetDefault.ts.md    |    2 +-
 .../docs/modules/sdk/EvalRedeemer.ts.md       |    2 +-
 .../evolution/docs/modules/sdk/Label.ts.md    |    2 +-
 .../evolution/docs/modules/sdk/OutRef.ts.md   |    2 +-
 .../evolution/docs/modules/sdk/PolicyId.ts.md |    2 +-
 .../docs/modules/sdk/ProtocolParameters.ts.md |    2 +-
 .../docs/modules/sdk/RewardAddress.ts.md      |    2 +-
 .../evolution/docs/modules/sdk/Script.ts.md   |    2 +-
 .../evolution/docs/modules/sdk/Type.ts.md     |    2 +-
 .../evolution/docs/modules/sdk/UTxO.ts.md     |    2 +-
 .../evolution/docs/modules/sdk/Unit.ts.md     |    2 +-
 .../modules/sdk/builders/SignBuilder.ts.md    |   61 +-
 .../sdk/builders/SignBuilderImpl.ts.md        |   51 +
 .../modules/sdk/builders/SubmitBuilder.ts.md  |   79 +
 .../sdk/builders/SubmitBuilderImpl.ts.md      |   45 +
 .../sdk/builders/TransactionBuilder.ts.md     |  231 +-
 .../sdk/builders/TransactionResult.ts.md      |  160 +
 .../modules/sdk/builders/TxBuilderImpl.ts.md  |    2 +-
 .../docs/modules/sdk/builders/Unfrack.ts.md   |    2 +-
 .../docs/modules/sdk/client/Client.ts.md      |  125 +-
 .../docs/modules/sdk/client/ClientImpl.ts.md  |    6 +-
 .../modules/sdk/provider/Blockfrost.ts.md     |    2 +-
 .../docs/modules/sdk/provider/Koios.ts.md     |    2 +-
 .../docs/modules/sdk/provider/Kupmios.ts.md   |    2 +-
 .../docs/modules/sdk/provider/Maestro.ts.md   |    2 +-
 .../docs/modules/sdk/provider/Provider.ts.md  |    2 +-
 .../docs/modules/sdk/wallet/Derivation.ts.md  |   14 +-
 .../docs/modules/sdk/wallet/Wallet.ts.md      |    2 +-
 .../docs/modules/sdk/wallet/WalletNew.ts.md   |    6 +-
 .../docs/modules/utils/FeeValidation.ts.md    |    2 +-
 .../evolution/docs/modules/utils/Hash.ts.md   |    2 +-
 .../docs/modules/utils/effect-runtime.ts.md   |   54 +
 packages/evolution/package.json               |    5 +-
 .../evolution/src/core/Bip32PrivateKey.ts     |  151 +-
 packages/evolution/src/core/Bip32PublicKey.ts |   23 +-
 packages/evolution/src/core/Function.ts       |   18 +-
 packages/evolution/src/core/PrivateKey.ts     |   51 +-
 packages/evolution/src/core/VKey.ts           |   15 +-
 packages/evolution/src/index.ts               |    1 +
 .../evolution/src/sdk/builders/SignBuilder.ts |   51 +-
 .../src/sdk/builders/SignBuilderImpl.ts       |  138 +
 .../src/sdk/builders/SubmitBuilder.ts         |   60 +
 .../src/sdk/builders/SubmitBuilderImpl.ts     |   64 +
 .../src/sdk/builders/TransactionBuilder.ts    | 2614 ++++-------------
 .../src/sdk/builders/TransactionResult.ts     |  160 +
 packages/evolution/src/sdk/builders/index.ts  |    6 +-
 packages/evolution/src/sdk/client/Client.ts   |  106 +-
 .../evolution/src/sdk/client/ClientImpl.ts    |  263 +-
 .../sdk/provider/internal/BlockfrostEffect.ts |   18 +-
 .../src/sdk/provider/internal/HttpUtils.ts    |    8 +-
 .../evolution/src/sdk/wallet/Derivation.ts    |  195 +-
 packages/evolution/src/sdk/wallet/Wallet.ts   |   16 +-
 .../evolution/src/sdk/wallet/WalletNew.ts     |    4 +-
 .../evolution/src/utils/effect-runtime.ts     |  117 +
 .../TxBuilder.CoinSelectionFailures.test.ts   |   59 +-
 .../test/TxBuilder.EdgeCases.test.ts          |   23 +-
 .../test/TxBuilder.InsufficientChange.test.ts |  119 +-
 .../test/TxBuilder.Reselection.test.ts        |  476 +--
 .../TxBuilder.UnfrackChangeHandling.test.ts   |   42 +-
 .../test/TxBuilder.UnfrackDrain.test.ts       |   46 +-
 .../test/TxBuilder.UnfrackMinUTxO.test.ts     |   41 +-
 .../evolution/test/WalletFromSeed.test.ts     |  188 +-
 pnpm-lock.yaml                                |   47 +-
 108 files changed, 3844 insertions(+), 3085 deletions(-)
 create mode 100644 docs/content/docs/modules/sdk/builders/SignBuilderImpl.mdx
 create mode 100644 docs/content/docs/modules/sdk/builders/SubmitBuilder.mdx
 create mode 100644 docs/content/docs/modules/sdk/builders/SubmitBuilderImpl.mdx
 create mode 100644 docs/content/docs/modules/sdk/builders/TransactionResult.mdx
 create mode 100644 docs/content/docs/modules/utils/effect-runtime.mdx
 create mode 100644 packages/evolution/docs/modules/sdk/builders/SignBuilderImpl.ts.md
 create mode 100644 packages/evolution/docs/modules/sdk/builders/SubmitBuilder.ts.md
 create mode 100644 packages/evolution/docs/modules/sdk/builders/SubmitBuilderImpl.ts.md
 create mode 100644 packages/evolution/docs/modules/sdk/builders/TransactionResult.ts.md
 create mode 100644 packages/evolution/docs/modules/utils/effect-runtime.ts.md
 create mode 100644 packages/evolution/src/sdk/builders/SignBuilderImpl.ts
 create mode 100644 packages/evolution/src/sdk/builders/SubmitBuilder.ts
 create mode 100644 packages/evolution/src/sdk/builders/SubmitBuilderImpl.ts
 create mode 100644 packages/evolution/src/sdk/builders/TransactionResult.ts
 create mode 100644 packages/evolution/src/utils/effect-runtime.ts

diff --git a/docs/content/docs/modules/core/Function.mdx b/docs/content/docs/modules/core/Function.mdx
index 51e69197..638e7639 100644
--- a/docs/content/docs/modules/core/Function.mdx
+++ b/docs/content/docs/modules/core/Function.mdx
@@ -121,7 +121,7 @@ export declare const makeCBOREncodeEither: <A, T extends CBOR.CBOR, E extends Er
   schemaTransformer: Schema.Schema<A, T>,
   ErrorClass: ErrorCtor<E>,
   defaultOptions?: CBOR.CodecOptions
-) => (input: A, options?: CBOR.CodecOptions) => Either.Either<Uint8Array, E>
+) => (value: A, options?: CBOR.CodecOptions) => Either.Either<Uint8Array, E>
 ```
 
 ## makeCBOREncodeHexEither
diff --git a/docs/content/docs/modules/core/Value.mdx b/docs/content/docs/modules/core/Value.mdx
index 9ea8f3c2..c0f1cd21 100644
--- a/docs/content/docs/modules/core/Value.mdx
+++ b/docs/content/docs/modules/core/Value.mdx
@@ -26,6 +26,8 @@ parent: Modules
   - [arbitrary](#arbitrary)
 - [model](#model)
   - [ValueCDDL (type alias)](#valuecddl-type-alias)
+- [ordering](#ordering)
+  - [geq](#geq)
 - [parsing](#parsing)
   - [fromCBORBytes](#fromcborbytes)
   - [fromCBORHex](#fromcborhex)
@@ -168,6 +170,21 @@ export type ValueCDDL = typeof FromCDDL.Type
 
 Added in v2.0.0
 
+# ordering
+
+## geq
+
+Check if Value a is greater than or equal to Value b.
+This means after subtracting b from a, the result would not be negative.
+
+**Signature**
+
+```ts
+export declare const geq: (a: Value, b: Value) => boolean
+```
+
+Added in v2.0.0
+
 # parsing
 
 ## fromCBORBytes
diff --git a/docs/content/docs/modules/sdk/Credential.mdx b/docs/content/docs/modules/sdk/Credential.mdx
index 1cbb8f7b..f0689c57 100644
--- a/docs/content/docs/modules/sdk/Credential.mdx
+++ b/docs/content/docs/modules/sdk/Credential.mdx
@@ -1,6 +1,6 @@
 ---
 title: sdk/Credential.ts
-nav_order: 135
+nav_order: 139
 parent: Modules
 ---
 
diff --git a/docs/content/docs/modules/sdk/Datum.mdx b/docs/content/docs/modules/sdk/Datum.mdx
index c8029612..e3128364 100644
--- a/docs/content/docs/modules/sdk/Datum.mdx
+++ b/docs/content/docs/modules/sdk/Datum.mdx
@@ -1,6 +1,6 @@
 ---
 title: sdk/Datum.ts
-nav_order: 136
+nav_order: 140
 parent: Modules
 ---
 
diff --git a/docs/content/docs/modules/sdk/Delegation.mdx b/docs/content/docs/modules/sdk/Delegation.mdx
index df19e34f..74858817 100644
--- a/docs/content/docs/modules/sdk/Delegation.mdx
+++ b/docs/content/docs/modules/sdk/Delegation.mdx
@@ -1,6 +1,6 @@
 ---
 title: sdk/Delegation.ts
-nav_order: 137
+nav_order: 141
 parent: Modules
 ---
 
diff --git a/docs/content/docs/modules/sdk/Devnet/Devnet.mdx b/docs/content/docs/modules/sdk/Devnet/Devnet.mdx
index 1937ef4c..29cbad5a 100644
--- a/docs/content/docs/modules/sdk/Devnet/Devnet.mdx
+++ b/docs/content/docs/modules/sdk/Devnet/Devnet.mdx
@@ -1,6 +1,6 @@
 ---
 title: sdk/Devnet/Devnet.ts
-nav_order: 138
+nav_order: 142
 parent: Modules
 ---
 
diff --git a/docs/content/docs/modules/sdk/Devnet/DevnetDefault.mdx b/docs/content/docs/modules/sdk/Devnet/DevnetDefault.mdx
index 8be3b4c1..9a88ecf7 100644
--- a/docs/content/docs/modules/sdk/Devnet/DevnetDefault.mdx
+++ b/docs/content/docs/modules/sdk/Devnet/DevnetDefault.mdx
@@ -1,6 +1,6 @@
 ---
 title: sdk/Devnet/DevnetDefault.ts
-nav_order: 139
+nav_order: 143
 parent: Modules
 ---
 
diff --git a/docs/content/docs/modules/sdk/EvalRedeemer.mdx b/docs/content/docs/modules/sdk/EvalRedeemer.mdx
index 9218e779..66881f96 100644
--- a/docs/content/docs/modules/sdk/EvalRedeemer.mdx
+++ b/docs/content/docs/modules/sdk/EvalRedeemer.mdx
@@ -1,6 +1,6 @@
 ---
 title: sdk/EvalRedeemer.ts
-nav_order: 140
+nav_order: 144
 parent: Modules
 ---
 
diff --git a/docs/content/docs/modules/sdk/Label.mdx b/docs/content/docs/modules/sdk/Label.mdx
index e0d922ff..401d9c5f 100644
--- a/docs/content/docs/modules/sdk/Label.mdx
+++ b/docs/content/docs/modules/sdk/Label.mdx
@@ -1,6 +1,6 @@
 ---
 title: sdk/Label.ts
-nav_order: 141
+nav_order: 145
 parent: Modules
 ---
 
diff --git a/docs/content/docs/modules/sdk/OutRef.mdx b/docs/content/docs/modules/sdk/OutRef.mdx
index 20184c8c..a3d1e7d9 100644
--- a/docs/content/docs/modules/sdk/OutRef.mdx
+++ b/docs/content/docs/modules/sdk/OutRef.mdx
@@ -1,6 +1,6 @@
 ---
 title: sdk/OutRef.ts
-nav_order: 142
+nav_order: 146
 parent: Modules
 ---
 
diff --git a/docs/content/docs/modules/sdk/PolicyId.mdx b/docs/content/docs/modules/sdk/PolicyId.mdx
index 20dbf9f6..4e7cd895 100644
--- a/docs/content/docs/modules/sdk/PolicyId.mdx
+++ b/docs/content/docs/modules/sdk/PolicyId.mdx
@@ -1,6 +1,6 @@
 ---
 title: sdk/PolicyId.ts
-nav_order: 143
+nav_order: 147
 parent: Modules
 ---
 
diff --git a/docs/content/docs/modules/sdk/ProtocolParameters.mdx b/docs/content/docs/modules/sdk/ProtocolParameters.mdx
index e40d7b46..c3b03bd7 100644
--- a/docs/content/docs/modules/sdk/ProtocolParameters.mdx
+++ b/docs/content/docs/modules/sdk/ProtocolParameters.mdx
@@ -1,6 +1,6 @@
 ---
 title: sdk/ProtocolParameters.ts
-nav_order: 144
+nav_order: 148
 parent: Modules
 ---
 
diff --git a/docs/content/docs/modules/sdk/RewardAddress.mdx b/docs/content/docs/modules/sdk/RewardAddress.mdx
index e70498e8..46f3c2f7 100644
--- a/docs/content/docs/modules/sdk/RewardAddress.mdx
+++ b/docs/content/docs/modules/sdk/RewardAddress.mdx
@@ -1,6 +1,6 @@
 ---
 title: sdk/RewardAddress.ts
-nav_order: 150
+nav_order: 154
 parent: Modules
 ---
 
diff --git a/docs/content/docs/modules/sdk/Script.mdx b/docs/content/docs/modules/sdk/Script.mdx
index 9dc6c484..bdfe562c 100644
--- a/docs/content/docs/modules/sdk/Script.mdx
+++ b/docs/content/docs/modules/sdk/Script.mdx
@@ -1,6 +1,6 @@
 ---
 title: sdk/Script.ts
-nav_order: 151
+nav_order: 155
 parent: Modules
 ---
 
diff --git a/docs/content/docs/modules/sdk/Type.mdx b/docs/content/docs/modules/sdk/Type.mdx
index 58d93023..03c39a03 100644
--- a/docs/content/docs/modules/sdk/Type.mdx
+++ b/docs/content/docs/modules/sdk/Type.mdx
@@ -1,6 +1,6 @@
 ---
 title: sdk/Type.ts
-nav_order: 152
+nav_order: 156
 parent: Modules
 ---
 
diff --git a/docs/content/docs/modules/sdk/UTxO.mdx b/docs/content/docs/modules/sdk/UTxO.mdx
index ee9ce64b..9783c1d1 100644
--- a/docs/content/docs/modules/sdk/UTxO.mdx
+++ b/docs/content/docs/modules/sdk/UTxO.mdx
@@ -1,6 +1,6 @@
 ---
 title: sdk/UTxO.ts
-nav_order: 154
+nav_order: 158
 parent: Modules
 ---
 
diff --git a/docs/content/docs/modules/sdk/Unit.mdx b/docs/content/docs/modules/sdk/Unit.mdx
index 42b0ba96..3c445ec7 100644
--- a/docs/content/docs/modules/sdk/Unit.mdx
+++ b/docs/content/docs/modules/sdk/Unit.mdx
@@ -1,6 +1,6 @@
 ---
 title: sdk/Unit.ts
-nav_order: 153
+nav_order: 157
 parent: Modules
 ---
 
diff --git a/docs/content/docs/modules/sdk/builders/SignBuilder.mdx b/docs/content/docs/modules/sdk/builders/SignBuilder.mdx
index 34bf2be4..2fb69a08 100644
--- a/docs/content/docs/modules/sdk/builders/SignBuilder.mdx
+++ b/docs/content/docs/modules/sdk/builders/SignBuilder.mdx
@@ -10,76 +10,57 @@ parent: Modules
 
 <h2 className="text-delta">Table of contents</h2>
 
-- [utils](#utils)
+- [interfaces](#interfaces)
   - [SignBuilder (interface)](#signbuilder-interface)
   - [SignBuilderEffect (interface)](#signbuildereffect-interface)
-  - [SubmitBuilder (interface)](#submitbuilder-interface)
-  - [SubmitBuilderEffect (interface)](#submitbuildereffect-interface)
 
 ---
 
-# utils
+# interfaces
 
 ## SignBuilder (interface)
 
+SignBuilder extends TransactionResultBase with signing capabilities.
+
+Only available when the client has a signing wallet (seed, private key, or API wallet).
+Provides access to unsigned transaction (via base interface) and signing operations.
+
 **Signature**
 
 ```ts
-export interface SignBuilder extends EffectToPromiseAPI<SignBuilderEffect> {
+export interface SignBuilder extends TransactionResultBase, EffectToPromiseAPI<SignBuilderEffect> {
   readonly Effect: SignBuilderEffect
 }
 ```
 
+Added in v2.0.0
+
 ## SignBuilderEffect (interface)
 
+Effect-based API for SignBuilder operations.
+
+Includes all TransactionResultBase.Effect methods plus signing-specific operations.
+
 **Signature**
 
 ```ts
 export interface SignBuilderEffect {
-  // Main signing method - produces a fully signed transaction ready for submission
-  readonly sign: () => Effect.Effect<SubmitBuilder, TransactionBuilderError>
+  // Base transaction methods (from TransactionResultBase)
+  readonly toTransaction: () => Effect.Effect<Transaction.Transaction, TransactionBuilderError>
+  readonly toTransactionWithFakeWitnesses: () => Effect.Effect<Transaction.Transaction, TransactionBuilderError>
+  readonly estimateFee: () => Effect.Effect<bigint, TransactionBuilderError>
 
-  // Add external witness and proceed to submission
+  // Signing methods
+  readonly sign: () => Effect.Effect<SubmitBuilder, TransactionBuilderError>
   readonly signWithWitness: (
     witnessSet: TransactionWitnessSet.TransactionWitnessSet
   ) => Effect.Effect<SubmitBuilder, TransactionBuilderError>
-
-  // Assemble multiple witnesses into a complete transaction ready for submission
   readonly assemble: (
     witnesses: ReadonlyArray<TransactionWitnessSet.TransactionWitnessSet>
   ) => Effect.Effect<SubmitBuilder, TransactionBuilderError>
-
-  // Partial signing - creates witness without advancing to submission (useful for multi-sig)
   readonly partialSign: () => Effect.Effect<TransactionWitnessSet.TransactionWitnessSet, TransactionBuilderError>
-
-  // Get witness set without signing (for inspection)
   readonly getWitnessSet: () => Effect.Effect<TransactionWitnessSet.TransactionWitnessSet, TransactionBuilderError>
-
-  // Get the unsigned transaction (for inspection)
-  readonly toTransaction: () => Effect.Effect<Transaction.Transaction, TransactionBuilderError>
-
-  // Get the transaction with fake witnesses (for fee validation)
-  readonly toTransactionWithFakeWitnesses: () => Effect.Effect<Transaction.Transaction, TransactionBuilderError>
-}
-```
-
-## SubmitBuilder (interface)
-
-**Signature**
-
-```ts
-export interface SubmitBuilder extends EffectToPromiseAPI<SubmitBuilderEffect> {
-  readonly Effect: SubmitBuilderEffect
-  readonly witnessSet: TransactionWitnessSet.TransactionWitnessSet
 }
 ```
 
-## SubmitBuilderEffect (interface)
-
-**Signature**
-
-```ts
-export interface SubmitBuilderEffect {
-  readonly submit: () => Effect.Effect<string, TransactionBuilderError>
-}
-```
+Added in v2.0.0
diff --git a/docs/content/docs/modules/sdk/builders/SignBuilderImpl.mdx b/docs/content/docs/modules/sdk/builders/SignBuilderImpl.mdx
new file mode 100644
index 00000000..5e77c21b
--- /dev/null
+++ b/docs/content/docs/modules/sdk/builders/SignBuilderImpl.mdx
@@ -0,0 +1,51 @@
+---
+title: sdk/builders/SignBuilderImpl.ts
+nav_order: 130
+parent: Modules
+---
+
+## SignBuilderImpl overview
+
+SignBuilder Implementation
+
+Handles transaction signing by delegating to the wallet's signTx Effect method.
+The SignBuilder is responsible for:
+
+1. Providing the transaction and UTxO context to the wallet
+2. Managing the transition from unsigned to signed transaction
+3. Creating the SubmitBuilder for transaction submission
+
+The actual signing logic (determining required signers, creating witnesses)
+is the wallet's responsibility.
+
+Added in v2.0.0
+
+---
+
+<h2 className="text-delta">Table of contents</h2>
+
+- [constructors](#constructors)
+  - [makeSignBuilder](#makesignbuilder)
+
+---
+
+# constructors
+
+## makeSignBuilder
+
+Create a SignBuilder instance for a built transaction.
+
+**Signature**
+
+```ts
+export declare const makeSignBuilder: (params: {
+  transaction: Transaction.Transaction
+  transactionWithFakeWitnesses: Transaction.Transaction
+  fee: bigint
+  utxos: ReadonlyArray<UTxO.UTxO>
+  provider: Provider.Provider
+  wallet: Wallet
+}) => SignBuilder
+```
+
+Added in v2.0.0
diff --git a/docs/content/docs/modules/sdk/builders/SubmitBuilder.mdx b/docs/content/docs/modules/sdk/builders/SubmitBuilder.mdx
new file mode 100644
index 00000000..122c2612
--- /dev/null
+++ b/docs/content/docs/modules/sdk/builders/SubmitBuilder.mdx
@@ -0,0 +1,79 @@
+---
+title: sdk/builders/SubmitBuilder.ts
+nav_order: 131
+parent: Modules
+---
+
+## SubmitBuilder overview
+
+SubmitBuilder - Final stage of transaction lifecycle
+
+Represents a signed transaction ready for submission to the blockchain.
+Provides the submit() method to broadcast the transaction and retrieve the transaction hash.
+
+Added in v2.0.0
+
+---
+
+<h2 className="text-delta">Table of contents</h2>
+
+- [interfaces](#interfaces)
+  - [SubmitBuilder (interface)](#submitbuilder-interface)
+  - [SubmitBuilderEffect (interface)](#submitbuildereffect-interface)
+
+---
+
+# interfaces
+
+## SubmitBuilder (interface)
+
+SubmitBuilder - represents a signed transaction ready for submission.
+
+The final stage in the transaction lifecycle after building and signing.
+Provides the submit() method to broadcast the transaction to the blockchain
+and retrieve the transaction hash.
+
+**Signature**
+
+```ts
+export interface SubmitBuilder extends EffectToPromiseAPI<SubmitBuilderEffect> {
+  /**
+   * Effect-based API for compositional workflows.
+   *
+   * @since 2.0.0
+   */
+  readonly Effect: SubmitBuilderEffect
+
+  /**
+   * The witness set containing all signatures for this transaction.
+   *
+   * Can be used to inspect the signatures or combine with other witness sets
+   * for multi-party signing scenarios.
+   *
+   * @since 2.0.0
+   */
+  readonly witnessSet: TransactionWitnessSet.TransactionWitnessSet
+}
+```
+
+Added in v2.0.0
+
+## SubmitBuilderEffect (interface)
+
+Effect-based API for SubmitBuilder operations.
+
+**Signature**
+
+```ts
+export interface SubmitBuilderEffect {
+  /**
+   * Submit the signed transaction to the blockchain via the provider.
+   *
+   * @returns Effect resolving to the transaction hash
+   * @since 2.0.0
+   */
+  readonly submit: () => Effect.Effect<string, TransactionBuilderError>
+}
+```
+
+Added in v2.0.0
diff --git a/docs/content/docs/modules/sdk/builders/SubmitBuilderImpl.mdx b/docs/content/docs/modules/sdk/builders/SubmitBuilderImpl.mdx
new file mode 100644
index 00000000..daf8587f
--- /dev/null
+++ b/docs/content/docs/modules/sdk/builders/SubmitBuilderImpl.mdx
@@ -0,0 +1,45 @@
+---
+title: sdk/builders/SubmitBuilderImpl.ts
+nav_order: 132
+parent: Modules
+---
+
+## SubmitBuilderImpl overview
+
+SubmitBuilder Implementation
+
+Handles transaction submission by delegating to the provider's submitTx method.
+The SubmitBuilder is responsible for:
+
+1. Converting the signed transaction to CBOR hex format
+2. Submitting to the provider's Effect.submitTx
+3. Returning the transaction hash
+
+Added in v2.0.0
+
+---
+
+<h2 className="text-delta">Table of contents</h2>
+
+- [constructors](#constructors)
+  - [makeSubmitBuilder](#makesubmitbuilder)
+
+---
+
+# constructors
+
+## makeSubmitBuilder
+
+Create a SubmitBuilder instance for a signed transaction.
+
+**Signature**
+
+```ts
+export declare const makeSubmitBuilder: (
+  signedTransaction: Transaction.Transaction,
+  witnessSet: TransactionWitnessSet.TransactionWitnessSet,
+  provider: Provider.Provider
+) => SubmitBuilder
+```
+
+Added in v2.0.0
diff --git a/docs/content/docs/modules/sdk/builders/TransactionBuilder.mdx b/docs/content/docs/modules/sdk/builders/TransactionBuilder.mdx
index ee84701c..b2ee14d5 100644
--- a/docs/content/docs/modules/sdk/builders/TransactionBuilder.mdx
+++ b/docs/content/docs/modules/sdk/builders/TransactionBuilder.mdx
@@ -1,6 +1,6 @@
 ---
 title: sdk/builders/TransactionBuilder.ts
-nav_order: 130
+nav_order: 133
 parent: Modules
 ---
 
@@ -38,6 +38,9 @@ double-spending. UTxOs can come from any source (wallet, DeFi protocols, other p
 - [constructors](#constructors)
   - [makeTxBuilder](#maketxbuilder)
 - [context](#context)
+  - [AvailableUtxosTag (class)](#availableutxostag-class)
+  - [ChangeAddressTag (class)](#changeaddresstag-class)
+  - [ProtocolParametersTag (class)](#protocolparameterstag-class)
   - [TxContext (class)](#txcontext-class)
   - [TxContextData (interface)](#txcontextdata-interface)
 - [errors](#errors)
@@ -107,34 +110,49 @@ Added in v2.0.0
 Configuration for TransactionBuilder.
 Immutable configuration passed to builder at creation time.
 
-Contains:
+Wallet-centric design (when wallet provided):
 
-- Protocol parameters for fee calculation
-- Change address for leftover funds
-- Available UTxOs for coin selection
+- Wallet provides change address (via wallet.Effect.address())
+- Provider + Wallet provide available UTxOs (via provider.Effect.getUtxos(wallet.address))
+- Override per-build via BuildOptions if needed
+
+Manual mode (no wallet):
+
+- Must provide changeAddress and availableUtxos in BuildOptions for each build
+- Used for read-only scenarios or advanced use cases
 
 **Signature**
 
 ```ts
 export interface TxBuilderConfig {
-  readonly protocolParameters: ProtocolParameters
-
   /**
-   * Address to send change (leftover assets) to.
-   * This is required for proper transaction balancing.
+   * Optional wallet provides:
+   * - Change address via wallet.Effect.address()
+   * - Available UTxOs via wallet.Effect.address() + provider.Effect.getUtxos()
+   * - Signing capability via wallet.Effect.signTx() (SigningWallet and ApiWallet only)
+   *
+   * When provided: Automatic change address and UTxO resolution.
+   * When omitted: Must provide changeAddress and availableUtxos in BuildOptions.
+   *
+   * ReadOnlyWallet: For read-only clients that can build but not sign transactions.
+   * SigningWallet/ApiWallet: For signing clients with full transaction signing capability.
+   *
+   * Override per-build via BuildOptions.changeAddress and BuildOptions.availableUtxos.
    */
-  readonly changeAddress: string
+  readonly wallet?: WalletNew.SigningWallet | WalletNew.ApiWallet | WalletNew.ReadOnlyWallet
 
   /**
-   * UTxOs available for coin selection.
-   * These can be from a wallet, another user, or any other source.
-   * Coin selection will automatically select from these UTxOs to cover
-   * required outputs + fees, excluding any already collected via collectFrom().
+   * Optional provider for:
+   * - Fetching UTxOs for the wallet's address (provider.Effect.getUtxos)
+   * - Transaction submission (provider.Effect.submitTx)
+   * - Protocol parameters
+   *
+   * Works together with wallet to provide everything needed for transaction building.
+   * When wallet is omitted, provider is only used if you call provider methods directly.
    */
-  readonly availableUtxos: ReadonlyArray<UTxO.UTxO>
+  readonly provider?: Provider.Provider
 
   // Future fields:
-  // readonly provider?: any // Provider interface for blockchain communication
   // readonly costModels?: Uint8Array // Cost models for script evaluation
 }
 ```
@@ -151,16 +169,75 @@ The builder accumulates chainable method calls as deferred ProgramSteps. Calling
 creates fresh state (new Refs) and executes all accumulated programs sequentially, ensuring
 no state pollution between invocations.
 
+Generic type parameter TResult determines what build() returns:
+
+- SignBuilder (default): When wallet has signing capability
+- TransactionResultBase: When wallet is read-only
+
 **Signature**
 
 ```ts
-export declare const makeTxBuilder: (config: TxBuilderConfig) => TransactionBuilder
+export declare const makeTxBuilder: <TResult = SignBuilder>(config: TxBuilderConfig) => TransactionBuilder<TResult>
 ```
 
 Added in v2.0.0
 
 # context
 
+## AvailableUtxosTag (class)
+
+Resolved available UTxOs for the current build.
+This is resolved once at the start of build() from either:
+
+- BuildOptions.availableUtxos (per-transaction override)
+- provider.Effect.getUtxos(wallet.address) (default from wallet + provider)
+
+Available to all phase functions via Effect Context.
+
+**Signature**
+
+```ts
+export declare class AvailableUtxosTag
+```
+
+Added in v2.0.0
+
+## ChangeAddressTag (class)
+
+Resolved change address for the current build.
+This is resolved once at the start of build() from either:
+
+- BuildOptions.changeAddress (per-transaction override)
+- TxBuilderConfig.wallet.Effect.address() (default from wallet)
+
+Available to all phase functions via Effect Context.
+
+**Signature**
+
+```ts
+export declare class ChangeAddressTag
+```
+
+Added in v2.0.0
+
+## ProtocolParametersTag (class)
+
+Resolved protocol parameters for the current build.
+This is resolved once at the start of build() from either:
+
+- BuildOptions.protocolParameters (per-transaction override)
+- provider.Effect.getProtocolParameters() (fetched from provider)
+
+Available to all phase functions via Effect Context.
+
+**Signature**
+
+```ts
+export declare class ProtocolParametersTag
+```
+
+Added in v2.0.0
+
 ## TxContext (class)
 
 Single Context service providing all transaction building data to programs.
@@ -248,6 +325,12 @@ Key Design Principle:
 Builder instance never mutates. Programs are deferred Effects that execute later.
 Each build() creates fresh TxBuilderState, executes programs, returns result.
 
+Generic Type Parameter:
+TResult determines the return type of build() methods:
+
+- SignBuilder: When wallet has signing capability (SigningClient)
+- TransactionResultBase: When wallet is read-only (ReadOnlyClient)
+
 Usage Pattern:
 
 ```typescript
@@ -265,7 +348,7 @@ const signBuilder2 = await builder.build()
 **Signature**
 
 ```ts
-export interface TransactionBuilder {
+export interface TransactionBuilder<TResult = SignBuilder> {
   // ============================================================================
   // Chainable Builder Methods - Create ProgramSteps, return same builder
   // ============================================================================
@@ -279,7 +362,7 @@ export interface TransactionBuilder {
    * @since 2.0.0
    * @category builder-methods
    */
-  readonly payToAddress: (params: PayToAddressParams) => TransactionBuilder
+  readonly payToAddress: (params: PayToAddressParams) => TransactionBuilder<TResult>
 
   /**
    * Specify transaction inputs from provided UTxOs.
@@ -290,7 +373,7 @@ export interface TransactionBuilder {
    * @since 2.0.0
    * @category builder-methods
    */
-  readonly collectFrom: (params: CollectFromParams) => TransactionBuilder
+  readonly collectFrom: (params: CollectFromParams) => TransactionBuilder<TResult>
 
   // Future expansion points for other operations:
   // readonly mintTokens: (params: MintTokensParams) => TransactionBuilder
@@ -309,10 +392,14 @@ export interface TransactionBuilder {
    * Creates fresh state and runs all accumulated ProgramSteps sequentially.
    * Can be called multiple times on the same builder instance with independent results.
    *
+   * Returns TResult which is:
+   * - SignBuilder for SigningClient (can sign transactions)
+   * - TransactionResultBase for ReadOnlyClient (unsigned transaction only)
+   *
    * @since 2.0.0
    * @category completion-methods
    */
-  readonly build: (options?: BuildOptions) => Promise<SignBuilder>
+  readonly build: (options?: BuildOptions) => Promise<TResult>
 
   /**
    * Execute all queued operations and return a signing-ready transaction via Effect.
@@ -320,25 +407,43 @@ export interface TransactionBuilder {
    * Creates fresh state and runs all accumulated ProgramSteps sequentially.
    * Suitable for Effect-TS compositional workflows and error handling.
    *
+   * Error types include WalletError and ProviderError from config Effects.
+   *
+   * Returns TResult which is:
+   * - SignBuilder for SigningClient (can sign transactions)
+   * - TransactionResultBase for ReadOnlyClient (unsigned transaction only)
+   *
    * @since 2.0.0
    * @category completion-methods
    */
   readonly buildEffect: (
     options?: BuildOptions
-  ) => Effect.Effect<SignBuilder, TransactionBuilderError | EvaluationError, unknown>
+  ) => Effect.Effect<
+    TResult,
+    TransactionBuilderError | EvaluationError | WalletNew.WalletError | Provider.ProviderError,
+    unknown
+  >
 
   /**
    * Execute all queued operations with explicit error handling via Either.
    *
    * Creates fresh state and runs all accumulated ProgramSteps sequentially.
-   * Returns Either<SignBuilder, Error> for pattern-matched error recovery.
+   * Returns Either<TResult, Error> for pattern-matched error recovery.
+   *
+   * Error types include WalletError and ProviderError from config Effects.
+   *
+   * Returns TResult which is:
+   * - SignBuilder for SigningClient (can sign transactions)
+   * - TransactionResultBase for ReadOnlyClient (unsigned transaction only)
    *
    * @since 2.0.0
    * @category completion-methods
    */
   readonly buildEither: (
     options?: BuildOptions
-  ) => Promise<Either<SignBuilder, TransactionBuilderError | EvaluationError>>
+  ) => Promise<
+    Either<TResult, TransactionBuilderError | EvaluationError | WalletNew.WalletError | Provider.ProviderError>
+  >
 
   // ============================================================================
   // Transaction Chaining Methods - Multi-transaction workflows
@@ -600,6 +705,29 @@ Added in v2.0.0
 
 ````ts
 export interface BuildOptions {
+  /**
+   * Override protocol parameters for this specific transaction build.
+   *
+   * By default, fetches from provider during build().
+   * Provide this to use different protocol parameters for testing or special cases.
+   *
+   * Use cases:
+   * - Testing with different fee parameters
+   * - Simulating future protocol changes
+   * - Using cached parameters to avoid provider fetch
+   *
+   * Example:
+   * ```typescript
+   * // Test with custom fee parameters
+   * builder.build({
+   *   protocolParameters: { ...params, minFeeCoefficient: 50n, minFeeConstant: 200000n }
+   * })
+   * ```
+   *
+   * @since 2.0.0
+   */
+  readonly protocolParameters?: ProtocolParameters
+
   /**
    * Coin selection strategy for automatic input selection.
    *
@@ -624,6 +752,56 @@ export interface BuildOptions {
   // Change Handling Configuration
   // ============================================================================
 
+  /**
+   * Override the change address for this specific transaction build.
+   *
+   * By default, uses wallet.Effect.address() from TxBuilderConfig.
+   * Provide this to use a different address for change outputs.
+   *
+   * Use cases:
+   * - Multi-address wallet (use account index 5 for change)
+   * - Different change address per transaction
+   * - Multi-sig workflows where change address varies
+   * - Testing with different addresses
+   *
+   * Example:
+   * ```typescript
+   * // Use different account for change
+   * builder.build({ changeAddress: wallet.addresses[5] })
+   *
+   * // Custom address
+   * builder.build({ changeAddress: "addr_test1..." })
+   * ```
+   *
+   * @since 2.0.0
+   */
+  readonly changeAddress?: string
+
+  /**
+   * Override the available UTxOs for this specific transaction build.
+   *
+   * By default, fetches UTxOs from provider.Effect.getUtxos(wallet.address).
+   * Provide this to use a specific set of UTxOs for coin selection.
+   *
+   * Use cases:
+   * - Use UTxOs from specific account index
+   * - Pre-filtered UTxO set
+   * - Testing with known UTxO set
+   * - Multi-address UTxO aggregation
+   *
+   * Example:
+   * ```typescript
+   * // Use UTxOs from specific account
+   * builder.build({ availableUtxos: utxosFromAccount5 })
+   *
+   * // Combine UTxOs from multiple addresses
+   * builder.build({ availableUtxos: [...utxos1, ...utxos2] })
+   * ```
+   *
+   * @since 2.0.0
+   */
+  readonly availableUtxos?: ReadonlyArray<UTxO.UTxO>
+
   /**
    * # Change Handling Strategy Matrix
    * 
@@ -739,12 +917,11 @@ export interface BuildOptions {
   readonly useStateMachine?: boolean
 
   /**
-   * **EXPERIMENTAL**: Use V3 4-phase state machine
    *
-   * When true, uses V3's simplified 4-phase state machine:
+   * When true, uses simplified 4-phase state machine:
    * - selection → changeValidation → balanceVerification → fallback → complete
    *
-   * V3 shares TxContext with V2 but uses mathematical validation approach.
+   * shares TxContext with V2 but uses mathematical validation approach.
    *
    * @experimental
    * @default false
diff --git a/docs/content/docs/modules/sdk/builders/TransactionResult.mdx b/docs/content/docs/modules/sdk/builders/TransactionResult.mdx
new file mode 100644
index 00000000..f34cc39f
--- /dev/null
+++ b/docs/content/docs/modules/sdk/builders/TransactionResult.mdx
@@ -0,0 +1,160 @@
+---
+title: sdk/builders/TransactionResult.ts
+nav_order: 134
+parent: Modules
+---
+
+## TransactionResult overview
+
+TransactionResult - Base interface for transaction building results
+
+Provides core functionality available to all transaction builders regardless
+of signing capability. This enables type-safe differentiation between
+read-only clients (can build but not sign) and signing clients (can build and sign).
+
+Added in v2.0.0
+
+---
+
+<h2 className="text-delta">Table of contents</h2>
+
+- [constructors](#constructors)
+  - [makeTransactionResult](#maketransactionresult)
+- [interfaces](#interfaces)
+  - [TransactionResultBase (interface)](#transactionresultbase-interface)
+
+---
+
+# constructors
+
+## makeTransactionResult
+
+Create a TransactionResultBase instance for a built transaction without signing capability.
+
+Used by ReadOnlyClient which can build transactions but cannot sign them.
+Provides access to the unsigned transaction, fake-witness transaction for fee validation,
+and fee estimation.
+
+**Signature**
+
+```ts
+export declare const makeTransactionResult: (params: {
+  transaction: Transaction.Transaction
+  transactionWithFakeWitnesses: Transaction.Transaction
+  fee: bigint
+}) => TransactionResultBase
+```
+
+Added in v2.0.0
+
+# interfaces
+
+## TransactionResultBase (interface)
+
+Base result interface for built transactions.
+
+Available on all transaction builders regardless of signing capability.
+Provides access to the unsigned transaction, fee estimates, and transaction
+with fake witnesses for size validation.
+
+**Signature**
+
+````ts
+export interface TransactionResultBase {
+  /**
+   * Get the unsigned transaction.
+   *
+   * This transaction has a complete body but no witness set (signatures).
+   * Can be serialized to CBOR for external signing (hardware wallets, browser extensions, etc.)
+   *
+   * @returns Promise resolving to the unsigned transaction
+   *
+   * @example
+   * ```typescript
+   * const result = await readOnlyClient.newTx()
+   *   .payToAddress({ address: "addr...", lovelace: 5_000_000n })
+   *   .build()
+   *
+   * const unsignedTx = await result.toTransaction()
+   * const txCbor = Transaction.toCBORHex(unsignedTx)
+   * // Export for external signing
+   * ```
+   *
+   * @since 2.0.0
+   * @category accessors
+   */
+  readonly toTransaction: () => Promise<Transaction.Transaction>
+
+  /**
+   * Get the transaction with fake witnesses for fee validation.
+   *
+   * This transaction includes fake witness sets (294 bytes each) to accurately
+   * calculate the final transaction size and fees. Useful for validating that
+   * the calculated fee is sufficient for the final signed transaction.
+   *
+   * @returns Promise resolving to the transaction with fake witnesses
+   *
+   * @since 2.0.0
+   * @category accessors
+   */
+  readonly toTransactionWithFakeWitnesses: () => Promise<Transaction.Transaction>
+
+  /**
+   * Get the calculated transaction fee in lovelace.
+   *
+   * This is the fee that was calculated during the build process based on
+   * the transaction size (including fake witnesses) and protocol parameters.
+   *
+   * @returns Promise resolving to the transaction fee in lovelace
+   *
+   * @example
+   * ```typescript
+   * const result = await client.newTx()
+   *   .payToAddress({ address: "addr...", lovelace: 5_000_000n })
+   *   .build()
+   *
+   * const fee = await result.estimateFee()
+   * console.log(`Transaction fee: ${fee} lovelace`)
+   * ```
+   *
+   * @since 2.0.0
+   * @category accessors
+   */
+  readonly estimateFee: () => Promise<bigint>
+
+  /**
+   * Effect-based API for compositional workflows.
+   *
+   * Provides the same functionality as the Promise-based methods but returns
+   * Effect values for use in Effect-TS workflows with proper error handling
+   * and composition.
+   *
+   * @since 2.0.0
+   * @category effects
+   */
+  readonly Effect: {
+    /**
+     * Get the unsigned transaction as an Effect.
+     *
+     * @since 2.0.0
+     */
+    readonly toTransaction: () => Effect.Effect<Transaction.Transaction, TransactionBuilderError>
+
+    /**
+     * Get the transaction with fake witnesses as an Effect.
+     *
+     * @since 2.0.0
+     */
+    readonly toTransactionWithFakeWitnesses: () => Effect.Effect<Transaction.Transaction, TransactionBuilderError>
+
+    /**
+     * Get the calculated fee as an Effect.
+     *
+     * @since 2.0.0
+     */
+    readonly estimateFee: () => Effect.Effect<bigint, TransactionBuilderError>
+  }
+}
+````
+
+Added in v2.0.0
diff --git a/docs/content/docs/modules/sdk/builders/TxBuilderImpl.mdx b/docs/content/docs/modules/sdk/builders/TxBuilderImpl.mdx
index 5d870494..be5a421a 100644
--- a/docs/content/docs/modules/sdk/builders/TxBuilderImpl.mdx
+++ b/docs/content/docs/modules/sdk/builders/TxBuilderImpl.mdx
@@ -1,6 +1,6 @@
 ---
 title: sdk/builders/TxBuilderImpl.ts
-nav_order: 131
+nav_order: 135
 parent: Modules
 ---
 
diff --git a/docs/content/docs/modules/sdk/builders/Unfrack.mdx b/docs/content/docs/modules/sdk/builders/Unfrack.mdx
index f94178fd..f1166327 100644
--- a/docs/content/docs/modules/sdk/builders/Unfrack.mdx
+++ b/docs/content/docs/modules/sdk/builders/Unfrack.mdx
@@ -1,6 +1,6 @@
 ---
 title: sdk/builders/Unfrack.ts
-nav_order: 132
+nav_order: 136
 parent: Modules
 ---
 
diff --git a/docs/content/docs/modules/sdk/client/Client.mdx b/docs/content/docs/modules/sdk/client/Client.mdx
index af3a96d0..135f9c4d 100644
--- a/docs/content/docs/modules/sdk/client/Client.mdx
+++ b/docs/content/docs/modules/sdk/client/Client.mdx
@@ -1,6 +1,6 @@
 ---
 title: sdk/client/Client.ts
-nav_order: 133
+nav_order: 137
 parent: Modules
 ---
 
@@ -24,6 +24,7 @@ parent: Modules
   - [MinimalClient (interface)](#minimalclient-interface)
   - [MinimalClientEffect (interface)](#minimalclienteffect-interface)
   - [NetworkId (type alias)](#networkid-type-alias)
+  - [PrivateKeyWalletConfig (interface)](#privatekeywalletconfig-interface)
   - [ProviderConfig (type alias)](#providerconfig-type-alias)
   - [ProviderOnlyClient (type alias)](#provideronlyclient-type-alias)
   - [ReadOnlyClient (type alias)](#readonlyclient-type-alias)
@@ -156,13 +157,21 @@ export interface MinimalClient {
     config: T
   ) => T extends SeedWalletConfig
     ? SigningWalletClient
-    : T extends ApiWalletConfig
-      ? ApiWalletClient
-      : ReadOnlyWalletClient
+    : T extends PrivateKeyWalletConfig
+      ? SigningWalletClient
+      : T extends ApiWalletConfig
+        ? ApiWalletClient
+        : ReadOnlyWalletClient
   readonly attach: <TW extends WalletConfig>(
     providerConfig: ProviderConfig,
     walletConfig: TW
-  ) => TW extends SeedWalletConfig ? SigningClient : TW extends ApiWalletConfig ? SigningClient : ReadOnlyClient
+  ) => TW extends SeedWalletConfig
+    ? SigningClient
+    : TW extends PrivateKeyWalletConfig
+      ? SigningClient
+      : TW extends ApiWalletConfig
+        ? SigningClient
+        : ReadOnlyClient
   // Effect namespace for methods with side effects only
   readonly Effect: MinimalClientEffect
 }
@@ -188,6 +197,19 @@ export interface MinimalClientEffect {
 export type NetworkId = "mainnet" | "preprod" | "preview" | number
 ```
 
+## PrivateKeyWalletConfig (interface)
+
+**Signature**
+
+```ts
+export interface PrivateKeyWalletConfig {
+  readonly type: "private-key"
+  readonly paymentKey: string // bech32 ed25519e_sk
+  readonly stakeKey?: string // bech32 ed25519e_sk (optional, for Base addresses)
+  readonly addressType?: "Base" | "Enterprise"
+}
+```
+
 ## ProviderConfig (type alias)
 
 **Signature**
@@ -207,7 +229,13 @@ export type ProviderOnlyClient = EffectToPromiseAPI<Provider.ProviderEffect> & {
   // Combinator methods (pure, no side effects) with type-aware conditional return type
   readonly attachWallet: <T extends WalletConfig>(
     config: T
-  ) => T extends SeedWalletConfig ? SigningClient : T extends ApiWalletConfig ? SigningClient : ReadOnlyClient
+  ) => T extends SeedWalletConfig
+    ? SigningClient
+    : T extends PrivateKeyWalletConfig
+      ? SigningClient
+      : T extends ApiWalletConfig
+        ? SigningClient
+        : ReadOnlyClient
   // Effect namespace - includes all provider methods as Effects
   readonly Effect: Provider.ProviderEffect
 }
@@ -217,15 +245,48 @@ export type ProviderOnlyClient = EffectToPromiseAPI<Provider.ProviderEffect> & {
 
 ReadOnlyClient - can query blockchain + wallet address operations
 
+ReadOnlyClient cannot sign transactions, so newTx() returns a TransactionBuilder
+that yields TransactionResultBase (unsigned transaction only).
+
 **Signature**
 
-```ts
+````ts
 export type ReadOnlyClient = EffectToPromiseAPI<ReadOnlyClientEffect> & {
-  readonly newTx: (utxos?: ReadonlyArray<UTxO.UTxO>) => any // TODO: Change to ReadOnlyTransactionBuilder when implementing tx builder
+  /**
+   * Create a new transaction builder for read-only operations.
+   *
+   * Returns a TransactionBuilder that builds unsigned transactions.
+   * The build() methods return TransactionResultBase which provides:
+   * - `.toTransaction()` - Get the unsigned transaction
+   * - `.toTransactionWithFakeWitnesses()` - Get transaction with fake witnesses for fee validation
+   * - `.estimateFee()` - Get the calculated fee
+   *
+   * @param utxos - Optional UTxOs to use for coin selection. If not provided, wallet UTxOs will be fetched automatically when build() is called.
+   * @returns A new TransactionBuilder instance configured with cached protocol parameters and wallet change address.
+   *
+   * @example
+   * ```typescript
+   * // Build unsigned transaction
+   * const result = await readOnlyClient.newTx()
+   *   .payToAddress({ address: "addr...", lovelace: 5000000n })
+   *   .build()
+   *
+   * // Get unsigned transaction for external signing
+   * const unsignedTx = await result.toTransaction()
+   * const txCbor = Transaction.toCBORHex(unsignedTx)
+   *
+   * // Get fee estimate
+   * const fee = await result.estimateFee()
+   * ```
+   *
+   * @since 2.0.0
+   * @category transaction-building
+   */
+  readonly newTx: (utxos?: ReadonlyArray<UTxO.UTxO>) => TransactionBuilder<TransactionResultBase>
   // Effect namespace - includes all provider + wallet methods as Effects
   readonly Effect: ReadOnlyClientEffect
 }
-```
+````
 
 ## ReadOnlyClientEffect (interface)
 
@@ -350,15 +411,53 @@ export interface SeedWalletConfig {
 
 SigningClient - full functionality: query blockchain + sign + submit
 
+SigningClient has wallet signing capability, so newTx() returns a TransactionBuilder
+that yields SignBuilder (can sign and submit transactions).
+
 **Signature**
 
-```ts
+````ts
 export type SigningClient = EffectToPromiseAPI<SigningClientEffect> & {
-  readonly newTx: (utxos?: ReadonlyArray<UTxO.UTxO>) => any // TODO: Change to ReadOnlyTransactionBuilder when implementing tx builder
+  /**
+   * Create a new transaction builder with signing capability.
+   *
+   * Returns a TransactionBuilder that can build and sign transactions.
+   * The build() methods return SignBuilder which provides:
+   * - `.sign()` - Sign and prepare for submission
+   * - `.toTransaction()` - Get the unsigned transaction
+   * - `.toTransactionWithFakeWitnesses()` - Get transaction with fake witnesses for fee validation
+   * - `.estimateFee()` - Get the calculated fee
+   * - `.partialSign()` - Create partial signature for multi-sig
+   * - `.assemble()` - Combine multiple signatures
+   *
+   * UTxOs for coin selection are fetched automatically from the wallet when build() is called.
+   * You can override UTxOs per-build using BuildOptions.availableUtxos.
+   *
+   * @returns A new TransactionBuilder instance configured with cached protocol parameters and wallet change address.
+   *
+   * @example
+   * ```typescript
+   * // Build and sign transaction
+   * const signBuilder = await signingClient.newTx()
+   *   .payToAddress({ address: "addr...", lovelace: 5000000n })
+   *   .build()
+   *
+   * // Sign and submit
+   * const submitBuilder = await signBuilder.sign()
+   * const txHash = await submitBuilder.submit()
+   *
+   * // Or get unsigned transaction
+   * const unsignedTx = await signBuilder.toTransaction()
+   * ```
+   *
+   * @since 2.0.0
+   * @category transaction-building
+   */
+  readonly newTx: () => TransactionBuilder
   // Effect namespace - includes all provider + wallet methods as Effects
   readonly Effect: SigningClientEffect
 }
-```
+````
 
 ## SigningClientEffect (interface)
 
@@ -396,5 +495,5 @@ export type SigningWalletClient = EffectToPromiseAPI<SigningWalletEffect> & {
 **Signature**
 
 ```ts
-export type WalletConfig = SeedWalletConfig | ReadOnlyWalletConfig | ApiWalletConfig
+export type WalletConfig = SeedWalletConfig | PrivateKeyWalletConfig | ReadOnlyWalletConfig | ApiWalletConfig
 ```
diff --git a/docs/content/docs/modules/sdk/client/ClientImpl.mdx b/docs/content/docs/modules/sdk/client/ClientImpl.mdx
index 6c6b4b33..a72bb2bf 100644
--- a/docs/content/docs/modules/sdk/client/ClientImpl.mdx
+++ b/docs/content/docs/modules/sdk/client/ClientImpl.mdx
@@ -1,6 +1,6 @@
 ---
 title: sdk/client/ClientImpl.ts
-nav_order: 134
+nav_order: 138
 parent: Modules
 ---
 
@@ -51,6 +51,10 @@ export declare function createClient(config: {
   wallet: ReadOnlyWalletConfig
 }): ReadOnlyWalletClient
 export declare function createClient(config: { network?: NetworkId; wallet: SeedWalletConfig }): SigningWalletClient
+export declare function createClient(config: {
+  network?: NetworkId
+  wallet: PrivateKeyWalletConfig
+}): SigningWalletClient
 export declare function createClient(config: { network?: NetworkId; wallet: ApiWalletConfig }): ApiWalletClient
 export declare function createClient(config?: { network?: NetworkId }): MinimalClient
 ```
diff --git a/docs/content/docs/modules/sdk/provider/Blockfrost.mdx b/docs/content/docs/modules/sdk/provider/Blockfrost.mdx
index cf29413c..79bf9115 100644
--- a/docs/content/docs/modules/sdk/provider/Blockfrost.mdx
+++ b/docs/content/docs/modules/sdk/provider/Blockfrost.mdx
@@ -1,6 +1,6 @@
 ---
 title: sdk/provider/Blockfrost.ts
-nav_order: 145
+nav_order: 149
 parent: Modules
 ---
 
diff --git a/docs/content/docs/modules/sdk/provider/Koios.mdx b/docs/content/docs/modules/sdk/provider/Koios.mdx
index a0c7949c..ce5fdff5 100644
--- a/docs/content/docs/modules/sdk/provider/Koios.mdx
+++ b/docs/content/docs/modules/sdk/provider/Koios.mdx
@@ -1,6 +1,6 @@
 ---
 title: sdk/provider/Koios.ts
-nav_order: 146
+nav_order: 150
 parent: Modules
 ---
 
diff --git a/docs/content/docs/modules/sdk/provider/Kupmios.mdx b/docs/content/docs/modules/sdk/provider/Kupmios.mdx
index 24d79283..488579f4 100644
--- a/docs/content/docs/modules/sdk/provider/Kupmios.mdx
+++ b/docs/content/docs/modules/sdk/provider/Kupmios.mdx
@@ -1,6 +1,6 @@
 ---
 title: sdk/provider/Kupmios.ts
-nav_order: 147
+nav_order: 151
 parent: Modules
 ---
 
diff --git a/docs/content/docs/modules/sdk/provider/Maestro.mdx b/docs/content/docs/modules/sdk/provider/Maestro.mdx
index 16df126c..46e1e94f 100644
--- a/docs/content/docs/modules/sdk/provider/Maestro.mdx
+++ b/docs/content/docs/modules/sdk/provider/Maestro.mdx
@@ -1,6 +1,6 @@
 ---
 title: sdk/provider/Maestro.ts
-nav_order: 148
+nav_order: 152
 parent: Modules
 ---
 
diff --git a/docs/content/docs/modules/sdk/provider/Provider.mdx b/docs/content/docs/modules/sdk/provider/Provider.mdx
index ce42f041..412d5a67 100644
--- a/docs/content/docs/modules/sdk/provider/Provider.mdx
+++ b/docs/content/docs/modules/sdk/provider/Provider.mdx
@@ -1,6 +1,6 @@
 ---
 title: sdk/provider/Provider.ts
-nav_order: 149
+nav_order: 153
 parent: Modules
 ---
 
diff --git a/docs/content/docs/modules/sdk/wallet/Derivation.mdx b/docs/content/docs/modules/sdk/wallet/Derivation.mdx
index 4f77e7ff..24376a7f 100644
--- a/docs/content/docs/modules/sdk/wallet/Derivation.mdx
+++ b/docs/content/docs/modules/sdk/wallet/Derivation.mdx
@@ -1,6 +1,6 @@
 ---
 title: sdk/wallet/Derivation.ts
-nav_order: 155
+nav_order: 159
 parent: Modules
 ---
 
@@ -38,6 +38,8 @@ Result of deriving keys and addresses from a seed or Bip32 root
 - address: bech32 payment address (addr... / addr_test...)
 - rewardAddress: bech32 reward address (stake... / stake_test...)
 - paymentKey / stakeKey: ed25519e_sk bech32 private keys
+- keyStore: Map of KeyHash hex -> PrivateKey for signing operations
+- paymentKhHex / stakeKhHex: KeyHash hex strings for quick lookup
 
 **Signature**
 
@@ -47,6 +49,9 @@ export type SeedDerivationResult = {
   rewardAddress: SdkRewardAddress.RewardAddress | undefined
   paymentKey: string
   stakeKey: string | undefined
+  keyStore: Map<string, PrivateKey.PrivateKey>
+  paymentKhHex: string
+  stakeKhHex: string | undefined
 }
 ```
 
@@ -116,7 +121,7 @@ export declare function walletFromPrivateKey(
     addressType?: "Base" | "Enterprise"
     network?: "Mainnet" | "Testnet" | "Custom"
   } = {}
-): SeedDerivationResult
+): Effect.Effect<SeedDerivationResult, DerivationError>
 ```
 
 ## walletFromSeed
@@ -132,8 +137,5 @@ export declare const walletFromSeed: (
     accountIndex?: number
     network?: "Mainnet" | "Testnet" | "Custom"
   }
-) => Either.Either<
-  { address: string; rewardAddress: string | undefined; paymentKey: string; stakeKey: string | undefined },
-  Bip32PrivateKey.Bip32PrivateKeyError | AddressEras.AddressError | DerivationError
->
+) => Effect.Effect<SeedDerivationResult, DerivationError | Bip32PrivateKey.Bip32PrivateKeyError>
 ```
diff --git a/docs/content/docs/modules/sdk/wallet/Wallet.mdx b/docs/content/docs/modules/sdk/wallet/Wallet.mdx
index 75a303e1..a514bd77 100644
--- a/docs/content/docs/modules/sdk/wallet/Wallet.mdx
+++ b/docs/content/docs/modules/sdk/wallet/Wallet.mdx
@@ -1,6 +1,6 @@
 ---
 title: sdk/wallet/Wallet.ts
-nav_order: 156
+nav_order: 160
 parent: Modules
 ---
 
diff --git a/docs/content/docs/modules/sdk/wallet/WalletNew.mdx b/docs/content/docs/modules/sdk/wallet/WalletNew.mdx
index cba9d0b9..b6a8e719 100644
--- a/docs/content/docs/modules/sdk/wallet/WalletNew.mdx
+++ b/docs/content/docs/modules/sdk/wallet/WalletNew.mdx
@@ -1,6 +1,6 @@
 ---
 title: sdk/wallet/WalletNew.ts
-nav_order: 157
+nav_order: 161
 parent: Modules
 ---
 
@@ -116,8 +116,8 @@ Suitable for read-only applications that need wallet information.
 
 ```ts
 export interface ReadOnlyWalletEffect {
-  readonly address: Effect.Effect<Address.Address, WalletError>
-  readonly rewardAddress: Effect.Effect<RewardAddress.RewardAddress | null, WalletError>
+  readonly address: () => Effect.Effect<Address.Address, WalletError>
+  readonly rewardAddress: () => Effect.Effect<RewardAddress.RewardAddress | null, WalletError>
 }
 ```
 
diff --git a/docs/content/docs/modules/utils/FeeValidation.mdx b/docs/content/docs/modules/utils/FeeValidation.mdx
index d48a6fef..6c025345 100644
--- a/docs/content/docs/modules/utils/FeeValidation.mdx
+++ b/docs/content/docs/modules/utils/FeeValidation.mdx
@@ -1,6 +1,6 @@
 ---
 title: utils/FeeValidation.ts
-nav_order: 158
+nav_order: 163
 parent: Modules
 ---
 
diff --git a/docs/content/docs/modules/utils/Hash.mdx b/docs/content/docs/modules/utils/Hash.mdx
index da602dbc..68e4ee85 100644
--- a/docs/content/docs/modules/utils/Hash.mdx
+++ b/docs/content/docs/modules/utils/Hash.mdx
@@ -1,6 +1,6 @@
 ---
 title: utils/Hash.ts
-nav_order: 159
+nav_order: 164
 parent: Modules
 ---
 
diff --git a/docs/content/docs/modules/utils/effect-runtime.mdx b/docs/content/docs/modules/utils/effect-runtime.mdx
new file mode 100644
index 00000000..b971673e
--- /dev/null
+++ b/docs/content/docs/modules/utils/effect-runtime.mdx
@@ -0,0 +1,54 @@
+---
+title: utils/effect-runtime.ts
+nav_order: 162
+parent: Modules
+---
+
+## effect-runtime overview
+
+---
+
+<h2 className="text-delta">Table of contents</h2>
+
+- [utilities](#utilities)
+  - [runEffect](#runeffect)
+
+---
+
+# utilities
+
+## runEffect
+
+Run an Effect and convert it to a Promise with clean error handling.
+
+- Executes the Effect using Effect.runPromiseExit
+- On failure, extracts the error from the Exit and cleans stack traces
+- Removes Effect.ts internal stack frames for cleaner error messages
+- Throws the cleaned error for standard Promise error handling
+
+**Signature**
+
+```ts
+export async function runEffect<A, E>(effect: Effect.Effect<A, E>): Promise<A>
+```
+
+**Example**
+
+```typescript
+import { Effect } from "effect"
+import { runEffect } from "@evolution-sdk/evolution/utils/effect-runtime"
+
+const myEffect = Effect.succeed(42)
+
+async function example() {
+  try {
+    const result = await runEffect(myEffect)
+    console.log(result)
+  } catch (error) {
+    // Error with clean stack trace, no Effect.ts internals
+    console.error(error)
+  }
+}
+```
+
+Added in v2.0.0
diff --git a/docs/next-env.d.ts b/docs/next-env.d.ts
index 830fb594..d39ca300 100644
--- a/docs/next-env.d.ts
+++ b/docs/next-env.d.ts
@@ -1,6 +1,6 @@
 /// <reference types="next" />
 /// <reference types="next/image-types/global" />
-/// <reference path="./.next/types/routes.d.ts" />
+/// <reference path="./out/types/routes.d.ts" />
 
 // NOTE: This file should not be edited
 // see https://nextjs.org/docs/app/api-reference/config/typescript for more information.
diff --git a/packages/evolution/docs/modules/core/Function.ts.md b/packages/evolution/docs/modules/core/Function.ts.md
index b2c6ec6b..5cdf002b 100644
--- a/packages/evolution/docs/modules/core/Function.ts.md
+++ b/packages/evolution/docs/modules/core/Function.ts.md
@@ -121,7 +121,7 @@ export declare const makeCBOREncodeEither: <A, T extends CBOR.CBOR, E extends Er
   schemaTransformer: Schema.Schema<A, T>,
   ErrorClass: ErrorCtor<E>,
   defaultOptions?: CBOR.CodecOptions
-) => (input: A, options?: CBOR.CodecOptions) => Either.Either<Uint8Array, E>
+) => (value: A, options?: CBOR.CodecOptions) => Either.Either<Uint8Array, E>
 ```
 
 ## makeCBOREncodeHexEither
diff --git a/packages/evolution/docs/modules/core/Value.ts.md b/packages/evolution/docs/modules/core/Value.ts.md
index 1b9c9d90..df8983e9 100644
--- a/packages/evolution/docs/modules/core/Value.ts.md
+++ b/packages/evolution/docs/modules/core/Value.ts.md
@@ -26,6 +26,8 @@ parent: Modules
   - [arbitrary](#arbitrary)
 - [model](#model)
   - [ValueCDDL (type alias)](#valuecddl-type-alias)
+- [ordering](#ordering)
+  - [geq](#geq)
 - [parsing](#parsing)
   - [fromCBORBytes](#fromcborbytes)
   - [fromCBORHex](#fromcborhex)
@@ -168,6 +170,21 @@ export type ValueCDDL = typeof FromCDDL.Type
 
 Added in v2.0.0
 
+# ordering
+
+## geq
+
+Check if Value a is greater than or equal to Value b.
+This means after subtracting b from a, the result would not be negative.
+
+**Signature**
+
+```ts
+export declare const geq: (a: Value, b: Value) => boolean
+```
+
+Added in v2.0.0
+
 # parsing
 
 ## fromCBORBytes
diff --git a/packages/evolution/docs/modules/sdk/Credential.ts.md b/packages/evolution/docs/modules/sdk/Credential.ts.md
index 7bd8d547..7d8afaab 100644
--- a/packages/evolution/docs/modules/sdk/Credential.ts.md
+++ b/packages/evolution/docs/modules/sdk/Credential.ts.md
@@ -1,6 +1,6 @@
 ---
 title: sdk/Credential.ts
-nav_order: 135
+nav_order: 139
 parent: Modules
 ---
 
diff --git a/packages/evolution/docs/modules/sdk/Datum.ts.md b/packages/evolution/docs/modules/sdk/Datum.ts.md
index 6834734b..dc4690bf 100644
--- a/packages/evolution/docs/modules/sdk/Datum.ts.md
+++ b/packages/evolution/docs/modules/sdk/Datum.ts.md
@@ -1,6 +1,6 @@
 ---
 title: sdk/Datum.ts
-nav_order: 136
+nav_order: 140
 parent: Modules
 ---
 
diff --git a/packages/evolution/docs/modules/sdk/Delegation.ts.md b/packages/evolution/docs/modules/sdk/Delegation.ts.md
index 206f7e1c..454a9aaa 100644
--- a/packages/evolution/docs/modules/sdk/Delegation.ts.md
+++ b/packages/evolution/docs/modules/sdk/Delegation.ts.md
@@ -1,6 +1,6 @@
 ---
 title: sdk/Delegation.ts
-nav_order: 137
+nav_order: 141
 parent: Modules
 ---
 
diff --git a/packages/evolution/docs/modules/sdk/Devnet/Devnet.ts.md b/packages/evolution/docs/modules/sdk/Devnet/Devnet.ts.md
index 80d4afe2..11db1761 100644
--- a/packages/evolution/docs/modules/sdk/Devnet/Devnet.ts.md
+++ b/packages/evolution/docs/modules/sdk/Devnet/Devnet.ts.md
@@ -1,6 +1,6 @@
 ---
 title: sdk/Devnet/Devnet.ts
-nav_order: 138
+nav_order: 142
 parent: Modules
 ---
 
diff --git a/packages/evolution/docs/modules/sdk/Devnet/DevnetDefault.ts.md b/packages/evolution/docs/modules/sdk/Devnet/DevnetDefault.ts.md
index 39e069a0..708e8b43 100644
--- a/packages/evolution/docs/modules/sdk/Devnet/DevnetDefault.ts.md
+++ b/packages/evolution/docs/modules/sdk/Devnet/DevnetDefault.ts.md
@@ -1,6 +1,6 @@
 ---
 title: sdk/Devnet/DevnetDefault.ts
-nav_order: 139
+nav_order: 143
 parent: Modules
 ---
 
diff --git a/packages/evolution/docs/modules/sdk/EvalRedeemer.ts.md b/packages/evolution/docs/modules/sdk/EvalRedeemer.ts.md
index 2ee48238..ce46978f 100644
--- a/packages/evolution/docs/modules/sdk/EvalRedeemer.ts.md
+++ b/packages/evolution/docs/modules/sdk/EvalRedeemer.ts.md
@@ -1,6 +1,6 @@
 ---
 title: sdk/EvalRedeemer.ts
-nav_order: 140
+nav_order: 144
 parent: Modules
 ---
 
diff --git a/packages/evolution/docs/modules/sdk/Label.ts.md b/packages/evolution/docs/modules/sdk/Label.ts.md
index 5bace55a..c5bd0832 100644
--- a/packages/evolution/docs/modules/sdk/Label.ts.md
+++ b/packages/evolution/docs/modules/sdk/Label.ts.md
@@ -1,6 +1,6 @@
 ---
 title: sdk/Label.ts
-nav_order: 141
+nav_order: 145
 parent: Modules
 ---
 
diff --git a/packages/evolution/docs/modules/sdk/OutRef.ts.md b/packages/evolution/docs/modules/sdk/OutRef.ts.md
index 8e54aeff..7a767257 100644
--- a/packages/evolution/docs/modules/sdk/OutRef.ts.md
+++ b/packages/evolution/docs/modules/sdk/OutRef.ts.md
@@ -1,6 +1,6 @@
 ---
 title: sdk/OutRef.ts
-nav_order: 142
+nav_order: 146
 parent: Modules
 ---
 
diff --git a/packages/evolution/docs/modules/sdk/PolicyId.ts.md b/packages/evolution/docs/modules/sdk/PolicyId.ts.md
index ebc3c6ad..aa67bc2a 100644
--- a/packages/evolution/docs/modules/sdk/PolicyId.ts.md
+++ b/packages/evolution/docs/modules/sdk/PolicyId.ts.md
@@ -1,6 +1,6 @@
 ---
 title: sdk/PolicyId.ts
-nav_order: 143
+nav_order: 147
 parent: Modules
 ---
 
diff --git a/packages/evolution/docs/modules/sdk/ProtocolParameters.ts.md b/packages/evolution/docs/modules/sdk/ProtocolParameters.ts.md
index f2c68665..56bce525 100644
--- a/packages/evolution/docs/modules/sdk/ProtocolParameters.ts.md
+++ b/packages/evolution/docs/modules/sdk/ProtocolParameters.ts.md
@@ -1,6 +1,6 @@
 ---
 title: sdk/ProtocolParameters.ts
-nav_order: 144
+nav_order: 148
 parent: Modules
 ---
 
diff --git a/packages/evolution/docs/modules/sdk/RewardAddress.ts.md b/packages/evolution/docs/modules/sdk/RewardAddress.ts.md
index bf6d6fa9..8265dc9f 100644
--- a/packages/evolution/docs/modules/sdk/RewardAddress.ts.md
+++ b/packages/evolution/docs/modules/sdk/RewardAddress.ts.md
@@ -1,6 +1,6 @@
 ---
 title: sdk/RewardAddress.ts
-nav_order: 150
+nav_order: 154
 parent: Modules
 ---
 
diff --git a/packages/evolution/docs/modules/sdk/Script.ts.md b/packages/evolution/docs/modules/sdk/Script.ts.md
index 1ab4b5b2..59845e04 100644
--- a/packages/evolution/docs/modules/sdk/Script.ts.md
+++ b/packages/evolution/docs/modules/sdk/Script.ts.md
@@ -1,6 +1,6 @@
 ---
 title: sdk/Script.ts
-nav_order: 151
+nav_order: 155
 parent: Modules
 ---
 
diff --git a/packages/evolution/docs/modules/sdk/Type.ts.md b/packages/evolution/docs/modules/sdk/Type.ts.md
index 842627f3..33d0f9b0 100644
--- a/packages/evolution/docs/modules/sdk/Type.ts.md
+++ b/packages/evolution/docs/modules/sdk/Type.ts.md
@@ -1,6 +1,6 @@
 ---
 title: sdk/Type.ts
-nav_order: 152
+nav_order: 156
 parent: Modules
 ---
 
diff --git a/packages/evolution/docs/modules/sdk/UTxO.ts.md b/packages/evolution/docs/modules/sdk/UTxO.ts.md
index 815bee85..29aad4a7 100644
--- a/packages/evolution/docs/modules/sdk/UTxO.ts.md
+++ b/packages/evolution/docs/modules/sdk/UTxO.ts.md
@@ -1,6 +1,6 @@
 ---
 title: sdk/UTxO.ts
-nav_order: 154
+nav_order: 158
 parent: Modules
 ---
 
diff --git a/packages/evolution/docs/modules/sdk/Unit.ts.md b/packages/evolution/docs/modules/sdk/Unit.ts.md
index 37c0c589..308ed336 100644
--- a/packages/evolution/docs/modules/sdk/Unit.ts.md
+++ b/packages/evolution/docs/modules/sdk/Unit.ts.md
@@ -1,6 +1,6 @@
 ---
 title: sdk/Unit.ts
-nav_order: 153
+nav_order: 157
 parent: Modules
 ---
 
diff --git a/packages/evolution/docs/modules/sdk/builders/SignBuilder.ts.md b/packages/evolution/docs/modules/sdk/builders/SignBuilder.ts.md
index e4fd94d8..6d394fb2 100644
--- a/packages/evolution/docs/modules/sdk/builders/SignBuilder.ts.md
+++ b/packages/evolution/docs/modules/sdk/builders/SignBuilder.ts.md
@@ -10,76 +10,57 @@ parent: Modules
 
 <h2 class="text-delta">Table of contents</h2>
 
-- [utils](#utils)
+- [interfaces](#interfaces)
   - [SignBuilder (interface)](#signbuilder-interface)
   - [SignBuilderEffect (interface)](#signbuildereffect-interface)
-  - [SubmitBuilder (interface)](#submitbuilder-interface)
-  - [SubmitBuilderEffect (interface)](#submitbuildereffect-interface)
 
 ---
 
-# utils
+# interfaces
 
 ## SignBuilder (interface)
 
+SignBuilder extends TransactionResultBase with signing capabilities.
+
+Only available when the client has a signing wallet (seed, private key, or API wallet).
+Provides access to unsigned transaction (via base interface) and signing operations.
+
 **Signature**
 
 ```ts
-export interface SignBuilder extends EffectToPromiseAPI<SignBuilderEffect> {
+export interface SignBuilder extends TransactionResultBase, EffectToPromiseAPI<SignBuilderEffect> {
   readonly Effect: SignBuilderEffect
 }
 ```
 
+Added in v2.0.0
+
 ## SignBuilderEffect (interface)
 
+Effect-based API for SignBuilder operations.
+
+Includes all TransactionResultBase.Effect methods plus signing-specific operations.
+
 **Signature**
 
 ```ts
 export interface SignBuilderEffect {
-  // Main signing method - produces a fully signed transaction ready for submission
-  readonly sign: () => Effect.Effect<SubmitBuilder, TransactionBuilderError>
+  // Base transaction methods (from TransactionResultBase)
+  readonly toTransaction: () => Effect.Effect<Transaction.Transaction, TransactionBuilderError>
+  readonly toTransactionWithFakeWitnesses: () => Effect.Effect<Transaction.Transaction, TransactionBuilderError>
+  readonly estimateFee: () => Effect.Effect<bigint, TransactionBuilderError>
 
-  // Add external witness and proceed to submission
+  // Signing methods
+  readonly sign: () => Effect.Effect<SubmitBuilder, TransactionBuilderError>
   readonly signWithWitness: (
     witnessSet: TransactionWitnessSet.TransactionWitnessSet
   ) => Effect.Effect<SubmitBuilder, TransactionBuilderError>
-
-  // Assemble multiple witnesses into a complete transaction ready for submission
   readonly assemble: (
     witnesses: ReadonlyArray<TransactionWitnessSet.TransactionWitnessSet>
   ) => Effect.Effect<SubmitBuilder, TransactionBuilderError>
-
-  // Partial signing - creates witness without advancing to submission (useful for multi-sig)
   readonly partialSign: () => Effect.Effect<TransactionWitnessSet.TransactionWitnessSet, TransactionBuilderError>
-
-  // Get witness set without signing (for inspection)
   readonly getWitnessSet: () => Effect.Effect<TransactionWitnessSet.TransactionWitnessSet, TransactionBuilderError>
-
-  // Get the unsigned transaction (for inspection)
-  readonly toTransaction: () => Effect.Effect<Transaction.Transaction, TransactionBuilderError>
-
-  // Get the transaction with fake witnesses (for fee validation)
-  readonly toTransactionWithFakeWitnesses: () => Effect.Effect<Transaction.Transaction, TransactionBuilderError>
-}
-```
-
-## SubmitBuilder (interface)
-
-**Signature**
-
-```ts
-export interface SubmitBuilder extends EffectToPromiseAPI<SubmitBuilderEffect> {
-  readonly Effect: SubmitBuilderEffect
-  readonly witnessSet: TransactionWitnessSet.TransactionWitnessSet
 }
 ```
 
-## SubmitBuilderEffect (interface)
-
-**Signature**
-
-```ts
-export interface SubmitBuilderEffect {
-  readonly submit: () => Effect.Effect<string, TransactionBuilderError>
-}
-```
+Added in v2.0.0
diff --git a/packages/evolution/docs/modules/sdk/builders/SignBuilderImpl.ts.md b/packages/evolution/docs/modules/sdk/builders/SignBuilderImpl.ts.md
new file mode 100644
index 00000000..40713c04
--- /dev/null
+++ b/packages/evolution/docs/modules/sdk/builders/SignBuilderImpl.ts.md
@@ -0,0 +1,51 @@
+---
+title: sdk/builders/SignBuilderImpl.ts
+nav_order: 130
+parent: Modules
+---
+
+## SignBuilderImpl overview
+
+SignBuilder Implementation
+
+Handles transaction signing by delegating to the wallet's signTx Effect method.
+The SignBuilder is responsible for:
+
+1. Providing the transaction and UTxO context to the wallet
+2. Managing the transition from unsigned to signed transaction
+3. Creating the SubmitBuilder for transaction submission
+
+The actual signing logic (determining required signers, creating witnesses)
+is the wallet's responsibility.
+
+Added in v2.0.0
+
+---
+
+<h2 class="text-delta">Table of contents</h2>
+
+- [constructors](#constructors)
+  - [makeSignBuilder](#makesignbuilder)
+
+---
+
+# constructors
+
+## makeSignBuilder
+
+Create a SignBuilder instance for a built transaction.
+
+**Signature**
+
+```ts
+export declare const makeSignBuilder: (params: {
+  transaction: Transaction.Transaction
+  transactionWithFakeWitnesses: Transaction.Transaction
+  fee: bigint
+  utxos: ReadonlyArray<UTxO.UTxO>
+  provider: Provider.Provider
+  wallet: Wallet
+}) => SignBuilder
+```
+
+Added in v2.0.0
diff --git a/packages/evolution/docs/modules/sdk/builders/SubmitBuilder.ts.md b/packages/evolution/docs/modules/sdk/builders/SubmitBuilder.ts.md
new file mode 100644
index 00000000..0a1c19a9
--- /dev/null
+++ b/packages/evolution/docs/modules/sdk/builders/SubmitBuilder.ts.md
@@ -0,0 +1,79 @@
+---
+title: sdk/builders/SubmitBuilder.ts
+nav_order: 131
+parent: Modules
+---
+
+## SubmitBuilder overview
+
+SubmitBuilder - Final stage of transaction lifecycle
+
+Represents a signed transaction ready for submission to the blockchain.
+Provides the submit() method to broadcast the transaction and retrieve the transaction hash.
+
+Added in v2.0.0
+
+---
+
+<h2 class="text-delta">Table of contents</h2>
+
+- [interfaces](#interfaces)
+  - [SubmitBuilder (interface)](#submitbuilder-interface)
+  - [SubmitBuilderEffect (interface)](#submitbuildereffect-interface)
+
+---
+
+# interfaces
+
+## SubmitBuilder (interface)
+
+SubmitBuilder - represents a signed transaction ready for submission.
+
+The final stage in the transaction lifecycle after building and signing.
+Provides the submit() method to broadcast the transaction to the blockchain
+and retrieve the transaction hash.
+
+**Signature**
+
+```ts
+export interface SubmitBuilder extends EffectToPromiseAPI<SubmitBuilderEffect> {
+  /**
+   * Effect-based API for compositional workflows.
+   *
+   * @since 2.0.0
+   */
+  readonly Effect: SubmitBuilderEffect
+
+  /**
+   * The witness set containing all signatures for this transaction.
+   *
+   * Can be used to inspect the signatures or combine with other witness sets
+   * for multi-party signing scenarios.
+   *
+   * @since 2.0.0
+   */
+  readonly witnessSet: TransactionWitnessSet.TransactionWitnessSet
+}
+```
+
+Added in v2.0.0
+
+## SubmitBuilderEffect (interface)
+
+Effect-based API for SubmitBuilder operations.
+
+**Signature**
+
+```ts
+export interface SubmitBuilderEffect {
+  /**
+   * Submit the signed transaction to the blockchain via the provider.
+   *
+   * @returns Effect resolving to the transaction hash
+   * @since 2.0.0
+   */
+  readonly submit: () => Effect.Effect<string, TransactionBuilderError>
+}
+```
+
+Added in v2.0.0
diff --git a/packages/evolution/docs/modules/sdk/builders/SubmitBuilderImpl.ts.md b/packages/evolution/docs/modules/sdk/builders/SubmitBuilderImpl.ts.md
new file mode 100644
index 00000000..db44c1a9
--- /dev/null
+++ b/packages/evolution/docs/modules/sdk/builders/SubmitBuilderImpl.ts.md
@@ -0,0 +1,45 @@
+---
+title: sdk/builders/SubmitBuilderImpl.ts
+nav_order: 132
+parent: Modules
+---
+
+## SubmitBuilderImpl overview
+
+SubmitBuilder Implementation
+
+Handles transaction submission by delegating to the provider's submitTx method.
+The SubmitBuilder is responsible for:
+
+1. Converting the signed transaction to CBOR hex format
+2. Submitting to the provider's Effect.submitTx
+3. Returning the transaction hash
+
+Added in v2.0.0
+
+---
+
+<h2 class="text-delta">Table of contents</h2>
+
+- [constructors](#constructors)
+  - [makeSubmitBuilder](#makesubmitbuilder)
+
+---
+
+# constructors
+
+## makeSubmitBuilder
+
+Create a SubmitBuilder instance for a signed transaction.
+
+**Signature**
+
+```ts
+export declare const makeSubmitBuilder: (
+  signedTransaction: Transaction.Transaction,
+  witnessSet: TransactionWitnessSet.TransactionWitnessSet,
+  provider: Provider.Provider
+) => SubmitBuilder
+```
+
+Added in v2.0.0
diff --git a/packages/evolution/docs/modules/sdk/builders/TransactionBuilder.ts.md b/packages/evolution/docs/modules/sdk/builders/TransactionBuilder.ts.md
index 1965a82d..dabd63c0 100644
--- a/packages/evolution/docs/modules/sdk/builders/TransactionBuilder.ts.md
+++ b/packages/evolution/docs/modules/sdk/builders/TransactionBuilder.ts.md
@@ -1,6 +1,6 @@
 ---
 title: sdk/builders/TransactionBuilder.ts
-nav_order: 130
+nav_order: 133
 parent: Modules
 ---
 
@@ -38,6 +38,9 @@ double-spending. UTxOs can come from any source (wallet, DeFi protocols, other p
 - [constructors](#constructors)
   - [makeTxBuilder](#maketxbuilder)
 - [context](#context)
+  - [AvailableUtxosTag (class)](#availableutxostag-class)
+  - [ChangeAddressTag (class)](#changeaddresstag-class)
+  - [ProtocolParametersTag (class)](#protocolparameterstag-class)
   - [TxContext (class)](#txcontext-class)
   - [TxContextData (interface)](#txcontextdata-interface)
 - [errors](#errors)
@@ -107,34 +110,49 @@ Added in v2.0.0
 Configuration for TransactionBuilder.
 Immutable configuration passed to builder at creation time.
 
-Contains:
+Wallet-centric design (when wallet provided):
 
-- Protocol parameters for fee calculation
-- Change address for leftover funds
-- Available UTxOs for coin selection
+- Wallet provides change address (via wallet.Effect.address())
+- Provider + Wallet provide available UTxOs (via provider.Effect.getUtxos(wallet.address))
+- Override per-build via BuildOptions if needed
+
+Manual mode (no wallet):
+
+- Must provide changeAddress and availableUtxos in BuildOptions for each build
+- Used for read-only scenarios or advanced use cases
 
 **Signature**
 
 ```ts
 export interface TxBuilderConfig {
-  readonly protocolParameters: ProtocolParameters
-
   /**
-   * Address to send change (leftover assets) to.
-   * This is required for proper transaction balancing.
+   * Optional wallet provides:
+   * - Change address via wallet.Effect.address()
+   * - Available UTxOs via wallet.Effect.address() + provider.Effect.getUtxos()
+   * - Signing capability via wallet.Effect.signTx() (SigningWallet and ApiWallet only)
+   *
+   * When provided: Automatic change address and UTxO resolution.
+   * When omitted: Must provide changeAddress and availableUtxos in BuildOptions.
+   *
+   * ReadOnlyWallet: For read-only clients that can build but not sign transactions.
+   * SigningWallet/ApiWallet: For signing clients with full transaction signing capability.
+   *
+   * Override per-build via BuildOptions.changeAddress and BuildOptions.availableUtxos.
    */
-  readonly changeAddress: string
+  readonly wallet?: WalletNew.SigningWallet | WalletNew.ApiWallet | WalletNew.ReadOnlyWallet
 
   /**
-   * UTxOs available for coin selection.
-   * These can be from a wallet, another user, or any other source.
-   * Coin selection will automatically select from these UTxOs to cover
-   * required outputs + fees, excluding any already collected via collectFrom().
+   * Optional provider for:
+   * - Fetching UTxOs for the wallet's address (provider.Effect.getUtxos)
+   * - Transaction submission (provider.Effect.submitTx)
+   * - Protocol parameters
+   *
+   * Works together with wallet to provide everything needed for transaction building.
+   * When wallet is omitted, provider is only used if you call provider methods directly.
    */
-  readonly availableUtxos: ReadonlyArray<UTxO.UTxO>
+  readonly provider?: Provider.Provider
 
   // Future fields:
-  // readonly provider?: any // Provider interface for blockchain communication
   // readonly costModels?: Uint8Array // Cost models for script evaluation
 }
 ```
@@ -151,16 +169,75 @@ The builder accumulates chainable method calls as deferred ProgramSteps. Calling
 creates fresh state (new Refs) and executes all accumulated programs sequentially, ensuring
 no state pollution between invocations.
 
+Generic type parameter TResult determines what build() returns:
+
+- SignBuilder (default): When wallet has signing capability
+- TransactionResultBase: When wallet is read-only
+
 **Signature**
 
 ```ts
-export declare const makeTxBuilder: (config: TxBuilderConfig) => TransactionBuilder
+export declare const makeTxBuilder: <TResult = SignBuilder>(config: TxBuilderConfig) => TransactionBuilder<TResult>
 ```
 
 Added in v2.0.0
 
 # context
 
+## AvailableUtxosTag (class)
+
+Resolved available UTxOs for the current build.
+This is resolved once at the start of build() from either:
+
+- BuildOptions.availableUtxos (per-transaction override)
+- provider.Effect.getUtxos(wallet.address) (default from wallet + provider)
+
+Available to all phase functions via Effect Context.
+
+**Signature**
+
+```ts
+export declare class AvailableUtxosTag
+```
+
+Added in v2.0.0
+
+## ChangeAddressTag (class)
+
+Resolved change address for the current build.
+This is resolved once at the start of build() from either:
+
+- BuildOptions.changeAddress (per-transaction override)
+- TxBuilderConfig.wallet.Effect.address() (default from wallet)
+
+Available to all phase functions via Effect Context.
+
+**Signature**
+
+```ts
+export declare class ChangeAddressTag
+```
+
+Added in v2.0.0
+
+## ProtocolParametersTag (class)
+
+Resolved protocol parameters for the current build.
+This is resolved once at the start of build() from either:
+
+- BuildOptions.protocolParameters (per-transaction override)
+- provider.Effect.getProtocolParameters() (fetched from provider)
+
+Available to all phase functions via Effect Context.
+
+**Signature**
+
+```ts
+export declare class ProtocolParametersTag
+```
+
+Added in v2.0.0
+
 ## TxContext (class)
 
 Single Context service providing all transaction building data to programs.
@@ -248,6 +325,12 @@ Key Design Principle:
 Builder instance never mutates. Programs are deferred Effects that execute later.
 Each build() creates fresh TxBuilderState, executes programs, returns result.
 
+Generic Type Parameter:
+TResult determines the return type of build() methods:
+
+- SignBuilder: When wallet has signing capability (SigningClient)
+- TransactionResultBase: When wallet is read-only (ReadOnlyClient)
+
 Usage Pattern:
 
 ```typescript
@@ -265,7 +348,7 @@ const signBuilder2 = await builder.build()
 **Signature**
 
 ```ts
-export interface TransactionBuilder {
+export interface TransactionBuilder<TResult = SignBuilder> {
   // ============================================================================
   // Chainable Builder Methods - Create ProgramSteps, return same builder
   // ============================================================================
@@ -279,7 +362,7 @@ export interface TransactionBuilder {
    * @since 2.0.0
    * @category builder-methods
    */
-  readonly payToAddress: (params: PayToAddressParams) => TransactionBuilder
+  readonly payToAddress: (params: PayToAddressParams) => TransactionBuilder<TResult>
 
   /**
    * Specify transaction inputs from provided UTxOs.
@@ -290,7 +373,7 @@ export interface TransactionBuilder {
    * @since 2.0.0
    * @category builder-methods
    */
-  readonly collectFrom: (params: CollectFromParams) => TransactionBuilder
+  readonly collectFrom: (params: CollectFromParams) => TransactionBuilder<TResult>
 
   // Future expansion points for other operations:
   // readonly mintTokens: (params: MintTokensParams) => TransactionBuilder
@@ -309,10 +392,14 @@ export interface TransactionBuilder {
    * Creates fresh state and runs all accumulated ProgramSteps sequentially.
    * Can be called multiple times on the same builder instance with independent results.
    *
+   * Returns TResult which is:
+   * - SignBuilder for SigningClient (can sign transactions)
+   * - TransactionResultBase for ReadOnlyClient (unsigned transaction only)
+   *
    * @since 2.0.0
    * @category completion-methods
    */
-  readonly build: (options?: BuildOptions) => Promise<SignBuilder>
+  readonly build: (options?: BuildOptions) => Promise<TResult>
 
   /**
    * Execute all queued operations and return a signing-ready transaction via Effect.
@@ -320,25 +407,43 @@ export interface TransactionBuilder {
    * Creates fresh state and runs all accumulated ProgramSteps sequentially.
    * Suitable for Effect-TS compositional workflows and error handling.
    *
+   * Error types include WalletError and ProviderError from config Effects.
+   *
+   * Returns TResult which is:
+   * - SignBuilder for SigningClient (can sign transactions)
+   * - TransactionResultBase for ReadOnlyClient (unsigned transaction only)
+   *
    * @since 2.0.0
    * @category completion-methods
    */
   readonly buildEffect: (
     options?: BuildOptions
-  ) => Effect.Effect<SignBuilder, TransactionBuilderError | EvaluationError, unknown>
+  ) => Effect.Effect<
+    TResult,
+    TransactionBuilderError | EvaluationError | WalletNew.WalletError | Provider.ProviderError,
+    unknown
+  >
 
   /**
    * Execute all queued operations with explicit error handling via Either.
    *
    * Creates fresh state and runs all accumulated ProgramSteps sequentially.
-   * Returns Either<SignBuilder, Error> for pattern-matched error recovery.
+   * Returns Either<TResult, Error> for pattern-matched error recovery.
+   *
+   * Error types include WalletError and ProviderError from config Effects.
+   *
+   * Returns TResult which is:
+   * - SignBuilder for SigningClient (can sign transactions)
+   * - TransactionResultBase for ReadOnlyClient (unsigned transaction only)
    *
    * @since 2.0.0
    * @category completion-methods
    */
   readonly buildEither: (
     options?: BuildOptions
-  ) => Promise<Either<SignBuilder, TransactionBuilderError | EvaluationError>>
+  ) => Promise<
+    Either<TResult, TransactionBuilderError | EvaluationError | WalletNew.WalletError | Provider.ProviderError>
+  >
 
   // ============================================================================
   // Transaction Chaining Methods - Multi-transaction workflows
@@ -600,6 +705,29 @@ Added in v2.0.0
 
 ````ts
 export interface BuildOptions {
+  /**
+   * Override protocol parameters for this specific transaction build.
+   *
+   * By default, fetches from provider during build().
+   * Provide this to use different protocol parameters for testing or special cases.
+   *
+   * Use cases:
+   * - Testing with different fee parameters
+   * - Simulating future protocol changes
+   * - Using cached parameters to avoid provider fetch
+   *
+   * Example:
+   * ```typescript
+   * // Test with custom fee parameters
+   * builder.build({
+   *   protocolParameters: { ...params, minFeeCoefficient: 50n, minFeeConstant: 200000n }
+   * })
+   * ```
+   *
+   * @since 2.0.0
+   */
+  readonly protocolParameters?: ProtocolParameters
+
   /**
    * Coin selection strategy for automatic input selection.
    *
@@ -624,6 +752,56 @@ export interface BuildOptions {
   // Change Handling Configuration
   // ============================================================================
 
+  /**
+   * Override the change address for this specific transaction build.
+   *
+   * By default, uses wallet.Effect.address() from TxBuilderConfig.
+   * Provide this to use a different address for change outputs.
+   *
+   * Use cases:
+   * - Multi-address wallet (use account index 5 for change)
+   * - Different change address per transaction
+   * - Multi-sig workflows where change address varies
+   * - Testing with different addresses
+   *
+   * Example:
+   * ```typescript
+   * // Use different account for change
+   * builder.build({ changeAddress: wallet.addresses[5] })
+   *
+   * // Custom address
+   * builder.build({ changeAddress: "addr_test1..." })
+   * ```
+   *
+   * @since 2.0.0
+   */
+  readonly changeAddress?: string
+
+  /**
+   * Override the available UTxOs for this specific transaction build.
+   *
+   * By default, fetches UTxOs from provider.Effect.getUtxos(wallet.address).
+   * Provide this to use a specific set of UTxOs for coin selection.
+   *
+   * Use cases:
+   * - Use UTxOs from specific account index
+   * - Pre-filtered UTxO set
+   * - Testing with known UTxO set
+   * - Multi-address UTxO aggregation
+   *
+   * Example:
+   * ```typescript
+   * // Use UTxOs from specific account
+   * builder.build({ availableUtxos: utxosFromAccount5 })
+   *
+   * // Combine UTxOs from multiple addresses
+   * builder.build({ availableUtxos: [...utxos1, ...utxos2] })
+   * ```
+   *
+   * @since 2.0.0
+   */
+  readonly availableUtxos?: ReadonlyArray<UTxO.UTxO>
+
   /**
    * # Change Handling Strategy Matrix
    * 
@@ -739,12 +917,11 @@ export interface BuildOptions {
   readonly useStateMachine?: boolean
 
   /**
-   * **EXPERIMENTAL**: Use V3 4-phase state machine
    *
-   * When true, uses V3's simplified 4-phase state machine:
+   * When true, uses simplified 4-phase state machine:
    * - selection → changeValidation → balanceVerification → fallback → complete
    *
-   * V3 shares TxContext with V2 but uses mathematical validation approach.
+   * shares TxContext with V2 but uses mathematical validation approach.
    *
    * @experimental
    * @default false
diff --git a/packages/evolution/docs/modules/sdk/builders/TransactionResult.ts.md b/packages/evolution/docs/modules/sdk/builders/TransactionResult.ts.md
new file mode 100644
index 00000000..a7a5222e
--- /dev/null
+++ b/packages/evolution/docs/modules/sdk/builders/TransactionResult.ts.md
@@ -0,0 +1,160 @@
+---
+title: sdk/builders/TransactionResult.ts
+nav_order: 134
+parent: Modules
+---
+
+## TransactionResult overview
+
+TransactionResult - Base interface for transaction building results
+
+Provides core functionality available to all transaction builders regardless
+of signing capability. This enables type-safe differentiation between
+read-only clients (can build but not sign) and signing clients (can build and sign).
+
+Added in v2.0.0
+
+---
+
+<h2 class="text-delta">Table of contents</h2>
+
+- [constructors](#constructors)
+  - [makeTransactionResult](#maketransactionresult)
+- [interfaces](#interfaces)
+  - [TransactionResultBase (interface)](#transactionresultbase-interface)
+
+---
+
+# constructors
+
+## makeTransactionResult
+
+Create a TransactionResultBase instance for a built transaction without signing capability.
+
+Used by ReadOnlyClient which can build transactions but cannot sign them.
+Provides access to the unsigned transaction, fake-witness transaction for fee validation,
+and fee estimation.
+
+**Signature**
+
+```ts
+export declare const makeTransactionResult: (params: {
+  transaction: Transaction.Transaction
+  transactionWithFakeWitnesses: Transaction.Transaction
+  fee: bigint
+}) => TransactionResultBase
+```
+
+Added in v2.0.0
+
+# interfaces
+
+## TransactionResultBase (interface)
+
+Base result interface for built transactions.
+
+Available on all transaction builders regardless of signing capability.
+Provides access to the unsigned transaction, fee estimates, and transaction
+with fake witnesses for size validation.
+
+**Signature**
+
+````ts
+export interface TransactionResultBase {
+  /**
+   * Get the unsigned transaction.
+   *
+   * This transaction has a complete body but no witness set (signatures).
+   * Can be serialized to CBOR for external signing (hardware wallets, browser extensions, etc.)
+   *
+   * @returns Promise resolving to the unsigned transaction
+   *
+   * @example
+   * ```typescript
+   * const result = await readOnlyClient.newTx()
+   *   .payToAddress({ address: "addr...", lovelace: 5_000_000n })
+   *   .build()
+   *
+   * const unsignedTx = await result.toTransaction()
+   * const txCbor = Transaction.toCBORHex(unsignedTx)
+   * // Export for external signing
+   * ```
+   *
+   * @since 2.0.0
+   * @category accessors
+   */
+  readonly toTransaction: () => Promise<Transaction.Transaction>
+
+  /**
+   * Get the transaction with fake witnesses for fee validation.
+   *
+   * This transaction includes fake witness sets (294 bytes each) to accurately
+   * calculate the final transaction size and fees. Useful for validating that
+   * the calculated fee is sufficient for the final signed transaction.
+   *
+   * @returns Promise resolving to the transaction with fake witnesses
+   *
+   * @since 2.0.0
+   * @category accessors
+   */
+  readonly toTransactionWithFakeWitnesses: () => Promise<Transaction.Transaction>
+
+  /**
+   * Get the calculated transaction fee in lovelace.
+   *
+   * This is the fee that was calculated during the build process based on
+   * the transaction size (including fake witnesses) and protocol parameters.
+   *
+   * @returns Promise resolving to the transaction fee in lovelace
+   *
+   * @example
+   * ```typescript
+   * const result = await client.newTx()
+   *   .payToAddress({ address: "addr...", lovelace: 5_000_000n })
+   *   .build()
+   *
+   * const fee = await result.estimateFee()
+   * console.log(`Transaction fee: ${fee} lovelace`)
+   * ```
+   *
+   * @since 2.0.0
+   * @category accessors
+   */
+  readonly estimateFee: () => Promise<bigint>
+
+  /**
+   * Effect-based API for compositional workflows.
+   *
+   * Provides the same functionality as the Promise-based methods but returns
+   * Effect values for use in Effect-TS workflows with proper error handling
+   * and composition.
+   *
+   * @since 2.0.0
+   * @category effects
+   */
+  readonly Effect: {
+    /**
+     * Get the unsigned transaction as an Effect.
+     *
+     * @since 2.0.0
+     */
+    readonly toTransaction: () => Effect.Effect<Transaction.Transaction, TransactionBuilderError>
+
+    /**
+     * Get the transaction with fake witnesses as an Effect.
+     *
+     * @since 2.0.0
+     */
+    readonly toTransactionWithFakeWitnesses: () => Effect.Effect<Transaction.Transaction, TransactionBuilderError>
+
+    /**
+     * Get the calculated fee as an Effect.
+     *
+     * @since 2.0.0
+     */
+    readonly estimateFee: () => Effect.Effect<bigint, TransactionBuilderError>
+  }
+}
+````
+
+Added in v2.0.0
diff --git a/packages/evolution/docs/modules/sdk/builders/TxBuilderImpl.ts.md b/packages/evolution/docs/modules/sdk/builders/TxBuilderImpl.ts.md
index 17730956..86a63091 100644
--- a/packages/evolution/docs/modules/sdk/builders/TxBuilderImpl.ts.md
+++ b/packages/evolution/docs/modules/sdk/builders/TxBuilderImpl.ts.md
@@ -1,6 +1,6 @@
 ---
 title: sdk/builders/TxBuilderImpl.ts
-nav_order: 131
+nav_order: 135
 parent: Modules
 ---
 
diff --git a/packages/evolution/docs/modules/sdk/builders/Unfrack.ts.md b/packages/evolution/docs/modules/sdk/builders/Unfrack.ts.md
index 27f014a2..63e8ea78 100644
--- a/packages/evolution/docs/modules/sdk/builders/Unfrack.ts.md
+++ b/packages/evolution/docs/modules/sdk/builders/Unfrack.ts.md
@@ -1,6 +1,6 @@
 ---
 title: sdk/builders/Unfrack.ts
-nav_order: 132
+nav_order: 136
 parent: Modules
 ---
 
diff --git a/packages/evolution/docs/modules/sdk/client/Client.ts.md b/packages/evolution/docs/modules/sdk/client/Client.ts.md
index 07c0f26a..eb64a85c 100644
--- a/packages/evolution/docs/modules/sdk/client/Client.ts.md
+++ b/packages/evolution/docs/modules/sdk/client/Client.ts.md
@@ -1,6 +1,6 @@
 ---
 title: sdk/client/Client.ts
-nav_order: 133
+nav_order: 137
 parent: Modules
 ---
 
@@ -24,6 +24,7 @@ parent: Modules
   - [MinimalClient (interface)](#minimalclient-interface)
   - [MinimalClientEffect (interface)](#minimalclienteffect-interface)
   - [NetworkId (type alias)](#networkid-type-alias)
+  - [PrivateKeyWalletConfig (interface)](#privatekeywalletconfig-interface)
   - [ProviderConfig (type alias)](#providerconfig-type-alias)
   - [ProviderOnlyClient (type alias)](#provideronlyclient-type-alias)
   - [ReadOnlyClient (type alias)](#readonlyclient-type-alias)
@@ -156,13 +157,21 @@ export interface MinimalClient {
     config: T
   ) => T extends SeedWalletConfig
     ? SigningWalletClient
-    : T extends ApiWalletConfig
-      ? ApiWalletClient
-      : ReadOnlyWalletClient
+    : T extends PrivateKeyWalletConfig
+      ? SigningWalletClient
+      : T extends ApiWalletConfig
+        ? ApiWalletClient
+        : ReadOnlyWalletClient
   readonly attach: <TW extends WalletConfig>(
     providerConfig: ProviderConfig,
     walletConfig: TW
-  ) => TW extends SeedWalletConfig ? SigningClient : TW extends ApiWalletConfig ? SigningClient : ReadOnlyClient
+  ) => TW extends SeedWalletConfig
+    ? SigningClient
+    : TW extends PrivateKeyWalletConfig
+      ? SigningClient
+      : TW extends ApiWalletConfig
+        ? SigningClient
+        : ReadOnlyClient
   // Effect namespace for methods with side effects only
   readonly Effect: MinimalClientEffect
 }
@@ -188,6 +197,19 @@ export interface MinimalClientEffect {
 export type NetworkId = "mainnet" | "preprod" | "preview" | number
 ```
 
+## PrivateKeyWalletConfig (interface)
+
+**Signature**
+
+```ts
+export interface PrivateKeyWalletConfig {
+  readonly type: "private-key"
+  readonly paymentKey: string // bech32 ed25519e_sk
+  readonly stakeKey?: string // bech32 ed25519e_sk (optional, for Base addresses)
+  readonly addressType?: "Base" | "Enterprise"
+}
+```
+
 ## ProviderConfig (type alias)
 
 **Signature**
@@ -207,7 +229,13 @@ export type ProviderOnlyClient = EffectToPromiseAPI<Provider.ProviderEffect> & {
   // Combinator methods (pure, no side effects) with type-aware conditional return type
   readonly attachWallet: <T extends WalletConfig>(
     config: T
-  ) => T extends SeedWalletConfig ? SigningClient : T extends ApiWalletConfig ? SigningClient : ReadOnlyClient
+  ) => T extends SeedWalletConfig
+    ? SigningClient
+    : T extends PrivateKeyWalletConfig
+      ? SigningClient
+      : T extends ApiWalletConfig
+        ? SigningClient
+        : ReadOnlyClient
   // Effect namespace - includes all provider methods as Effects
   readonly Effect: Provider.ProviderEffect
 }
@@ -217,15 +245,48 @@ export type ProviderOnlyClient = EffectToPromiseAPI<Provider.ProviderEffect> & {
 
 ReadOnlyClient - can query blockchain + wallet address operations
 
+ReadOnlyClient cannot sign transactions, so newTx() returns a TransactionBuilder
+that yields TransactionResultBase (unsigned transaction only).
+
 **Signature**
 
-```ts
+````ts
 export type ReadOnlyClient = EffectToPromiseAPI<ReadOnlyClientEffect> & {
-  readonly newTx: (utxos?: ReadonlyArray<UTxO.UTxO>) => any // TODO: Change to ReadOnlyTransactionBuilder when implementing tx builder
+  /**
+   * Create a new transaction builder for read-only operations.
+   *
+   * Returns a TransactionBuilder that builds unsigned transactions.
+   * The build() methods return TransactionResultBase which provides:
+   * - `.toTransaction()` - Get the unsigned transaction
+   * - `.toTransactionWithFakeWitnesses()` - Get transaction with fake witnesses for fee validation
+   * - `.estimateFee()` - Get the calculated fee
+   *
+   * @param utxos - Optional UTxOs to use for coin selection. If not provided, wallet UTxOs will be fetched automatically when build() is called.
+   * @returns A new TransactionBuilder instance configured with cached protocol parameters and wallet change address.
+   *
+   * @example
+   * ```typescript
+   * // Build unsigned transaction
+   * const result = await readOnlyClient.newTx()
+   *   .payToAddress({ address: "addr...", lovelace: 5000000n })
+   *   .build()
+   *
+   * // Get unsigned transaction for external signing
+   * const unsignedTx = await result.toTransaction()
+   * const txCbor = Transaction.toCBORHex(unsignedTx)
+   *
+   * // Get fee estimate
+   * const fee = await result.estimateFee()
+   * ```
+   *
+   * @since 2.0.0
+   * @category transaction-building
+   */
+  readonly newTx: (utxos?: ReadonlyArray<UTxO.UTxO>) => TransactionBuilder<TransactionResultBase>
   // Effect namespace - includes all provider + wallet methods as Effects
   readonly Effect: ReadOnlyClientEffect
 }
-```
+````
 
 ## ReadOnlyClientEffect (interface)
 
@@ -350,15 +411,53 @@ export interface SeedWalletConfig {
 
 SigningClient - full functionality: query blockchain + sign + submit
 
+SigningClient has wallet signing capability, so newTx() returns a TransactionBuilder
+that yields SignBuilder (can sign and submit transactions).
+
 **Signature**
 
-```ts
+````ts
 export type SigningClient = EffectToPromiseAPI<SigningClientEffect> & {
-  readonly newTx: (utxos?: ReadonlyArray<UTxO.UTxO>) => any // TODO: Change to ReadOnlyTransactionBuilder when implementing tx builder
+  /**
+   * Create a new transaction builder with signing capability.
+   *
+   * Returns a TransactionBuilder that can build and sign transactions.
+   * The build() methods return SignBuilder which provides:
+   * - `.sign()` - Sign and prepare for submission
+   * - `.toTransaction()` - Get the unsigned transaction
+   * - `.toTransactionWithFakeWitnesses()` - Get transaction with fake witnesses for fee validation
+   * - `.estimateFee()` - Get the calculated fee
+   * - `.partialSign()` - Create partial signature for multi-sig
+   * - `.assemble()` - Combine multiple signatures
+   *
+   * UTxOs for coin selection are fetched automatically from the wallet when build() is called.
+   * You can override UTxOs per-build using BuildOptions.availableUtxos.
+   *
+   * @returns A new TransactionBuilder instance configured with cached protocol parameters and wallet change address.
+   *
+   * @example
+   * ```typescript
+   * // Build and sign transaction
+   * const signBuilder = await signingClient.newTx()
+   *   .payToAddress({ address: "addr...", lovelace: 5000000n })
+   *   .build()
+   *
+   * // Sign and submit
+   * const submitBuilder = await signBuilder.sign()
+   * const txHash = await submitBuilder.submit()
+   *
+   * // Or get unsigned transaction
+   * const unsignedTx = await signBuilder.toTransaction()
+   * ```
+   *
+   * @since 2.0.0
+   * @category transaction-building
+   */
+  readonly newTx: () => TransactionBuilder
   // Effect namespace - includes all provider + wallet methods as Effects
   readonly Effect: SigningClientEffect
 }
-```
+````
 
 ## SigningClientEffect (interface)
 
@@ -396,5 +495,5 @@ export type SigningWalletClient = EffectToPromiseAPI<SigningWalletEffect> & {
 **Signature**
 
 ```ts
-export type WalletConfig = SeedWalletConfig | ReadOnlyWalletConfig | ApiWalletConfig
+export type WalletConfig = SeedWalletConfig | PrivateKeyWalletConfig | ReadOnlyWalletConfig | ApiWalletConfig
 ```
diff --git a/packages/evolution/docs/modules/sdk/client/ClientImpl.ts.md b/packages/evolution/docs/modules/sdk/client/ClientImpl.ts.md
index 2ac94538..50fa7dea 100644
--- a/packages/evolution/docs/modules/sdk/client/ClientImpl.ts.md
+++ b/packages/evolution/docs/modules/sdk/client/ClientImpl.ts.md
@@ -1,6 +1,6 @@
 ---
 title: sdk/client/ClientImpl.ts
-nav_order: 134
+nav_order: 138
 parent: Modules
 ---
 
@@ -51,6 +51,10 @@ export declare function createClient(config: {
   wallet: ReadOnlyWalletConfig
 }): ReadOnlyWalletClient
 export declare function createClient(config: { network?: NetworkId; wallet: SeedWalletConfig }): SigningWalletClient
+export declare function createClient(config: {
+  network?: NetworkId
+  wallet: PrivateKeyWalletConfig
+}): SigningWalletClient
 export declare function createClient(config: { network?: NetworkId; wallet: ApiWalletConfig }): ApiWalletClient
 export declare function createClient(config?: { network?: NetworkId }): MinimalClient
 ```
diff --git a/packages/evolution/docs/modules/sdk/provider/Blockfrost.ts.md b/packages/evolution/docs/modules/sdk/provider/Blockfrost.ts.md
index 3540ca02..4f3d5824 100644
--- a/packages/evolution/docs/modules/sdk/provider/Blockfrost.ts.md
+++ b/packages/evolution/docs/modules/sdk/provider/Blockfrost.ts.md
@@ -1,6 +1,6 @@
 ---
 title: sdk/provider/Blockfrost.ts
-nav_order: 145
+nav_order: 149
 parent: Modules
 ---
 
diff --git a/packages/evolution/docs/modules/sdk/provider/Koios.ts.md b/packages/evolution/docs/modules/sdk/provider/Koios.ts.md
index d25ddf3c..dfbc3499 100644
--- a/packages/evolution/docs/modules/sdk/provider/Koios.ts.md
+++ b/packages/evolution/docs/modules/sdk/provider/Koios.ts.md
@@ -1,6 +1,6 @@
 ---
 title: sdk/provider/Koios.ts
-nav_order: 146
+nav_order: 150
 parent: Modules
 ---
 
diff --git a/packages/evolution/docs/modules/sdk/provider/Kupmios.ts.md b/packages/evolution/docs/modules/sdk/provider/Kupmios.ts.md
index 1a0d0252..30a3506c 100644
--- a/packages/evolution/docs/modules/sdk/provider/Kupmios.ts.md
+++ b/packages/evolution/docs/modules/sdk/provider/Kupmios.ts.md
@@ -1,6 +1,6 @@
 ---
 title: sdk/provider/Kupmios.ts
-nav_order: 147
+nav_order: 151
 parent: Modules
 ---
 
diff --git a/packages/evolution/docs/modules/sdk/provider/Maestro.ts.md b/packages/evolution/docs/modules/sdk/provider/Maestro.ts.md
index 20d587d9..be63f6c5 100644
--- a/packages/evolution/docs/modules/sdk/provider/Maestro.ts.md
+++ b/packages/evolution/docs/modules/sdk/provider/Maestro.ts.md
@@ -1,6 +1,6 @@
 ---
 title: sdk/provider/Maestro.ts
-nav_order: 148
+nav_order: 152
 parent: Modules
 ---
 
diff --git a/packages/evolution/docs/modules/sdk/provider/Provider.ts.md b/packages/evolution/docs/modules/sdk/provider/Provider.ts.md
index db8888c2..5f20e785 100644
--- a/packages/evolution/docs/modules/sdk/provider/Provider.ts.md
+++ b/packages/evolution/docs/modules/sdk/provider/Provider.ts.md
@@ -1,6 +1,6 @@
 ---
 title: sdk/provider/Provider.ts
-nav_order: 149
+nav_order: 153
 parent: Modules
 ---
 
diff --git a/packages/evolution/docs/modules/sdk/wallet/Derivation.ts.md b/packages/evolution/docs/modules/sdk/wallet/Derivation.ts.md
index d385b78d..de2f7983 100644
--- a/packages/evolution/docs/modules/sdk/wallet/Derivation.ts.md
+++ b/packages/evolution/docs/modules/sdk/wallet/Derivation.ts.md
@@ -1,6 +1,6 @@
 ---
 title: sdk/wallet/Derivation.ts
-nav_order: 155
+nav_order: 159
 parent: Modules
 ---
 
@@ -38,6 +38,8 @@ Result of deriving keys and addresses from a seed or Bip32 root
 - address: bech32 payment address (addr... / addr_test...)
 - rewardAddress: bech32 reward address (stake... / stake_test...)
 - paymentKey / stakeKey: ed25519e_sk bech32 private keys
+- keyStore: Map of KeyHash hex -> PrivateKey for signing operations
+- paymentKhHex / stakeKhHex: KeyHash hex strings for quick lookup
 
 **Signature**
 
@@ -47,6 +49,9 @@ export type SeedDerivationResult = {
   rewardAddress: SdkRewardAddress.RewardAddress | undefined
   paymentKey: string
   stakeKey: string | undefined
+  keyStore: Map<string, PrivateKey.PrivateKey>
+  paymentKhHex: string
+  stakeKhHex: string | undefined
 }
 ```
 
@@ -116,7 +121,7 @@ export declare function walletFromPrivateKey(
     addressType?: "Base" | "Enterprise"
     network?: "Mainnet" | "Testnet" | "Custom"
   } = {}
-): SeedDerivationResult
+): Effect.Effect<SeedDerivationResult, DerivationError>
 ```
 
 ## walletFromSeed
@@ -132,8 +137,5 @@ export declare const walletFromSeed: (
     accountIndex?: number
     network?: "Mainnet" | "Testnet" | "Custom"
   }
-) => Either.Either<
-  { address: string; rewardAddress: string | undefined; paymentKey: string; stakeKey: string | undefined },
-  Bip32PrivateKey.Bip32PrivateKeyError | AddressEras.AddressError | DerivationError
->
+) => Effect.Effect<SeedDerivationResult, DerivationError | Bip32PrivateKey.Bip32PrivateKeyError>
 ```
diff --git a/packages/evolution/docs/modules/sdk/wallet/Wallet.ts.md b/packages/evolution/docs/modules/sdk/wallet/Wallet.ts.md
index 6cb6ae3d..449b61de 100644
--- a/packages/evolution/docs/modules/sdk/wallet/Wallet.ts.md
+++ b/packages/evolution/docs/modules/sdk/wallet/Wallet.ts.md
@@ -1,6 +1,6 @@
 ---
 title: sdk/wallet/Wallet.ts
-nav_order: 156
+nav_order: 160
 parent: Modules
 ---
 
diff --git a/packages/evolution/docs/modules/sdk/wallet/WalletNew.ts.md b/packages/evolution/docs/modules/sdk/wallet/WalletNew.ts.md
index b6970c89..1c276369 100644
--- a/packages/evolution/docs/modules/sdk/wallet/WalletNew.ts.md
+++ b/packages/evolution/docs/modules/sdk/wallet/WalletNew.ts.md
@@ -1,6 +1,6 @@
 ---
 title: sdk/wallet/WalletNew.ts
-nav_order: 157
+nav_order: 161
 parent: Modules
 ---
 
@@ -116,8 +116,8 @@ Suitable for read-only applications that need wallet information.
 
 ```ts
 export interface ReadOnlyWalletEffect {
-  readonly address: Effect.Effect<Address.Address, WalletError>
-  readonly rewardAddress: Effect.Effect<RewardAddress.RewardAddress | null, WalletError>
+  readonly address: () => Effect.Effect<Address.Address, WalletError>
+  readonly rewardAddress: () => Effect.Effect<RewardAddress.RewardAddress | null, WalletError>
 }
 ```
 
diff --git a/packages/evolution/docs/modules/utils/FeeValidation.ts.md b/packages/evolution/docs/modules/utils/FeeValidation.ts.md
index 9f639545..0c75155b 100644
--- a/packages/evolution/docs/modules/utils/FeeValidation.ts.md
+++ b/packages/evolution/docs/modules/utils/FeeValidation.ts.md
@@ -1,6 +1,6 @@
 ---
 title: utils/FeeValidation.ts
-nav_order: 158
+nav_order: 163
 parent: Modules
 ---
 
diff --git a/packages/evolution/docs/modules/utils/Hash.ts.md b/packages/evolution/docs/modules/utils/Hash.ts.md
index 422a33b7..fde83735 100644
--- a/packages/evolution/docs/modules/utils/Hash.ts.md
+++ b/packages/evolution/docs/modules/utils/Hash.ts.md
@@ -1,6 +1,6 @@
 ---
 title: utils/Hash.ts
-nav_order: 159
+nav_order: 164
 parent: Modules
 ---
 
diff --git a/packages/evolution/docs/modules/utils/effect-runtime.ts.md b/packages/evolution/docs/modules/utils/effect-runtime.ts.md
new file mode 100644
index 00000000..e3766a63
--- /dev/null
+++ b/packages/evolution/docs/modules/utils/effect-runtime.ts.md
@@ -0,0 +1,54 @@
+---
+title: utils/effect-runtime.ts
+nav_order: 162
+parent: Modules
+---
+
+## effect-runtime overview
+
+---
+
+<h2 class="text-delta">Table of contents</h2>
+
+- [utilities](#utilities)
+  - [runEffect](#runeffect)
+
+---
+
+# utilities
+
+## runEffect
+
+Run an Effect and convert it to a Promise with clean error handling.
+
+- Executes the Effect using Effect.runPromiseExit
+- On failure, extracts the error from the Exit and cleans stack traces
+- Removes Effect.ts internal stack frames for cleaner error messages
+- Throws the cleaned error for standard Promise error handling
+
+**Signature**
+
+```ts
+export async function runEffect<A, E>(effect: Effect.Effect<A, E>): Promise<A>
+```
+
+**Example**
+
+```typescript
+import { Effect } from "effect"
+import { runEffect } from "@evolution-sdk/evolution/utils/effect-runtime"
+
+const myEffect = Effect.succeed(42)
+
+async function example() {
+  try {
+    const result = await runEffect(myEffect)
+    console.log(result)
+  } catch (error) {
+    // Error with clean stack trace, no Effect.ts internals
+    console.error(error)
+  }
+}
+```
+
+Added in v2.0.0
diff --git a/packages/evolution/package.json b/packages/evolution/package.json
index e2a30f2f..9c0cdebb 100644
--- a/packages/evolution/package.json
+++ b/packages/evolution/package.json
@@ -39,7 +39,6 @@
   "devDependencies": {
     "@dcspark/cardano-multiplatform-lib-nodejs": "^6.2.0",
     "@types/dockerode": "^3.3.43",
-    "@types/libsodium-wrappers-sumo": "^0.7.8",
     "tinybench": "^5.0.0",
     "tsx": "^4.20.4",
     "typescript": "^5.9.2"
@@ -47,6 +46,7 @@
   "dependencies": {
     "@effect/platform": "^0.90.6",
     "@effect/platform-node": "^0.96.0",
+    "@noble/curves": "^2.0.1",
     "@noble/hashes": "^1.8.0",
     "@scure/base": "^1.2.6",
     "@scure/bip32": "^1.7.0",
@@ -54,8 +54,7 @@
     "@types/bip39": "^3.0.4",
     "bip39": "^3.1.0",
     "dockerode": "^4.0.7",
-    "effect": "^3.17.9",
-    "libsodium-wrappers-sumo": "^0.7.15"
+    "effect": "^3.17.9"
   },
   "keywords": [
     "cardano",
diff --git a/packages/evolution/src/core/Bip32PrivateKey.ts b/packages/evolution/src/core/Bip32PrivateKey.ts
index e785c12e..efe69d1a 100644
--- a/packages/evolution/src/core/Bip32PrivateKey.ts
+++ b/packages/evolution/src/core/Bip32PrivateKey.ts
@@ -1,7 +1,10 @@
+import { mod } from "@noble/curves/abstract/modular.js"
+import { ed25519 } from "@noble/curves/ed25519.js"
+import { bytesToNumberLE } from "@noble/curves/utils.js"
+import { hmac } from "@noble/hashes/hmac.js"
 import { pbkdf2 } from "@noble/hashes/pbkdf2"
 import { sha512 } from "@noble/hashes/sha2"
-import { Data, Either as E, FastCheck, Schema } from "effect"
-import sodium from "libsodium-wrappers-sumo"
+import { Data, Effect, FastCheck, Schema } from "effect"
 
 import * as Bip32PublicKey from "./Bip32PublicKey.js"
 import * as Bytes from "./Bytes.js"
@@ -9,9 +12,6 @@ import * as Bytes96 from "./Bytes96.js"
 import * as Function from "./Function.js"
 import * as PrivateKey from "./PrivateKey.js"
 
-// Initialize libsodium - IIFE executes immediately but doesn't block module loading
-void (async () => await sodium.ready)()
-
 /**
  * Error class for Bip32PrivateKey related operations.
  *
@@ -180,9 +180,7 @@ export const toHex = Function.makeEncodeSync(FromHex, Bip32PrivateKeyError, "Bip
  * @category bip39
  */
 export const fromBip39Entropy = (entropy: Uint8Array, password: string = ""): Bip32PrivateKey => {
-  return E.getOrThrowWith(Either.fromBip39Entropy(entropy, password), (err) => {
-    throw err
-  })
+  return Effect.runSync(Either.fromBip39Entropy(entropy, password))
 }
 
 /**
@@ -193,9 +191,7 @@ export const fromBip39Entropy = (entropy: Uint8Array, password: string = ""): Bi
  * @category bip32
  */
 export const deriveChild = (bip32PrivateKey: Bip32PrivateKey, index: number): Bip32PrivateKey => {
-  return E.getOrThrowWith(Either.deriveChild(bip32PrivateKey, index), (err) => {
-    throw err
-  })
+  return Effect.runSync(Either.deriveChild(bip32PrivateKey, index))
 }
 
 /**
@@ -205,9 +201,7 @@ export const deriveChild = (bip32PrivateKey: Bip32PrivateKey, index: number): Bi
  * @category bip32
  */
 export const derive = (bip32PrivateKey: Bip32PrivateKey, indices: Array<number>): Bip32PrivateKey => {
-  return E.getOrThrowWith(Either.derive(bip32PrivateKey, indices), (err) => {
-    throw err
-  })
+  return Effect.runSync(Either.derive(bip32PrivateKey, indices))
 }
 
 /**
@@ -218,9 +212,7 @@ export const derive = (bip32PrivateKey: Bip32PrivateKey, indices: Array<number>)
  * @category bip32
  */
 export const derivePath = (bip32PrivateKey: Bip32PrivateKey, path: string): Bip32PrivateKey => {
-  return E.getOrThrowWith(Either.derivePath(bip32PrivateKey, path), (err) => {
-    throw err
-  })
+  return Effect.runSync(Either.derivePath(bip32PrivateKey, path))
 }
 
 /**
@@ -230,9 +222,7 @@ export const derivePath = (bip32PrivateKey: Bip32PrivateKey, path: string): Bip3
  * @category conversion
  */
 export const toPrivateKey = (bip32PrivateKey: Bip32PrivateKey): PrivateKey.PrivateKey => {
-  return E.getOrThrowWith(Either.toPrivateKey(bip32PrivateKey), (err) => {
-    throw err
-  })
+  return Effect.runSync(Either.toPrivateKey(bip32PrivateKey))
 }
 
 /**
@@ -242,9 +232,7 @@ export const toPrivateKey = (bip32PrivateKey: Bip32PrivateKey): PrivateKey.Priva
  * @category cryptography
  */
 export const toPublicKey = (bip32PrivateKey: Bip32PrivateKey): Bip32PublicKey.Bip32PublicKey => {
-  return E.getOrThrowWith(Either.toPublicKey(bip32PrivateKey), (err) => {
-    throw err
-  })
+  return Effect.runSync(Either.toPublicKey(bip32PrivateKey))
 }
 
 /**
@@ -254,9 +242,7 @@ export const toPublicKey = (bip32PrivateKey: Bip32PrivateKey): Bip32PublicKey.Bi
  * @category cml-compatibility
  */
 export const to128XPRV = (bip32PrivateKey: Bip32PrivateKey): Uint8Array => {
-  return E.getOrThrowWith(Either.to_128_xprv(bip32PrivateKey), (err) => {
-    throw err
-  })
+  return Effect.runSync(Either.to_128_xprv(bip32PrivateKey))
 }
 
 /**
@@ -266,9 +252,7 @@ export const to128XPRV = (bip32PrivateKey: Bip32PrivateKey): Uint8Array => {
  * @category cml-compatibility
  */
 export const from128XPRV = (bytes: Uint8Array): Bip32PrivateKey => {
-  return E.getOrThrowWith(Either.from_128_xprv(bytes), (err) => {
-    throw err
-  })
+  return Effect.runSync(Either.from_128_xprv(bytes))
 }
 
 // ============================================================================
@@ -280,7 +264,7 @@ export const arbitrary = FastCheck.uint8Array({ minLength: 96, maxLength: 96 }).
 )
 
 // ============================================================================
-// Either Namespace (Composable API)
+// Either Namespace (Composable API - for backward compatibility)
 // ============================================================================
 
 export namespace Either {
@@ -290,16 +274,22 @@ export namespace Either {
   export const toHex = Function.makeEncodeEither(FromHex, Bip32PrivateKeyError)
 
   export const fromBip39Entropy = (entropy: Uint8Array, password: string = "") =>
-    E.gen(function* () {
+    Effect.gen(function* () {
       const keyMaterial = pbkdf2(sha512, password, entropy, { c: PBKDF2_ITERATIONS, dkLen: PBKDF2_KEY_SIZE })
       const clamped = new Uint8Array(keyMaterial)
       clamped.set(clampScalar(keyMaterial.slice(0, 32)), 0)
-      return yield* fromBytes(clamped)
+      return yield* Effect.try({
+        try: () => Schema.decodeUnknownSync(FromBytes)(clamped),
+        catch: (cause) => new Bip32PrivateKeyError({ message: "fromBip39Entropy failed", cause })
+      })
     })
 
   export const deriveChild = (bip32PrivateKey: Bip32PrivateKey, index: number) =>
-    E.gen(function* () {
-      const keyBytes = yield* toBytes(bip32PrivateKey)
+    Effect.gen(function* () {
+      const keyBytes = yield* Effect.try({
+        try: () => Schema.encodeSync(FromBytes)(bip32PrivateKey),
+        catch: (cause) => new Bip32PrivateKeyError({ message: "toBytes failed", cause })
+      })
       const scalar = extractScalar(keyBytes)
       const iv = extractIV(keyBytes)
       const chainCode = extractChainCode(keyBytes)
@@ -325,13 +315,15 @@ export namespace Either {
         zInput.set(indexBytes, 65)
       } else {
         // 0x02 || publicKey || index
-        const publicKey = sodium.crypto_scalarmult_ed25519_base_noclamp(scalar)
+        const scalarBigInt = mod(bytesToNumberLE(scalar), ed25519.Point.Fn.ORDER)
+        const publicKeyPoint = ed25519.Point.BASE.multiplyUnsafe(scalarBigInt)
+        const publicKey = publicKeyPoint.toBytes()
         zInput = new Uint8Array(1 + 32 + 4)
         zInput.set(zTag, 0)
         zInput.set(publicKey, 1)
         zInput.set(indexBytes, 33)
       }
-      const hmacZ = sodium.crypto_auth_hmacsha512(zInput, chainCode)
+      const hmacZ = hmac(sha512, chainCode, zInput)
       const z = new Uint8Array(hmacZ)
       const zl = z.slice(0, 32)
       const zr = z.slice(32, 64)
@@ -352,13 +344,15 @@ export namespace Either {
         ccInput.set(indexBytes, 65)
       } else {
         // 0x03 || publicKey || index (use parent public key)
-        const publicKey = sodium.crypto_scalarmult_ed25519_base_noclamp(scalar)
+        const scalarBigInt = mod(bytesToNumberLE(scalar), ed25519.Point.Fn.ORDER)
+        const publicKeyPoint = ed25519.Point.BASE.multiplyUnsafe(scalarBigInt)
+        const publicKey = publicKeyPoint.toBytes()
         ccInput = new Uint8Array(1 + 32 + 4)
         ccInput.set(ccTag, 0)
         ccInput.set(publicKey, 1)
         ccInput.set(indexBytes, 33)
       }
-      const hmacCC = sodium.crypto_auth_hmacsha512(ccInput, chainCode)
+      const hmacCC = hmac(sha512, chainCode, ccInput)
       const newChainCode = new Uint8Array(hmacCC).slice(32, 64)
 
       const out = new Uint8Array(96)
@@ -370,7 +364,7 @@ export namespace Either {
     })
 
   export const derive = (bip32PrivateKey: Bip32PrivateKey, indices: Array<number>) =>
-    E.gen(function* () {
+    Effect.gen(function* () {
       let current = bip32PrivateKey
       for (const idx of indices) {
         current = yield* deriveChild(current, idx)
@@ -379,37 +373,53 @@ export namespace Either {
     })
 
   const parsePath = (path: string) =>
-    E.try(() => {
-      const clean = path.startsWith("m/") ? path.slice(2) : path
-      if (clean.length === 0) return [] as Array<number>
-      return clean.split("/").map((seg) => {
-        const hardened = seg.endsWith("'") || seg.endsWith("h") || seg.endsWith("H")
-        const core = hardened ? seg.slice(0, -1) : seg
-        const n = Number(core)
-        if (!Number.isInteger(n) || n < 0) throw new Error(`Invalid path segment: ${seg}`)
-        return hardened ? (0x80000000 + n) >>> 0 : n >>> 0
-      })
+    Effect.try({
+      try: () => {
+        const clean = path.startsWith("m/") ? path.slice(2) : path
+        if (clean.length === 0) return [] as Array<number>
+        return clean.split("/").map((seg) => {
+          const hardened = seg.endsWith("'") || seg.endsWith("h") || seg.endsWith("H")
+          const core = hardened ? seg.slice(0, -1) : seg
+          const n = Number(core)
+          if (!Number.isInteger(n) || n < 0) throw new Error(`Invalid path segment: ${seg}`)
+          return hardened ? (0x80000000 + n) >>> 0 : n >>> 0
+        })
+      },
+      catch: (cause) => new Bip32PrivateKeyError({ message: "Invalid derivation path", cause })
     })
 
   export const derivePath = (bip32PrivateKey: Bip32PrivateKey, path: string) =>
-    E.gen(function* () {
+    Effect.gen(function* () {
       const indices = yield* parsePath(path)
       return yield* derive(bip32PrivateKey, indices)
     })
 
   export const toPrivateKey = (bip32PrivateKey: Bip32PrivateKey) =>
-    E.gen(function* () {
-      const keyBytes = yield* toBytes(bip32PrivateKey)
+    Effect.gen(function* () {
+      const keyBytes = yield* Effect.try({
+        try: () => Schema.encodeSync(FromBytes)(bip32PrivateKey),
+        catch: (cause) => new Bip32PrivateKeyError({ message: "toBytes failed", cause })
+      })
       const priv = keyBytes.slice(0, 64)
       return new PrivateKey.PrivateKey({ key: priv }, { disableValidation: true })
     })
 
   export const toPublicKey = (bip32PrivateKey: Bip32PrivateKey) =>
-    E.gen(function* () {
-      const keyBytes = yield* toBytes(bip32PrivateKey)
+    Effect.gen(function* () {
+      const keyBytes = yield* Effect.try({
+        try: () => Schema.encodeSync(FromBytes)(bip32PrivateKey),
+        catch: (cause) => new Bip32PrivateKeyError({ message: "toBytes failed", cause })
+      })
       const scalar = extractScalar(keyBytes)
       const chainCode = extractChainCode(keyBytes)
-      const publicKeyBytes = yield* E.try(() => sodium.crypto_scalarmult_ed25519_base_noclamp(scalar))
+      const publicKeyBytes = yield* Effect.try({
+        try: () => {
+          const scalarBigInt = mod(bytesToNumberLE(scalar), ed25519.Point.Fn.ORDER)
+          const publicKeyPoint = ed25519.Point.BASE.multiplyUnsafe(scalarBigInt)
+          return publicKeyPoint.toBytes()
+        },
+        catch: (cause) => new Bip32PrivateKeyError({ message: "toPublicKey failed", cause })
+      })
       const combined = new Uint8Array(64)
       combined.set(publicKeyBytes, 0)
       combined.set(chainCode, 32)
@@ -417,12 +427,22 @@ export namespace Either {
     })
 
   export const to_128_xprv = (bip32PrivateKey: Bip32PrivateKey) =>
-    E.gen(function* () {
-      const keyBytes = yield* toBytes(bip32PrivateKey)
+    Effect.gen(function* () {
+      const keyBytes = yield* Effect.try({
+        try: () => Schema.encodeSync(FromBytes)(bip32PrivateKey),
+        catch: (cause) => new Bip32PrivateKeyError({ message: "toBytes failed", cause })
+      })
       const scalar = extractScalar(keyBytes)
       const iv = extractIV(keyBytes)
       const chainCode = extractChainCode(keyBytes)
-      const publicKeyBytes = yield* E.try(() => sodium.crypto_scalarmult_ed25519_base_noclamp(scalar))
+      const publicKeyBytes = yield* Effect.try({
+        try: () => {
+          const scalarBigInt = mod(bytesToNumberLE(scalar), ed25519.Point.Fn.ORDER)
+          const publicKeyPoint = ed25519.Point.BASE.multiplyUnsafe(scalarBigInt)
+          return publicKeyPoint.toBytes()
+        },
+        catch: (cause) => new Bip32PrivateKeyError({ message: "to_128_xprv failed", cause })
+      })
       const out = new Uint8Array(128)
       out.set(scalar, 0)
       out.set(iv, 32)
@@ -432,19 +452,26 @@ export namespace Either {
     })
 
   export const from_128_xprv = (bytes: Uint8Array) =>
-    E.gen(function* () {
+    Effect.gen(function* () {
       if (bytes.length !== 128) {
-        return yield* E.left(new Bip32PrivateKeyError({ message: `Expected exactly 128 bytes, got ${bytes.length}` }))
+        return yield* Effect.fail(new Bip32PrivateKeyError({ message: `Expected exactly 128 bytes, got ${bytes.length}` }))
       }
       const scalar = bytes.slice(0, 32)
       const iv = bytes.slice(32, 64)
       const publicKeyExpected = bytes.slice(64, 96)
       const chaincode = bytes.slice(96, 128)
 
-      const derivedPK = yield* E.try(() => sodium.crypto_scalarmult_ed25519_base_noclamp(scalar))
+      const derivedPK = yield* Effect.try({
+        try: () => {
+          const scalarBigInt = mod(bytesToNumberLE(scalar), ed25519.Point.Fn.ORDER)
+          const publicKeyPoint = ed25519.Point.BASE.multiplyUnsafe(scalarBigInt)
+          return publicKeyPoint.toBytes()
+        },
+        catch: (cause) => new Bip32PrivateKeyError({ message: "from_128_xprv failed", cause })
+      })
       const matches = derivedPK.every((b, i) => b === publicKeyExpected[i])
       if (!matches) {
-        return yield* E.left(
+        return yield* Effect.fail(
           new Bip32PrivateKeyError({ message: "Public key does not match private key in 128-byte blob" })
         )
       }
diff --git a/packages/evolution/src/core/Bip32PublicKey.ts b/packages/evolution/src/core/Bip32PublicKey.ts
index 81673668..326418d6 100644
--- a/packages/evolution/src/core/Bip32PublicKey.ts
+++ b/packages/evolution/src/core/Bip32PublicKey.ts
@@ -1,13 +1,14 @@
+import { mod } from "@noble/curves/abstract/modular.js"
+import { ed25519 } from "@noble/curves/ed25519.js"
+import { bytesToNumberLE } from "@noble/curves/utils.js"
+import { hmac } from "@noble/hashes/hmac.js"
+import { sha512 } from "@noble/hashes/sha2.js"
 import { Data, Either as E, FastCheck, Schema } from "effect"
-import sodium from "libsodium-wrappers-sumo"
 
 import * as Bytes from "./Bytes.js"
 import * as Bytes64 from "./Bytes64.js"
 import * as Function from "./Function.js"
 
-// Initialize libsodium - IIFE executes immediately but doesn't block module loading
-void (async () => await sodium.ready)()
-
 /**
  * Error class for Bip32PublicKey related operations.
  *
@@ -285,7 +286,7 @@ export namespace Either {
         zInput.set(indexBytes, 33)
 
         // HMAC-SHA512 with chain code as key
-        const hmacZ = sodium.crypto_auth_hmacsha512(zInput, parentChainCode)
+        const hmacZ = hmac(sha512, parentChainCode, zInput)
         const z = new Uint8Array(hmacZ)
         const zl = z.slice(0, 32)
 
@@ -311,10 +312,16 @@ export namespace Either {
         }
 
         // Now compute zl8*G (scalar multiplication with base point using processed zl)
-        const zl8G = sodium.crypto_scalarmult_ed25519_base_noclamp(zl8)
+        // Apply modular reduction to ensure scalar is in valid range [0, curve.n)
+        const zl8BigInt = mod(bytesToNumberLE(zl8), ed25519.Point.Fn.ORDER)
+        const zl8GPoint = ed25519.Point.BASE.multiplyUnsafe(zl8BigInt)
+        const zl8G = zl8GPoint.toBytes()
 
         // Then add parentPublicKey + zl8G (point addition)
-        const childPublicKey = sodium.crypto_core_ed25519_add(parentPublicKey, zl8G)
+        const parentPublicKeyPoint = ed25519.Point.fromBytes(parentPublicKey)
+        const zl8GPointForAdd = ed25519.Point.fromBytes(zl8G)
+        const childPublicKeyPoint = parentPublicKeyPoint.add(zl8GPointForAdd)
+        const childPublicKey = childPublicKeyPoint.toBytes()
 
         // Derive new chain code: tag(0x03) + public_key(32 bytes) + index(4 bytes)
         const ccTag = new Uint8Array([0x03]) // TAG_DERIVE_CC_SOFT - corrected to 0x03
@@ -323,7 +330,7 @@ export namespace Either {
         ccInput.set(parentPublicKey, 1)
         ccInput.set(indexBytes, 33)
 
-        const hmacCC = sodium.crypto_auth_hmacsha512(ccInput, parentChainCode)
+        const hmacCC = hmac(sha512, parentChainCode, ccInput)
         const newChainCode = new Uint8Array(hmacCC).slice(32, 64) // Take right 32 bytes
 
         return {
diff --git a/packages/evolution/src/core/Function.ts b/packages/evolution/src/core/Function.ts
index 00ba90e5..ff1bf9e8 100644
--- a/packages/evolution/src/core/Function.ts
+++ b/packages/evolution/src/core/Function.ts
@@ -98,14 +98,14 @@ export const makeDecodeEither =
   <T, A, E extends Error>(schema: Schema.Schema<T, A>, ErrorClass: ErrorCtor<E>) =>
   (input: A) =>
     Schema.decodeEither(schema)(input).pipe(
-      Either.mapLeft((e) => new ErrorClass({ message: "Failed to decode input", cause: e }))
+      Either.mapLeft((e) => new ErrorClass({ message: e.message, cause: e }))
     )
 
 export const makeEncodeEither =
   <T, A, E extends Error>(schema: Schema.Schema<T, A>, ErrorClass: ErrorCtor<E>) =>
   (input: T) =>
     Schema.encodeEither(schema)(input).pipe(
-      Either.mapLeft((e) => new ErrorClass({ message: "Failed to encode input", cause: e }))
+      Either.mapLeft((e) => new ErrorClass({ message: e.message, cause: e }))
     )
 
 /**
@@ -212,7 +212,7 @@ export const makeCBORDecodeEither =
   (bytes: Uint8Array, options?: CBOR.CodecOptions) =>
     Either.try(() => CBOR.internalDecodeSync(bytes, options || defaultOptions)).pipe(
       Either.flatMap((cbor) => Schema.decodeEither(schemaTransformer)(cbor as T)),
-      Either.mapLeft((e) => new ErrorClass({ message: "Failed to decode CBOR bytes", cause: e }))
+      Either.mapLeft((e) => new ErrorClass({ message: (e as Error).message, cause: e as Error }))
     )
 
 /**
@@ -228,7 +228,7 @@ export const makeCBORDecodeHexEither =
     Either.try(() => Bytes.fromHex(hex)).pipe(
       Either.flatMap((bytes) => Either.try(() => CBOR.internalDecodeSync(bytes, options || defaultOptions))),
       Either.flatMap((cbor) => Schema.decodeEither(schemaTransformer)(cbor as T)),
-      Either.mapLeft((e) => new ErrorClass({ message: "Failed to decode CBOR hex", cause: e }))
+      Either.mapLeft((e) => new ErrorClass({ message: (e as Error).message, cause: e as Error }))
     )
 
 /**
@@ -240,10 +240,10 @@ export const makeCBOREncodeEither =
     ErrorClass: ErrorCtor<E>,
     defaultOptions?: CBOR.CodecOptions
   ) =>
-  (input: A, options?: CBOR.CodecOptions) =>
-    Schema.encodeEither(schemaTransformer)(input).pipe(
-      Either.flatMap((cborValue) => Either.try(() => CBOR.internalEncodeSync(cborValue, options || defaultOptions))),
-      Either.mapLeft((e) => new ErrorClass({ message: "Failed to encode CBOR bytes", cause: e }))
+  (value: A, options?: CBOR.CodecOptions) =>
+    Schema.encodeEither(schemaTransformer)(value).pipe(
+      Either.flatMap((cbor) => Either.try(() => CBOR.internalEncodeSync(cbor, options || defaultOptions))),
+      Either.mapLeft((e) => new ErrorClass({ message: (e as Error).message, cause: e as Error }))
     )
 
 /**
@@ -259,5 +259,5 @@ export const makeCBOREncodeHexEither =
     Schema.encodeEither(schemaTransformer)(input).pipe(
       Either.flatMap((cborValue) => Either.try(() => CBOR.internalEncodeSync(cborValue, options || defaultOptions))),
       Either.map((bytes) => Bytes.toHexUnsafe(bytes)),
-      Either.mapLeft((e) => new ErrorClass({ message: "Failed to encode CBOR hex string", cause: e }))
+      Either.mapLeft((e) => new ErrorClass({ message: (e as Error).message, cause: e as Error }))
     )
diff --git a/packages/evolution/src/core/PrivateKey.ts b/packages/evolution/src/core/PrivateKey.ts
index 85c24f6c..53c57c53 100644
--- a/packages/evolution/src/core/PrivateKey.ts
+++ b/packages/evolution/src/core/PrivateKey.ts
@@ -1,9 +1,13 @@
+import { mod } from "@noble/curves/abstract/modular.js"
+import { ed25519 } from "@noble/curves/ed25519.js"
+import { bytesToNumberLE, numberToBytesLE } from "@noble/curves/utils.js"
+import { sha512 } from "@noble/hashes/sha2.js"
+import { randomBytes } from "@noble/hashes/utils.js"
 import { bech32 } from "@scure/base"
 import * as BIP32 from "@scure/bip32"
 import * as BIP39 from "@scure/bip39"
 import { wordlist } from "@scure/bip39/wordlists/english"
 import { Data, Either as E, FastCheck, ParseResult, Schema } from "effect"
-import sodium from "libsodium-wrappers-sumo"
 
 import * as Bytes from "./Bytes.js"
 import * as Bytes32 from "./Bytes32.js"
@@ -66,7 +70,7 @@ export const FromBech32 = Schema.transformOrFail(Schema.String, Schema.typeSchem
     E.gen(function* () {
       const { prefix, words } = yield* ParseResult.try({
         try: () => bech32.decode(fromA as any, 1023),
-        catch: (error) => new ParseResult.Type(ast, fromA, `Failed to decode Bech32: ${(error as Error).message}`)
+        catch: (error) => new ParseResult.Type(ast, fromA, `Failed to decode bech32 string: ${(error as Error).message}`)
       })
       if (prefix !== "ed25519e_sk") {
         throw new ParseResult.Type(ast, fromA, `Expected ed25519e_sk prefix, got ${prefix}`)
@@ -177,7 +181,7 @@ export const toBech32 = Function.makeEncodeSync(FromBech32, PrivateKeyError, "Pr
  * @since 2.0.0
  * @category generators
  */
-export const generate = () => sodium.randombytes_buf(32)
+export const generate = () => randomBytes(32)
 
 /**
  * Generate a random 64-byte extended Ed25519 private key.
@@ -186,7 +190,7 @@ export const generate = () => sodium.randombytes_buf(32)
  * @since 2.0.0
  * @category generators
  */
-export const generateExtended = () => sodium.randombytes_buf(64)
+export const generateExtended = () => randomBytes(64)
 
 /**
  * Derive the public key (VKey) from a private key.
@@ -388,23 +392,38 @@ export namespace Either {
         const scalar = privateKeyBytes.slice(0, 32)
         const iv = privateKeyBytes.slice(32, 64)
 
-        const publicKey = sodium.crypto_scalarmult_ed25519_base_noclamp(scalar)
-        const nonceHash = sodium.crypto_hash_sha512(new Uint8Array([...iv, ...message]))
-        const nonce = sodium.crypto_core_ed25519_scalar_reduce(nonceHash)
-        const r = sodium.crypto_scalarmult_ed25519_base_noclamp(nonce)
-        const hramHash = sodium.crypto_hash_sha512(new Uint8Array([...r, ...publicKey, ...message]))
-        const hram = sodium.crypto_core_ed25519_scalar_reduce(hramHash)
-        const s = sodium.crypto_core_ed25519_scalar_add(sodium.crypto_core_ed25519_scalar_mul(hram, scalar), nonce)
+        // Get curve order from the field
+        const CURVE_ORDER = ed25519.Point.Fn.ORDER
 
-        // return new Uint8Array([...r, ...s])
-        const signature = new Uint8Array([...r, ...s])
+        // Calculate public key from scalar: publicKey = scalar * G
+        // Apply modular reduction to ensure scalar is in valid range [0, curve.n)
+        const scalarBigInt = mod(bytesToNumberLE(scalar), CURVE_ORDER)
+        const publicKeyPoint = ed25519.Point.BASE.multiplyUnsafe(scalarBigInt)
+        const publicKey = publicKeyPoint.toBytes()
+
+        // Calculate nonce: nonce = reduce(sha512(iv || message))
+        const nonceHash = sha512(new Uint8Array([...iv, ...message]))
+        const nonce = mod(bytesToNumberLE(nonceHash), CURVE_ORDER)
+
+        // Calculate R: R = nonce * G
+        const rPoint = ed25519.Point.BASE.multiply(nonce)
+        const r = rPoint.toBytes()
+
+        // Calculate challenge: hram = reduce(sha512(R || publicKey || message))
+        const hramHash = sha512(new Uint8Array([...r, ...publicKey, ...message]))
+        const hram = mod(bytesToNumberLE(hramHash), CURVE_ORDER)
+
+        // Calculate s: s = (hram * scalar + nonce) mod L
+        const s = mod(hram * scalarBigInt + nonce, CURVE_ORDER)
+
+        // Encode s as little-endian 32 bytes
+        const sBytes = numberToBytesLE(s, 32)
+        const signature = new Uint8Array([...r, ...sBytes])
         return Ed25519Signature.make({ bytes: signature })
       }
 
       // Standard 32-byte Ed25519 signing
-      const publicKey = sodium.crypto_sign_seed_keypair(privateKeyBytes).publicKey
-      const secretKey = new Uint8Array([...privateKeyBytes, ...publicKey])
-      const signature = sodium.crypto_sign_detached(message, secretKey)
+      const signature = ed25519.sign(message, privateKeyBytes)
       return Ed25519Signature.make({ bytes: signature })
     })
 }
diff --git a/packages/evolution/src/core/VKey.ts b/packages/evolution/src/core/VKey.ts
index 291fd461..f3d1a45d 100644
--- a/packages/evolution/src/core/VKey.ts
+++ b/packages/evolution/src/core/VKey.ts
@@ -1,5 +1,7 @@
+import { mod } from "@noble/curves/abstract/modular.js"
+import { ed25519 } from "@noble/curves/ed25519.js"
+import { bytesToNumberLE } from "@noble/curves/utils.js"
 import { Data, FastCheck, Schema } from "effect"
-import sodium from "libsodium-wrappers-sumo"
 
 import * as Bytes from "./Bytes.js"
 import * as Bytes32 from "./Bytes32.js"
@@ -141,10 +143,13 @@ export const fromPrivateKey = (privateKey: PrivateKey.PrivateKey): VKey => {
   if (privateKeyBytes.length === 64) {
     // CML-compatible extended private key: use first 32 bytes as scalar
     const scalar = privateKeyBytes.slice(0, 32)
-    publicKeyBytes = sodium.crypto_scalarmult_ed25519_base_noclamp(scalar)
+    // Apply modular reduction to ensure scalar is in valid range [0, curve.n)
+    const scalarBigInt = mod(bytesToNumberLE(scalar), ed25519.Point.Fn.ORDER)
+    const publicKeyPoint = ed25519.Point.BASE.multiplyUnsafe(scalarBigInt)
+    publicKeyBytes = publicKeyPoint.toBytes()
   } else {
-    // Standard 32-byte Ed25519 private key using sodium
-    publicKeyBytes = sodium.crypto_sign_seed_keypair(privateKeyBytes).publicKey
+    // Standard 32-byte Ed25519 private key: derive public key
+    publicKeyBytes = ed25519.getPublicKey(privateKeyBytes)
   }
 
   return new VKey({ bytes: publicKeyBytes })
@@ -168,7 +173,7 @@ export const fromPrivateKey = (privateKey: PrivateKey.PrivateKey): VKey => {
 export const verify = (vkey: VKey, message: Uint8Array, signature: Uint8Array): boolean => {
   // Convert VKey to bytes
   const publicKeyBytes = vkey.bytes
-  return sodium.crypto_sign_verify_detached(signature, message, publicKeyBytes)
+  return ed25519.verify(signature, message, publicKeyBytes)
 }
 
 // ============================================================================
diff --git a/packages/evolution/src/index.ts b/packages/evolution/src/index.ts
index c9372c5c..5fd126dc 100644
--- a/packages/evolution/src/index.ts
+++ b/packages/evolution/src/index.ts
@@ -114,5 +114,6 @@ export * as Withdrawals from "./core/Withdrawals.js"
 export { createClient } from "./sdk/client/ClientImpl.js"
 export * as Devnet from "./sdk/Devnet/Devnet.js"
 export * as DevnetDefault from "./sdk/Devnet/DevnetDefault.js"
+export { runEffect } from "./utils/effect-runtime.js"
 export * as FeeValidation from "./utils/FeeValidation.js"
 export { Effect, Either, pipe, Schema } from "effect"
diff --git a/packages/evolution/src/sdk/builders/SignBuilder.ts b/packages/evolution/src/sdk/builders/SignBuilder.ts
index 25ef2974..faa2198c 100644
--- a/packages/evolution/src/sdk/builders/SignBuilder.ts
+++ b/packages/evolution/src/sdk/builders/SignBuilder.ts
@@ -3,48 +3,49 @@ import type { Effect } from "effect"
 import type * as Transaction from "../../core/Transaction.js"
 import type * as TransactionWitnessSet from "../../core/TransactionWitnessSet.js"
 import type { EffectToPromiseAPI } from "../Type.js"
+import type { SubmitBuilder } from "./SubmitBuilder.js"
 import type { TransactionBuilderError } from "./TransactionBuilder.js"
+import type { TransactionResultBase } from "./TransactionResult.js"
 
 // ============================================================================
 // Progressive Builder Interfaces
 // ============================================================================
 
+/**
+ * Effect-based API for SignBuilder operations.
+ * 
+ * Includes all TransactionResultBase.Effect methods plus signing-specific operations.
+ * 
+ * @since 2.0.0
+ * @category interfaces
+ */
 export interface SignBuilderEffect {
-  // Main signing method - produces a fully signed transaction ready for submission
-  readonly sign: () => Effect.Effect<SubmitBuilder, TransactionBuilderError>
+  // Base transaction methods (from TransactionResultBase)
+  readonly toTransaction: () => Effect.Effect<Transaction.Transaction, TransactionBuilderError>
+  readonly toTransactionWithFakeWitnesses: () => Effect.Effect<Transaction.Transaction, TransactionBuilderError>
+  readonly estimateFee: () => Effect.Effect<bigint, TransactionBuilderError>
 
-  // Add external witness and proceed to submission
+  // Signing methods
+  readonly sign: () => Effect.Effect<SubmitBuilder, TransactionBuilderError>
   readonly signWithWitness: (
     witnessSet: TransactionWitnessSet.TransactionWitnessSet
   ) => Effect.Effect<SubmitBuilder, TransactionBuilderError>
-
-  // Assemble multiple witnesses into a complete transaction ready for submission
   readonly assemble: (
     witnesses: ReadonlyArray<TransactionWitnessSet.TransactionWitnessSet>
   ) => Effect.Effect<SubmitBuilder, TransactionBuilderError>
-
-  // Partial signing - creates witness without advancing to submission (useful for multi-sig)
   readonly partialSign: () => Effect.Effect<TransactionWitnessSet.TransactionWitnessSet, TransactionBuilderError>
-
-  // Get witness set without signing (for inspection)
   readonly getWitnessSet: () => Effect.Effect<TransactionWitnessSet.TransactionWitnessSet, TransactionBuilderError>
-
-  // Get the unsigned transaction (for inspection)
-  readonly toTransaction: () => Effect.Effect<Transaction.Transaction, TransactionBuilderError>
-  
-  // Get the transaction with fake witnesses (for fee validation)
-  readonly toTransactionWithFakeWitnesses: () => Effect.Effect<Transaction.Transaction, TransactionBuilderError>
 }
 
-export interface SignBuilder extends EffectToPromiseAPI<SignBuilderEffect> {
+/**
+ * SignBuilder extends TransactionResultBase with signing capabilities.
+ * 
+ * Only available when the client has a signing wallet (seed, private key, or API wallet).
+ * Provides access to unsigned transaction (via base interface) and signing operations.
+ * 
+ * @since 2.0.0
+ * @category interfaces
+ */
+export interface SignBuilder extends TransactionResultBase, EffectToPromiseAPI<SignBuilderEffect> {
   readonly Effect: SignBuilderEffect
 }
-
-export interface SubmitBuilderEffect {
-  readonly submit: () => Effect.Effect<string, TransactionBuilderError>
-}
-
-export interface SubmitBuilder extends EffectToPromiseAPI<SubmitBuilderEffect> {
-  readonly Effect: SubmitBuilderEffect
-  readonly witnessSet: TransactionWitnessSet.TransactionWitnessSet
-}
\ No newline at end of file
diff --git a/packages/evolution/src/sdk/builders/SignBuilderImpl.ts b/packages/evolution/src/sdk/builders/SignBuilderImpl.ts
new file mode 100644
index 00000000..1d8d417e
--- /dev/null
+++ b/packages/evolution/src/sdk/builders/SignBuilderImpl.ts
@@ -0,0 +1,138 @@
+/**
+ * SignBuilder Implementation
+ * 
+ * Handles transaction signing by delegating to the wallet's signTx Effect method.
+ * The SignBuilder is responsible for:
+ * 1. Providing the transaction and UTxO context to the wallet
+ * 2. Managing the transition from unsigned to signed transaction
+ * 3. Creating the SubmitBuilder for transaction submission
+ * 
+ * The actual signing logic (determining required signers, creating witnesses) 
+ * is the wallet's responsibility.
+ * 
+ * @since 2.0.0
+ * @category builders
+ */
+
+import { Effect } from "effect"
+
+import * as Transaction from "../../core/Transaction.js"
+import type * as TransactionWitnessSet from "../../core/TransactionWitnessSet.js"
+import type * as Provider from "../provider/Provider.js"
+import type * as UTxO from "../UTxO.js"
+import type * as WalletNew from "../wallet/WalletNew.js"
+import type { SignBuilder, SignBuilderEffect } from "./SignBuilder.js"
+import { makeSubmitBuilder } from "./SubmitBuilderImpl.js"
+import { TransactionBuilderError } from "./TransactionBuilder.js"
+
+// ============================================================================
+// SignBuilder Factory
+// ============================================================================
+
+/**
+ * Wallet type - can be SigningWallet or ApiWallet (both have Effect.signTx)
+ */
+type Wallet = WalletNew.SigningWallet | WalletNew.ApiWallet
+
+/**
+ * Create a SignBuilder instance for a built transaction.
+ * 
+ * @param transaction - The unsigned transaction (body only, no witnesses)
+ * @param transactionWithFakeWitnesses - The transaction with fake witnesses for size validation
+ * @param fee - The calculated transaction fee in lovelace
+ * @param utxos - The UTxOs that were used as inputs (for wallet to determine required signers)
+ * @param wallet - The wallet that will sign the transaction
+ * @param provider - The provider to submit the transaction to
+ * 
+ * @since 2.0.0
+ * @category constructors
+ */
+export const makeSignBuilder = (params: {
+  transaction: Transaction.Transaction
+  transactionWithFakeWitnesses: Transaction.Transaction
+  fee: bigint
+  utxos: ReadonlyArray<UTxO.UTxO>
+  provider: Provider.Provider
+  wallet: Wallet
+}): SignBuilder => {
+  const { fee, provider, transaction, transactionWithFakeWitnesses, utxos, wallet } = params
+
+  // ============================================================================
+  // Effect Namespace Implementation
+  // ============================================================================
+
+  const signEffect: SignBuilderEffect = {
+    /**
+     * Sign the transaction by delegating to the wallet's Effect.signTx method.
+     * 
+     * The wallet will:
+     * 1. Determine which keys are required based on transaction inputs/outputs
+     * 2. Create VKey witnesses for each required signature
+     * 3. Return the witness set
+     * 
+     * SignBuilder then assembles the signed transaction and returns SubmitBuilder.
+     */
+    sign: () =>
+      Effect.gen(function* () {
+        yield* Effect.logDebug("Starting transaction signing (delegating to wallet Effect)")
+
+        // Delegate to wallet's Effect.signTx with UTxO context
+        const witnessSet = yield* wallet.Effect.signTx(transaction, { utxos }).pipe(
+          Effect.mapError(
+            (walletError) =>
+              new TransactionBuilderError({ message: "Failed to sign transaction", cause: walletError })
+          )
+        )
+
+        yield* Effect.logDebug(`Received witness set from wallet: ${witnessSet.vkeyWitnesses?.length ?? 0} VKey witnesses`)
+
+        // Create signed transaction by combining transaction body with witness set
+        const signedTransaction = new Transaction.Transaction({
+          body: transaction.body,
+          witnessSet,
+          isValid: transaction.isValid,
+          auxiliaryData: transaction.auxiliaryData
+        })
+
+        yield* Effect.logDebug("Transaction signed successfully")
+
+        // Return SubmitBuilder
+        return makeSubmitBuilder(signedTransaction, witnessSet, provider)
+      }),
+
+    // TODO: Implement these methods
+    signWithWitness: (_witnessSet: TransactionWitnessSet.TransactionWitnessSet) =>
+      Effect.fail(new TransactionBuilderError({ message: "signWithWitness not yet implemented" })),
+
+    assemble: (_witnesses: ReadonlyArray<TransactionWitnessSet.TransactionWitnessSet>) =>
+      Effect.fail(new TransactionBuilderError({ message: "assemble not yet implemented" })),
+
+    partialSign: () => Effect.fail(new TransactionBuilderError({ message: "partialSign not yet implemented" })),
+
+    getWitnessSet: () => Effect.succeed(transaction.witnessSet),
+
+    toTransaction: () => Effect.succeed(transaction),
+
+    toTransactionWithFakeWitnesses: () => Effect.succeed(transactionWithFakeWitnesses),
+
+    estimateFee: () => Effect.succeed(fee)
+  }
+
+  // ============================================================================
+  // Promise-based API (using Effect.runPromise)
+  // ============================================================================
+
+  return {
+    Effect: signEffect,
+    sign: () => Effect.runPromise(signEffect.sign()),
+    signWithWitness: (witnessSet: TransactionWitnessSet.TransactionWitnessSet) =>
+      Effect.runPromise(signEffect.signWithWitness(witnessSet)),
+    assemble: (witnesses: ReadonlyArray<TransactionWitnessSet.TransactionWitnessSet>) =>
+      Effect.runPromise(signEffect.assemble(witnesses)),
+    partialSign: () => Effect.runPromise(signEffect.partialSign()),
+    getWitnessSet: () => Effect.runPromise(signEffect.getWitnessSet()),
+    toTransaction: () => Effect.runPromise(signEffect.toTransaction()),
+    toTransactionWithFakeWitnesses: () => Effect.runPromise(signEffect.toTransactionWithFakeWitnesses()),
+    estimateFee: () => Effect.runPromise(signEffect.estimateFee())
+  }
+}
diff --git a/packages/evolution/src/sdk/builders/SubmitBuilder.ts b/packages/evolution/src/sdk/builders/SubmitBuilder.ts
new file mode 100644
index 00000000..512fe2f9
--- /dev/null
+++ b/packages/evolution/src/sdk/builders/SubmitBuilder.ts
@@ -0,0 +1,60 @@
+/**
+ * SubmitBuilder - Final stage of transaction lifecycle
+ * 
+ * Represents a signed transaction ready for submission to the blockchain.
+ * Provides the submit() method to broadcast the transaction and retrieve the transaction hash.
+ * 
+ * @since 2.0.0
+ * @category builders
+ */
+
+import type { Effect } from "effect"
+
+import type * as TransactionWitnessSet from "../../core/TransactionWitnessSet.js"
+import type { EffectToPromiseAPI } from "../Type.js"
+import type { TransactionBuilderError } from "./TransactionBuilder.js"
+
+/**
+ * Effect-based API for SubmitBuilder operations.
+ * 
+ * @since 2.0.0
+ * @category interfaces
+ */
+export interface SubmitBuilderEffect {
+  /**
+   * Submit the signed transaction to the blockchain via the provider.
+   * 
+   * @returns Effect resolving to the transaction hash
+   * @since 2.0.0
+   */
+  readonly submit: () => Effect.Effect<string, TransactionBuilderError>
+}
+
+/**
+ * SubmitBuilder - represents a signed transaction ready for submission.
+ * 
+ * The final stage in the transaction lifecycle after building and signing.
+ * Provides the submit() method to broadcast the transaction to the blockchain
+ * and retrieve the transaction hash.
+ * 
+ * @since 2.0.0
+ * @category interfaces
+ */
+export interface SubmitBuilder extends EffectToPromiseAPI<SubmitBuilderEffect> {
+  /**
+   * Effect-based API for compositional workflows.
+   * 
+   * @since 2.0.0
+   */
+  readonly Effect: SubmitBuilderEffect
+
+  /**
+   * The witness set containing all signatures for this transaction.
+   * 
+   * Can be used to inspect the signatures or combine with other witness sets
+   * for multi-party signing scenarios.
+   * 
+   * @since 2.0.0
+   */
+  readonly witnessSet: TransactionWitnessSet.TransactionWitnessSet
+}
diff --git a/packages/evolution/src/sdk/builders/SubmitBuilderImpl.ts b/packages/evolution/src/sdk/builders/SubmitBuilderImpl.ts
new file mode 100644
index 00000000..4e203fc3
--- /dev/null
+++ b/packages/evolution/src/sdk/builders/SubmitBuilderImpl.ts
@@ -0,0 +1,64 @@
+/**
+ * SubmitBuilder Implementation
+ * 
+ * Handles transaction submission by delegating to the provider's submitTx method.
+ * The SubmitBuilder is responsible for:
+ * 1. Converting the signed transaction to CBOR hex format
+ * 2. Submitting to the provider's Effect.submitTx
+ * 3. Returning the transaction hash
+ * 
+ * @since 2.0.0
+ * @category builders
+ */
+
+import { Effect } from "effect"
+
+import * as Transaction from "../../core/Transaction.js"
+import type * as TransactionWitnessSet from "../../core/TransactionWitnessSet.js"
+import type * as Provider from "../provider/Provider.js"
+import type { SubmitBuilder, SubmitBuilderEffect } from "./SubmitBuilder.js"
+import { TransactionBuilderError } from "./TransactionBuilder.js"
+
+/**
+ * Create a SubmitBuilder instance for a signed transaction.
+ * 
+ * @param signedTransaction - The signed transaction ready for submission
+ * @param witnessSet - The witness set containing signatures
+ * @param provider - The provider to submit the transaction to
+ * 
+ * @since 2.0.0
+ * @category constructors
+ */
+export const makeSubmitBuilder = (
+  signedTransaction: Transaction.Transaction,
+  witnessSet: TransactionWitnessSet.TransactionWitnessSet,
+  provider: Provider.Provider
+): SubmitBuilder => {
+  const submitEffect: SubmitBuilderEffect = {
+    submit: () =>
+      Effect.gen(function* () {
+        yield* Effect.logDebug("Submitting transaction to provider")
+        
+        // Convert transaction to CBOR hex for provider submission
+        const txCborHex = Transaction.toCBORHex(signedTransaction)
+        
+        // Submit via provider's Effect.submitTx
+        const txHash = yield* provider.Effect.submitTx(txCborHex).pipe(
+          Effect.mapError(
+            (providerError) =>
+              new TransactionBuilderError({ message: "Failed to submit transaction", cause: providerError })
+          )
+        )
+        
+        yield* Effect.logDebug(`Transaction submitted successfully: ${txHash}`)
+        
+        return txHash
+      })
+  }
+  
+  return {
+    Effect: submitEffect,
+    submit: () => Effect.runPromise(submitEffect.submit()),
+    witnessSet
+  }
+}
diff --git a/packages/evolution/src/sdk/builders/TransactionBuilder.ts b/packages/evolution/src/sdk/builders/TransactionBuilder.ts
index 83572e53..274c154c 100644
--- a/packages/evolution/src/sdk/builders/TransactionBuilder.ts
+++ b/packages/evolution/src/sdk/builders/TransactionBuilder.ts
@@ -32,11 +32,15 @@ import type * as Coin from "../../core/Coin.js"
 import * as Transaction from "../../core/Transaction.js"
 import * as Assets from "../Assets.js"
 import type { EvalRedeemer } from "../EvalRedeemer.js"
+import type * as Provider from "../provider/Provider.js"
 import type * as UTxO from "../UTxO.js"
+import type * as WalletNew from "../wallet/WalletNew.js"
 import type { CoinSelectionAlgorithm, CoinSelectionFunction } from "./CoinSelection.js"
 import { largestFirstSelection } from "./CoinSelection.js"
 import type { CollectFromParams, PayToAddressParams } from "./operations/Operations.js"
 import type { SignBuilder } from "./SignBuilder.js"
+import { makeSignBuilder } from "./SignBuilderImpl.js"
+import { makeTransactionResult } from "./TransactionResult.js"
 import {
   assembleTransaction,
   buildFakeWitnessSet,
@@ -45,33 +49,11 @@ import {
   calculateMinimumUtxoLovelace,
   calculateTotalAssets,
   calculateTransactionSize,
-  createChangeOutput,
   createCollectFromProgram,
-  createPayToAddressProgram,
-  makeTxOutput,
-  verifyTransactionBalance
+  createPayToAddressProgram
 } from "./TxBuilderImpl.js"
 import * as Unfrack from "./Unfrack.js"
 
-// ============================================================================
-// Constants
-// ============================================================================
-
-/**
- * Maximum number of re-selection attempts when balancing transaction.
- *
- * During transaction building, if the actual fee (calculated with fake witnesses)
- * exceeds the initial estimate and causes insufficient balance, the builder will
- * retry coin selection up to this many times with updated fee estimates.
- *
- * @since 2.0.0
- */
-const MAX_RESELECTION_ATTEMPTS = 3
-
-// ============================================================================
-// Error Types
-// ============================================================================
-
 /**
  * Error type for failures occurring during transaction builder operations.
  *
@@ -83,10 +65,6 @@ export class TransactionBuilderError extends Data.TaggedError("TransactionBuilde
   cause?: unknown
 }> {}
 
-// ============================================================================
-// Transaction Types
-// ============================================================================
-
 export interface ChainResult {
   readonly transaction: Transaction.Transaction
   readonly newOutputs: ReadonlyArray<UTxO.UTxO> // UTxOs created by this transaction
@@ -295,6 +273,29 @@ export interface UnfrackOptions {
 
 // Build configuration options
 export interface BuildOptions {
+  /**
+   * Override protocol parameters for this specific transaction build.
+   *
+   * By default, fetches from provider during build().
+   * Provide this to use different protocol parameters for testing or special cases.
+   *
+   * Use cases:
+   * - Testing with different fee parameters
+   * - Simulating future protocol changes
+   * - Using cached parameters to avoid provider fetch
+   *
+   * Example:
+   * ```typescript
+   * // Test with custom fee parameters
+   * builder.build({
+   *   protocolParameters: { ...params, minFeeCoefficient: 50n, minFeeConstant: 200000n }
+   * })
+   * ```
+   *
+   * @since 2.0.0
+   */
+  readonly protocolParameters?: ProtocolParameters
+
   /**
    * Coin selection strategy for automatic input selection.
    *
@@ -319,6 +320,56 @@ export interface BuildOptions {
   // Change Handling Configuration
   // ============================================================================
 
+  /**
+   * Override the change address for this specific transaction build.
+   *
+   * By default, uses wallet.Effect.address() from TxBuilderConfig.
+   * Provide this to use a different address for change outputs.
+   *
+   * Use cases:
+   * - Multi-address wallet (use account index 5 for change)
+   * - Different change address per transaction
+   * - Multi-sig workflows where change address varies
+   * - Testing with different addresses
+   *
+   * Example:
+   * ```typescript
+   * // Use different account for change
+   * builder.build({ changeAddress: wallet.addresses[5] })
+   *
+   * // Custom address
+   * builder.build({ changeAddress: "addr_test1..." })
+   * ```
+   *
+   * @since 2.0.0
+   */
+  readonly changeAddress?: string
+
+  /**
+   * Override the available UTxOs for this specific transaction build.
+   *
+   * By default, fetches UTxOs from provider.Effect.getUtxos(wallet.address).
+   * Provide this to use a specific set of UTxOs for coin selection.
+   *
+   * Use cases:
+   * - Use UTxOs from specific account index
+   * - Pre-filtered UTxO set
+   * - Testing with known UTxO set
+   * - Multi-address UTxO aggregation
+   *
+   * Example:
+   * ```typescript
+   * // Use UTxOs from specific account
+   * builder.build({ availableUtxos: utxosFromAccount5 })
+   *
+   * // Combine UTxOs from multiple addresses
+   * builder.build({ availableUtxos: [...utxos1, ...utxos2] })
+   * ```
+   *
+   * @since 2.0.0
+   */
+  readonly availableUtxos?: ReadonlyArray<UTxO.UTxO>
+
   /**
    * # Change Handling Strategy Matrix
    * 
@@ -434,12 +485,11 @@ export interface BuildOptions {
   readonly useStateMachine?: boolean
 
   /**
-   * **EXPERIMENTAL**: Use V3 4-phase state machine
    *
-   * When true, uses V3's simplified 4-phase state machine:
+   * When true, uses simplified 4-phase state machine:
    * - selection → changeValidation → balanceVerification → fallback → complete
    *
-   * V3 shares TxContext with V2 but uses mathematical validation approach.
+   * shares TxContext with V2 but uses mathematical validation approach.
    *
    * @experimental
    * @default false
@@ -506,33 +556,47 @@ export interface ProtocolParameters {
  * Configuration for TransactionBuilder.
  * Immutable configuration passed to builder at creation time.
  *
- * Contains:
- * - Protocol parameters for fee calculation
- * - Change address for leftover funds
- * - Available UTxOs for coin selection
+ * Wallet-centric design (when wallet provided):
+ * - Wallet provides change address (via wallet.Effect.address())
+ * - Provider + Wallet provide available UTxOs (via provider.Effect.getUtxos(wallet.address))
+ * - Override per-build via BuildOptions if needed
+ *
+ * Manual mode (no wallet):
+ * - Must provide changeAddress and availableUtxos in BuildOptions for each build
+ * - Used for read-only scenarios or advanced use cases
  *
  * @since 2.0.0
  * @category config
  */
 export interface TxBuilderConfig {
-  readonly protocolParameters: ProtocolParameters
-
   /**
-   * Address to send change (leftover assets) to.
-   * This is required for proper transaction balancing.
+   * Optional wallet provides:
+   * - Change address via wallet.Effect.address()
+   * - Available UTxOs via wallet.Effect.address() + provider.Effect.getUtxos()
+   * - Signing capability via wallet.Effect.signTx() (SigningWallet and ApiWallet only)
+   *
+   * When provided: Automatic change address and UTxO resolution.
+   * When omitted: Must provide changeAddress and availableUtxos in BuildOptions.
+   *
+   * ReadOnlyWallet: For read-only clients that can build but not sign transactions.
+   * SigningWallet/ApiWallet: For signing clients with full transaction signing capability.
+   *
+   * Override per-build via BuildOptions.changeAddress and BuildOptions.availableUtxos.
    */
-  readonly changeAddress: string
+  readonly wallet?: WalletNew.SigningWallet | WalletNew.ApiWallet | WalletNew.ReadOnlyWallet
 
   /**
-   * UTxOs available for coin selection.
-   * These can be from a wallet, another user, or any other source.
-   * Coin selection will automatically select from these UTxOs to cover
-   * required outputs + fees, excluding any already collected via collectFrom().
+   * Optional provider for:
+   * - Fetching UTxOs for the wallet's address (provider.Effect.getUtxos)
+   * - Transaction submission (provider.Effect.submitTx)
+   * - Protocol parameters
+   *
+   * Works together with wallet to provide everything needed for transaction building.
+   * When wallet is omitted, provider is only used if you call provider methods directly.
    */
-  readonly availableUtxos: ReadonlyArray<UTxO.UTxO>
+  readonly provider?: Provider.Provider
 
   // Future fields:
-  // readonly provider?: any // Provider interface for blockchain communication
   // readonly costModels?: Uint8Array // Cost models for script evaluation
 }
 
@@ -613,6 +677,48 @@ export interface TxContextData {
  */
 export class TxContext extends Context.Tag("TxContext")<TxContext, TxContextData>() {}
 
+/**
+ * Resolved change address for the current build.
+ * This is resolved once at the start of build() from either:
+ * - BuildOptions.changeAddress (per-transaction override)
+ * - TxBuilderConfig.wallet.Effect.address() (default from wallet)
+ *
+ * Available to all phase functions via Effect Context.
+ *
+ * @since 2.0.0
+ * @category context
+ */
+export class ChangeAddressTag extends Context.Tag("ChangeAddress")<ChangeAddressTag, string>() {}
+
+/**
+ * Resolved protocol parameters for the current build.
+ * This is resolved once at the start of build() from either:
+ * - BuildOptions.protocolParameters (per-transaction override)
+ * - provider.Effect.getProtocolParameters() (fetched from provider)
+ *
+ * Available to all phase functions via Effect Context.
+ *
+ * @since 2.0.0
+ * @category context
+ */
+export class ProtocolParametersTag extends Context.Tag("ProtocolParameters")<
+  ProtocolParametersTag,
+  ProtocolParameters
+>() {}
+
+/**
+ * Resolved available UTxOs for the current build.
+ * This is resolved once at the start of build() from either:
+ * - BuildOptions.availableUtxos (per-transaction override)
+ * - provider.Effect.getUtxos(wallet.address) (default from wallet + provider)
+ *
+ * Available to all phase functions via Effect Context.
+ *
+ * @since 2.0.0
+ * @category context
+ */
+export class AvailableUtxosTag extends Context.Tag("AvailableUtxos")<AvailableUtxosTag, ReadonlyArray<UTxO.UTxO>>() {}
+
 // ============================================================================
 // Program Step Type - Deferred Execution Pattern
 // ============================================================================
@@ -664,6 +770,11 @@ export type ProgramStep = Effect.Effect<void, TransactionBuilderError, TxContext
  * Builder instance never mutates. Programs are deferred Effects that execute later.
  * Each build() creates fresh TxBuilderState, executes programs, returns result.
  *
+ * Generic Type Parameter:
+ * TResult determines the return type of build() methods:
+ * - SignBuilder: When wallet has signing capability (SigningClient)
+ * - TransactionResultBase: When wallet is read-only (ReadOnlyClient)
+ *
  * Usage Pattern:
  * ```typescript
  * const builder = makeTxBuilder(provider, params, costModels, utxos)
@@ -677,10 +788,12 @@ export type ProgramStep = Effect.Effect<void, TransactionBuilderError, TxContext
  * const signBuilder2 = await builder.build()
  * ```
  *
+ * @typeParam TResult - The result type returned by build methods (SignBuilder or TransactionResultBase)
+ *
  * @since 2.0.0
  * @category interfaces
  */
-export interface TransactionBuilder {
+export interface TransactionBuilder<TResult = SignBuilder> {
   // ============================================================================
   // Chainable Builder Methods - Create ProgramSteps, return same builder
   // ============================================================================
@@ -694,7 +807,7 @@ export interface TransactionBuilder {
    * @since 2.0.0
    * @category builder-methods
    */
-  readonly payToAddress: (params: PayToAddressParams) => TransactionBuilder
+  readonly payToAddress: (params: PayToAddressParams) => TransactionBuilder<TResult>
 
   /**
    * Specify transaction inputs from provided UTxOs.
@@ -705,7 +818,7 @@ export interface TransactionBuilder {
    * @since 2.0.0
    * @category builder-methods
    */
-  readonly collectFrom: (params: CollectFromParams) => TransactionBuilder
+  readonly collectFrom: (params: CollectFromParams) => TransactionBuilder<TResult>
 
   // Future expansion points for other operations:
   // readonly mintTokens: (params: MintTokensParams) => TransactionBuilder
@@ -724,10 +837,14 @@ export interface TransactionBuilder {
    * Creates fresh state and runs all accumulated ProgramSteps sequentially.
    * Can be called multiple times on the same builder instance with independent results.
    *
+   * Returns TResult which is:
+   * - SignBuilder for SigningClient (can sign transactions)
+   * - TransactionResultBase for ReadOnlyClient (unsigned transaction only)
+   *
    * @since 2.0.0
    * @category completion-methods
    */
-  readonly build: (options?: BuildOptions) => Promise<SignBuilder>
+  readonly build: (options?: BuildOptions) => Promise<TResult>
 
   /**
    * Execute all queued operations and return a signing-ready transaction via Effect.
@@ -735,25 +852,43 @@ export interface TransactionBuilder {
    * Creates fresh state and runs all accumulated ProgramSteps sequentially.
    * Suitable for Effect-TS compositional workflows and error handling.
    *
+   * Error types include WalletError and ProviderError from config Effects.
+   *
+   * Returns TResult which is:
+   * - SignBuilder for SigningClient (can sign transactions)
+   * - TransactionResultBase for ReadOnlyClient (unsigned transaction only)
+   *
    * @since 2.0.0
    * @category completion-methods
    */
   readonly buildEffect: (
     options?: BuildOptions
-  ) => Effect.Effect<SignBuilder, TransactionBuilderError | EvaluationError, unknown>
+  ) => Effect.Effect<
+    TResult,
+    TransactionBuilderError | EvaluationError | WalletNew.WalletError | Provider.ProviderError,
+    unknown
+  >
 
   /**
    * Execute all queued operations with explicit error handling via Either.
    *
    * Creates fresh state and runs all accumulated ProgramSteps sequentially.
-   * Returns Either<SignBuilder, Error> for pattern-matched error recovery.
+   * Returns Either<TResult, Error> for pattern-matched error recovery.
+   *
+   * Error types include WalletError and ProviderError from config Effects.
+   *
+   * Returns TResult which is:
+   * - SignBuilder for SigningClient (can sign transactions)
+   * - TransactionResultBase for ReadOnlyClient (unsigned transaction only)
    *
    * @since 2.0.0
    * @category completion-methods
    */
   readonly buildEither: (
     options?: BuildOptions
-  ) => Promise<Either<SignBuilder, TransactionBuilderError | EvaluationError>>
+  ) => Promise<
+    Either<TResult, TransactionBuilderError | EvaluationError | WalletNew.WalletError | Provider.ProviderError>
+  >
 
   // ============================================================================
   // Transaction Chaining Methods - Multi-transaction workflows
@@ -825,1854 +960,121 @@ export interface TransactionBuilder {
 
 // ============================================================================
 // Factory Function - Creates TransactionBuilder instances
-// ============================================================================
-
-/**
- * Construct a TransactionBuilder instance from protocol configuration.
- * 
- * The builder accumulates chainable method calls as deferred ProgramSteps. Calling build() or chain()
- * creates fresh state (new Refs) and executes all accumulated programs sequentially, ensuring
- * no state pollution between invocations.
- * 
- * @since 2.0.0
- * @category constructors
- */
-export const makeTxBuilder = (config: TxBuilderConfig): TransactionBuilder => {
-  // Validate protocol parameters
-  if (config.protocolParameters.minFeeCoefficient < 0n) {
-    throw new Error("minFeeCoefficient must be non-negative")
-  }
-
-  if (config.protocolParameters.minFeeConstant < 0n) {
-    throw new Error("minFeeConstant must be non-negative")
-  }
-
-  if (config.protocolParameters.coinsPerUtxoByte < 0n) {
-    throw new Error("coinsPerUtxoByte must be non-negative")
-  }
-
-  if (config.protocolParameters.maxTxSize <= 0) {
-    throw new Error("maxTxSize must be positive")
-  }
-
-  // ProgramSteps array - stores deferred operations
-  // NO state created here - state is fresh per build()
-  const programs: Array<ProgramStep> = []
-
-  // Helper: Get coin selection algorithm function from name
-  const getCoinSelectionAlgorithm = (algorithm: CoinSelectionAlgorithm): CoinSelectionFunction => {
-    switch (algorithm) {
-      case "largest-first":
-        return largestFirstSelection
-      case "random-improve":
-        throw new TransactionBuilderError({
-          message: "random-improve algorithm not yet implemented",
-          cause: { algorithm }
-        })
-      case "optimal":
-        throw new TransactionBuilderError({
-          message: "optimal algorithm not yet implemented",
-          cause: { algorithm }
-        })
-      default:
-        throw new TransactionBuilderError({
-          message: `Unknown coin selection algorithm: ${algorithm}`,
-          cause: { algorithm }
-        })
-    }
-  }
-
-  // Helper: Create fresh state Effect
-  const createFreshState = () =>
-    Effect.gen(function* () {
-      return {
-        selectedUtxos: yield* Ref.make<ReadonlyArray<UTxO.UTxO>>([]), // Array for ordering
-        outputs: yield* Ref.make<ReadonlyArray<any>>([]),
-        scripts: yield* Ref.make(new Map<string, any>()),
-        totalOutputAssets: yield* Ref.make<Assets.Assets>({ lovelace: 0n }),
-        totalInputAssets: yield* Ref.make<Assets.Assets>({ lovelace: 0n }),
-        redeemers: yield* Ref.make(new Map<string, RedeemerData>())
-      }
-    })
-
-  // Core Effect logic for building transaction
-  const buildEffectCore = (options?: BuildOptions) =>
-    Effect.gen(function* () {
-      const ctx = yield* TxContext
-
-      // 1. Execute all programs to populate state
-      yield* Effect.all(programs, { concurrency: "unbounded" })
-
-      // 2. Initial Coin Selection Phase
-      // collectFrom = explicit selection (user-specified inputs)
-      // availableUtxos = pool for automatic balancing (wallet UTxOs)
-      yield* Effect.logDebug("Starting initial coin selection phase")
-
-      // Get current input and output assets
-      const inputAssets = yield* Ref.get(ctx.state.totalInputAssets)
-      const outputAssets = yield* Ref.get(ctx.state.totalOutputAssets)
-      const estimatedFee = 200_000n // Conservative initial estimate
-
-      // Calculate asset delta: (outputs + estimated fee) - inputs
-      const assetDelta: Assets.Assets = { lovelace: 0n }
-      let hasPositiveDelta = false
-
-      // Calculate required assets (outputs + estimated fee)
-      const outputLovelace = outputAssets.lovelace || 0n
-      const requiredAssets: Assets.Assets = {
-        ...outputAssets,
-        lovelace: outputLovelace + estimatedFee
-      }
-
-      // Calculate delta for each asset unit
-      for (const [unit, required] of Object.entries(requiredAssets)) {
-        const available = (inputAssets[unit] as bigint) || 0n
-        const delta = required - available
-
-        if (delta > 0n) {
-          assetDelta[unit] = delta
-          hasPositiveDelta = true
-        }
-      }
-
-      // Run initial coin selection if we have positive asset delta
-      if (hasPositiveDelta) {
-        const assetDeltaStr = Object.entries(assetDelta)
-          .map(([unit, amount]) => `${unit}:${amount.toString()}`)
-          .join(", ")
-
-        yield* Effect.logDebug(`Initial coin selection for: {${assetDeltaStr}}`)
-
-        // Get available UTxOs from config for automatic balancing
-        const configUtxos = ctx.config.availableUtxos
-
-        // Get already-collected UTxOs to prevent double-spending
-        const alreadyCollected = yield* Ref.get(ctx.state.selectedUtxos)
-
-        // Filter out already-collected UTxOs
-        const availableUtxos = configUtxos.filter(
-          (utxo) =>
-            !alreadyCollected.some(
-              (collected) => collected.txHash === utxo.txHash && collected.outputIndex === utxo.outputIndex
-            )
-        )
-
-        // Determine coin selection function
-        const coinSelectionFn = options?.coinSelection
-          ? typeof options.coinSelection === "function"
-            ? options.coinSelection
-            : getCoinSelectionAlgorithm(options.coinSelection)
-          : largestFirstSelection // Default: largest-first
-
-        const { selectedUtxos: additionalUtxos } = yield* Effect.try({
-          try: () => coinSelectionFn(availableUtxos, assetDelta),
-          catch: (error) =>
-            new TransactionBuilderError({
-              message: "Initial coin selection failed",
-              cause: error
-            })
-        })
-
-        yield* Effect.logDebug(
-          `Initial coin selection added ${additionalUtxos.length} UTxOs ` + `(${availableUtxos.length} available)`
-        )
-
-        // Add selected UTxOs to state
-        yield* Ref.update(ctx.state.selectedUtxos, (current) => [...current, ...additionalUtxos])
-
-        // Update total input assets
-        for (const utxo of additionalUtxos) {
-          yield* Ref.update(ctx.state.totalInputAssets, (current) => {
-            const updated = { ...current }
-            for (const [unit, amount] of Object.entries(utxo.assets)) {
-              updated[unit] = (updated[unit] || 0n) + (amount as bigint)
-            }
-            return updated
-          })
-        }
-
-        yield* Effect.logDebug(`Initial coin selection added ${additionalUtxos.length} UTxOs`)
-      } else {
-        yield* Effect.logDebug("Inputs already cover outputs + estimated fee, skipping initial coin selection")
-      }
-
-      // 3. Reselection Loop: Create change, calculate actual fee, verify balance
-      // Now that we have initial coin selection, we iteratively:
-      // 1. Create change outputs from leftover assets
-      // 2. Calculate actual fee with complete output set
-      // 3. Verify balance is sufficient
-      // 4. If insufficient, select more UTxOs and retry
-      yield* Effect.logDebug("Starting reselection loop with change creation")
-
-      let attempt = 0
-      let calculatedFee = 0n
-      let balanceVerificationPassed = false
-
-      while (attempt < MAX_RESELECTION_ATTEMPTS && !balanceVerificationPassed) {
-        attempt++
-
-        yield* Effect.logDebug(`Reselection attempt ${attempt}/${MAX_RESELECTION_ATTEMPTS}`)
-
-        // Get current state
-        const selectedUtxos = yield* Ref.get(ctx.state.selectedUtxos)
-        const baseOutputs = yield* Ref.get(ctx.state.outputs)
-        const inputAssets = yield* Ref.get(ctx.state.totalInputAssets)
-        const outputAssets = yield* Ref.get(ctx.state.totalOutputAssets)
-
-        yield* Effect.logDebug(
-          `Reselection state: ${selectedUtxos.length} UTxOs selected, ` +
-            `inputs: ${inputAssets.lovelace || 0n} lovelace, ` +
-            `outputs: ${outputAssets.lovelace || 0n} lovelace`
-        )
-
-        // Convert UTxOs to TransactionInputs for fee calculation
-        const inputs = yield* Effect.catchAll(buildTransactionInputs(selectedUtxos), (error) =>
-          Effect.gen(function* () {
-            yield* Effect.logError(`Failed to build transaction inputs: ${JSON.stringify(error, null, 2)}`)
-            return yield* Effect.fail(error)
-          })
-        )
-
-        yield* Effect.logDebug(`Successfully built ${inputs.length} transaction inputs`)
-
-        // Estimate fee for current transaction WITHOUT change outputs
-        // This gives us a baseline fee to reserve from leftover
-        const baseFee = yield* calculateFeeIteratively(selectedUtxos, inputs, baseOutputs, {
-          minFeeCoefficient: ctx.config.protocolParameters.minFeeCoefficient,
-          minFeeConstant: ctx.config.protocolParameters.minFeeConstant
-        })
-
-        yield* Effect.logDebug(`Base fee (without change): ${baseFee} lovelace`)
-
-        // Calculate leftover assets (inputs - outputs - estimatedFee)
-        // Reserve estimated fee so change outputs don't consume it
-        const leftoverAssets: Assets.Assets = { ...inputAssets, lovelace: 0n }
-        for (const [unit, amount] of Object.entries(outputAssets)) {
-          const current = leftoverAssets[unit] || 0n
-          const remaining = current - (amount as bigint)
-          if (remaining > 0n) {
-            leftoverAssets[unit] = remaining
-          } else {
-            delete leftoverAssets[unit]
-          }
-        }
-
-        // Subtract base fee from lovelace leftover
-        leftoverAssets.lovelace = Assets.getAsset(leftoverAssets, "lovelace") - baseFee
-
-        // Attempt to create change output(s) from leftover assets
-        let changeOutputs: Array<UTxO.TxOutput> = []
-
-        const leftoverLovelace = Assets.getAsset(leftoverAssets, "lovelace")
-
-        // BUG FIX: Check if leftover lovelace is negative BEFORE attempting change creation
-        // If we have insufficient funds (negative lovelace), skip change creation entirely
-        // and let balance verification trigger reselection
-        if (leftoverLovelace < 0n) {
-          yield* Effect.logDebug(
-            `Insufficient lovelace for fee: leftover is ${leftoverLovelace}. ` +
-              `Skipping change creation, balance verification will trigger reselection.`
-          )
-          // Set leftover to empty to skip change creation
-          // Native assets (if any) will be included in next reselection iteration
-        } else if (leftoverLovelace > 0n || Object.keys(leftoverAssets).length > 1) {
-          yield* Effect.logDebug("Attempting to create change output from leftover assets")
-
-          // Calculate actual minimum UTxO requirement using CBOR encoding
-          // This ensures accurate decision-making for complex asset bundles
-          const nativeAssetCount = Object.keys(leftoverAssets).length - 1 // Exclude 'lovelace'
-          yield* Effect.logDebug(`Change calculation: ${leftoverLovelace} lovelace + ${nativeAssetCount} native assets`)
-
-          const minUtxo = yield* calculateMinimumUtxoLovelace({
-            address: ctx.config.changeAddress,
-            assets: leftoverAssets,
-            coinsPerUtxoByte: ctx.config.protocolParameters.coinsPerUtxoByte
-          })
-
-          yield* Effect.logDebug(`MinUTxO requirement: ${minUtxo} lovelace (via actual CBOR calculation)`)
-
-          if (leftoverLovelace >= minUtxo) {
-            // SUCCESS: Leftover is sufficient for change output(s)
-
-            // Priority 1: Apply unfracking if configured
-            if (options?.unfrack) {
-              yield* Effect.logDebug("Applying unfrack optimization to change outputs")
-              const unfrackedOutputs = yield* createChangeOutput({
-                leftoverAssets,
-                changeAddress: ctx.config.changeAddress,
-                coinsPerUtxoByte: ctx.config.protocolParameters.coinsPerUtxoByte,
-                unfrackOptions: options.unfrack
-              })
-              changeOutputs = [...unfrackedOutputs]
-              yield* Effect.logDebug(`Created ${unfrackedOutputs.length} unfracked change outputs`)
-            } else {
-              // Priority 2: Create simple change output (no unfracking)
-              changeOutputs.push({
-                address: ctx.config.changeAddress,
-                assets: leftoverAssets
-              })
-              yield* Effect.logDebug(
-                `Created change output: ${leftoverLovelace} lovelace + ${Object.keys(leftoverAssets).length - 1} asset units`
-              )
-            }
-          } else {
-            // INSUFFICIENT: Try fallback strategies
-            yield* Effect.logDebug(`Change too small (${leftoverLovelace} < ${minUtxo}), attempting fallback`)
-
-            // Strategy 1: drainTo (merge with existing output)
-            if (options?.drainTo !== undefined) {
-              const drainToIndex = options.drainTo
-              const targetOutput = baseOutputs[drainToIndex]
-
-              if (!targetOutput) {
-                return yield* Effect.fail(
-                  new TransactionBuilderError({
-                    message: `drainTo index ${drainToIndex} out of bounds (${baseOutputs.length} outputs)`
-                  })
-                )
-              }
-
-              yield* Effect.logDebug(`Merging leftover into output #${drainToIndex} (drainTo strategy)`)
-
-              // Merge leftover into target output
-              const updatedAssets = Assets.add(targetOutput.assets, leftoverAssets)
-
-              const updatedOutput: UTxO.TxOutput = {
-                ...targetOutput,
-                assets: updatedAssets
-              }
-
-              // Validate that the merged output meets minimum UTxO requirements
-              const mergedMinUtxo = yield* calculateMinimumUtxoLovelace({
-                address: updatedOutput.address,
-                assets: updatedAssets,
-                datum: updatedOutput.datumOption,
-                scriptRef: updatedOutput.scriptRef,
-                coinsPerUtxoByte: ctx.config.protocolParameters.coinsPerUtxoByte
-              })
-
-              const updatedLovelace = Assets.getAsset(updatedAssets, "lovelace")
-
-              yield* Effect.logDebug(
-                `drainTo validation: Merged output has ${updatedLovelace} lovelace ` + `(minUTxO: ${mergedMinUtxo})`
-              )
-
-              if (updatedLovelace < mergedMinUtxo) {
-                return yield* Effect.fail(
-                  new TransactionBuilderError({
-                    message:
-                      `drainTo validation failed: Merged output at index ${drainToIndex} ` +
-                      `has ${updatedLovelace} lovelace but requires minimum ${mergedMinUtxo}. ` +
-                      `The target output has too many assets to absorb the small leftover. ` +
-                      `Consider using a different drainTo target or adding more funds.`
-                  })
-                )
-              }
-
-              // Replace the target output in base outputs
-              const updatedBaseOutputs = [...baseOutputs]
-              updatedBaseOutputs[drainToIndex] = updatedOutput
-
-              yield* Ref.set(ctx.state.outputs, updatedBaseOutputs)
-              yield* Effect.logDebug(
-                `Successfully merged leftover via drainTo (validated: ${updatedLovelace} >= ${mergedMinUtxo})`
-              )
-
-              // No change outputs needed (merged into existing)
-              changeOutputs = []
-            } else {
-              // Strategy 2: Check onInsufficientChange option
-              const hasNativeAssets = Object.keys(leftoverAssets).length > 1
-
-              if (hasNativeAssets) {
-                // Native assets cannot be burned as fee - they would be lost forever
-                // STRATEGY: Create a change output with minUTxO requirement even though
-                // we don't have enough lovelace yet. This will cause balance verification
-                // to detect the shortfall and trigger reselection for more lovelace.
-                const lovelaceShortfall = minUtxo - leftoverLovelace
-
-                yield* Effect.logDebug(
-                  `Insufficient change with native assets: ${leftoverLovelace} < ${minUtxo}. ` +
-                    `Shortfall: ${lovelaceShortfall} lovelace. ` +
-                    `Creating change output with minUTxO requirement to trigger reselection.`
-                )
-
-                // Create change output with the REQUIRED minUTxO amount (not what we have)
-                // This will cause balance verification to see we're short on lovelace
-                changeOutputs.push({
-                  address: ctx.config.changeAddress,
-                  assets: {
-                    ...leftoverAssets,
-                    lovelace: minUtxo // Use required amount, not available amount
-                  }
-                })
-
-                // Balance verification will detect:
-                // - We need minUtxo lovelace for change
-                // - We only have leftoverLovelace available
-                // - Shortfall = minUtxo - leftoverLovelace
-                // This will trigger reselection to add more UTxOs
-              } else {
-                // Only lovelace left and it's below minUtxo
-                const insufficientChangeStrategy = options?.onInsufficientChange ?? "error"
-
-                if (insufficientChangeStrategy === "burn") {
-                  // User explicitly consented to burn leftover lovelace as extra fee
-                  yield* Effect.logWarning(
-                    `Burning ${leftoverLovelace} lovelace as extra fee (below minUtxo ${minUtxo})`
-                  )
-                  // Leftover becomes extra fee (not added to outputs)
-                  changeOutputs = []
-                } else {
-                  // Default: Error to prevent accidental loss
-                  return yield* Effect.fail(
-                    new TransactionBuilderError({
-                      message:
-                        `Insufficient change: ${leftoverLovelace} lovelace is below ` +
-                        `minimum UTxO (${minUtxo}). Configure drainTo to merge with an existing output, ` +
-                        `or set onInsufficientChange: 'burn' to explicitly allow burning as extra fee.`
-                    })
-                  )
-                }
-              }
-            }
-          }
-        } else {
-          yield* Effect.logDebug("No leftover assets, skipping change creation")
-        }
-
-        // Build complete output set: base outputs + change outputs
-        const currentBaseOutputs = yield* Ref.get(ctx.state.outputs) // Re-fetch in case drainTo modified it
-        const allOutputs = [...currentBaseOutputs, ...changeOutputs]
-
-        // Calculate actual fee with complete outputs (including change)
-        calculatedFee = yield* calculateFeeIteratively(selectedUtxos, inputs, allOutputs, {
-          minFeeCoefficient: ctx.config.protocolParameters.minFeeCoefficient,
-          minFeeConstant: ctx.config.protocolParameters.minFeeConstant
-        })
-
-        yield* Effect.logDebug(`Calculated fee with ${allOutputs.length} outputs: ${calculatedFee} lovelace`)
-
-        // Check if actual fee differs from base fee
-        // Recalculation needed when: (1) change outputs exist, OR (2) drainTo was used
-        const needsRecalculation = changeOutputs.length > 0 || options?.drainTo !== undefined
-        if (calculatedFee !== baseFee && needsRecalculation) {
-          const feeDelta = calculatedFee - baseFee
-          yield* Effect.logDebug(
-            `Fee adjustment triggered: ${baseFee} → ${calculatedFee} (Δ +${feeDelta} lovelace). ` +
-              `Recalculating change outputs with correct fee.`
-          )
-
-          // Recalculate leftover with ACTUAL fee
-          const correctedLeftover: Assets.Assets = { ...inputAssets, lovelace: 0n }
-          for (const [unit, amount] of Object.entries(outputAssets)) {
-            const current = correctedLeftover[unit] || 0n
-            const remaining = current - (amount as bigint)
-            if (remaining > 0n) {
-              correctedLeftover[unit] = remaining
-            } else {
-              delete correctedLeftover[unit]
-            }
-          }
-
-          // Subtract ACTUAL fee from lovelace leftover
-          const feeUsedForLeftover = calculatedFee // Track which fee we used
-          const currentCorrectedLovelace = Assets.getAsset(correctedLeftover, "lovelace")
-          correctedLeftover.lovelace = currentCorrectedLovelace - calculatedFee
-
-          const correctedLovelace = Assets.getAsset(correctedLeftover, "lovelace")
-          if (correctedLovelace >= 0n && (correctedLovelace > 0n || Object.keys(correctedLeftover).length > 1)) {
-            // Recreate change outputs with corrected leftover
-            if (options?.unfrack) {
-              yield* Effect.logDebug("Applying unfrack to corrected change outputs")
-              const recalculatedOutputs = yield* createChangeOutput({
-                leftoverAssets: correctedLeftover,
-                changeAddress: ctx.config.changeAddress,
-                coinsPerUtxoByte: ctx.config.protocolParameters.coinsPerUtxoByte,
-                unfrackOptions: options.unfrack
-              })
-              changeOutputs = [...recalculatedOutputs]
-
-              // Rebuild complete output set with corrected change
-              const updatedAllOutputs = [...currentBaseOutputs, ...changeOutputs]
-
-              // Recalculate fee with corrected outputs
-              const recalculatedFee = yield* calculateFeeIteratively(selectedUtxos, inputs, updatedAllOutputs, {
-                minFeeCoefficient: ctx.config.protocolParameters.minFeeCoefficient,
-                minFeeConstant: ctx.config.protocolParameters.minFeeConstant
-              })
-
-              calculatedFee = recalculatedFee
-              // Update allOutputs for balance verification
-              let allOutputsFixed = updatedAllOutputs
-
-              yield* Effect.logDebug(`Recalculated fee after correction: ${calculatedFee} lovelace`)
-
-              // If fee changed during recalculation, adjust the outputs again
-              if (recalculatedFee !== feeUsedForLeftover) {
-                const feeAdjustment = feeUsedForLeftover - recalculatedFee
-                yield* Effect.logDebug(
-                  `Fee changed during unfrack recalculation. Adjusting outputs by ${feeAdjustment} lovelace`
-                )
-
-                // Add the fee difference to the first change output
-                if (allOutputsFixed.length > currentBaseOutputs.length) {
-                  const firstChangeIndex = currentBaseOutputs.length
-                  allOutputsFixed = [...allOutputsFixed]
-                  allOutputsFixed[firstChangeIndex] = {
-                    ...allOutputsFixed[firstChangeIndex],
-                    assets: {
-                      ...allOutputsFixed[firstChangeIndex].assets,
-                      lovelace: allOutputsFixed[firstChangeIndex].assets.lovelace + feeAdjustment
-                    }
-                  }
-                }
-              }
-
-              // Use corrected outputs for balance check
-              const balanceCheckCorrected = verifyTransactionBalance(selectedUtxos, allOutputsFixed, calculatedFee)
-
-              if (balanceCheckCorrected.sufficient) {
-                // ✅ SUCCESS with corrected change
-                balanceVerificationPassed = true
-                yield* Ref.set(ctx.state.outputs, allOutputsFixed)
-                yield* Effect.logDebug(
-                  `Balance verification passed after correction on attempt ${attempt}. ` +
-                    `Fee: ${calculatedFee}, Change: ${balanceCheckCorrected.change} lovelace`
-                )
-                continue // Skip to next iteration (which will exit since balanceVerificationPassed = true)
-              }
-            } else if (options?.drainTo !== undefined) {
-              // Handle drainTo without unfrack: merge corrected leftover into target output
-              const drainToIndex = options.drainTo
-              const targetOutput = baseOutputs[drainToIndex] // Use ORIGINAL base outputs, not modified ones
-
-              if (!targetOutput) {
-                return yield* Effect.fail(
-                  new TransactionBuilderError({
-                    message: `drainTo index ${drainToIndex} out of bounds after recalculation`
-                  })
-                )
-              }
-
-              // Merge corrected leftover into target output
-              const updatedAssets = Assets.add(targetOutput.assets, correctedLeftover)
-
-              const updatedOutput: UTxO.TxOutput = {
-                ...targetOutput,
-                assets: updatedAssets
-              }
-
-              // Validate that the merged output meets minimum UTxO requirements
-              const mergedMinUtxo = yield* calculateMinimumUtxoLovelace({
-                address: updatedOutput.address,
-                assets: updatedAssets,
-                datum: updatedOutput.datumOption,
-                scriptRef: updatedOutput.scriptRef,
-                coinsPerUtxoByte: ctx.config.protocolParameters.coinsPerUtxoByte
-              })
-
-              const recalcUpdatedLovelace = Assets.getAsset(updatedAssets, "lovelace")
-              if (recalcUpdatedLovelace < mergedMinUtxo) {
-                return yield* Effect.fail(
-                  new TransactionBuilderError({
-                    message:
-                      `drainTo validation failed after fee recalculation: Merged output at index ${drainToIndex} ` +
-                      `has ${recalcUpdatedLovelace} lovelace but requires minimum ${mergedMinUtxo}. ` +
-                      `The target output has too many assets to absorb the corrected leftover. ` +
-                      `Consider using a different drainTo target or adding more funds.`
-                  })
-                )
-              }
-
-              // Replace the target output
-              const updatedBaseOutputs = [...baseOutputs] // Start from ORIGINAL outputs
-              updatedBaseOutputs[drainToIndex] = updatedOutput
-
-              // Recalculate fee with corrected drainTo output
-              const recalculatedFee = yield* calculateFeeIteratively(selectedUtxos, inputs, updatedBaseOutputs, {
-                minFeeCoefficient: ctx.config.protocolParameters.minFeeCoefficient,
-                minFeeConstant: ctx.config.protocolParameters.minFeeConstant
-              })
-
-              calculatedFee = recalculatedFee
-
-              yield* Effect.logDebug(`Recalculated fee after drainTo correction: ${calculatedFee} lovelace`)
-
-              // If fee changed during recalculation, adjust the output again
-              if (recalculatedFee !== feeUsedForLeftover) {
-                const feeAdjustment = feeUsedForLeftover - recalculatedFee
-                yield* Effect.logDebug(
-                  `Fee changed during recalculation. Adjusting output by ${feeAdjustment} lovelace`
-                )
-                const currentDrainToLovelace = Assets.getAsset(updatedBaseOutputs[drainToIndex].assets, "lovelace")
-                updatedBaseOutputs[drainToIndex] = {
-                  ...updatedBaseOutputs[drainToIndex],
-                  assets: {
-                    ...updatedBaseOutputs[drainToIndex].assets,
-                    lovelace: currentDrainToLovelace + feeAdjustment
-                  }
-                }
-
-                // Re-validate after fee adjustment
-                const adjustedMinUtxo = yield* calculateMinimumUtxoLovelace({
-                  address: updatedBaseOutputs[drainToIndex].address,
-                  assets: updatedBaseOutputs[drainToIndex].assets,
-                  datum: updatedBaseOutputs[drainToIndex].datumOption,
-                  scriptRef: updatedBaseOutputs[drainToIndex].scriptRef,
-                  coinsPerUtxoByte: ctx.config.protocolParameters.coinsPerUtxoByte
-                })
-
-                const adjustedLovelace = Assets.getAsset(updatedBaseOutputs[drainToIndex].assets, "lovelace")
-                if (adjustedLovelace < adjustedMinUtxo) {
-                  return yield* Effect.fail(
-                    new TransactionBuilderError({
-                      message:
-                        `drainTo validation failed after fee adjustment: Output at index ${drainToIndex} ` +
-                        `has ${adjustedLovelace} lovelace but requires minimum ${adjustedMinUtxo}.`
-                    })
-                  )
-                }
-              }
-
-              // Use corrected outputs for balance check
-              const balanceCheckCorrected = verifyTransactionBalance(selectedUtxos, updatedBaseOutputs, calculatedFee)
-
-              if (balanceCheckCorrected.sufficient) {
-                // ✅ SUCCESS with corrected drainTo
-                balanceVerificationPassed = true
-                yield* Ref.set(ctx.state.outputs, updatedBaseOutputs)
-                yield* Effect.logDebug(
-                  `Balance verification passed after drainTo correction on attempt ${attempt}. ` +
-                    `Fee: ${calculatedFee}, Change: ${balanceCheckCorrected.change} lovelace`
-                )
-                continue // Skip to next iteration (which will exit since balanceVerificationPassed = true)
-              } else {
-                yield* Effect.logWarning(
-                  `Balance check failed after drainTo correction. Shortfall: ${balanceCheckCorrected.shortfall}`
-                )
-              }
-            } else {
-              // Handle simple change output (no unfrack, no drainTo)
-              // Just update the change output's lovelace with the corrected amount
-              if (changeOutputs.length > 0) {
-                const feeDifference = calculatedFee - baseFee
-                yield* Effect.logDebug(`Adjusting simple change output by -${feeDifference} lovelace (fee increased)`)
-
-                changeOutputs = changeOutputs.map((output) => {
-                  const currentOutputLovelace = Assets.getAsset(output.assets, "lovelace")
-                  return {
-                    ...output,
-                    assets: {
-                      ...output.assets,
-                      lovelace: currentOutputLovelace - feeDifference
-                    }
-                  }
-                })
-
-                // Rebuild complete output set with adjusted change
-                const adjustedAllOutputs = [...currentBaseOutputs, ...changeOutputs]
-
-                // Verify the adjusted outputs meet balance
-                const balanceCheckAdjusted = verifyTransactionBalance(selectedUtxos, adjustedAllOutputs, calculatedFee)
-
-                if (balanceCheckAdjusted.sufficient) {
-                  // ✅ SUCCESS with adjusted change
-                  balanceVerificationPassed = true
-                  yield* Ref.set(ctx.state.outputs, adjustedAllOutputs)
-                  yield* Effect.logDebug(
-                    `Balance verification passed after simple change adjustment on attempt ${attempt}. ` +
-                      `Fee: ${calculatedFee}, Adjusted change: ${changeOutputs[0].assets.lovelace} lovelace`
-                  )
-                  continue // Skip to next iteration (which will exit since balanceVerificationPassed = true)
-                } else {
-                  yield* Effect.logWarning(
-                    `Balance check failed after simple change adjustment. Shortfall: ${balanceCheckAdjusted.shortfall}`
-                  )
-                }
-              }
-            }
-          }
-        }
-
-        // Verify balance with actual fee
-        const balanceCheck = verifyTransactionBalance(selectedUtxos, allOutputs, calculatedFee)
-
-        if (balanceCheck.sufficient) {
-          // ✅ SUCCESS: Balance is sufficient
-          balanceVerificationPassed = true
-
-          // Update outputs in state (base + change)
-          yield* Ref.set(ctx.state.outputs, allOutputs)
-
-          yield* Effect.logDebug(
-            `Balance verification passed on attempt ${attempt}. ` +
-              `Fee: ${calculatedFee}, Change: ${balanceCheck.change} lovelace`
-          )
-        } else {
-          // ❌ INSUFFICIENT: Need more UTxOs
-          const shortfall = balanceCheck.shortfall
-
-          if (attempt < MAX_RESELECTION_ATTEMPTS) {
-            yield* Effect.logWarning(
-              `Balance verification failed on attempt ${attempt}. ` +
-                `Shortfall: ${shortfall} lovelace. Selecting more UTxOs...`
-            )
-
-            // Get available UTxOs for reselection
-            const configUtxos = ctx.config.availableUtxos
-            const alreadyCollected = yield* Ref.get(ctx.state.selectedUtxos)
-
-            const availableUtxos = configUtxos.filter(
-              (utxo) =>
-                !alreadyCollected.some(
-                  (collected) => collected.txHash === utxo.txHash && collected.outputIndex === utxo.outputIndex
-                )
-            )
-
-            // Select more UTxOs to cover shortfall
-            const coinSelectionFn = options?.coinSelection
-              ? typeof options.coinSelection === "function"
-                ? options.coinSelection
-                : getCoinSelectionAlgorithm(options.coinSelection)
-              : largestFirstSelection
-
-            const { selectedUtxos: additionalUtxos } = yield* Effect.try({
-              try: () => coinSelectionFn(availableUtxos, { lovelace: shortfall }),
-              catch: (error) =>
-                new TransactionBuilderError({
-                  message: `Reselection failed to cover ${shortfall} lovelace shortfall`,
-                  cause: error
-                })
-            })
-
-            const totalInputsBefore = alreadyCollected.reduce((sum, u) => sum + u.assets.lovelace, 0n)
-            const additionalLovelace = additionalUtxos.reduce((sum, u) => sum + u.assets.lovelace, 0n)
-
-            yield* Effect.logDebug(
-              `Reselection added ${additionalUtxos.length} UTxOs ` +
-                `(${availableUtxos.length} available). ` +
-                `Total inputs: ${totalInputsBefore} → ${totalInputsBefore + additionalLovelace} lovelace`
-            )
-
-            // Add selected UTxOs to state
-            yield* Ref.update(ctx.state.selectedUtxos, (current) => [...current, ...additionalUtxos])
-
-            // Update total input assets
-            for (const utxo of additionalUtxos) {
-              yield* Ref.update(ctx.state.totalInputAssets, (current) => {
-                const updated = { ...current }
-                for (const [unit, amount] of Object.entries(utxo.assets)) {
-                  updated[unit] = (updated[unit] || 0n) + (amount as bigint)
-                }
-                return updated
-              })
-            }
-
-            yield* Effect.logDebug(`Reselection added ${additionalUtxos.length} UTxOs`)
-          } else {
-            // Max attempts reached - fail with detailed error
-            return yield* Effect.fail(
-              new TransactionBuilderError({
-                message:
-                  `Cannot balance transaction after ${MAX_RESELECTION_ATTEMPTS} attempts. ` +
-                  `Final shortfall: ${shortfall} lovelace. ` +
-                  `This may indicate insufficient funds in available UTxOs.`,
-                cause: {
-                  attempts: MAX_RESELECTION_ATTEMPTS,
-                  finalShortfall: shortfall.toString(),
-                  calculatedFee: calculatedFee.toString(),
-                  selectedUtxos: selectedUtxos.length
-                }
-              })
-            )
-          }
-        }
-      }
-
-      // 4. Fee Assignment and Final Assembly
-      // After reselection loop, we have final outputs (with change) and calculated fee
-      const selectedUtxos = yield* Ref.get(ctx.state.selectedUtxos)
-      const finalOutputs = yield* Ref.get(ctx.state.outputs)
-      const fee = calculatedFee
-
-      // 5. Convert UTxOs to TransactionInputs (sorted deterministically)
-      const inputs = yield* buildTransactionInputs(selectedUtxos)
-
-      // 6. Assemble final transaction with calculated fee and final outputs
-      const transaction = yield* assembleTransaction(inputs, finalOutputs, fee)
-
-      // 10. Validate transaction size against protocol limit
-      // Build transaction WITH fake witnesses (same as fee calculation does) for accurate size check
-      const fakeWitnessSet = yield* buildFakeWitnessSet(selectedUtxos)
-
-      yield* Effect.logDebug(
-        `Fake witness set: ${fakeWitnessSet.vkeyWitnesses?.length ?? 0} vkey witnesses, ` + `${inputs.length} inputs`
-      )
-
-      const txWithWitnesses = new Transaction.Transaction({
-        body: transaction.body,
-        witnessSet: fakeWitnessSet,
-        isValid: true,
-        auxiliaryData: null
-      })
-
-      // Get actual CBOR size with fake witnesses
-      const txSizeWithWitnesses = yield* calculateTransactionSize(txWithWitnesses)
-
-      yield* Effect.logDebug(
-        `Transaction size check: ${txSizeWithWitnesses} bytes ` +
-          `(with ${fakeWitnessSet.vkeyWitnesses?.length ?? 0} fake witnesses), max=${ctx.config.protocolParameters.maxTxSize} bytes`
-      )
-
-      if (txSizeWithWitnesses > ctx.config.protocolParameters.maxTxSize) {
-        return yield* Effect.fail(
-          new TransactionBuilderError({
-            message:
-              `Transaction size (${txSizeWithWitnesses} bytes) exceeds maximum ` +
-              `allowed (${ctx.config.protocolParameters.maxTxSize} bytes). ` +
-              `Try reducing inputs (${inputs.length}) or outputs (${finalOutputs.length}).`,
-            cause: {
-              txSizeBytes: txSizeWithWitnesses,
-              maxTxSize: ctx.config.protocolParameters.maxTxSize,
-              inputCount: inputs.length,
-              outputCount: finalOutputs.length,
-              suggestion: "Use larger UTxOs or consolidate outputs to reduce transaction size"
-            }
-          })
-        )
-      }
-
-      // TODO Step 4: Build witness set with redeemers and detect required signers
-      // TODO Step 5: Run script evaluation to fill ExUnits
-      // TODO Step 6: Add change output (balancing)
-
-      // Build transaction with fake witnesses for validation
-      const txWithFakeWitnesses = new Transaction.Transaction({
-        body: transaction.body,
-        witnessSet: fakeWitnessSet,
-        isValid: true,
-        auxiliaryData: null
-      })
-
-      // 10. Return minimal SignBuilder stub
-      const signBuilder: SignBuilder = {
-        Effect: {
-          sign: () => Effect.fail(new TransactionBuilderError({ message: "Signing not yet implemented" })),
-          signWithWitness: () =>
-            Effect.fail(new TransactionBuilderError({ message: "Witness signing not yet implemented" })),
-          assemble: () => Effect.fail(new TransactionBuilderError({ message: "Assemble not yet implemented" })),
-          partialSign: () =>
-            Effect.fail(new TransactionBuilderError({ message: "Partial signing not yet implemented" })),
-          getWitnessSet: () => Effect.succeed(transaction.witnessSet),
-          toTransaction: () => Effect.succeed(transaction),
-          toTransactionWithFakeWitnesses: () => Effect.succeed(txWithFakeWitnesses)
-        },
-        sign: () => Promise.reject(new Error("Signing not yet implemented")),
-        signWithWitness: () => Promise.reject(new Error("Witness signing not yet implemented")),
-        assemble: () => Promise.reject(new Error("Assemble not yet implemented")),
-        partialSign: () => Promise.reject(new Error("Partial signing not yet implemented")),
-        getWitnessSet: () => Promise.resolve(transaction.witnessSet),
-        toTransaction: () => Promise.resolve(transaction),
-        toTransactionWithFakeWitnesses: () => Promise.resolve(txWithFakeWitnesses)
-      }
-
-      return signBuilder
-    }).pipe(
-      Effect.provideServiceEffect(
-        TxContext,
-        Effect.gen(function* () {
-          return {
-            config,
-            state: yield* createFreshState(),
-            options: options ?? {}
-          }
-        })
-      ),
-      Effect.mapError(
-        (error) =>
-          new TransactionBuilderError({
-            message: "Build failed",
-            cause: error
-          })
-      )
-    )
-
-  // ============================================================================
-  // State Machine Implementation (Parallel/Experimental)
-  // ============================================================================
-
-  // ============================================================================
-  // EXPERIMENTAL STATE MACHINE IMPLEMENTATION
-  // ============================================================================
-  // This is a parallel implementation to buildEffectCore using state machine pattern.
-  // NOT YET ACTIVE in production - has Context.Tag type system issues to resolve.
-  // TypeScript errors suppressed below as this is experimental/WIP code.
-  // ============================================================================
-
-  // @ts-nocheck - Experimental state machine code below
-
-  /**
-   * Build phases representing the transaction building lifecycle
-   *
-   * Context-driven state machine:
-   * - Being IN a phase means DO that work
-   * - Phases read/write context, return next phase
-   * - selection is reusable (called initially or for reselection)
-   * - Fallbacks (drainTo, burnAsFee) only when attempts exhausted
-   */
-  type BuildPhase =
-    | "selection" // Select coins if needed (checks context)
-    | "changeCreation" // Create change outputs
-    | "feeCalculation" // Calculate fee with change
-    | "balanceVerification" // Verify balance, decide next
-    | "drainTo" // Fallback: merge to existing output
-    | "burnAsFee" // Fallback: burn remaining as fee
-    | "complete" // Done
-
-  /**
-   * Build context carrying state machine execution state
-   * Note: Removed duplication - selectedUtxos/baseOutputs read from TxContext.state
-   */
-  interface BuildContext {
-    /**
-     * Current state machine phase
-     *
-     * Determines which phase executes next:
-     * - `selection`: Select UTxOs to cover outputs + fee
-     * - `changeCreation`: Create change outputs from leftover
-     * - `feeCalculation`: Calculate actual fee with change included
-     * - `balanceVerification`: Verify balance and route to completion/retry/fallback
-     * - `drainTo`: Fallback to merge small leftover into existing output
-     * - `burnAsFee`: Fallback to burn small leftover as extra fee
-     * - `complete`: Terminal state - transaction successfully built
-     */
-    readonly phase: BuildPhase
-
-    /**
-     * Current reselection attempt number (1-based)
-     *
-     * Tracks how many times we've tried to select UTxOs and create change.
-     * Used to prevent infinite loops (MAX_ATTEMPTS = 3).
-     *
-     * Example flow:
-     * - Attempt 1: Select 3 ADA, need change but insufficient → shortfall
-     * - Attempt 2: Select more UTxOs (5 ADA total), create change → success
-     */
-    readonly attempt: number
-
-    /**
-     * Final calculated transaction fee in lovelace
-     *
-     * Fee includes:
-     * - Base transaction structure
-     * - All inputs (from selected UTxOs)
-     * - All outputs (user outputs + change outputs)
-     * - Witness estimates
-     *
-     * Updated after:
-     * - Fee calculation phase (includes change outputs)
-     * - Fee adjustment (when change affects fee)
-     */
-    readonly calculatedFee: bigint
-
-    /**
-     * Amount of lovelace we're short when inputs insufficient
-     *
-     * Calculated by balance verification as the total deficit:
-     * shortfall = (outputs + changeOutputs + fee) - inputs
-     *
-     * This represents ALL missing lovelace, including:
-     * - Output requirements
-     * - Fee payment
-     * - Change output minUTxO needs (for both single and unfrack bundles)
-     *
-     * Used to:
-     * - Trigger reselection (select more UTxOs to cover shortfall)
-     * - Single source of truth for deficit during reselection
-     * - Debug insufficient balance errors
-     * - Track progress across attempts
-     *
-     * Set by: Balance verification when inputs < outputs
-     * Used by: Selection phase during reselection attempts
-     * Reset to: 0n after selection completes
-     */
-    readonly shortfall: bigint
-
-    /**
-     * Change outputs created from leftover assets
-     *
-     * Created in changeCreation phase when:
-     * - Leftover has native assets (MUST create change - ledger rule)
-     * - Leftover ADA >= minUTxO (can create valid change)
-     *
-     * Empty array when:
-     * - Leftover too small (triggers drainTo or burnAsFee)
-     * - No leftover after paying outputs + fee
-     *
-     * Used in:
-     * - Fee calculation (affects transaction size)
-     * - Balance verification (check if change created)
-     */
-    readonly changeOutputs: ReadonlyArray<UTxO.TxOutput>
-
-    /**
-     * Leftover assets AFTER subtracting the fee
-     *
-     * Calculated as: leftoverBeforeFee - calculatedFee
-     * Set in Phase 2 (Change Creation), used in Phase 4+ (Balance Verification, DrainTo, BurnAsFee)
-     *
-     * Purpose:
-     * - Single source of truth for what's available after fee payment
-     * - Eliminates redundant calculations across phases
-     * - Used for minUTxO checks, drainTo validation, burn decisions
-     *
-     * Example: leftoverBeforeFee = 5 ADA, calculatedFee = 0.17 ADA
-     *   → leftoverAfterFee = 4.83 ADA
-     *
-     * Initialized to zero assets before Phase 2 completes
-     *
-     * @since 2.0.0
-     */
-    readonly leftoverAfterFee: Assets.Assets
-
-    /**
-     * Index of output modified by drainTo fallback (optional)
-     *
-     * When leftover < minUTxO and ADA-only:
-     * - DrainTo merges leftover into existing output
-     * - This index tracks which output was modified
-     *
-     * Purpose:
-     * - Validation: Ensure merged output still meets minUTxO
-     * - Debugging: Track which output received extra funds
-     *
-     * Example: drainToIndex = 0 means leftover merged into first output
-     *
-     * Only set when:
-     * - drainTo configured in options
-     * - Leftover < minUTxO
-     * - Leftover is ADA-only (no native assets)
-     */
-    readonly drainToIndex?: number
-
-    /**
-     * Whether unfrack optimization is allowed for this build
-     *
-     * Controls whether ChangeCreation should attempt to create unfracked
-     * change outputs (splitting tokens into multiple bundles).
-     *
-     * Initialized based on options:
-     * - true: If unfrack option is configured
-     * - false: If unfrack option is not configured
-     *
-     * Can be set to false during build if:
-     * - Unfrack attempted but failed due to insufficient lovelace
-     * - Fallback to single change output triggered
-     *
-     * Purpose:
-     * - Allow precise fallback without heuristics
-     * - Try unfrack, detect failure, retry without it
-     * - Prevent re-attempting unfrack after it fails
-     *
-     * @since 2.0.0
-     */
-    readonly canUnfrack: boolean
-  }
-
-  /**
-   * Phase result - describes what to do next.
-   *
-   * Each phase has ONE responsibility: decide what to do next.
-   * Phases read context, do their work, update context, return next phase.
-   *
-   * This pattern enables:
-   * - Single Responsibility: Phases do one thing
-   * - State Reuse: Selection logic reusable from different contexts
-   * - Context-driven: All state in context, no data passing
-   * - Effect-idiomatic: Composable state machine
-   */
-  type PhaseResult = {
-    readonly next: BuildPhase
-  }
-
-  /**
-   * BuildContext service tag
-   */
-  class BuildContextTag extends Context.Tag("BuildContextTag")<BuildContextTag, Ref.Ref<BuildContext>>() {}
-
-  // ============================================================================
-  // V2: CLEAN STATE MACHINE IMPLEMENTATION
-  // ============================================================================
-
-  /**
-   * NEW State Machine V2 - Clean context-driven implementation
-   *
-   * Key principles:
-   * - Start with fee = 0, let balance verification drive everything
-   * - Phases read context, do work, return next phase
-   * - Trust fee convergence (usually 1-2 iterations)
-   * - Selection is reusable
-   * - Fallbacks only when attempts exhausted
-   */
-  const buildEffectCoreStateMachineV2 = (options?: BuildOptions) =>
-    Effect.gen(function* () {
-      const ctx = yield* TxContext
-
-      // Execute all programs to populate initial state
-      yield* Effect.all(programs, { concurrency: "unbounded" })
-
-      // Create initial build context
-      const initialBuildCtx: BuildContext = {
-        phase: "selection" as const,
-        attempt: 0,
-        calculatedFee: 0n, // Start with 0!
-        shortfall: 0n,
-        changeOutputs: [],
-        leftoverAfterFee: { lovelace: 0n },
-        canUnfrack: ctx.options?.unfrack !== undefined
-      }
-
-      const buildCtxRef = yield* Ref.make(initialBuildCtx)
-
-      return yield* Effect.gen(function* () {
-        // State machine loop
-        while (true) {
-          const buildCtx = yield* Ref.get(buildCtxRef)
-
-          if (buildCtx.phase === "complete") {
-            break
-          }
-
-          yield* Effect.logDebug(
-            `[StateMachineV2] Phase: ${buildCtx.phase}, Attempt: ${buildCtx.attempt}, Fee: ${buildCtx.calculatedFee}`
-          )
-
-          // Execute phase
-          yield* executePhaseV2
-        }
-
-        // Build final transaction
-        const selectedUtxos = yield* Ref.get(ctx.state.selectedUtxos)
-        const baseOutputs = yield* Ref.get(ctx.state.outputs)
-        const finalBuildCtx = yield* Ref.get(buildCtxRef)
-
-        yield* Effect.logDebug(
-          `[buildEffectCoreStateMachineV2] Base outputs: ${baseOutputs.length}, ` +
-            `Change outputs: ${finalBuildCtx.changeOutputs.length}`
-        )
-
-        const inputs = yield* buildTransactionInputs(selectedUtxos)
-        const allOutputs = [...baseOutputs, ...finalBuildCtx.changeOutputs]
-
-        yield* Effect.logDebug(`[buildEffectCoreStateMachineV2] Total outputs: ${allOutputs.length}`)
-
-        const transaction = yield* assembleTransaction(inputs, allOutputs, finalBuildCtx.calculatedFee)
-
-        // SAFETY CHECK: Validate transaction size against protocol limit
-        // Build transaction WITH fake witnesses for accurate size check (same as old impl)
-        const fakeWitnessSet = yield* buildFakeWitnessSet(selectedUtxos)
-
-        yield* Effect.logDebug(
-          `[StateMachineV2] Fake witness set: ${fakeWitnessSet.vkeyWitnesses?.length ?? 0} vkey witnesses, ` +
-            `${inputs.length} inputs`
-        )
-
-        const txWithFakeWitnesses = new Transaction.Transaction({
-          body: transaction.body,
-          witnessSet: fakeWitnessSet,
-          isValid: true,
-          auxiliaryData: null
-        })
-
-        // Get actual CBOR size with fake witnesses
-        const txSizeWithWitnesses = yield* calculateTransactionSize(txWithFakeWitnesses)
-
-        yield* Effect.logDebug(
-          `[StateMachineV2] Transaction size: ${txSizeWithWitnesses} bytes ` +
-            `(with ${fakeWitnessSet.vkeyWitnesses?.length ?? 0} fake witnesses), ` +
-            `max=${ctx.config.protocolParameters.maxTxSize} bytes`
-        )
-
-        if (txSizeWithWitnesses > ctx.config.protocolParameters.maxTxSize) {
-          return yield* Effect.fail(
-            new TransactionBuilderError({
-              message:
-                `Transaction size (${txSizeWithWitnesses} bytes) exceeds maximum ` +
-                `allowed (${ctx.config.protocolParameters.maxTxSize} bytes). ` +
-                `Try reducing inputs (${inputs.length}) or outputs (${allOutputs.length}).`,
-              cause: {
-                txSizeBytes: txSizeWithWitnesses,
-                maxTxSize: ctx.config.protocolParameters.maxTxSize,
-                inputCount: inputs.length,
-                outputCount: allOutputs.length,
-                suggestion: "Use larger UTxOs or consolidate outputs to reduce transaction size"
-              }
-            })
-          )
-        }
-
-        // Log final build summary
-        yield* Effect.logDebug(
-          `[StateMachineV2] Build complete: ${inputs.length} input(s), ${allOutputs.length} output(s) ` +
-            `(${baseOutputs.length} base + ${finalBuildCtx.changeOutputs.length} change), ` +
-            `Fee: ${finalBuildCtx.calculatedFee} lovelace, Size: ${txSizeWithWitnesses} bytes, Attempts: ${finalBuildCtx.attempt}`
-        )
-
-        // Return SignBuilder (matching old implementation)
-        const signBuilder: SignBuilder = {
-          Effect: {
-            sign: () => Effect.fail(new TransactionBuilderError({ message: "Signing not yet implemented" })),
-            signWithWitness: () =>
-              Effect.fail(new TransactionBuilderError({ message: "Witness signing not yet implemented" })),
-            assemble: () => Effect.fail(new TransactionBuilderError({ message: "Assemble not yet implemented" })),
-            partialSign: () =>
-              Effect.fail(new TransactionBuilderError({ message: "Partial signing not yet implemented" })),
-            getWitnessSet: () => Effect.succeed(transaction.witnessSet),
-            toTransaction: () => Effect.succeed(transaction),
-            toTransactionWithFakeWitnesses: () => Effect.succeed(txWithFakeWitnesses)
-          },
-          sign: () => Promise.reject(new Error("Signing not yet implemented")),
-          signWithWitness: () => Promise.reject(new Error("Witness signing not yet implemented")),
-          assemble: () => Promise.reject(new Error("Assemble not yet implemented")),
-          partialSign: () => Promise.reject(new Error("Partial signing not yet implemented")),
-          getWitnessSet: () => Promise.resolve(transaction.witnessSet),
-          toTransaction: () => Promise.resolve(transaction),
-          toTransactionWithFakeWitnesses: () => Promise.resolve(txWithFakeWitnesses)
-        }
-
-        return signBuilder
-      }).pipe(Effect.provideService(BuildContextTag, buildCtxRef))
-    }).pipe(
-      Effect.provideServiceEffect(
-        TxContext,
-        createFreshState().pipe(Effect.map((state) => ({ config, options: options ?? {}, state })))
-      )
-    )
-
-  /**
-   * Helper: Format assets for logging (BigInt-safe, truncates long unit names)
-   */
-  const formatAssetsForLog = (assets: Assets.Assets): string => {
-    return Object.entries(assets)
-      .map(([unit, amount]) => `${unit.substring(0, 16)}...: ${amount.toString()}`)
-      .join(", ")
-  }
-
-  /**
-   * Phase executor V2 - simpler, just updates phase in context
-   */
-  const executePhaseV2 = Effect.gen(function* () {
-    const buildCtxRef = yield* BuildContextTag
-    const buildCtx = yield* Ref.get(buildCtxRef)
-
-    let result: PhaseResult
-
-    switch (buildCtx.phase) {
-      case "selection":
-        result = yield* phaseSelectionV2
-        break
-
-      case "changeCreation":
-        result = yield* phaseChangeCreationV2
-        break
-
-      case "feeCalculation":
-        result = yield* phaseFeeCalculationV2
-        break
-
-      case "balanceVerification":
-        result = yield* phaseBalanceVerificationV2
-        break
-
-      case "drainTo":
-        result = yield* phaseDrainToV2
-        break
-
-      case "burnAsFee":
-        result = yield* phaseBurnAsFeeV2
-        break
-
-      case "complete":
-        return
-    }
-
-    // Update phase
-    yield* Ref.update(buildCtxRef, (ctx) => ({ ...ctx, phase: result.next }))
-  })
-
-  /**
-   * V2 Phase 1: Selection
-   * Precisely calculates what's needed based on outputs + calculatedFee
-   */
-  const phaseSelectionV2 = Effect.gen(function* () {
-    const ctx = yield* TxContext
-    const buildCtxRef = yield* BuildContextTag
-    const buildCtx = yield* Ref.get(buildCtxRef)
-
-    yield* Effect.logDebug(`[SelectionV2] Attempt ${buildCtx.attempt + 1}`)
-
-    // Check max attempts
-    if (buildCtx.attempt >= MAX_RESELECTION_ATTEMPTS) {
-      return yield* Effect.fail(
-        new TransactionBuilderError({
-          message: `Cannot balance after ${MAX_RESELECTION_ATTEMPTS} attempts`,
-          cause: { attempts: buildCtx.attempt, shortfall: buildCtx.shortfall.toString() }
-        })
-      )
-    }
-
-    const inputAssets = yield* Ref.get(ctx.state.totalInputAssets)
-    const outputAssets = yield* Ref.get(ctx.state.totalOutputAssets)
-
-    // Ensure lovelace field exists for Assets utilities
-    const inputAssetsWithLovelace: Assets.Assets = {
-      ...inputAssets,
-      lovelace: inputAssets.lovelace || 0n
-    }
-
-    // PRECISE calculation: what we need = outputs + fee + shortfall (if retrying)
-    // On first attempt (attempt=0): shortfall is 0n
-    // On retry (attempt>0): shortfall is set by balance verification with the TOTAL deficit
-    //
-    // NOTE: We use ONLY shortfall during reselection, NOT requiredChangeMinUTxO.
-    // The shortfall already accounts for ALL missing lovelace (including change minUTxO needs).
-    // Adding both would double-count!
-    yield* Effect.logDebug(
-      `[SelectionV2] buildCtx.shortfall: ${buildCtx.shortfall}, buildCtx.calculatedFee: ${buildCtx.calculatedFee}`
-    )
-    const totalNeeded: Assets.Assets = {
-      ...outputAssets,
-      lovelace: (outputAssets.lovelace || 0n) + buildCtx.calculatedFee + buildCtx.shortfall
-    }
-
-    // Calculate precise asset delta: needed - available
-    // Positive values = shortfalls (need more), Negative = excess (have more)
-    const assetDelta = Assets.subtract(totalNeeded, inputAssetsWithLovelace)
-
-    // Extract only the shortfalls (positive values)
-    const assetShortfalls = Assets.filter(assetDelta, (_unit, amount) => amount > 0n)
-
-    const needsSelection = !Assets.isEmpty(assetShortfalls)
-
-    yield* Effect.logDebug(
-      `[SelectionV2] Needed: {${formatAssetsForLog(totalNeeded)}}, ` +
-        `Available: {${formatAssetsForLog(inputAssetsWithLovelace)}}, ` +
-        `Shortfalls: {${formatAssetsForLog(assetShortfalls)}}`
-    )
-
-    if (!needsSelection) {
-      yield* Effect.logDebug("[SelectionV2] Assets sufficient")
-      const selectedUtxos = yield* Ref.get(ctx.state.selectedUtxos)
-      yield* Effect.logDebug(
-        `[SelectionV2] Selection complete: ${selectedUtxos.length} UTxO(s) selected, ` +
-          `Total lovelace: ${inputAssets.lovelace || 0n}`
-      )
-    } else {
-      // Perform selection for precise shortfall
-      const shortfallStr = Object.entries(assetShortfalls)
-        .map(([_unit, amount]) => amount.toString())
-        .join(", ")
-      yield* Effect.logDebug(`[SelectionV2] Selecting for shortfall: ${shortfallStr}`)
-
-      const beforeCount = (yield* Ref.get(ctx.state.selectedUtxos)).length
-      yield* performCoinSelectionUpdateState(assetShortfalls)
-      const afterCount = (yield* Ref.get(ctx.state.selectedUtxos)).length
-      const addedCount = afterCount - beforeCount
-
-      const updatedInputAssets = yield* Ref.get(ctx.state.totalInputAssets)
-      yield* Effect.logDebug(
-        `[SelectionV2] Added ${addedCount} UTxO(s), ` +
-          `Total selected: ${afterCount}, ` +
-          `New total lovelace: ${updatedInputAssets.lovelace || 0n}`
-      )
-    }
-
-    // Common path: increment attempt, clear shortfall (we've accounted for it), and proceed to change creation
-    yield* Ref.update(buildCtxRef, (ctx) => ({ ...ctx, attempt: ctx.attempt + 1, shortfall: 0n }))
-    return { next: "changeCreation" as const }
-  })
-
-  /**
-   * V2 Phase 2: Change Creation
-   *
-   * Creates change outputs using tentative leftover (inputs - outputs - fee).
-   * Each output created is valid (meets minUTxO). Balance phase verifies total sufficiency.
-   */
-  const phaseChangeCreationV2 = Effect.gen(function* () {
-    const ctx = yield* TxContext
-    const buildCtxRef = yield* BuildContextTag
-    const buildCtx = yield* Ref.get(buildCtxRef)
-
-    yield* Effect.logDebug(`[ChangeCreationV2] Fee from context: ${buildCtx.calculatedFee}`)
-
-    // Calculate tentative leftover after fee
-    const inputAssets = yield* Ref.get(ctx.state.totalInputAssets)
-    const outputAssets = yield* Ref.get(ctx.state.totalOutputAssets)
-    const leftoverBeforeFee = calculateLeftoverAssets(inputAssets, outputAssets)
-
-    const tentativeLeftover: Assets.Assets = {
-      ...leftoverBeforeFee,
-      lovelace: leftoverBeforeFee.lovelace - buildCtx.calculatedFee
-    }
-
-    // Early exit if negative - balance phase will trigger reselection
-    if (tentativeLeftover.lovelace < 0n) {
-      yield* Effect.logDebug(
-        `[ChangeCreationV2] Insufficient lovelace for fee: ${tentativeLeftover.lovelace}. ` +
-          `Skipping change, balance verification will trigger reselection.`
-      )
-
-      yield* Ref.update(buildCtxRef, (ctx) => ({
-        ...ctx,
-        changeOutputs: []
-      }))
-      return { next: "feeCalculation" as const }
-    }
-
-    // Unfrack path: Create multiple outputs
-    if (ctx.options?.unfrack && buildCtx.canUnfrack) {
-      const changeOutputs = yield* createChangeOutputs(tentativeLeftover, ctx)
-
-      yield* Effect.logDebug(`[ChangeCreationV2] Successfully created ${changeOutputs.length} unfracked outputs`)
-
-      // Store outputs and proceed to fee calculation
-      yield* Ref.update(buildCtxRef, (ctx) => ({
-        ...ctx,
-        changeOutputs
-      }))
-      return { next: "feeCalculation" as const }
-    }
-
-    // Single output path: Validate minUTxO requirement
-    const minLovelace = yield* calculateMinimumUtxoLovelace({
-      address: ctx.config.changeAddress,
-      assets: tentativeLeftover,
-      coinsPerUtxoByte: ctx.config.protocolParameters.coinsPerUtxoByte
-    })
-
-    if (tentativeLeftover.lovelace < minLovelace) {
-      const hasNativeAssets = Object.keys(tentativeLeftover).length > 1
-
-      if (hasNativeAssets) {
-        // Native assets MUST go in change output (ledger rule)
-        // Create placeholder with required minUTxO - balance will detect shortfall
-        yield* Effect.logDebug(
-          `[ChangeCreationV2] Native assets need ${minLovelace} lovelace, only have ${tentativeLeftover.lovelace}. ` +
-            `Creating placeholder change to trigger reselection.`
-        )
-
-        const changeOutputs = [
-          {
-            address: ctx.config.changeAddress,
-            assets: { ...tentativeLeftover, lovelace: minLovelace }
-          }
-        ]
-
-        yield* Ref.update(buildCtxRef, (ctx) => ({
-          ...ctx,
-          changeOutputs
-        }))
-        return { next: "feeCalculation" as const }
-      }
-
-      // Insufficient ADA-only leftover - return empty, balance will handle (drainTo/burn)
-      yield* Effect.logDebug(
-        `[ChangeCreationV2] Insufficient lovelace for change (${tentativeLeftover.lovelace} < ${minLovelace}), returning empty change`
-      )
-
-      yield* Ref.update(buildCtxRef, (ctx) => ({ ...ctx, changeOutputs: [] }))
-      return { next: "feeCalculation" as const }
-    }
-
-    // Create valid single change output
-    const changeOutput = yield* makeTxOutput({
-      address: ctx.config.changeAddress,
-      assets: tentativeLeftover
-    })
-
-    yield* Effect.logDebug(`[ChangeCreationV2] Created 1 change output with ${tentativeLeftover.lovelace} lovelace`)
-
-    yield* Ref.update(buildCtxRef, (ctx) => ({
-      ...ctx,
-      changeOutputs: [changeOutput]
-    }))
-    return { next: "feeCalculation" as const }
-  })
-
-  /**
-   * Helper: Create unfracked change outputs (multiple outputs)
-   * Only called when unfrack option is enabled.
-   * Returns change outputs array or undefined if unfrack is not viable.
-   *
-   * @param leftoverAfterFee - Tentative leftover calculated with previous fee estimate
-   * @param ctx - Transaction context data
-   * @returns ReadonlyArray<TxOutput> or undefined if not viable
-   */
-  const createChangeOutputs = (
-    leftoverAfterFee: Assets.Assets,
-    ctx: TxContextData
-  ): Effect.Effect<
-    ReadonlyArray<UTxO.TxOutput>,
-    TransactionBuilderError
-  > =>
-    Effect.gen(function* () {
-      // Empty leftover = no change needed
-      if (Assets.isEmpty(leftoverAfterFee)) {
-        return []
-      }
-
-      // Create unfracked outputs with proper minUTxO calculation
-      const unfrackOptions = ctx.options!.unfrack! // Safe: only called when unfrack is enabled
-      
-      const changeOutputs = yield* Unfrack.createUnfrackedChangeOutputs(
-        ctx.config.changeAddress,
-        leftoverAfterFee,
-        unfrackOptions,
-        ctx.config.protocolParameters.coinsPerUtxoByte
-      ).pipe(
-        Effect.mapError(
-          (err) =>
-            new TransactionBuilderError({
-              message: `Failed to create unfracked change outputs: ${err.message}`,
-              cause: err
-            })
-        )
-      )
-
-      yield* Effect.logDebug(
-        `[ChangeCreationV2] Created ${changeOutputs.length} unfracked change outputs`
-      )
-
-      return changeOutputs
-    })
-
-  /**
-   * V2 Phase 3: Fee Calculation
-   */
-  const phaseFeeCalculationV2 = Effect.gen(function* () {
-    const ctx = yield* TxContext
-    const buildCtxRef = yield* BuildContextTag
-    const buildCtx = yield* Ref.get(buildCtxRef)
-
-    const selectedUtxos = yield* Ref.get(ctx.state.selectedUtxos)
-    const baseOutputs = yield* Ref.get(ctx.state.outputs)
-    const inputs = yield* buildTransactionInputs(selectedUtxos)
-
-    yield* Effect.logDebug(
-      `[FeeCalculationV2] Starting fee calculation with ${baseOutputs.length} base outputs + ${buildCtx.changeOutputs.length} change outputs`
-    )
-
-    // Calculate fee WITH change outputs
-    const allOutputs = [...baseOutputs, ...buildCtx.changeOutputs]
-    const calculatedFee = yield* calculateFeeIteratively(selectedUtxos, inputs, allOutputs, {
-      minFeeCoefficient: ctx.config.protocolParameters.minFeeCoefficient,
-      minFeeConstant: ctx.config.protocolParameters.minFeeConstant
-    })
-
-    yield* Effect.logDebug(`[FeeCalculationV2] Calculated fee: ${calculatedFee}`)
-
-    // Calculate leftover after fee NOW (after fee is known)
-    const inputAssets = yield* Ref.get(ctx.state.totalInputAssets)
-    const outputAssets = yield* Ref.get(ctx.state.totalOutputAssets)
-    const leftoverBeforeFee = calculateLeftoverAssets(inputAssets, outputAssets)
-
-    const leftoverAfterFee: Assets.Assets = {
-      ...leftoverBeforeFee,
-      lovelace: leftoverBeforeFee.lovelace - calculatedFee
-    }
-
-    // Store both fee and leftoverAfterFee in context
-    yield* Ref.update(buildCtxRef, (ctx) => ({
-      ...ctx,
-      calculatedFee,
-      leftoverAfterFee
-    }))
-
-    return { next: "balanceVerification" as const }
-  })
-
-  /**
-   * V2 Phase 4: Balance Verification - Decides what to do next
-   */
-  const phaseBalanceVerificationV2 = Effect.gen(function* () {
-    const ctx = yield* TxContext
-    const buildCtxRef = yield* BuildContextTag
-    const buildCtx = yield* Ref.get(buildCtxRef)
-
-    yield* Effect.logDebug(`[BalanceVerificationV2] Starting balance verification (attempt ${buildCtx.attempt})`)
-
-    const inputAssets = yield* Ref.get(ctx.state.totalInputAssets)
-    const outputAssets = yield* Ref.get(ctx.state.totalOutputAssets)
-
-    // Calculate total output (outputs + change + fee)
-    const changeTotal = buildCtx.changeOutputs.reduce(
-      (sum, output) => sum + Assets.getAsset(output.assets, "lovelace"),
-      0n
-    )
-
-    const totalOut = outputAssets.lovelace + changeTotal + buildCtx.calculatedFee
-    const totalIn = inputAssets.lovelace
-    const difference = totalOut - totalIn
-
-    yield* Effect.logDebug(`[BalanceVerificationV2] In: ${totalIn}, Out: ${totalOut}, Diff: ${difference}`)
-
-    // Balanced!
-    if (difference === 0n) {
-      yield* Effect.logDebug("[BalanceVerificationV2] Transaction balanced!")
-      return { next: "complete" as const }
-    }
-
-    // Not balanced - decide strategy
-    if (difference < 0n) {
-      // Too much leftover (excess)
-      const excessAmount = -difference
-
-      // Get leftover assets after fee from context
-      const leftoverAssets = buildCtx.leftoverAfterFee
-
-      // Calculate actual minUTxO requirement for these assets
-      const minUtxo = yield* calculateMinimumUtxoLovelace({
-        address: ctx.config.changeAddress,
-        assets: leftoverAssets,
-        coinsPerUtxoByte: ctx.config.protocolParameters.coinsPerUtxoByte
-      })
-
-      yield* Effect.logDebug(`[BalanceVerificationV2] Excess: ${excessAmount}, MinUTxO: ${minUtxo} for leftover`)
-
-      // If excess is less than minUTxO, can't create valid change output
-      // Use drainTo to merge into existing output
-      if (excessAmount < minUtxo && ctx.options?.drainTo !== undefined) {
-        // MANDATORY: drainTo ONLY works with ADA-only leftover
-        const hasNativeAssets = Object.keys(leftoverAssets).some((k) => k !== "lovelace")
-        if (hasNativeAssets) {
-          return yield* Effect.fail(
-            new TransactionBuilderError({
-              message: `drainTo cannot be used with native assets in leftover. Use change output or unfrack instead.`
-            })
-          )
-        }
-        yield* Effect.logDebug(`[BalanceVerificationV2] Excess < minUTxO, using drainTo`)
-        return { next: "drainTo" as const }
-      }
-
-      // If excess is too small and burn is explicitly allowed
-      if (excessAmount < minUtxo && ctx.options?.onInsufficientChange === "burn") {
-        yield* Effect.logDebug(`[BalanceVerificationV2] Excess < minUTxO, burning as fee`)
-        return { next: "burnAsFee" as const }
-      }
-
-      // If excess is too small but no fallback configured, fail
-      if (excessAmount < minUtxo) {
-        return yield* Effect.fail(
-          new TransactionBuilderError({
-            message:
-              `Change output insufficient: ${excessAmount} lovelace < ${minUtxo} minUTxO. ` +
-              `Configure drainTo to merge with an existing output, or set onInsufficientChange: 'burn' ` +
-              `to explicitly allow burning as extra fee.`,
-            cause: { excessAmount: excessAmount.toString(), minUtxo: minUtxo.toString() }
-          })
-        )
-      }
-
-      // Otherwise recreate change with correct amount
-      yield* Effect.logDebug(`[BalanceVerificationV2] Excess >= minUTxO, recreating change`)
-      return { next: "changeCreation" as const }
-    }
-
-    // Short on lovelace (difference > 0)
-
-    // Strategy 1: Try reselection if attempts remaining
-    if (buildCtx.attempt < MAX_RESELECTION_ATTEMPTS) {
-      yield* Effect.logDebug(`[BalanceVerificationV2] Shortfall: ${difference}, triggering reselection`)
-      yield* Ref.update(buildCtxRef, (ctx) => ({ ...ctx, shortfall: difference }))
-      return { next: "selection" as const }
-    }
-
-    // Attempts exhausted - try fallbacks
-
-    // Strategy 2: DrainTo if configured
-    if (ctx.options?.drainTo !== undefined) {
-      // MANDATORY: drainTo ONLY works with ADA-only leftover
-      const leftoverAssets = buildCtx.leftoverAfterFee
-      const hasNativeAssets = Object.keys(leftoverAssets).some((k) => k !== "lovelace")
-      if (hasNativeAssets) {
-        return yield* Effect.fail(
-          new TransactionBuilderError({
-            message: `drainTo cannot be used with native assets in leftover. Use change output or unfrack instead.`
-          })
-        )
-      }
-      yield* Effect.logDebug("[BalanceVerificationV2] Attempts exhausted, trying drainTo")
-      return { next: "drainTo" as const }
-    }
-
-    // Strategy 3: Burn as fee (TODO: add allowBurnAsFee to BuildOptions)
-    // if (ctx.options?.allowBurnAsFee && difference < 10_000n) {
-    //   yield* Effect.logDebug("[BalanceVerificationV2] Attempts exhausted, burning as fee")
-    //   return { next: "burnAsFee" as const }
-    // }
-
-    // No fallbacks available
-    return yield* Effect.fail(
-      new TransactionBuilderError({
-        message: `Cannot balance transaction after ${buildCtx.attempt} attempts`,
-        cause: { shortfall: difference.toString(), noFallbacksAvailable: true }
-      })
-    )
-  })
-
-  /**
-   * V2 Phase 5: DrainTo Fallback
-   */
-  const phaseDrainToV2 = Effect.gen(function* () {
-    const ctx = yield* TxContext
-    const buildCtxRef = yield* BuildContextTag
-    const buildCtx = yield* Ref.get(buildCtxRef)
-
-    yield* Effect.logDebug(`[DrainToV2] Starting drainTo fallback (attempt ${buildCtx.attempt})`)
-
-    const drainToIndex = ctx.options?.drainTo
-    if (drainToIndex === undefined) {
-      return yield* Effect.fail(
-        new TransactionBuilderError({
-          message: "drainTo index not configured"
-        })
-      )
-    }
-    const baseOutputs = yield* Ref.get(ctx.state.outputs)
-    const targetOutput = baseOutputs[drainToIndex]
-
-    if (!targetOutput) {
-      return yield* Effect.fail(
-        new TransactionBuilderError({
-          message: `drainTo index ${drainToIndex} out of bounds`
-        })
-      )
-    }
-
-    // Get leftover after fee from context
-    const leftoverAfterFee = buildCtx.leftoverAfterFee
-
-    // MANDATORY: drainTo ONLY works with ADA-only leftover
-    // Native assets would increase CBOR size -> fee increase -> potential imbalance
-    const hasNativeAssets = Object.keys(leftoverAfterFee).some((k) => k !== "lovelace")
-    if (hasNativeAssets) {
-      return yield* Effect.fail(
-        new TransactionBuilderError({
-          message: `drainTo cannot be used with native assets in leftover. Use change output or unfrack instead.`
-        })
-      )
-    }
-
-    // Merge leftover into target output
-    const mergedAssets = Assets.add(targetOutput.assets, leftoverAfterFee)
-
-    const mergedOutput: UTxO.TxOutput = {
-      ...targetOutput,
-      assets: mergedAssets
-    }
-
-    // SAFETY CHECK: Validate merged output meets minUTxO requirement
-    // This is critical - the old implementation validates this 3 times!
-    const mergedMinUtxo = yield* calculateMinimumUtxoLovelace({
-      address: mergedOutput.address,
-      assets: mergedAssets,
-      datum: mergedOutput.datumOption,
-      scriptRef: mergedOutput.scriptRef,
-      coinsPerUtxoByte: ctx.config.protocolParameters.coinsPerUtxoByte
-    })
+// ============================================================================
 
-    const mergedLovelace = Assets.getAsset(mergedAssets, "lovelace")
+/**
+ * Construct a TransactionBuilder instance from protocol configuration.
+ *
+ * The builder accumulates chainable method calls as deferred ProgramSteps. Calling build() or chain()
+ * creates fresh state (new Refs) and executes all accumulated programs sequentially, ensuring
+ * no state pollution between invocations.
+ *
+ * Generic type parameter TResult determines what build() returns:
+ * - SignBuilder (default): When wallet has signing capability
+ * - TransactionResultBase: When wallet is read-only
+ *
+ * @typeParam TResult - The result type for build() methods (SignBuilder or TransactionResultBase)
+ *
+ * @since 2.0.0
+ * @category constructors
+ */
+export const makeTxBuilder = <TResult = SignBuilder>(config: TxBuilderConfig): TransactionBuilder<TResult> => {
+  // Protocol parameters validation is deferred to build time when they are resolved
+  // (from BuildOptions > config > provider)
 
-    yield* Effect.logDebug(
-      `[DrainToV2] Merged output validation: ${mergedLovelace} lovelace ` + `(minUTxO: ${mergedMinUtxo})`
-    )
+  // ProgramSteps array - stores deferred operations
+  // NO state created here - state is fresh per build()
+  const programs: Array<ProgramStep> = []
 
-    if (mergedLovelace < mergedMinUtxo) {
-      return yield* Effect.fail(
-        new TransactionBuilderError({
-          message:
-            `drainTo validation failed: Merged output at index ${drainToIndex} ` +
-            `has ${mergedLovelace} lovelace but requires minimum ${mergedMinUtxo}. ` +
-            `The target output has too many assets to absorb the leftover. ` +
-            `Consider using a different drainTo target or adding more funds.`,
-          cause: {
-            drainToIndex,
-            mergedLovelace: mergedLovelace.toString(),
-            requiredMinUtxo: mergedMinUtxo.toString()
-          }
+  // Helper: Get coin selection algorithm function from name
+  const getCoinSelectionAlgorithm = (algorithm: CoinSelectionAlgorithm): CoinSelectionFunction => {
+    switch (algorithm) {
+      case "largest-first":
+        return largestFirstSelection
+      case "random-improve":
+        throw new TransactionBuilderError({
+          message: "random-improve algorithm not yet implemented",
+          cause: { algorithm }
+        })
+      case "optimal":
+        throw new TransactionBuilderError({
+          message: "optimal algorithm not yet implemented",
+          cause: { algorithm }
+        })
+      default:
+        throw new TransactionBuilderError({
+          message: `Unknown coin selection algorithm: ${algorithm}`,
+          cause: { algorithm }
         })
-      )
     }
+  }
 
-    // Update outputs
-    yield* Ref.update(ctx.state.outputs, (outputs) => outputs.map((o, i) => (i === drainToIndex ? mergedOutput : o)))
-
-    // Clear change outputs
-    yield* Ref.update(buildCtxRef, (ctx) => ({ ...ctx, changeOutputs: [] }))
+  // Helper: Create fresh state Effect
+  const createFreshState = () =>
+    Effect.gen(function* () {
+      return {
+        selectedUtxos: yield* Ref.make<ReadonlyArray<UTxO.UTxO>>([]), // Array for ordering
+        outputs: yield* Ref.make<ReadonlyArray<any>>([]),
+        scripts: yield* Ref.make(new Map<string, any>()),
+        totalOutputAssets: yield* Ref.make<Assets.Assets>({ lovelace: 0n }),
+        totalInputAssets: yield* Ref.make<Assets.Assets>({ lovelace: 0n }),
+        redeemers: yield* Ref.make(new Map<string, RedeemerData>())
+      }
+    })
 
-    yield* Effect.logDebug(`[DrainToV2] Successfully merged leftover (validated: ${mergedLovelace} >= ${mergedMinUtxo})`)
-    return { next: "complete" as const }
-  })
+  /**
+   * Helper: Format assets for logging (BigInt-safe, truncates long unit names)
+   */
+  const formatAssetsForLog = (assets: Assets.Assets): string => {
+    return Object.entries(assets)
+      .map(([unit, amount]) => `${unit.substring(0, 16)}...: ${amount.toString()}`)
+      .join(", ")
+  }
 
   /**
-   * V2 Phase 6: BurnAsFee Fallback
+   * Helper: Create unfracked change outputs (multiple outputs)
+   * Only called when unfrack option is enabled.
+   * Returns change outputs array or undefined if unfrack is not viable.
+   *
+   * @param leftoverAfterFee - Tentative leftover calculated with previous fee estimate
+   * @param ctx - Transaction context data
+   * @param changeAddress - Resolved change address for this build
+   * @returns ReadonlyArray<TxOutput> or undefined if not viable
    */
-  const phaseBurnAsFeeV2 = Effect.gen(function* () {
-    const buildCtxRef = yield* BuildContextTag
-    const buildCtx = yield* Ref.get(buildCtxRef)
+  const createChangeOutputs = (
+    leftoverAfterFee: Assets.Assets,
+    ctx: TxContextData,
+    changeAddress: string,
+    coinsPerUtxoByte: bigint
+  ): Effect.Effect<ReadonlyArray<UTxO.TxOutput>, TransactionBuilderError> =>
+    Effect.gen(function* () {
+      // Empty leftover = no change needed
+      if (Assets.isEmpty(leftoverAfterFee)) {
+        return []
+      }
 
-    // Get leftover after fee from context
-    const leftoverAfterFee = buildCtx.leftoverAfterFee
+      // Create unfracked outputs with proper minUTxO calculation
+      const unfrackOptions = ctx.options!.unfrack! // Safe: only called when unfrack is enabled
 
-    // SAFETY CHECK: Cannot burn leftover when native assets present
-    // Native assets can only be transferred to outputs (ledger rules enforce this)
-    // Attempting to burn without including them in outputs would result in a rejected transaction
-    const hasNativeAssets = Object.keys(leftoverAfterFee).some((k) => k !== "lovelace")
-    if (hasNativeAssets) {
-      return yield* Effect.fail(
-        new TransactionBuilderError({
-          message:
-            `Cannot burn leftover as fee: Native assets present and must be transferred to outputs. ` +
-            `Leftover contains: ${JSON.stringify(leftoverAfterFee)}. ` +
-            `Transaction would be rejected by ledger. ` +
-            `Use change output, drainTo, or unfrack to preserve native assets.`
-        })
+      const changeOutputs = yield* Unfrack.createUnfrackedChangeOutputs(
+        changeAddress,
+        leftoverAfterFee,
+        unfrackOptions,
+        coinsPerUtxoByte
+      ).pipe(
+        Effect.mapError(
+          (err) =>
+            new TransactionBuilderError({
+              message: `Failed to create unfracked change outputs: ${err.message}`,
+              cause: err
+            })
+        )
       )
-    }
-
-    yield* Effect.logDebug(
-      `[BurnAsFeeV2] Burning ${leftoverAfterFee.lovelace} lovelace as extra fee ` + `(below minUTxO, no native assets)`
-    )
-
-    // Just accept the higher fee, no adjustment needed
-    return { next: "complete" as const }
-  })
 
-  // ============================================================================
-  // END V2 IMPLEMENTATION
-  // ============================================================================
+      yield* Effect.logDebug(`[ChangeCreationV2] Created ${changeOutputs.length} unfracked change outputs`)
 
-  /**
-   * Helper: Calculate leftover assets (inputs - outputs)
-   */
-  const calculateLeftoverAssets = (
-    inputAssets: Record<string, bigint>,
-    outputAssets: Record<string, bigint>
-  ): Assets.Assets => {
-    const leftover: Assets.Assets = { ...inputAssets, lovelace: inputAssets.lovelace || 0n }
-    for (const [unit, amount] of Object.entries(outputAssets)) {
-      const current = leftover[unit] || 0n
-      const remaining = current - (amount as bigint)
-      if (remaining > 0n) {
-        leftover[unit] = remaining
-      } else {
-        delete leftover[unit]
-      }
-    }
-    return leftover
-  }
+      return changeOutputs
+    })
 
   // ============================================================================
   // Coin Selection Helper Functions
@@ -2735,7 +1137,9 @@ export const makeTxBuilder = (config: TxBuilderConfig): TransactionBuilder => {
       const ctx = yield* TxContext
       const alreadySelected = yield* Ref.get(ctx.state.selectedUtxos)
 
-      const availableUtxos = getAvailableUtxos(ctx.config.availableUtxos, alreadySelected)
+      // Get resolved availableUtxos from context tag
+      const allAvailableUtxos = yield* AvailableUtxosTag
+      const availableUtxos = getAvailableUtxos(allAvailableUtxos, alreadySelected)
       const coinSelectionFn = resolveCoinSelectionFn(ctx.options?.coinSelection)
 
       const { selectedUtxos } = yield* Effect.try({
@@ -2753,23 +1157,19 @@ export const makeTxBuilder = (config: TxBuilderConfig): TransactionBuilder => {
     })
 
   // ============================================================================
-  // End of State Machine V2 Implementation
-  // ============================================================================
-
-  // ============================================================================
-  // V3 State Machine Implementation - Mathematical Validation Approach
+  // State Machine Implementation - Mathematical Validation Approach
   // ============================================================================
 
   /**
-   * V3 Build phases
+   * Build phases
    */
-  type V3Phase = "selection" | "changeCreation" | "feeCalculation" | "balance" | "fallback" | "complete"
+  type Phase = "selection" | "changeCreation" | "feeCalculation" | "balance" | "fallback" | "complete"
 
   /**
-   * V3 BuildContext - state machine context
+   * BuildContext - state machine context
    */
-  interface V3BuildContext {
-    readonly phase: V3Phase
+  interface BuildContext {
+    readonly phase: Phase
     readonly attempt: number
     readonly calculatedFee: bigint
     readonly shortfall: bigint
@@ -2778,25 +1178,15 @@ export const makeTxBuilder = (config: TxBuilderConfig): TransactionBuilder => {
     readonly canUnfrack: boolean
   }
 
-  /**
-   * V3 BuildContext Tag for Effect Context
-   */
-  const V3BuildContextTag = Context.GenericTag<Ref.Ref<V3BuildContext>>("V3BuildContext")
+  const BuildContextTag = Context.GenericTag<Ref.Ref<BuildContext>>("V3BuildContext")
 
-  /**
-   * V3 Phase result
-   */
-  interface V3PhaseResult {
-    readonly next: V3Phase
+  interface PhaseResult {
+    readonly next: Phase
   }
 
-  // ============================================================================
-  // V3 PHASE: Selection
-  // ============================================================================
-
   const phaseSelectionV3 = Effect.gen(function* () {
     const ctx = yield* TxContext
-    const buildCtxRef = yield* V3BuildContextTag
+    const buildCtxRef = yield* BuildContextTag
     const buildCtx = yield* Ref.get(buildCtxRef)
 
     const inputAssets = yield* Ref.get(ctx.state.totalInputAssets)
@@ -2812,7 +1202,7 @@ export const makeTxBuilder = (config: TxBuilderConfig): TransactionBuilder => {
     // Step 4: Calculate asset delta & extract shortfalls
     const assetDelta = Assets.subtract(totalNeeded, inputAssets)
     const assetShortfalls = Assets.filter(assetDelta, (_unit, amount) => amount > 0n)
-    
+
     // During reselection (shortfall > 0), we need to select MORE lovelace
     // even if inputAssets >= totalNeeded, because the shortfall indicates
     // insufficient lovelace for change output minUTxO requirement
@@ -2852,25 +1242,21 @@ export const makeTxBuilder = (config: TxBuilderConfig): TransactionBuilder => {
     // Step 6: Update context and proceed
     yield* Ref.update(buildCtxRef, (ctx) => ({ ...ctx, attempt: ctx.attempt + 1, shortfall: 0n }))
 
-    return { next: "changeCreation" as V3Phase }
+    return { next: "changeCreation" as Phase }
   })
 
-  // ============================================================================
-  // V3 PHASE: Change Creation
-  // ============================================================================
-  
   /**
-   * V3 Change Creation Phase
-   * 
+   * Change Creation Phase
+   *
    * Creates change outputs from leftover assets using a cascading retry strategy.
    * Both unfrack (N outputs) and single output follow the same retry pattern:
    * try with available funds → if insufficient, reselect (up to MAX_ATTEMPTS) → fallback.
-   * 
+   *
    * **Symmetric Retry Flow (Unfrack vs Single Output):**
    * ```
    * UNFRACK (N outputs)                    SINGLE OUTPUT (1 output)
    * ─────────────────────────────────────────────────────────────────
-   * 
+   *
    * Try: Create N outputs                  Try: Create 1 output
    * ↓                                      ↓
    * Check: leftover >= (minUTxO × N)?      Check: leftover >= minUTxO?
@@ -2884,31 +1270,31 @@ export const makeTxBuilder = (config: TxBuilderConfig): TransactionBuilder => {
    *       ├─ (retry/fallback)                ├─ burn (leftover → fee)
    *       └─ ...                             └─ error
    * ```
-   * 
+   *
    * **Detailed Flow:**
    * ```
    * 1. Calculate tentative leftover (inputs - outputs - contextFee)
-   * 
+   *
    * 2. If unfrack enabled and canUnfrack=true:
    *    → Try createUnfrackedChangeOutputs() (N outputs)
    *    → Success: store N outputs, goto FeeCalculation
    *    → Not affordable:
    *       ├─ If attempt < MAX_ATTEMPTS: reselect (add more UTxOs)
    *       └─ If attempt >= MAX_ATTEMPTS: canUnfrack=false, goto step 3
-   * 
+   *
    * 3. Single output approach:
    *    → Create 1 change output with leftover
    *    → Success: store 1 output, goto FeeCalculation
    *    → Not affordable:
    *       ├─ If attempt < MAX_ATTEMPTS: reselect (add more UTxOs)
    *       └─ If attempt >= MAX_ATTEMPTS: goto step 4
-   * 
+   *
    * 4. Insufficient change fallbacks (single-output only):
    *    a. If drainTo specified: merge into existing output
    *    b. If onInsufficientChange="burn": leftover becomes fee
    *    c. If onInsufficientChange="error": throw error
    * ```
-   * 
+   *
    * **Key Principles:**
    * - Unfrack and single output use SAME retry mechanism (reselection up to MAX_ATTEMPTS)
    * - Phase loop handles fee convergence (leftover recalculated each iteration)
@@ -2916,13 +1302,14 @@ export const makeTxBuilder = (config: TxBuilderConfig): TransactionBuilder => {
    * - canUnfrack flag prevents retry loops (once false, stays false)
    * - drainTo and burn are terminal fallbacks (single-output only)
    * - Unfrack outputs bypass drainTo/burn (they're already valid)
-   * 
+   *
    * @returns Next phase to transition to
    */
   const phaseChangeCreationV3 = Effect.gen(function* () {
     const ctx = yield* TxContext
-    const buildCtxRef = yield* V3BuildContextTag
+    const buildCtxRef = yield* BuildContextTag
     const buildCtx = yield* Ref.get(buildCtxRef)
+    const changeAddress = yield* ChangeAddressTag
 
     yield* Effect.logDebug(`[ChangeCreationV3] Fee from context: ${buildCtx.calculatedFee}`)
 
@@ -2951,16 +1338,17 @@ export const makeTxBuilder = (config: TxBuilderConfig): TransactionBuilder => {
         shortfall,
         changeOutputs: []
       }))
-      return { next: "selection" as V3Phase }
+      return { next: "selection" as Phase }
     }
 
     // Step 4: Affordability check - verify minimum (single output) is affordable
     // This pre-flight check ensures we can create at least one valid change output
     // before attempting any unfrack strategies
+    const protocolParams = yield* ProtocolParametersTag
     const minLovelaceForSingle = yield* calculateMinimumUtxoLovelace({
-      address: ctx.config.changeAddress,
+      address: changeAddress,
       assets: tentativeLeftover,
-      coinsPerUtxoByte: ctx.config.protocolParameters.coinsPerUtxoByte
+      coinsPerUtxoByte: protocolParams.coinsPerUtxoByte
     })
 
     if (tentativeLeftover.lovelace < minLovelaceForSingle) {
@@ -2974,7 +1362,8 @@ export const makeTxBuilder = (config: TxBuilderConfig): TransactionBuilder => {
 
       // Check if we have available UTxOs for reselection
       const alreadySelected = yield* Ref.get(ctx.state.selectedUtxos)
-      const availableUtxos = getAvailableUtxos(ctx.config.availableUtxos, alreadySelected)
+      const allAvailableUtxos = yield* AvailableUtxosTag
+      const availableUtxos = getAvailableUtxos(allAvailableUtxos, alreadySelected)
       const hasMoreUtxos = availableUtxos.length > 0
 
       // Try reselection up to MAX_ATTEMPTS (if UTxOs available)
@@ -2991,7 +1380,7 @@ export const makeTxBuilder = (config: TxBuilderConfig): TransactionBuilder => {
           changeOutputs: []
         }))
 
-        return { next: "selection" as V3Phase }
+        return { next: "selection" as Phase }
       }
 
       // No more UTxOs OR MAX_ATTEMPTS exhausted - check fallback options
@@ -3042,12 +1431,18 @@ export const makeTxBuilder = (config: TxBuilderConfig): TransactionBuilder => {
       }
 
       // Fallback strategies configured - proceed to Fallback phase
-      return { next: "fallback" as V3Phase }
+      return { next: "fallback" as Phase }
     }
 
     // Step 5: Unfrack path (single output IS affordable, try bundles/subdivision)
     if (ctx.options?.unfrack && buildCtx.canUnfrack) {
-      const changeOutputs = yield* createChangeOutputs(tentativeLeftover, ctx)
+      const protocolParams = yield* ProtocolParametersTag
+      const changeOutputs = yield* createChangeOutputs(
+        tentativeLeftover,
+        ctx,
+        changeAddress,
+        protocolParams.coinsPerUtxoByte
+      )
 
       yield* Effect.logDebug(`[ChangeCreationV3] Successfully created ${changeOutputs.length} unfracked outputs`)
 
@@ -3056,13 +1451,13 @@ export const makeTxBuilder = (config: TxBuilderConfig): TransactionBuilder => {
         ...ctx,
         changeOutputs
       }))
-      return { next: "feeCalculation" as V3Phase }
+      return { next: "feeCalculation" as Phase }
     }
 
     // Step 6: Single output path - create single change output
     // Affordability already verified in Step 4, so we can create output directly
     const singleOutput: UTxO.TxOutput = {
-      address: ctx.config.changeAddress,
+      address: changeAddress,
       assets: tentativeLeftover,
       datumOption: undefined,
       scriptRef: undefined
@@ -3073,17 +1468,13 @@ export const makeTxBuilder = (config: TxBuilderConfig): TransactionBuilder => {
       changeOutputs: [singleOutput]
     }))
 
-    return { next: "feeCalculation" as V3Phase }
+    return { next: "feeCalculation" as Phase }
   })
 
-  // ============================================================================
-  // V3 PHASE: Fee Calculation
-  // ============================================================================
-
   const phaseFeeCalculationV3 = Effect.gen(function* () {
     // Step 1: Get contexts and current state
     const ctx = yield* TxContext
-    const buildCtxRef = yield* V3BuildContextTag
+    const buildCtxRef = yield* BuildContextTag
     const buildCtx = yield* Ref.get(buildCtxRef)
 
     const selectedUtxos = yield* Ref.get(ctx.state.selectedUtxos)
@@ -3100,9 +1491,10 @@ export const makeTxBuilder = (config: TxBuilderConfig): TransactionBuilder => {
     const allOutputs = [...baseOutputs, ...buildCtx.changeOutputs]
 
     // Step 4: Calculate fee WITH change outputs
+    const protocolParams = yield* ProtocolParametersTag
     const calculatedFee = yield* calculateFeeIteratively(selectedUtxos, inputs, allOutputs, {
-      minFeeCoefficient: ctx.config.protocolParameters.minFeeCoefficient,
-      minFeeConstant: ctx.config.protocolParameters.minFeeConstant
+      minFeeCoefficient: protocolParams.minFeeCoefficient,
+      minFeeConstant: protocolParams.minFeeConstant
     })
 
     yield* Effect.logDebug(`[FeeCalculationV3] Calculated fee: ${calculatedFee}`)
@@ -3124,17 +1516,13 @@ export const makeTxBuilder = (config: TxBuilderConfig): TransactionBuilder => {
       leftoverAfterFee
     }))
 
-    return { next: "balance" as V3Phase }
+    return { next: "balance" as Phase }
   })
 
-  // ============================================================================
-  // V3 PHASE: Balance Verification
-  // ============================================================================
-
   const phaseBalanceV3 = Effect.gen(function* () {
     // Step 1: Get contexts and log start
     const ctx = yield* TxContext
-    const buildCtxRef = yield* V3BuildContextTag
+    const buildCtxRef = yield* BuildContextTag
     const buildCtx = yield* Ref.get(buildCtxRef)
 
     yield* Effect.logDebug(`[BalanceV3] Starting balance verification (attempt ${buildCtx.attempt})`)
@@ -3168,7 +1556,7 @@ export const makeTxBuilder = (config: TxBuilderConfig): TransactionBuilder => {
     // Step 3: Check if balanced (delta is empty) → complete
     if (isBalanced) {
       yield* Effect.logDebug("[BalanceV3] Transaction balanced!")
-      return { next: "complete" as V3Phase }
+      return { next: "complete" as Phase }
     }
 
     // Step 4: Not balanced - check for native assets in delta (shouldn't happen)
@@ -3186,71 +1574,69 @@ export const makeTxBuilder = (config: TxBuilderConfig): TransactionBuilder => {
     const deltaLovelace = delta.lovelace
 
     // Excess: inputs > outputs + change + fee
-    // This should NEVER happen with V3's Option B design, EXCEPT:
+    // This should NEVER happen with Option B design, EXCEPT:
     // - Burn strategy: Positive delta is the burned leftover (expected and correct!)
     // - ChangeCreation creates change = tentativeLeftover (when sufficient)
     // - ChangeCreation routes to selection (when insufficient, never returns empty)
     // - Balance should only see: delta = 0 (balanced) or delta < 0 (shortfall) or delta > 0 (burn mode)
-    
+
     if (deltaLovelace > 0n) {
       // Check if this is expected from burn strategy
       const isBurnMode = ctx.options?.onInsufficientChange === "burn" && buildCtx.changeOutputs.length === 0
-      
+
       // Check if this is expected from drainTo strategy
       const isDrainToMode = ctx.options?.drainTo !== undefined && buildCtx.changeOutputs.length === 0
-      
+
       if (isDrainToMode) {
         // DrainTo mode: Merge positive delta (leftover after fee) into target output
         const drainToIndex = ctx.options.drainTo!
         const outputs = yield* Ref.get(ctx.state.outputs)
-        
+
         // Validate drainTo index (should already be validated in Fallback, but double-check)
         if (drainToIndex < 0 || drainToIndex >= outputs.length) {
           return yield* Effect.fail(
             new TransactionBuilderError({
-              message: `[V3 Balance] Invalid drainTo index: ${drainToIndex}. Must be between 0 and ${outputs.length - 1}`,
+              message: `Invalid drainTo index: ${drainToIndex}. Must be between 0 and ${outputs.length - 1}`,
               cause: { drainToIndex, outputCount: outputs.length }
             })
           )
         }
-        
+
         // Merge delta into target output
         const targetOutput = outputs[drainToIndex]
         const newLovelace = targetOutput.assets.lovelace + deltaLovelace
         const newAssets = { ...targetOutput.assets, lovelace: newLovelace }
         const updatedOutput = { ...targetOutput, assets: newAssets }
-        
+
         // Update outputs
         const newOutputs = [...outputs]
         newOutputs[drainToIndex] = updatedOutput
         yield* Ref.set(ctx.state.outputs, newOutputs)
-        
+
         // Recalculate totalOutputAssets
-        const newTotalOutputAssets = newOutputs.reduce(
-          (acc, output) => Assets.merge(acc, output.assets),
-          { lovelace: 0n } as Assets.Assets
-        )
+        const newTotalOutputAssets = newOutputs.reduce((acc, output) => Assets.merge(acc, output.assets), {
+          lovelace: 0n
+        } as Assets.Assets)
         yield* Ref.set(ctx.state.totalOutputAssets, newTotalOutputAssets)
-        
+
         yield* Effect.logDebug(
           `[BalanceV3] DrainTo mode: Merged ${deltaLovelace} lovelace into output[${drainToIndex}]. ` +
             `New output value: ${newLovelace}. Transaction balanced.`
         )
-        return { next: "complete" as V3Phase }
+        return { next: "complete" as Phase }
       } else if (isBurnMode) {
         // Burn mode: Positive delta is the burned leftover (becomes implicit fee)
         yield* Effect.logDebug(
-          `[BalanceV3] Burn mode: ${deltaLovelace} lovelace burned as implicit fee. ` +
-            `Transaction balanced.`
+          `[BalanceV3] Burn mode: ${deltaLovelace} lovelace burned as implicit fee. ` + `Transaction balanced.`
         )
-        return { next: "complete" as V3Phase }
+        return { next: "complete" as Phase }
       } else {
         // Not burn mode or drainTo: This is a bug
         return yield* Effect.fail(
           new TransactionBuilderError({
             message:
-              `[V3 Balance] CRITICAL BUG: Excess lovelace detected (${deltaLovelace}). ` +
-              `V3's Option B design should never produce positive delta. ` +
+              ` CRITICAL BUG: Excess lovelace detected (${deltaLovelace}). ` +
+              `s Option B design should never produce positive delta. ` +
               `This indicates incorrect change creation or fee calculation logic.`,
             cause: {
               delta: formatAssetsForLog(delta),
@@ -3269,28 +1655,25 @@ export const makeTxBuilder = (config: TxBuilderConfig): TransactionBuilder => {
     // Shortfall: inputs < outputs + change + fee
     // Return to changeCreation to recreate change with correct fee
     // If leftover < minLovelace, changeCreation will trigger selection
-    
+
     yield* Effect.logDebug(
       `[BalanceV3] Shortfall detected: ${-deltaLovelace} lovelace. ` +
         `Returning to changeCreation to adjust change output.`
     )
 
-    return { next: "changeCreation" as V3Phase }
+    return { next: "changeCreation" as Phase }
   })
 
-  // ============================================================================
-  // V3 PHASE: Fallback
-  // ============================================================================
   // Handles insufficient change scenarios with drain or burn strategies.
   // This phase is reached after MAX_ATTEMPTS exhausted in ChangeCreation.
   // Only applies to ADA-only leftover (native assets cannot be drained/burned).
   // Note: ChangeCreation ensures only ADA-only cases reach this phase.
 
   const phaseFallbackV3 = Effect.gen(function* () {
-    yield* Effect.logDebug("[V3] Phase: Fallback")
+    yield* Effect.logDebug("Phase: Fallback")
 
     const ctx = yield* TxContext
-    const buildCtxRef = yield* V3BuildContextTag
+    const buildCtxRef = yield* BuildContextTag
     // Note: We don't merge the leftover here. Instead, we just clear change outputs
     // and let the balance phase handle the merge after fee calculation.
     // This avoids circular dependency: fee depends on outputs, but drain amount depends on fee.
@@ -3330,7 +1713,7 @@ export const makeTxBuilder = (config: TxBuilderConfig): TransactionBuilder => {
       )
 
       // Go to fee calculation to recalculate without change outputs
-      return { next: "feeCalculation" as V3Phase }
+      return { next: "feeCalculation" as Phase }
     }
 
     // ---------------------------------------------------------------
@@ -3350,7 +1733,7 @@ export const makeTxBuilder = (config: TxBuilderConfig): TransactionBuilder => {
       )
 
       // Go to fee calculation to recalculate fee for transaction without change outputs
-      return { next: "feeCalculation" as V3Phase }
+      return { next: "feeCalculation" as Phase }
     }
 
     // ---------------------------------------------------------------
@@ -3371,19 +1754,65 @@ export const makeTxBuilder = (config: TxBuilderConfig): TransactionBuilder => {
     )
   })
 
-  // ============================================================================
-  // V3 Main Build Loop
-  // ============================================================================
-
   const buildEffectCoreV3 = (options?: BuildOptions) =>
     Effect.gen(function* () {
       const _ctx = yield* TxContext
 
-      // 1. Execute all programs to populate state
+      // Resolve protocol parameters once at build start
+      // Priority: BuildOptions override > provider.Effect.getProtocolParameters() > error
+      const protocolParameters: ProtocolParameters = yield* options?.protocolParameters !== undefined
+        ? Effect.succeed(options.protocolParameters)
+        : _ctx.config.provider
+          ? Effect.map(
+              _ctx.config.provider.Effect.getProtocolParameters(),
+              (params): ProtocolParameters => ({
+                minFeeCoefficient: BigInt(params.minFeeA),
+                minFeeConstant: BigInt(params.minFeeB),
+                coinsPerUtxoByte: params.coinsPerUtxoByte,
+                maxTxSize: params.maxTxSize
+              })
+            )
+          : Effect.fail(
+              new TransactionBuilderError({
+                message:
+                  "No protocol parameters provided. Either provide protocolParameters in BuildOptions or provider in config.",
+                cause: null
+              })
+            )
+
+      // Resolve change address once at build start
+      // Priority: BuildOptions override > wallet.Effect.address() > error
+      const changeAddress: string = yield* options?.changeAddress
+        ? Effect.succeed(options.changeAddress)
+        : _ctx.config.wallet
+          ? _ctx.config.wallet.Effect.address()
+          : Effect.fail(
+              new TransactionBuilderError({
+                message:
+                  "No change address provided. Either provide wallet in config or changeAddress in build options.",
+                cause: null
+              })
+            )
+
+      // Resolve available UTxOs once at build start
+      // Priority: BuildOptions override > provider.Effect.getUtxos(wallet.address) > error
+      const availableUtxos: ReadonlyArray<UTxO.UTxO> = yield* options?.availableUtxos
+        ? Effect.succeed(options.availableUtxos)
+        : _ctx.config.wallet && _ctx.config.provider
+          ? Effect.flatMap(_ctx.config.wallet.Effect.address(), (addr) => _ctx.config.provider!.Effect.getUtxos(addr))
+          : Effect.fail(
+              new TransactionBuilderError({
+                message:
+                  "No available UTxOs provided. Either provide wallet+provider in config or availableUtxos in build options.",
+                cause: null
+              })
+            )
+
+      // No need to create resolvedConfig - we provide resolved values via context tags below
+
       yield* Effect.all(programs, { concurrency: "unbounded" })
 
-      // 2. Create initial V3 build context
-      const initialBuildCtx: V3BuildContext = {
+      const initialBuildCtx: BuildContext = {
         phase: "selection" as const,
         attempt: 0,
         calculatedFee: 0n,
@@ -3395,8 +1824,9 @@ export const makeTxBuilder = (config: TxBuilderConfig): TransactionBuilder => {
 
       const ctxRef = yield* Ref.make(initialBuildCtx)
 
-      // 3. Run V3 state machine
-      yield* Effect.gen(function* () {
+      // Run phase loop and transaction assembly with all services provided
+      const { buildCtx, selectedUtxos, transaction, txWithFakeWitnesses } = yield* Effect.gen(function* () {
+        // Phase loop
         while (true) {
           const buildCtx = yield* Ref.get(ctxRef)
 
@@ -3406,7 +1836,7 @@ export const makeTxBuilder = (config: TxBuilderConfig): TransactionBuilder => {
           }
 
           // Route to phase
-          let result: V3PhaseResult
+          let result: PhaseResult
 
           switch (buildCtx.phase) {
             case "selection": {
@@ -3435,93 +1865,109 @@ export const makeTxBuilder = (config: TxBuilderConfig): TransactionBuilder => {
             }
 
             default:
-              return yield* Effect.fail(
-                new TransactionBuilderError({ message: `V3: Unknown phase: ${buildCtx.phase}` })
-              )
+              return yield* Effect.fail(new TransactionBuilderError({ message: `Unknown phase: ${buildCtx.phase}` }))
           }
 
           // Update phase
           yield* Ref.update(ctxRef, (c) => ({ ...c, phase: result.next }))
         }
-      }).pipe(Effect.provideService(V3BuildContextTag, ctxRef))
-
-      // 4. Add change outputs to transaction and assemble
-      const buildCtx = yield* Ref.get(ctxRef)
-      const ctx = yield* TxContext
 
-      yield* Effect.logDebug(`[V3] Build complete - fee: ${buildCtx.calculatedFee}`)
+        // 4. Add change outputs to transaction and assemble
+        const buildCtx = yield* Ref.get(ctxRef)
+        const ctx = yield* TxContext
 
-      // Add change outputs to the transaction outputs
-      if (buildCtx.changeOutputs.length > 0) {
-        const currentOutputs = yield* Ref.get(ctx.state.outputs)
-        yield* Ref.set(ctx.state.outputs, [...currentOutputs, ...buildCtx.changeOutputs])
+        yield* Effect.logDebug(`Build complete - fee: ${buildCtx.calculatedFee}`)
 
-        yield* Effect.logDebug(`[V3] Added ${buildCtx.changeOutputs.length} change output(s) to transaction`)
-      }
+        // Add change outputs to the transaction outputs
+        if (buildCtx.changeOutputs.length > 0) {
+          const currentOutputs = yield* Ref.get(ctx.state.outputs)
+          yield* Ref.set(ctx.state.outputs, [...currentOutputs, ...buildCtx.changeOutputs])
 
-      // Get final inputs and outputs for transaction assembly
-      const selectedUtxos = yield* Ref.get(ctx.state.selectedUtxos)
-      const allOutputs = yield* Ref.get(ctx.state.outputs)
+          yield* Effect.logDebug(`Added ${buildCtx.changeOutputs.length} change output(s) to transaction`)
+        }
 
-      yield* Effect.logDebug(
-        `[V3] Assembling transaction: ${selectedUtxos.length} inputs, ${allOutputs.length} outputs, fee: ${buildCtx.calculatedFee}`
-      )
+        // Get final inputs and outputs for transaction assembly
+        const selectedUtxos = yield* Ref.get(ctx.state.selectedUtxos)
+        const allOutputs = yield* Ref.get(ctx.state.outputs)
 
-      // Build transaction inputs and assemble transaction body
-      const inputs = yield* buildTransactionInputs(selectedUtxos)
-      const transaction = yield* assembleTransaction(inputs, allOutputs, buildCtx.calculatedFee)
+        yield* Effect.logDebug(
+          `Assembling transaction: ${selectedUtxos.length} inputs, ${allOutputs.length} outputs, fee: ${buildCtx.calculatedFee}`
+        )
 
-      // SAFETY CHECK: Validate transaction size against protocol limit
-      const fakeWitnessSet = yield* buildFakeWitnessSet(selectedUtxos)
+        // Build transaction inputs and assemble transaction body
+        const inputs = yield* buildTransactionInputs(selectedUtxos)
+        const transaction = yield* assembleTransaction(inputs, allOutputs, buildCtx.calculatedFee)
 
-      const txWithFakeWitnesses = new Transaction.Transaction({
-        body: transaction.body,
-        witnessSet: fakeWitnessSet,
-        isValid: true,
-        auxiliaryData: null
-      })
+        // SAFETY CHECK: Validate transaction size against protocol limit
+        const fakeWitnessSet = yield* buildFakeWitnessSet(selectedUtxos)
 
-      const txSizeWithWitnesses = yield* calculateTransactionSize(txWithFakeWitnesses)
+        const txWithFakeWitnesses = new Transaction.Transaction({
+          body: transaction.body,
+          witnessSet: fakeWitnessSet,
+          isValid: true,
+          auxiliaryData: null
+        })
 
-      yield* Effect.logDebug(
-        `[V3] Transaction size: ${txSizeWithWitnesses} bytes ` +
-          `(with ${fakeWitnessSet.vkeyWitnesses?.length ?? 0} fake witnesses), ` +
-          `max=${ctx.config.protocolParameters.maxTxSize} bytes`
-      )
+        const txSizeWithWitnesses = yield* calculateTransactionSize(txWithFakeWitnesses)
+        const protocolParams = yield* ProtocolParametersTag
 
-      if (txSizeWithWitnesses > ctx.config.protocolParameters.maxTxSize) {
-        return yield* Effect.fail(
-          new TransactionBuilderError({
-            message:
-              `Transaction size (${txSizeWithWitnesses} bytes) exceeds protocol maximum (${ctx.config.protocolParameters.maxTxSize} bytes). ` +
-              `Consider splitting into multiple transactions.`
-          })
+        yield* Effect.logDebug(
+          `Transaction size: ${txSizeWithWitnesses} bytes ` +
+            `(with ${fakeWitnessSet.vkeyWitnesses?.length ?? 0} fake witnesses), ` +
+            `max=${protocolParams.maxTxSize} bytes`
         )
-      }
 
-      // Return SignBuilder with the assembled transaction
-      const signBuilder: SignBuilder = {
-        Effect: {
-          sign: () => Effect.fail(new TransactionBuilderError({ message: "[V3] Signing not yet implemented" })),
-          signWithWitness: () =>
-            Effect.fail(new TransactionBuilderError({ message: "[V3] Witness signing not yet implemented" })),
-          assemble: () => Effect.fail(new TransactionBuilderError({ message: "[V3] Assemble not yet implemented" })),
-          partialSign: () =>
-            Effect.fail(new TransactionBuilderError({ message: "[V3] Partial signing not yet implemented" })),
-          getWitnessSet: () => Effect.succeed(transaction.witnessSet),
-          toTransaction: () => Effect.succeed(transaction),
-          toTransactionWithFakeWitnesses: () => Effect.succeed(txWithFakeWitnesses)
-        },
-        sign: () => Promise.reject(new Error("[V3] Signing not yet implemented")),
-        signWithWitness: () => Promise.reject(new Error("[V3] Witness signing not yet implemented")),
-        assemble: () => Promise.reject(new Error("[V3] Assemble not yet implemented")),
-        partialSign: () => Promise.reject(new Error("[V3] Partial signing not yet implemented")),
-        getWitnessSet: () => Promise.resolve(transaction.witnessSet),
-        toTransaction: () => Promise.resolve(transaction),
-        toTransactionWithFakeWitnesses: () => Promise.resolve(txWithFakeWitnesses)
-      }
+        if (txSizeWithWitnesses > protocolParams.maxTxSize) {
+          return yield* Effect.fail(
+            new TransactionBuilderError({
+              message:
+                `Transaction size (${txSizeWithWitnesses} bytes) exceeds protocol maximum (${protocolParams.maxTxSize} bytes). ` +
+                `Consider splitting into multiple transactions.`
+            })
+          )
+        }
 
-      return signBuilder
+        // Return data for final result assembly
+        return {
+          transaction,
+          txWithFakeWitnesses,
+          buildCtx,
+          selectedUtxos
+        }
+      }).pipe(
+        Effect.provideService(BuildContextTag, ctxRef),
+        Effect.provideService(ProtocolParametersTag, protocolParameters),
+        Effect.provideService(ChangeAddressTag, changeAddress),
+        Effect.provideService(AvailableUtxosTag, availableUtxos)
+      )
+
+      // Assemble final result based on wallet capabilities
+      const ctx = yield* TxContext
+      const wallet = ctx.config.wallet
+
+      // Type guard: Check if wallet is signing-capable (has signTx method)
+      const isSigningWallet = wallet && "signTx" in wallet
+
+      if (isSigningWallet) {
+        // Return SignBuilder for signing-capable wallets
+        const signBuilder = makeSignBuilder({
+          transaction,
+          transactionWithFakeWitnesses: txWithFakeWitnesses,
+          fee: buildCtx.calculatedFee,
+          utxos: selectedUtxos,
+          provider: ctx.config.provider!,
+          wallet: wallet as WalletNew.SigningWallet | WalletNew.ApiWallet
+        })
+        return signBuilder
+      } else {
+        // Return TransactionResultBase for read-only wallets
+        const transactionResult = makeTransactionResult({
+          transaction,
+          transactionWithFakeWitnesses: txWithFakeWitnesses,
+          fee: buildCtx.calculatedFee
+        })
+        return transactionResult
+      }
     }).pipe(
       Effect.provideServiceEffect(
         TxContext,
@@ -3535,10 +1981,6 @@ export const makeTxBuilder = (config: TxBuilderConfig): TransactionBuilder => {
       )
     )
 
-  // ============================================================================
-  // End of V3 State Machine Implementation
-  // ============================================================================
-
   // Core Effect logic for chaining
   const chainEffectCore = (options?: BuildOptions) =>
     Effect.gen(function* () {
@@ -3592,7 +2034,7 @@ export const makeTxBuilder = (config: TxBuilderConfig): TransactionBuilder => {
       )
     )
 
-  const txBuilder: TransactionBuilder = {
+  const txBuilder: TransactionBuilder<TResult> = {
     // ============================================================================
     // Chainable builder methods - Create ProgramSteps, return same instance
     // ============================================================================
@@ -3616,43 +2058,29 @@ export const makeTxBuilder = (config: TxBuilderConfig): TransactionBuilder => {
     // ============================================================================
 
     buildEffect: (options?: BuildOptions) => {
-      if (options?.useV3) {
-        return buildEffectCoreV3(options)
-      }
-      const buildFn = options?.useStateMachine ? buildEffectCoreStateMachineV2 : buildEffectCore
-      return buildFn(options)
+      return buildEffectCoreV3(options) as unknown as Effect.Effect<
+        TResult,
+        TransactionBuilderError | EvaluationError | WalletNew.WalletError | Provider.ProviderError,
+        unknown
+      >
     },
 
     build: (options?: BuildOptions) => {
-      if (options?.useV3) {
-        return Effect.runPromise(
-          buildEffectCoreV3(options).pipe(
-            Effect.provide(Layer.merge(Logger.pretty, Logger.minimumLogLevel(LogLevel.Debug)))
-          )
-        )
-      }
-      const buildFn = options?.useStateMachine ? buildEffectCoreStateMachineV2 : buildEffectCore
       return Effect.runPromise(
-        buildFn(options).pipe(Effect.provide(Layer.merge(Logger.pretty, Logger.minimumLogLevel(LogLevel.Debug))))
-      )
+        buildEffectCoreV3(options).pipe(
+          Effect.provide(Layer.merge(Logger.pretty, Logger.minimumLogLevel(LogLevel.Debug)))
+        )
+      ) as unknown as Promise<TResult>
     },
-
     buildEither: (options?: BuildOptions) => {
-      if (options?.useV3) {
-        return Effect.runPromise(
-          buildEffectCoreV3(options).pipe(
-            Effect.either,
-            Effect.provide(Layer.merge(Logger.pretty, Logger.minimumLogLevel(LogLevel.Debug)))
-          )
-        )
-      }
-      const buildFn = options?.useStateMachine ? buildEffectCoreStateMachineV2 : buildEffectCore
       return Effect.runPromise(
-        buildFn(options).pipe(
+        buildEffectCoreV3(options).pipe(
           Effect.either,
           Effect.provide(Layer.merge(Logger.pretty, Logger.minimumLogLevel(LogLevel.Debug)))
         )
-      )
+      ) as unknown as Promise<
+        Either<TResult, TransactionBuilderError | EvaluationError | WalletNew.WalletError | Provider.ProviderError>
+      >
     },
 
     // ============================================================================
@@ -3676,9 +2104,3 @@ export const makeTxBuilder = (config: TxBuilderConfig): TransactionBuilder => {
 
   return txBuilder
 }
-
-// ============================================================================
-// Helper Functions - To be implemented
-// ============================================================================
-
-// Implementation functions are imported from TxBuilderImpl.js at top of file
diff --git a/packages/evolution/src/sdk/builders/TransactionResult.ts b/packages/evolution/src/sdk/builders/TransactionResult.ts
new file mode 100644
index 00000000..0f4df25f
--- /dev/null
+++ b/packages/evolution/src/sdk/builders/TransactionResult.ts
@@ -0,0 +1,160 @@
+/**
+ * TransactionResult - Base interface for transaction building results
+ * 
+ * Provides core functionality available to all transaction builders regardless
+ * of signing capability. This enables type-safe differentiation between
+ * read-only clients (can build but not sign) and signing clients (can build and sign).
+ * 
+ * @since 2.0.0
+ * @category builders
+ */
+
+import { Effect } from "effect"
+
+import type * as Transaction from "../../core/Transaction.js"
+import type { TransactionBuilderError } from "./TransactionBuilder.js"
+
+/**
+ * Base result interface for built transactions.
+ * 
+ * Available on all transaction builders regardless of signing capability.
+ * Provides access to the unsigned transaction, fee estimates, and transaction
+ * with fake witnesses for size validation.
+ * 
+ * @since 2.0.0
+ * @category interfaces
+ */
+export interface TransactionResultBase {
+  /**
+   * Get the unsigned transaction.
+   * 
+   * This transaction has a complete body but no witness set (signatures).
+   * Can be serialized to CBOR for external signing (hardware wallets, browser extensions, etc.)
+   * 
+   * @returns Promise resolving to the unsigned transaction
+   * 
+   * @example
+   * ```typescript
+   * const result = await readOnlyClient.newTx()
+   *   .payToAddress({ address: "addr...", lovelace: 5_000_000n })
+   *   .build()
+   * 
+   * const unsignedTx = await result.toTransaction()
+   * const txCbor = Transaction.toCBORHex(unsignedTx)
+   * // Export for external signing
+   * ```
+   * 
+   * @since 2.0.0
+   * @category accessors
+   */
+  readonly toTransaction: () => Promise<Transaction.Transaction>
+
+  /**
+   * Get the transaction with fake witnesses for fee validation.
+   * 
+   * This transaction includes fake witness sets (294 bytes each) to accurately
+   * calculate the final transaction size and fees. Useful for validating that
+   * the calculated fee is sufficient for the final signed transaction.
+   * 
+   * @returns Promise resolving to the transaction with fake witnesses
+   * 
+   * @since 2.0.0
+   * @category accessors
+   */
+  readonly toTransactionWithFakeWitnesses: () => Promise<Transaction.Transaction>
+
+  /**
+   * Get the calculated transaction fee in lovelace.
+   * 
+   * This is the fee that was calculated during the build process based on
+   * the transaction size (including fake witnesses) and protocol parameters.
+   * 
+   * @returns Promise resolving to the transaction fee in lovelace
+   * 
+   * @example
+   * ```typescript
+   * const result = await client.newTx()
+   *   .payToAddress({ address: "addr...", lovelace: 5_000_000n })
+   *   .build()
+   * 
+   * const fee = await result.estimateFee()
+   * console.log(`Transaction fee: ${fee} lovelace`)
+   * ```
+   * 
+   * @since 2.0.0
+   * @category accessors
+   */
+  readonly estimateFee: () => Promise<bigint>
+
+  /**
+   * Effect-based API for compositional workflows.
+   * 
+   * Provides the same functionality as the Promise-based methods but returns
+   * Effect values for use in Effect-TS workflows with proper error handling
+   * and composition.
+   * 
+   * @since 2.0.0
+   * @category effects
+   */
+  readonly Effect: {
+    /**
+     * Get the unsigned transaction as an Effect.
+     * 
+     * @since 2.0.0
+     */
+    readonly toTransaction: () => Effect.Effect<Transaction.Transaction, TransactionBuilderError>
+
+    /**
+     * Get the transaction with fake witnesses as an Effect.
+     * 
+     * @since 2.0.0
+     */
+    readonly toTransactionWithFakeWitnesses: () => Effect.Effect<Transaction.Transaction, TransactionBuilderError>
+
+    /**
+     * Get the calculated fee as an Effect.
+     * 
+     * @since 2.0.0
+     */
+    readonly estimateFee: () => Effect.Effect<bigint, TransactionBuilderError>
+  }
+}
+
+// ============================================================================
+// TransactionResultBase Factory
+// ============================================================================
+
+/**
+ * Create a TransactionResultBase instance for a built transaction without signing capability.
+ * 
+ * Used by ReadOnlyClient which can build transactions but cannot sign them.
+ * Provides access to the unsigned transaction, fake-witness transaction for fee validation,
+ * and fee estimation.
+ * 
+ * @param transaction - The unsigned transaction
+ * @param transactionWithFakeWitnesses - The transaction with fake witnesses for size validation
+ * @param fee - The calculated transaction fee in lovelace
+ * 
+ * @since 2.0.0
+ * @category constructors
+ */
+export const makeTransactionResult = (params: {
+  transaction: Transaction.Transaction
+  transactionWithFakeWitnesses: Transaction.Transaction
+  fee: bigint
+}): TransactionResultBase => {
+  const { fee, transaction, transactionWithFakeWitnesses } = params
+
+  const resultEffect: TransactionResultBase["Effect"] = {
+    toTransaction: () => Effect.succeed(transaction),
+    toTransactionWithFakeWitnesses: () => Effect.succeed(transactionWithFakeWitnesses),
+    estimateFee: () => Effect.succeed(fee)
+  }
+
+  return {
+    toTransaction: () => Promise.resolve(transaction),
+    toTransactionWithFakeWitnesses: () => Promise.resolve(transactionWithFakeWitnesses),
+    estimateFee: () => Promise.resolve(fee),
+    Effect: resultEffect
+  }
+}
diff --git a/packages/evolution/src/sdk/builders/index.ts b/packages/evolution/src/sdk/builders/index.ts
index 7aaf40db..b31d903e 100644
--- a/packages/evolution/src/sdk/builders/index.ts
+++ b/packages/evolution/src/sdk/builders/index.ts
@@ -1,4 +1,8 @@
 export * from "./CoinSelection.js"
 export * from "./operations/index.js"
 export * from "./SignBuilder.js"
-export * from "./TransactionBuilder.js"
\ No newline at end of file
+export * from "./SignBuilderImpl.js"
+export * from "./SubmitBuilder.js"
+export * from "./SubmitBuilderImpl.js"
+export * from "./TransactionBuilder.js"
+export * from "./TransactionResult.js"
\ No newline at end of file
diff --git a/packages/evolution/src/sdk/client/Client.ts b/packages/evolution/src/sdk/client/Client.ts
index 0a1399b3..6361aaeb 100644
--- a/packages/evolution/src/sdk/client/Client.ts
+++ b/packages/evolution/src/sdk/client/Client.ts
@@ -3,6 +3,8 @@
 
 import { Data, type Effect, type Schedule } from "effect"
 
+import type { TransactionBuilder } from "../builders/TransactionBuilder.js"
+import type { TransactionResultBase } from "../builders/TransactionResult.js"
 import type * as Delegation from "../Delegation.js"
 import type * as Provider from "../provider/Provider.js"
 import type { EffectToPromiseAPI } from "../Type.js"
@@ -73,17 +75,21 @@ export interface MinimalClient {
     config: T
   ) => T extends SeedWalletConfig
     ? SigningWalletClient
-    : T extends ApiWalletConfig
-      ? ApiWalletClient
-      : ReadOnlyWalletClient
+    : T extends PrivateKeyWalletConfig
+      ? SigningWalletClient
+      : T extends ApiWalletConfig
+        ? ApiWalletClient
+        : ReadOnlyWalletClient
   readonly attach: <TW extends WalletConfig>(
     providerConfig: ProviderConfig,
     walletConfig: TW
   ) => TW extends SeedWalletConfig
     ? SigningClient
-    : TW extends ApiWalletConfig
+    : TW extends PrivateKeyWalletConfig
       ? SigningClient
-      : ReadOnlyClient
+      : TW extends ApiWalletConfig
+        ? SigningClient
+        : ReadOnlyClient
   // Effect namespace for methods with side effects only
   readonly Effect: MinimalClientEffect
 }
@@ -97,27 +103,100 @@ export type ProviderOnlyClient = EffectToPromiseAPI<Provider.ProviderEffect> & {
     config: T
   ) => T extends SeedWalletConfig
     ? SigningClient
-    : T extends ApiWalletConfig
+    : T extends PrivateKeyWalletConfig
       ? SigningClient
-      : ReadOnlyClient
+      : T extends ApiWalletConfig
+        ? SigningClient
+        : ReadOnlyClient
   // Effect namespace - includes all provider methods as Effects
   readonly Effect: Provider.ProviderEffect
 }
 
 /**
  * ReadOnlyClient - can query blockchain + wallet address operations
+ * 
+ * ReadOnlyClient cannot sign transactions, so newTx() returns a TransactionBuilder
+ * that yields TransactionResultBase (unsigned transaction only).
  */
 export type ReadOnlyClient = EffectToPromiseAPI<ReadOnlyClientEffect> & {
-  readonly newTx: (utxos?: ReadonlyArray<UTxO.UTxO>) => any // TODO: Change to ReadOnlyTransactionBuilder when implementing tx builder
+  /**
+   * Create a new transaction builder for read-only operations.
+   *
+   * Returns a TransactionBuilder that builds unsigned transactions.
+   * The build() methods return TransactionResultBase which provides:
+   * - `.toTransaction()` - Get the unsigned transaction
+   * - `.toTransactionWithFakeWitnesses()` - Get transaction with fake witnesses for fee validation
+   * - `.estimateFee()` - Get the calculated fee
+   *
+   * @param utxos - Optional UTxOs to use for coin selection. If not provided, wallet UTxOs will be fetched automatically when build() is called.
+   * @returns A new TransactionBuilder instance configured with cached protocol parameters and wallet change address.
+   *
+   * @example
+   * ```typescript
+   * // Build unsigned transaction
+   * const result = await readOnlyClient.newTx()
+   *   .payToAddress({ address: "addr...", lovelace: 5000000n })
+   *   .build()
+   *
+   * // Get unsigned transaction for external signing
+   * const unsignedTx = await result.toTransaction()
+   * const txCbor = Transaction.toCBORHex(unsignedTx)
+   * 
+   * // Get fee estimate
+   * const fee = await result.estimateFee()
+   * ```
+   *
+   * @since 2.0.0
+   * @category transaction-building
+   */
+  readonly newTx: (utxos?: ReadonlyArray<UTxO.UTxO>) => TransactionBuilder<TransactionResultBase>
   // Effect namespace - includes all provider + wallet methods as Effects
   readonly Effect: ReadOnlyClientEffect
 }
 
 /**
  * SigningClient - full functionality: query blockchain + sign + submit
+ * 
+ * SigningClient has wallet signing capability, so newTx() returns a TransactionBuilder
+ * that yields SignBuilder (can sign and submit transactions).
  */
 export type SigningClient = EffectToPromiseAPI<SigningClientEffect> & {
-  readonly newTx: (utxos?: ReadonlyArray<UTxO.UTxO>) => any // TODO: Change to ReadOnlyTransactionBuilder when implementing tx builder
+  /**
+   * Create a new transaction builder with signing capability.
+   *
+   * Returns a TransactionBuilder that can build and sign transactions.
+   * The build() methods return SignBuilder which provides:
+   * - `.sign()` - Sign and prepare for submission
+   * - `.toTransaction()` - Get the unsigned transaction  
+   * - `.toTransactionWithFakeWitnesses()` - Get transaction with fake witnesses for fee validation
+   * - `.estimateFee()` - Get the calculated fee
+   * - `.partialSign()` - Create partial signature for multi-sig
+   * - `.assemble()` - Combine multiple signatures
+   *
+   * UTxOs for coin selection are fetched automatically from the wallet when build() is called.
+   * You can override UTxOs per-build using BuildOptions.availableUtxos.
+   *
+   * @returns A new TransactionBuilder instance configured with cached protocol parameters and wallet change address.
+   *
+   * @example
+   * ```typescript
+   * // Build and sign transaction
+   * const signBuilder = await signingClient.newTx()
+   *   .payToAddress({ address: "addr...", lovelace: 5000000n })
+   *   .build()
+   *
+   * // Sign and submit
+   * const submitBuilder = await signBuilder.sign()
+   * const txHash = await submitBuilder.submit()
+   * 
+   * // Or get unsigned transaction
+   * const unsignedTx = await signBuilder.toTransaction()
+   * ```
+   *
+   * @since 2.0.0
+   * @category transaction-building
+   */
+  readonly newTx: () => TransactionBuilder
   // Effect namespace - includes all provider + wallet methods as Effects
   readonly Effect: SigningClientEffect
 }
@@ -241,6 +320,13 @@ export interface SeedWalletConfig {
   readonly password?: string
 }
 
+export interface PrivateKeyWalletConfig {
+  readonly type: "private-key"
+  readonly paymentKey: string // bech32 ed25519e_sk
+  readonly stakeKey?: string // bech32 ed25519e_sk (optional, for Base addresses)
+  readonly addressType?: "Base" | "Enterprise"
+}
+
 export interface ReadOnlyWalletConfig {
   readonly type: "read-only"
   readonly address: string
@@ -252,5 +338,5 @@ export interface ApiWalletConfig {
   readonly api: WalletApi // CIP-30 wallet API interface
 }
 
-export type WalletConfig = SeedWalletConfig | ReadOnlyWalletConfig | ApiWalletConfig
+export type WalletConfig = SeedWalletConfig | PrivateKeyWalletConfig | ReadOnlyWalletConfig | ApiWalletConfig
 
diff --git a/packages/evolution/src/sdk/client/ClientImpl.ts b/packages/evolution/src/sdk/client/ClientImpl.ts
index 80d6b19a..a8d035a8 100644
--- a/packages/evolution/src/sdk/client/ClientImpl.ts
+++ b/packages/evolution/src/sdk/client/ClientImpl.ts
@@ -1,6 +1,6 @@
 // ClientImpl.ts - Step-by-step implementation starting with MinimalClient
 
-import { Effect, Either } from "effect"
+import { Effect } from "effect"
 
 import * as KeyHash from "../../core/KeyHash.js"
 import * as PrivateKey from "../../core/PrivateKey.js"
@@ -9,8 +9,12 @@ import * as Transaction from "../../core/Transaction.js"
 import * as TransactionHash from "../../core/TransactionHash.js"
 import * as TransactionWitnessSet from "../../core/TransactionWitnessSet.js"
 import * as VKey from "../../core/VKey.js"
+import { runEffect } from "../../utils/effect-runtime.js"
 import { hashTransaction } from "../../utils/Hash.js"
 import type * as Address from "../Address.js"
+import type { SignBuilder } from "../builders/SignBuilder.js"
+import { makeTxBuilder, type TransactionBuilder } from "../builders/TransactionBuilder.js"
+import type { TransactionResultBase } from "../builders/TransactionResult.js"
 import * as Blockfrost from "../provider/Blockfrost.js"
 import * as Koios from "../provider/Koios.js"
 import * as Kupmios from "../provider/Kupmios.js"
@@ -26,6 +30,7 @@ import {
   type MinimalClient,
   type MinimalClientEffect,
   type NetworkId,
+  type PrivateKeyWalletConfig,
   type ProviderConfig,
   type ProviderOnlyClient,
   type ReadOnlyClient,
@@ -76,6 +81,8 @@ const normalizeNetworkId = (network: NetworkId): number => {
   }
 }
 
+/**
+ * Convert SDK ProtocolParameters to TransactionBuilder format.
 /**
  * Map NetworkId discriminant to wallet network enumeration.
  * 
@@ -115,14 +122,14 @@ const createReadOnlyWallet = (
 ): WalletNew.ReadOnlyWallet => {
   // Effect interface - methods that return Effects
   const walletEffect: WalletNew.ReadOnlyWalletEffect = {
-    address: Effect.succeed(address),
-    rewardAddress: Effect.succeed(rewardAddress ?? null)
+    address: () => Effect.succeed(address),
+    rewardAddress: () => Effect.succeed(rewardAddress ?? null)
   }
 
   return {
-    // Promise-based API - these are Promises, not functions
-    address: Promise.resolve(address),
-    rewardAddress: Promise.resolve(rewardAddress ?? null),
+    // Promise-based API - these are functions returning Promises
+    address: () => Promise.resolve(address),
+    rewardAddress: () => Promise.resolve(rewardAddress ?? null),
     // Effect namespace
     Effect: walletEffect,
     type: "read-only"
@@ -188,9 +195,15 @@ const createReadOnlyClient = (
       if (!rewardAddr) throw new Error("No reward address configured")
       return provider.getDelegation(rewardAddr)
     },
-    // Transaction builder (TODO: implement later)
-    newTx: (_utxos?: any): any => {
-      throw new Error("newTx not yet implemented")
+    // Transaction builder - creates a new builder instance
+    newTx: (): TransactionBuilder<TransactionResultBase> => {
+      // ReadOnlyWallet provides change address and UTxO fetching via wallet.Effect.address()
+      // The wallet is passed to the builder config, which handles address and UTxO resolution automatically
+      // Protocol parameters are auto-fetched from provider during build()
+      return makeTxBuilder<TransactionResultBase>({
+        wallet,
+        provider
+      })
     },
     // Effect namespace - combined provider + wallet Effects
     Effect: {
@@ -282,50 +295,38 @@ const computeRequiredKeyHashesSync = (params: {
 }
 
 /**
- * Construct a SigningWallet from mnemonic seed phrase by deriving keys and building a keystore.
- * 
- * Derives payment and optional stake keys from the seed using the specified address type and account index.
- * Returns a wallet with signing capability via both Promise and Effect APIs.
+ * Create a signing wallet from a seed phrase.
  * 
- * @since 2.0.0
+ * Wallet creation is synchronous - sodium initialization and key derivation
+ * happen lazily on first crypto operation (signTx, signMessage).
+ *
  * @category constructors
  */
 const createSigningWallet = (network: WalletNew.Network, config: SeedWalletConfig): WalletNew.SigningWallet => {
-  // Derive keys and address from seed
-  const derivation = Derivation.walletFromSeed(config.mnemonic, {
+  const derivationEffect = Derivation.walletFromSeed(config.mnemonic, {
     addressType: config.addressType ?? "Base",
     accountIndex: config.accountIndex ?? 0,
     password: config.password,
     network
-  }).pipe(Either.getOrThrow)
-
-  // Build keystore: map KeyHash hex -> PrivateKey
-  const keyStore = new Map<string, PrivateKey.PrivateKey>()
-  const paymentSk = PrivateKey.fromBech32(derivation.paymentKey)
-  const paymentKh = KeyHash.fromPrivateKey(paymentSk)
-  const paymentKhHex = KeyHash.toHex(paymentKh)
-  keyStore.set(paymentKhHex, paymentSk)
-
-  let stakeSk: PrivateKey.PrivateKey | undefined
-  let stakeKhHex: string | undefined
-  if (derivation.stakeKey) {
-    stakeSk = PrivateKey.fromBech32(derivation.stakeKey)
-    const stakeKh = KeyHash.fromPrivateKey(stakeSk)
-    stakeKhHex = KeyHash.toHex(stakeKh)
-    keyStore.set(stakeKhHex, stakeSk)
-  }
+  }).pipe(
+    Effect.mapError(
+      (cause) => new WalletNew.WalletError({ message: cause.message, cause })
+    )
+  )
 
   // Effect implementations are the source of truth
   const effectInterface: WalletNew.SigningWalletEffect = {
-    address: Effect.succeed(derivation.address),
-    rewardAddress: Effect.succeed(derivation.rewardAddress ?? null),
+    address: () => Effect.map(derivationEffect, (d) => d.address),
+    rewardAddress: () => Effect.map(derivationEffect, (d) => d.rewardAddress ?? null),
     signTx: (txOrHex: Transaction.Transaction | string, context?: { utxos?: ReadonlyArray<UTxO.UTxO> }) =>
       Effect.gen(function* () {
+        const derivation = yield* derivationEffect
+        
         const tx =
           typeof txOrHex === "string"
             ? yield* Transaction.Either.fromCBORHex(txOrHex).pipe(
                 Effect.mapError(
-                  (cause) => new WalletNew.WalletError({ message: "Failed to decode transaction", cause })
+                  (cause) => new WalletNew.WalletError({ message: cause.message, cause })
                 )
               )
             : txOrHex
@@ -333,9 +334,9 @@ const createSigningWallet = (network: WalletNew.Network, config: SeedWalletConfi
 
         // Determine required key hashes for signing
         const required = computeRequiredKeyHashesSync({
-          paymentKhHex,
+          paymentKhHex: derivation.paymentKhHex,
           rewardAddress: derivation.rewardAddress ?? null,
-          stakeKhHex,
+          stakeKhHex: derivation.stakeKhHex,
           tx,
           utxos
         })
@@ -347,7 +348,7 @@ const createSigningWallet = (network: WalletNew.Network, config: SeedWalletConfi
         const witnesses: Array<TransactionWitnessSet.VKeyWitness> = []
         const seenVKeys = new Set<string>()
         for (const khHex of required) {
-          const sk = keyStore.get(khHex)
+          const sk = derivation.keyStore.get(khHex)
           if (!sk) continue
           const sig = PrivateKey.sign(sk, msg)
           const vk = VKey.fromPrivateKey(sk)
@@ -360,8 +361,9 @@ const createSigningWallet = (network: WalletNew.Network, config: SeedWalletConfi
         return witnesses.length > 0 ? TransactionWitnessSet.fromVKeyWitnesses(witnesses) : TransactionWitnessSet.empty()
       }),
     signMessage: (_address: Address.Address | RewardAddress.RewardAddress, payload: WalletNew.Payload) =>
-      Effect.sync(() => {
+      Effect.map(derivationEffect, (derivation) => {
         // For now, always use payment key for message signing
+        const paymentSk = PrivateKey.fromBech32(derivation.paymentKey)
         const vk = VKey.fromPrivateKey(paymentSk)
         const bytes = typeof payload === "string" ? new TextEncoder().encode(payload) : payload
         const _sig = PrivateKey.sign(paymentSk, bytes)
@@ -373,14 +375,101 @@ const createSigningWallet = (network: WalletNew.Network, config: SeedWalletConfi
   // Promise API runs the Effect implementations
   return {
     type: "signing",
-    address: Effect.runPromise(effectInterface.address),
-    rewardAddress: Effect.runPromise(effectInterface.rewardAddress),
+    address: () => Effect.runPromise(effectInterface.address()),
+    rewardAddress: () => Effect.runPromise(effectInterface.rewardAddress()),
     signTx: (txOrHex, context) => Effect.runPromise(effectInterface.signTx(txOrHex, context)),
     signMessage: (address, payload) => Effect.runPromise(effectInterface.signMessage(address, payload)),
     Effect: effectInterface
   }
 }
 
+/**
+ * Create a signing wallet from private keys.
+ * 
+ * @category constructors
+ */
+const createPrivateKeyWallet = (
+  network: WalletNew.Network,
+  config: PrivateKeyWalletConfig
+): WalletNew.SigningWallet => {
+  // walletFromPrivateKey now returns an Effect directly
+  const derivationEffect = Derivation.walletFromPrivateKey(config.paymentKey, {
+    stakeKeyBech32: config.stakeKey,
+    addressType: config.addressType ?? (config.stakeKey ? "Base" : "Enterprise"),
+    network
+  }).pipe(
+    Effect.mapError((cause) => new WalletNew.WalletError({ message: cause.message, cause }))
+  )
+
+  // Effect implementations are the source of truth
+  const effectInterface: WalletNew.SigningWalletEffect = {
+    address: () => Effect.map(derivationEffect, (d) => d.address),
+    rewardAddress: () => Effect.map(derivationEffect, (d) => d.rewardAddress ?? null),
+    signTx: (txOrHex: Transaction.Transaction | string, context?: { utxos?: ReadonlyArray<UTxO.UTxO> }) =>
+      Effect.gen(function* () {
+        const derivation = yield* derivationEffect
+        
+        const tx =
+          typeof txOrHex === "string"
+            ? yield* Transaction.Either.fromCBORHex(txOrHex).pipe(
+                Effect.mapError(
+                  (cause) => new WalletNew.WalletError({ message: cause.message, cause })
+                )
+              )
+            : txOrHex
+        const utxos = context?.utxos ?? []
+
+        // Determine required key hashes for signing
+        const required = computeRequiredKeyHashesSync({
+          paymentKhHex: derivation.paymentKhHex,
+          rewardAddress: derivation.rewardAddress ?? null,
+          stakeKhHex: derivation.stakeKhHex,
+          tx,
+          utxos
+        })
+
+        // Build witnesses for keys we have
+        const txHash = hashTransaction(tx.body)
+        const msg = txHash.hash
+
+        const witnesses: Array<TransactionWitnessSet.VKeyWitness> = []
+        const seenVKeys = new Set<string>()
+        for (const khHex of required) {
+          const sk = derivation.keyStore.get(khHex)
+          if (!sk) continue
+          const sig = PrivateKey.sign(sk, msg)
+          const vk = VKey.fromPrivateKey(sk)
+          const vkHex = VKey.toHex(vk)
+          if (seenVKeys.has(vkHex)) continue
+          seenVKeys.add(vkHex)
+          witnesses.push(new TransactionWitnessSet.VKeyWitness({ vkey: vk, signature: sig }))
+        }
+
+        return witnesses.length > 0 ? TransactionWitnessSet.fromVKeyWitnesses(witnesses) : TransactionWitnessSet.empty()
+      }),
+    signMessage: (_address: Address.Address | RewardAddress.RewardAddress, payload: WalletNew.Payload) =>
+      Effect.map(derivationEffect, (derivation) => {
+        // For now, always use payment key for message signing
+        const paymentSk = PrivateKey.fromBech32(derivation.paymentKey)
+        const vk = VKey.fromPrivateKey(paymentSk)
+        const bytes = typeof payload === "string" ? new TextEncoder().encode(payload) : payload
+        const _sig = PrivateKey.sign(paymentSk, bytes)
+        const sigHex = VKey.toHex(vk) // TODO: Convert signature properly
+        return { payload, signature: sigHex }
+      })
+  }
+
+  // Promise API runs the Effect implementations
+  return {
+    type: "signing",
+    address: () => runEffect(effectInterface.address()),
+    rewardAddress: () => runEffect(effectInterface.rewardAddress()),
+    signTx: (txOrHex, context) => runEffect(effectInterface.signTx(txOrHex, context)),
+    signMessage: (address, payload) => runEffect(effectInterface.signMessage(address, payload)),
+    Effect: effectInterface
+  }
+}
+
 /**
  * Construct an ApiWallet wrapping a CIP-30 browser wallet API.
  * 
@@ -399,11 +488,11 @@ const createApiWallet = (_network: WalletNew.Network, config: ApiWalletConfig):
     if (cachedAddress) return cachedAddress
     const used = yield* Effect.tryPromise({
       try: () => api.getUsedAddresses(),
-      catch: (cause) => new WalletNew.WalletError({ message: "Failed to get used addresses", cause })
+      catch: (cause) => new WalletNew.WalletError({ message: (cause as Error).message, cause: cause as Error })
     })
     const unused = yield* Effect.tryPromise({
       try: () => api.getUnusedAddresses(),
-      catch: (cause) => new WalletNew.WalletError({ message: "Failed to get unused addresses", cause })
+      catch: (cause) => new WalletNew.WalletError({ message: (cause as Error).message, cause: cause as Error })
     })
     const addr = used[0] ?? unused[0]
     if (!addr) {
@@ -417,7 +506,7 @@ const createApiWallet = (_network: WalletNew.Network, config: ApiWalletConfig):
     if (cachedReward !== null) return cachedReward
     const rewards = yield* Effect.tryPromise({
       try: () => api.getRewardAddresses(),
-      catch: (cause) => new WalletNew.WalletError({ message: "Failed to get reward addresses", cause })
+      catch: (cause) => new WalletNew.WalletError({ message: (cause as Error).message, cause: cause as Error })
     })
     cachedReward = rewards[0] ?? null
     return cachedReward
@@ -425,8 +514,8 @@ const createApiWallet = (_network: WalletNew.Network, config: ApiWalletConfig):
 
   // Effect implementations are the source of truth
   const effectInterface: WalletNew.ApiWalletEffect = {
-    address: getPrimaryAddress,
-    rewardAddress: getPrimaryRewardAddress,
+    address: () => getPrimaryAddress,
+    rewardAddress: () => getPrimaryRewardAddress,
     signTx: (txOrHex: Transaction.Transaction | string, _context?: { utxos?: ReadonlyArray<UTxO.UTxO> }) =>
       Effect.gen(function* () {
         const cbor = typeof txOrHex === "string" ? txOrHex : Transaction.toCBORHex(txOrHex)
@@ -435,7 +524,7 @@ const createApiWallet = (_network: WalletNew.Network, config: ApiWalletConfig):
           catch: (cause) => new WalletNew.WalletError({ message: "User rejected transaction signing", cause })
         })
         return yield* TransactionWitnessSet.Either.fromCBORHex(witnessHex).pipe(
-          Effect.mapError((cause) => new WalletNew.WalletError({ message: "Failed to decode witness set", cause }))
+          Effect.mapError((cause) => new WalletNew.WalletError({ message: cause.message, cause }))
         )
       }),
     signMessage: (address: Address.Address | RewardAddress.RewardAddress, payload: WalletNew.Payload) =>
@@ -451,7 +540,7 @@ const createApiWallet = (_network: WalletNew.Network, config: ApiWalletConfig):
         const cbor = typeof txOrHex === "string" ? txOrHex : Transaction.toCBORHex(txOrHex)
         return yield* Effect.tryPromise({
           try: () => api.submitTx(cbor),
-          catch: (cause) => new WalletNew.WalletError({ message: "Failed to submit transaction", cause })
+          catch: (cause) => new WalletNew.WalletError({ message: (cause as Error).message, cause: cause as Error })
         })
       })
   }
@@ -460,8 +549,8 @@ const createApiWallet = (_network: WalletNew.Network, config: ApiWalletConfig):
   return {
     type: "api" as const,
     api,
-    address: Effect.runPromise(effectInterface.address),
-    rewardAddress: Effect.runPromise(effectInterface.rewardAddress),
+    address: () => Effect.runPromise(effectInterface.address()),
+    rewardAddress: () => Effect.runPromise(effectInterface.rewardAddress()),
     signTx: (txOrHex, context) => Effect.runPromise(effectInterface.signTx(txOrHex, context)),
     signMessage: (address, payload) => Effect.runPromise(effectInterface.signMessage(address, payload)),
     submitTx: (txOrHex) => Effect.runPromise(effectInterface.submitTx(txOrHex)),
@@ -477,9 +566,11 @@ const createApiWallet = (_network: WalletNew.Network, config: ApiWalletConfig):
  * @since 2.0.0
  * @category constructors
  */
-const createSigningWalletClient = (network: NetworkId, config: SeedWalletConfig): SigningWalletClient => {
+const createSigningWalletClient = (network: NetworkId, config: SeedWalletConfig | PrivateKeyWalletConfig): SigningWalletClient => {
   const walletNetwork = toWalletNetwork(network)
-  const wallet = createSigningWallet(walletNetwork, config)
+  const wallet = config.type === "seed"
+    ? createSigningWallet(walletNetwork, config)
+    : createPrivateKeyWallet(walletNetwork, config)
   const networkId = normalizeNetworkId(network)
 
   return {
@@ -530,16 +621,18 @@ const createApiWalletClient = (network: NetworkId, config: ApiWalletConfig): Api
 const createSigningClient = (
   network: NetworkId,
   providerConfig: ProviderConfig,
-  walletConfig: SeedWalletConfig | ApiWalletConfig
+  walletConfig: SeedWalletConfig | PrivateKeyWalletConfig | ApiWalletConfig
 ): SigningClient => {
   const provider = createProvider(providerConfig)
   const walletNetwork = toWalletNetwork(network)
 
-  // Create appropriate wallet based on type
+  // Create appropriate wallet based on type (both are now sync)
   const wallet =
     walletConfig.type === "seed"
       ? createSigningWallet(walletNetwork, walletConfig)
-      : createApiWallet(walletNetwork, walletConfig)
+      : walletConfig.type === "private-key"
+        ? createPrivateKeyWallet(walletNetwork, walletConfig)
+        : createApiWallet(walletNetwork, walletConfig)
 
   // Effect implementations are the source of truth
   const effectInterface = {
@@ -547,25 +640,34 @@ const createSigningClient = (
     ...provider.Effect, // Provider methods override wallet methods (e.g., submitTx uses ProviderError not WalletError)
     // Wallet-scoped convenience methods as Effects - expose union types (Effect-TS idiom)
     getWalletUtxos: () =>
-      Effect.flatMap(wallet.Effect.address, (addr) => provider.Effect.getUtxos(addr)),
+      Effect.flatMap(wallet.Effect.address(), (addr) => provider.Effect.getUtxos(addr)),
     getWalletDelegation: () =>
-      Effect.flatMap(wallet.Effect.rewardAddress, (rewardAddr) => {
+      Effect.flatMap(wallet.Effect.rewardAddress(), (rewardAddr) => {
         if (!rewardAddr) return Effect.fail(new Provider.ProviderError({ message: "No reward address configured", cause: null }))
         return provider.Effect.getDelegation(rewardAddr)
-      }),
-    newTx: (_utxos?: any) => {
-      return Effect.fail(new Provider.ProviderError({ message: "newTx not yet implemented", cause: null }))
-    }
+      })
   }
 
   // Combine provider + signing wallet via spreading
+  // Define getWalletUtxos first so we can reference it in newTx
+  const getWalletUtxos = () => Effect.runPromise(effectInterface.getWalletUtxos())
+
   return {
     ...provider,
     ...wallet,
     // Promise methods call Effect implementations
-    getWalletUtxos: () => Effect.runPromise(effectInterface.getWalletUtxos()),
+    getWalletUtxos,
     getWalletDelegation: () => Effect.runPromise(effectInterface.getWalletDelegation()),
-    newTx: (_utxos?: any) => Effect.runPromise(effectInterface.newTx(_utxos)),
+    // Transaction builder - creates a new builder instance
+    newTx: (): TransactionBuilder<SignBuilder> => {
+      // Wallet provides change address and UTxO fetching via wallet.Effect.address()
+      // The wallet is passed to the builder config, which handles address and UTxO resolution automatically
+      // Protocol parameters are auto-fetched from provider during build()
+      return makeTxBuilder<SignBuilder>({
+        provider, // Pass provider for submission
+        wallet // Pass wallet for signing
+      })
+    },
     // Effect namespace
     Effect: effectInterface
   } 
@@ -671,14 +773,14 @@ export function createClient(config: {
   wallet: ReadOnlyWalletConfig
 }): ReadOnlyClient
 
-// Provider + Seed Wallet → SigningClient (TODO: implement)
+// Provider + Seed Wallet → SigningClient
 export function createClient(config: {
   network?: NetworkId
   provider: ProviderConfig
   wallet: SeedWalletConfig
 }): SigningClient
 
-// Provider + API Wallet → SigningClient (TODO: implement)
+// Provider + API Wallet → SigningClient
 export function createClient(config: {
   network?: NetworkId
   provider: ProviderConfig
@@ -691,26 +793,31 @@ export function createClient(config: { network?: NetworkId; provider: ProviderCo
 // ReadOnly Wallet only → ReadOnlyWalletClient
 export function createClient(config: { network?: NetworkId; wallet: ReadOnlyWalletConfig }): ReadOnlyWalletClient
 
-// Seed Wallet only → SigningWalletClient (TODO: implement)
+// Seed Wallet only → SigningWalletClient
 export function createClient(config: { network?: NetworkId; wallet: SeedWalletConfig }): SigningWalletClient
 
-// API Wallet only → ApiWalletClient (TODO: implement)
+// Private Key Wallet only → SigningWalletClient
+export function createClient(config: { network?: NetworkId; wallet: PrivateKeyWalletConfig }): SigningWalletClient
+
+// API Wallet only → ApiWalletClient
 export function createClient(config: { network?: NetworkId; wallet: ApiWalletConfig }): ApiWalletClient
 
 // Network only or minimal → MinimalClient
 export function createClient(config?: { network?: NetworkId }): MinimalClient
 
-// Implementation signature - handles all cases
-export function createClient(config?: {
-  network?: NetworkId
-  provider?: ProviderConfig
-  wallet?: WalletConfig
-}):
+// Implementation signature - handles all cases (all synchronous now)
+export function createClient(
+  config?: {
+    network?: NetworkId
+    provider?: ProviderConfig
+    wallet?: WalletConfig
+  },
+):
   | MinimalClient
-  | ProviderOnlyClient
-  | ReadOnlyWalletClient
   | ReadOnlyClient
   | SigningClient
+  | ProviderOnlyClient
+  | ReadOnlyWalletClient
   | SigningWalletClient
   | ApiWalletClient {
   const network = config?.network ?? "mainnet"
@@ -722,6 +829,8 @@ export function createClient(config?: {
         return createReadOnlyClient(network, config.provider, config.wallet)
       case "seed":
         return createSigningClient(network, config.provider, config.wallet)
+      case "private-key":
+        return createSigningClient(network, config.provider, config.wallet)
       case "api":
         return createSigningClient(network, config.provider, config.wallet)
     }
@@ -734,6 +843,8 @@ export function createClient(config?: {
         return createReadOnlyWalletClient(network, config.wallet)
       case "seed":
         return createSigningWalletClient(network, config.wallet)
+      case "private-key":
+        return createSigningWalletClient(network, config.wallet)
       case "api":
         return createApiWalletClient(network, config.wallet)
     }
diff --git a/packages/evolution/src/sdk/provider/internal/BlockfrostEffect.ts b/packages/evolution/src/sdk/provider/internal/BlockfrostEffect.ts
index 094ab526..2b47e8d9 100644
--- a/packages/evolution/src/sdk/provider/internal/BlockfrostEffect.ts
+++ b/packages/evolution/src/sdk/provider/internal/BlockfrostEffect.ts
@@ -5,6 +5,7 @@
 
 import { Effect, Schedule, Schema } from "effect"
 
+import * as Bytes from "../../../core/Bytes.js"
 import type * as Address from "../../Address.js"
 import type * as Credential from "../../Credential.js"
 import type * as OutRef from "../../OutRef.js"
@@ -244,17 +245,24 @@ export const awaitTx = (baseUrl: string, projectId?: string) =>
  * Returns: (baseUrl, projectId?) => (cbor) => Effect<string, ProviderError>
  */
 export const submitTx = (baseUrl: string, projectId?: string) =>
-  (cbor: string) =>
-    withRateLimit(
-      HttpUtils.postJson(
+  (cbor: string) => {
+    // Convert CBOR hex string to Uint8Array for submission
+    const cborBytes = Bytes.fromHex(cbor)
+    
+    // Create headers without Content-Type (will be set by postUint8Array)
+    const headers = projectId ? { "project_id": projectId } : undefined
+    
+    return withRateLimit(
+      HttpUtils.postUint8Array(
         `${baseUrl}/tx/submit`,
-        { cbor },
+        cborBytes,
         Blockfrost.BlockfrostSubmitResponse,
-        createHeaders(projectId)
+        headers
       ).pipe(
         Effect.mapError(wrapError("submitTx"))
       )
     )
+  }
 
 /**
  * Evaluate transaction
diff --git a/packages/evolution/src/sdk/provider/internal/HttpUtils.ts b/packages/evolution/src/sdk/provider/internal/HttpUtils.ts
index dbebcda2..f2a2a7c1 100644
--- a/packages/evolution/src/sdk/provider/internal/HttpUtils.ts
+++ b/packages/evolution/src/sdk/provider/internal/HttpUtils.ts
@@ -71,10 +71,12 @@ export const postUint8Array = <A, I>(
 ) =>
   Effect.gen(function* () {
     let request = HttpClientRequest.post(url)
+    // Set body with content-type
     request = HttpClientRequest.bodyUint8Array(request, body, "application/cbor")
-    request = HttpClientRequest.setHeaders(request, {
-      ...(headers || {})
-    })
+    // Set additional headers AFTER body (so they don't get overridden)
+    if (headers) {
+      request = HttpClientRequest.setHeaders(request, headers)
+    }
 
     const response = yield* HttpClient.execute(request)
     const filteredResponse = yield* filterStatusOk(response)
diff --git a/packages/evolution/src/sdk/wallet/Derivation.ts b/packages/evolution/src/sdk/wallet/Derivation.ts
index cf4ffb47..0d41feeb 100644
--- a/packages/evolution/src/sdk/wallet/Derivation.ts
+++ b/packages/evolution/src/sdk/wallet/Derivation.ts
@@ -1,7 +1,8 @@
 import { mnemonicToEntropy } from "@scure/bip39"
 import { wordlist as English } from "@scure/bip39/wordlists/english"
 import * as Data from "effect/Data"
-import * as Either from "effect/Either"
+import * as Effect from "effect/Effect"
+import * as Schema from "effect/Schema"
 
 import * as AddressEras from "../../core/AddressEras.js"
 import * as BaseAddress from "../../core/BaseAddress.js"
@@ -23,12 +24,17 @@ export class DerivationError extends Data.TaggedError("DerivationError")<{
  * - address: bech32 payment address (addr... / addr_test...)
  * - rewardAddress: bech32 reward address (stake... / stake_test...)
  * - paymentKey / stakeKey: ed25519e_sk bech32 private keys
+ * - keyStore: Map of KeyHash hex -> PrivateKey for signing operations
+ * - paymentKhHex / stakeKhHex: KeyHash hex strings for quick lookup
  */
 export type SeedDerivationResult = {
   address: SdkAddress.Address
   rewardAddress: SdkRewardAddress.RewardAddress | undefined
   paymentKey: string
   stakeKey: string | undefined
+  keyStore: Map<string, PrivateKey.PrivateKey>
+  paymentKhHex: string
+  stakeKhHex: string | undefined
 }
 
 export const walletFromSeed = (
@@ -39,10 +45,10 @@ export const walletFromSeed = (
     accountIndex?: number
     network?: "Mainnet" | "Testnet" | "Custom"
   } = {}
-) =>
-  Either.gen(function* () {
+): Effect.Effect<SeedDerivationResult, DerivationError | Bip32PrivateKey.Bip32PrivateKeyError> => {
+  return Effect.gen(function* () {
     const { accountIndex = 0, addressType = "Base", network = "Mainnet" } = options
-    const entropy = yield* Either.try({
+    const entropy = yield* Effect.try({
       try: () => mnemonicToEntropy(seed, English),
       catch: (cause) => new DerivationError({ message: "Invalid seed phrase", cause })
     })
@@ -64,37 +70,73 @@ export const walletFromSeed = (
 
     const address =
       addressType === "Base"
-        ? yield* AddressEras.Either.toBech32(
-            new BaseAddress.BaseAddress({
-              networkId,
-              paymentCredential: paymentKeyHash,
-              stakeCredential: stakeKeyHash
-            })
-          )
-        : yield* AddressEras.Either.toBech32(
-            new EnterpriseAddress.EnterpriseAddress({
-              networkId,
-              paymentCredential: paymentKeyHash
-            })
-          )
+        ? yield* Effect.try({
+            try: () => {
+              const result = AddressEras.Either.toBech32(
+                new BaseAddress.BaseAddress({
+                  networkId,
+                  paymentCredential: paymentKeyHash,
+                  stakeCredential: stakeKeyHash
+                })
+              )
+              if (result._tag === "Left") throw result.left
+              return result.right
+            },
+            catch: (cause) => new DerivationError({ message: (cause as Error).message, cause: cause as Error })
+          })
+        : yield* Effect.try({
+            try: () => {
+              const result = AddressEras.Either.toBech32(
+                new EnterpriseAddress.EnterpriseAddress({
+                  networkId,
+                  paymentCredential: paymentKeyHash
+                })
+              )
+              if (result._tag === "Left") throw result.left
+              return result.right
+            },
+            catch: (cause) => new DerivationError({ message: (cause as Error).message, cause: cause as Error })
+          })
 
     const rewardAddress =
       addressType === "Base"
-        ? yield* AddressEras.Either.toBech32(
-            new RewardAccount.RewardAccount({
-              networkId,
-              stakeCredential: stakeKeyHash
-            })
-          )
+        ? yield* Effect.try({
+            try: () => {
+              const result = AddressEras.Either.toBech32(
+                new RewardAccount.RewardAccount({
+                  networkId,
+                  stakeCredential: stakeKeyHash
+                })
+              )
+              if (result._tag === "Left") throw result.left
+              return result.right
+            },
+            catch: (cause) => new DerivationError({ message: (cause as Error).message, cause: cause as Error })
+          })
         : undefined
 
+    // Build keyStore: map KeyHash hex -> PrivateKey for signing
+    const keyStore = new Map<string, PrivateKey.PrivateKey>()
+    const paymentKhHex = KeyHash.toHex(paymentKeyHash)
+    keyStore.set(paymentKhHex, paymentKey)
+
+    let stakeKhHex: string | undefined
+    if (addressType === "Base") {
+      stakeKhHex = KeyHash.toHex(stakeKeyHash)
+      keyStore.set(stakeKhHex, stakeKey)
+    }
+
     return {
       address,
       rewardAddress,
       paymentKey: PrivateKey.toBech32(paymentKey),
-      stakeKey: addressType === "Base" ? PrivateKey.toBech32(stakeKey) : undefined
+      stakeKey: addressType === "Base" ? PrivateKey.toBech32(stakeKey) : undefined,
+      keyStore,
+      paymentKhHex,
+      stakeKhHex
     }
   })
+}
 /**
  * Derive only the bech32 private keys (ed25519e_sk...) from a seed.
  */
@@ -215,11 +257,25 @@ export function walletFromBip32(
         )
       : undefined
 
+  // Build keyStore
+  const keyStore = new Map<string, PrivateKey.PrivateKey>()
+  const paymentKhHex = KeyHash.toHex(paymentKeyHash)
+  keyStore.set(paymentKhHex, paymentKey)
+
+  let stakeKhHex: string | undefined
+  if (addressType === "Base") {
+    stakeKhHex = KeyHash.toHex(stakeKeyHash)
+    keyStore.set(stakeKhHex, stakeKey)
+  }
+
   return {
     address,
     rewardAddress,
     paymentKey: PrivateKey.toBech32(paymentKey),
-    stakeKey: addressType === "Base" ? PrivateKey.toBech32(stakeKey) : undefined
+    stakeKey: addressType === "Base" ? PrivateKey.toBech32(stakeKey) : undefined,
+    keyStore,
+    paymentKhHex,
+    stakeKhHex
   }
 }
 
@@ -234,37 +290,66 @@ export function walletFromPrivateKey(
     addressType?: "Base" | "Enterprise"
     network?: "Mainnet" | "Testnet" | "Custom"
   } = {}
-): SeedDerivationResult {
-  const { stakeKeyBech32, addressType = stakeKeyBech32 ? "Base" : "Enterprise", network = "Mainnet" } = options
-  const paymentKey = PrivateKey.fromBech32(paymentKeyBech32)
-  const paymentKeyHash = KeyHash.fromPrivateKey(paymentKey)
+): Effect.Effect<SeedDerivationResult, DerivationError> {
+  return Effect.gen(function* () {
+    const { stakeKeyBech32, addressType = stakeKeyBech32 ? "Base" : "Enterprise", network = "Mainnet" } = options
+    
+    // Use the Effect-based Either API from PrivateKey module - can yield directly on Either
+    const paymentKey = yield* Effect.mapError(
+      // PrivateKey.Either.fromBech32(paymentKeyBech32),
+      Schema.decode(PrivateKey.FromBech32)(paymentKeyBech32),
+      (cause) => new DerivationError({ message: cause.message, cause })
+    )
+    const paymentKeyHash = KeyHash.fromPrivateKey(paymentKey)
 
-  const networkId = network === "Mainnet" ? 1 : 0
-  const address =
-    addressType === "Base"
-      ? (() => {
-          if (!stakeKeyBech32) throw new Error("stakeKeyBech32 required for Base address")
-          const stakeKey = PrivateKey.fromBech32(stakeKeyBech32)
-          const stakeKeyHash = KeyHash.fromPrivateKey(stakeKey)
-          return AddressEras.toBech32(
-            new BaseAddress.BaseAddress({ networkId, paymentCredential: paymentKeyHash, stakeCredential: stakeKeyHash })
-          )
-        })()
-      : AddressEras.toBech32(new EnterpriseAddress.EnterpriseAddress({ networkId, paymentCredential: paymentKeyHash }))
+    const networkId = network === "Mainnet" ? 1 : 0
+    
+    let address: string
+    let stakeKey: PrivateKey.PrivateKey | undefined
+    let stakeKeyHash: KeyHash.KeyHash | undefined
+    
+    if (addressType === "Base") {
+      if (!stakeKeyBech32) {
+        return yield* Effect.fail(new DerivationError({ message: "stakeKeyBech32 required for Base address" }))
+      }
+      stakeKey = yield* Effect.mapError(
+        PrivateKey.Either.fromBech32(stakeKeyBech32),
+        (cause) => new DerivationError({ message: cause.message, cause })
+      )
+      stakeKeyHash = KeyHash.fromPrivateKey(stakeKey)
+      address = AddressEras.toBech32(
+        new BaseAddress.BaseAddress({ networkId, paymentCredential: paymentKeyHash, stakeCredential: stakeKeyHash })
+      )
+    } else {
+      address = AddressEras.toBech32(
+        new EnterpriseAddress.EnterpriseAddress({ networkId, paymentCredential: paymentKeyHash })
+      )
+    }
 
-  const rewardAddress =
-    addressType === "Base" && stakeKeyBech32
-      ? (() => {
-          const stakeKey = PrivateKey.fromBech32(stakeKeyBech32)
-          const stakeKeyHash = KeyHash.fromPrivateKey(stakeKey)
-          return AddressEras.toBech32(new RewardAccount.RewardAccount({ networkId, stakeCredential: stakeKeyHash }))
-        })()
-      : undefined
+    const rewardAddress =
+      addressType === "Base" && stakeKeyHash
+        ? AddressEras.toBech32(new RewardAccount.RewardAccount({ networkId, stakeCredential: stakeKeyHash }))
+        : undefined
 
-  return {
-    address,
-    rewardAddress,
-    paymentKey: paymentKeyBech32,
-    stakeKey: stakeKeyBech32
-  }
+    // Build keyStore
+    const keyStore = new Map<string, PrivateKey.PrivateKey>()
+    const paymentKhHex = KeyHash.toHex(paymentKeyHash)
+    keyStore.set(paymentKhHex, paymentKey)
+
+    let stakeKhHex: string | undefined
+    if (addressType === "Base" && stakeKey && stakeKeyHash) {
+      stakeKhHex = KeyHash.toHex(stakeKeyHash)
+      keyStore.set(stakeKhHex, stakeKey)
+    }
+
+    return {
+      address,
+      rewardAddress,
+      paymentKey: paymentKeyBech32,
+      stakeKey: stakeKeyBech32,
+      keyStore,
+      paymentKhHex,
+      stakeKhHex
+    }
+  })
 }
diff --git a/packages/evolution/src/sdk/wallet/Wallet.ts b/packages/evolution/src/sdk/wallet/Wallet.ts
index a7fe3911..5ee551cf 100644
--- a/packages/evolution/src/sdk/wallet/Wallet.ts
+++ b/packages/evolution/src/sdk/wallet/Wallet.ts
@@ -1,5 +1,5 @@
 // Parent imports (../../)
-import * as Either from "effect/Either"
+import * as Effect from "effect/Effect"
 
 import * as CoreAddressStructure from "../../core/AddressStructure.js"
 import * as Ed25519Signature from "../../core/Ed25519Signature.js"
@@ -139,12 +139,14 @@ export function makeWalletFromSeed(
 ): Wallet {
   const config = { overriddenUTxOs: [] as Array<UTxO.UTxO> }
 
-  const { address, paymentKey, rewardAddress, stakeKey } = walletFromSeed(seed, {
-    addressType: options?.addressType ?? "Base",
-    accountIndex: options?.accountIndex ?? 0,
-    password: options?.password,
-    network
-  }).pipe(Either.getOrThrow)
+  const { address, paymentKey, rewardAddress, stakeKey } = Effect.runSync(
+    walletFromSeed(seed, {
+      addressType: options?.addressType ?? "Base",
+      accountIndex: options?.accountIndex ?? 0,
+      password: options?.password,
+      network
+    })
+  )
 
   // Minimal keystore: map KeyHash hex -> PrivateKey
   type KeyStore = Map<string, PrivateKey.PrivateKey>
diff --git a/packages/evolution/src/sdk/wallet/WalletNew.ts b/packages/evolution/src/sdk/wallet/WalletNew.ts
index 112273ff..2bd1acb1 100644
--- a/packages/evolution/src/sdk/wallet/WalletNew.ts
+++ b/packages/evolution/src/sdk/wallet/WalletNew.ts
@@ -50,8 +50,8 @@ export interface SignedMessage {
  * @category interfaces
  */
 export interface ReadOnlyWalletEffect {
-  readonly address: Effect.Effect<Address.Address, WalletError>
-  readonly rewardAddress: Effect.Effect<RewardAddress.RewardAddress | null, WalletError>
+  readonly address: () => Effect.Effect<Address.Address, WalletError>
+  readonly rewardAddress: () => Effect.Effect<RewardAddress.RewardAddress | null, WalletError>
 }
 
 export interface ReadOnlyWallet extends EffectToPromiseAPI<ReadOnlyWalletEffect> {
diff --git a/packages/evolution/src/utils/effect-runtime.ts b/packages/evolution/src/utils/effect-runtime.ts
new file mode 100644
index 00000000..2bdae464
--- /dev/null
+++ b/packages/evolution/src/utils/effect-runtime.ts
@@ -0,0 +1,117 @@
+import { Cause, Effect, Exit } from "effect"
+
+/**
+ * Patterns to filter from stack traces - Effect.ts internal implementation details
+ */
+const EFFECT_INTERNAL_PATTERNS = [
+  /node_modules\/.pnpm\/effect@.*\/node_modules\/effect\//,
+  /at FiberRuntime\./,
+  /at EffectPrimitive\./,
+  /at Object\.Iterator/,
+  /at runLoop/,
+  /at evaluateEffect/,
+  /at body \(/,
+  /effect_instruction_i\d+/,
+  /at pipeArguments/,
+  /at pipe \(/,
+  /at Arguments\./,
+  /at Module\./,
+  /at issue \(/,
+  /at \.\.\.$/  // Lines like "... 7 lines matching cause stack trace ..."
+]
+
+/**
+ * Clean a single error's stack trace by removing Effect.ts internals
+ */
+function cleanStackTrace(stack: string | undefined): string {
+  if (!stack) return ""
+  
+  const lines = stack.split("\n")
+  const cleaned = lines.filter(line => {
+    // Keep the error message line (first line)
+    if (!line.trim().startsWith("at ")) return true
+    
+    // Filter out Effect.ts internal lines
+    return !EFFECT_INTERNAL_PATTERNS.some(pattern => pattern.test(line))
+  })
+  
+  return cleaned.join("\n")
+}
+
+/**
+ * Recursively clean error chain (error and all causes)
+ */
+function cleanErrorChain(error: any): any {
+  if (!error) return error
+  
+  // Clean current error's stack
+  if (error.stack) {
+    error.stack = cleanStackTrace(error.stack)
+  }
+  
+  // Recursively clean cause chain
+  if (error.cause) {
+    error.cause = cleanErrorChain(error.cause)
+  }
+  
+  // Handle Effect.ts internal cause field
+  if (error[Symbol.for("effect/Runtime/FiberFailure/Cause")]) {
+    const cause = error[Symbol.for("effect/Runtime/FiberFailure/Cause")]
+    if (cause && typeof cause === "object") {
+      if (cause.error) {
+        cause.error = cleanErrorChain(cause.error)
+      }
+    }
+  }
+  
+  return error
+}
+
+/**
+ * Run an Effect and convert it to a Promise with clean error handling.
+ * 
+ * - Executes the Effect using Effect.runPromiseExit
+ * - On failure, extracts the error from the Exit and cleans stack traces
+ * - Removes Effect.ts internal stack frames for cleaner error messages
+ * - Throws the cleaned error for standard Promise error handling
+ * 
+ * @example
+ * ```typescript
+ * import { Effect } from "effect"
+ * import { runEffect } from "@evolution-sdk/evolution/utils/effect-runtime"
+ * 
+ * const myEffect = Effect.succeed(42)
+ * 
+ * async function example() {
+ *   try {
+ *     const result = await runEffect(myEffect)
+ *     console.log(result)
+ *   } catch (error) {
+ *     // Error with clean stack trace, no Effect.ts internals
+ *     console.error(error)
+ *   }
+ * }
+ * ```
+ * 
+ * @param effect - The Effect to execute
+ * @returns Promise that resolves to the Effect's success value
+ * @throws The Effect's error with cleaned stack trace
+ * 
+ * @since 2.0.0
+ * @category utilities
+ */
+export async function runEffect<A, E>(effect: Effect.Effect<A, E>): Promise<A> {
+  const exit = await Effect.runPromiseExit(effect)
+  
+  if (Exit.isFailure(exit)) {
+    // Extract the error from the failure
+    const error = Cause.squash(exit.cause)
+    
+    // Clean the error's stack trace
+    const cleanedError = cleanErrorChain(error)
+    
+    throw cleanedError
+  }
+  
+  return exit.value
+}
diff --git a/packages/evolution/test/TxBuilder.CoinSelectionFailures.test.ts b/packages/evolution/test/TxBuilder.CoinSelectionFailures.test.ts
index 4470b733..652cb40b 100644
--- a/packages/evolution/test/TxBuilder.CoinSelectionFailures.test.ts
+++ b/packages/evolution/test/TxBuilder.CoinSelectionFailures.test.ts
@@ -19,9 +19,6 @@ const RECEIVER_ADDRESS =
   "addr_test1qpw0djgj0x59ngrjvqthn7enhvruxnsavsw5th63la3mjel3tkc974sr23jmlzgq5zda4gtv8k9cy38756r9y3qgmkqqjz6aa7"
 
 const baseConfig: TxBuilderConfig = {
-  protocolParameters: PROTOCOL_PARAMS,
-  changeAddress: CHANGE_ADDRESS,
-  availableUtxos: []
 }
 
 describe("Insufficient Lovelace", () => {
@@ -31,12 +28,12 @@ describe("Insufficient Lovelace", () => {
       createTestUtxo({ txHash: "tx1", outputIndex: 0, address: CHANGE_ADDRESS, lovelace: 1_000_000n })
     ]
 
-    const builder = makeTxBuilder({ ...baseConfig, availableUtxos: utxos }).payToAddress({
+    const builder = makeTxBuilder(baseConfig).payToAddress({
       address: RECEIVER_ADDRESS,
       assets: Assets.fromLovelace(5_000_000n)
     })
 
-    await expect(builder.build({ useStateMachine: true, useV3: true })).rejects.toThrow(/Coin selection failed for/)
+    await expect(builder.build({ changeAddress: CHANGE_ADDRESS, availableUtxos: utxos, useStateMachine: true, useV3: true, protocolParameters: PROTOCOL_PARAMS })).rejects.toThrow(/Coin selection failed for/)
   })
 
   it("should fail when lovelace covers payment but not payment + fees", async () => {
@@ -45,12 +42,12 @@ describe("Insufficient Lovelace", () => {
       createTestUtxo({ txHash: "tx1", outputIndex: 0, address: CHANGE_ADDRESS, lovelace: 2_000_000n })
     ]
 
-    const builder = makeTxBuilder({ ...baseConfig, availableUtxos: utxos }).payToAddress({
+    const builder = makeTxBuilder(baseConfig).payToAddress({
       address: RECEIVER_ADDRESS,
       assets: Assets.fromLovelace(1_950_000n)
     })
 
-    await expect(builder.build({ useStateMachine: true, useV3: true })).rejects.toThrow(/Cannot create valid change/)
+    await expect(builder.build({ changeAddress: CHANGE_ADDRESS, availableUtxos: utxos, useStateMachine: true, useV3: true, protocolParameters: PROTOCOL_PARAMS })).rejects.toThrow(/Cannot create valid change/)
   })
 
   it("should fail with multiple small UTxOs that sum to insufficient amount", async () => {
@@ -63,12 +60,12 @@ describe("Insufficient Lovelace", () => {
       createTestUtxo({ txHash: "tx5", outputIndex: 0, address: CHANGE_ADDRESS, lovelace: 100_000n })
     ]
 
-    const builder = makeTxBuilder({ ...baseConfig, availableUtxos: utxos }).payToAddress({
+    const builder = makeTxBuilder(baseConfig).payToAddress({
       address: RECEIVER_ADDRESS,
       assets: Assets.fromLovelace(1_000_000n)
     })
 
-    await expect(builder.build({ useStateMachine: true, useV3: true })).rejects.toThrow(/Coin selection failed for/)
+    await expect(builder.build({ changeAddress: CHANGE_ADDRESS, availableUtxos: utxos, useStateMachine: true, useV3: true, protocolParameters: PROTOCOL_PARAMS })).rejects.toThrow(/Coin selection failed for/)
   })
 })
 
@@ -96,12 +93,12 @@ describe("Missing Native Assets", () => {
       [tokenB]: 100n // Requesting token that doesn't exist
     }
 
-    const builder = makeTxBuilder({ ...baseConfig, availableUtxos: utxos }).payToAddress({
+    const builder = makeTxBuilder(baseConfig).payToAddress({
       address: RECEIVER_ADDRESS,
       assets: paymentAssets
     })
 
-    await expect(builder.build({ useStateMachine: true, useV3: true })).rejects.toThrow(/Coin selection failed for/)
+    await expect(builder.build({ changeAddress: CHANGE_ADDRESS, availableUtxos: utxos, useStateMachine: true, useV3: true, protocolParameters: PROTOCOL_PARAMS })).rejects.toThrow(/Coin selection failed for/)
   })
 
   it("should fail when multiple assets requested but one is missing", async () => {
@@ -135,12 +132,12 @@ describe("Missing Native Assets", () => {
       [tokenC]: 10n // Missing token
     }
 
-    const builder = makeTxBuilder({ ...baseConfig, availableUtxos: utxos }).payToAddress({
+    const builder = makeTxBuilder(baseConfig).payToAddress({
       address: RECEIVER_ADDRESS,
       assets: paymentAssets
     })
 
-    await expect(builder.build({ useStateMachine: true, useV3: true })).rejects.toThrow(/Coin selection failed for/)
+    await expect(builder.build({ changeAddress: CHANGE_ADDRESS, availableUtxos: utxos, useStateMachine: true, useV3: true, protocolParameters: PROTOCOL_PARAMS })).rejects.toThrow(/Coin selection failed for/)
   })
 })
 
@@ -165,12 +162,12 @@ describe("Insufficient Native Asset Quantity", () => {
       [tokenA]: 100n // Need 100, only have 50
     }
 
-    const builder = makeTxBuilder({ ...baseConfig, availableUtxos: utxos }).payToAddress({
+    const builder = makeTxBuilder(baseConfig).payToAddress({
       address: RECEIVER_ADDRESS,
       assets: paymentAssets
     })
 
-    await expect(builder.build({ useStateMachine: true, useV3: true })).rejects.toThrow(/Coin selection failed for/)
+    await expect(builder.build({ changeAddress: CHANGE_ADDRESS, availableUtxos: utxos, useStateMachine: true, useV3: true, protocolParameters: PROTOCOL_PARAMS })).rejects.toThrow(/Coin selection failed for/)
   })
 
   it("should fail when tokens are fragmented across UTxOs but total is insufficient", async () => {
@@ -207,12 +204,12 @@ describe("Insufficient Native Asset Quantity", () => {
       [tokenA]: 100n // Need 100, only have 90 total
     }
 
-    const builder = makeTxBuilder({ ...baseConfig, availableUtxos: utxos }).payToAddress({
+    const builder = makeTxBuilder(baseConfig).payToAddress({
       address: RECEIVER_ADDRESS,
       assets: paymentAssets
     })
 
-    await expect(builder.build({ useStateMachine: true, useV3: true })).rejects.toThrow(/Coin selection failed for/)
+    await expect(builder.build({ changeAddress: CHANGE_ADDRESS, availableUtxos: utxos, useStateMachine: true, useV3: true, protocolParameters: PROTOCOL_PARAMS })).rejects.toThrow(/Coin selection failed for/)
   })
 
   it("should fail when one of multiple required assets is insufficient", async () => {
@@ -242,12 +239,12 @@ describe("Insufficient Native Asset Quantity", () => {
       [tokenB]: 100n // Insufficient
     }
 
-    const builder = makeTxBuilder({ ...baseConfig, availableUtxos: utxos }).payToAddress({
+    const builder = makeTxBuilder(baseConfig).payToAddress({
       address: RECEIVER_ADDRESS,
       assets: paymentAssets
     })
 
-    await expect(builder.build({ useStateMachine: true, useV3: true })).rejects.toThrow(/Coin selection failed for/)
+    await expect(builder.build({ changeAddress: CHANGE_ADDRESS, availableUtxos: utxos, useStateMachine: true, useV3: true, protocolParameters: PROTOCOL_PARAMS })).rejects.toThrow(/Coin selection failed for/)
   })
 })
 
@@ -255,13 +252,13 @@ describe("Complex Mixed Failures", () => {
   it("should fail with empty wallet (no UTxOs)", async () => {
     const utxos: Array<UTxO.UTxO> = []
 
-    const builder = makeTxBuilder({ ...baseConfig, availableUtxos: utxos }).payToAddress({
+    const builder = makeTxBuilder(baseConfig).payToAddress({
       address: RECEIVER_ADDRESS,
       assets: Assets.fromLovelace(1_000_000n)
     })
 
     // Empty wallet fails coin selection
-    await expect(builder.build({ useStateMachine: true, useV3: true })).rejects.toThrow(/Coin selection failed/)
+    await expect(builder.build({ changeAddress: CHANGE_ADDRESS, availableUtxos: utxos, useStateMachine: true, useV3: true, protocolParameters: PROTOCOL_PARAMS })).rejects.toThrow(/Coin selection failed/)
   })
 
   it("should fail when UTxOs exist but all are too small for min UTxO + fees", async () => {
@@ -271,12 +268,12 @@ describe("Complex Mixed Failures", () => {
       (_, i) => createTestUtxo({ txHash: `tx${i}`, outputIndex: 0, address: CHANGE_ADDRESS, lovelace: 1000n }) // 0.001 ADA each
     )
 
-    const builder = makeTxBuilder({ ...baseConfig, availableUtxos: utxos }).payToAddress({
+    const builder = makeTxBuilder(baseConfig).payToAddress({
       address: RECEIVER_ADDRESS,
       assets: Assets.fromLovelace(50_000n)
     })
 
-    await expect(builder.build({ useStateMachine: true, useV3: true })).rejects.toThrow(/Coin selection failed for/)
+    await expect(builder.build({ changeAddress: CHANGE_ADDRESS, availableUtxos: utxos, useStateMachine: true, useV3: true, protocolParameters: PROTOCOL_PARAMS })).rejects.toThrow(/Coin selection failed for/)
   })
 
   it("should fail with sufficient lovelace but missing native asset", async () => {
@@ -293,12 +290,12 @@ describe("Complex Mixed Failures", () => {
       [tokenA]: 1n // Even 1 token will fail
     }
 
-    const builder = makeTxBuilder({ ...baseConfig, availableUtxos: utxos }).payToAddress({
+    const builder = makeTxBuilder(baseConfig).payToAddress({
       address: RECEIVER_ADDRESS,
       assets: paymentAssets
     })
 
-    await expect(builder.build({ useStateMachine: true, useV3: true })).rejects.toThrow(/Coin selection failed for/)
+    await expect(builder.build({ changeAddress: CHANGE_ADDRESS, availableUtxos: utxos, useStateMachine: true, useV3: true, protocolParameters: PROTOCOL_PARAMS })).rejects.toThrow(/Coin selection failed for/)
   })
 
   it("should fail when combined shortfalls across lovelace and multiple assets", async () => {
@@ -328,12 +325,12 @@ describe("Complex Mixed Failures", () => {
       [tokenB]: 50n // Need 50, have 5
     }
 
-    const builder = makeTxBuilder({ ...baseConfig, availableUtxos: utxos }).payToAddress({
+    const builder = makeTxBuilder(baseConfig).payToAddress({
       address: RECEIVER_ADDRESS,
       assets: paymentAssets
     })
 
-    await expect(builder.build({ useStateMachine: true, useV3: true })).rejects.toThrow(/Coin selection failed for/)
+    await expect(builder.build({ changeAddress: CHANGE_ADDRESS, availableUtxos: utxos, useStateMachine: true, useV3: true, protocolParameters: PROTOCOL_PARAMS })).rejects.toThrow(/Coin selection failed for/)
   })
 })
 
@@ -346,13 +343,13 @@ describe("Edge Case: drainTo Cannot Save Insufficient Funds", () => {
       createTestUtxo({ txHash: "tx1", outputIndex: 0, address: CHANGE_ADDRESS, lovelace: 1_000_000n })
     ]
 
-    const builder = makeTxBuilder({ ...baseConfig, availableUtxos: utxos }).payToAddress({
+    const builder = makeTxBuilder(baseConfig).payToAddress({
       address: RECEIVER_ADDRESS,
       assets: Assets.fromLovelace(5_000_000n) // Way more than available
     })
 
     await expect(
-      builder.build({ drainTo: 0, useStateMachine: true, useV3: true }) // drainTo cannot save this
+      builder.build({ changeAddress: CHANGE_ADDRESS, availableUtxos: utxos, drainTo: 0, useStateMachine: true, useV3: true, protocolParameters: PROTOCOL_PARAMS }) // drainTo cannot save this
     ).rejects.toThrow(/Coin selection failed for/)
   })
 
@@ -363,11 +360,11 @@ describe("Edge Case: drainTo Cannot Save Insufficient Funds", () => {
       createTestUtxo({ txHash: "tx1", outputIndex: 0, address: CHANGE_ADDRESS, lovelace: 800_000n })
     ]
 
-    const builder = makeTxBuilder({ ...baseConfig, availableUtxos: utxos }).payToAddress({
+    const builder = makeTxBuilder(baseConfig).payToAddress({
       address: RECEIVER_ADDRESS,
       assets: Assets.fromLovelace(2_000_000n)
     })
 
-    await expect(builder.build({ useStateMachine: true, useV3: true })).rejects.toThrow(/Coin selection failed for/)
+    await expect(builder.build({ changeAddress: CHANGE_ADDRESS, availableUtxos: utxos, useStateMachine: true, useV3: true, protocolParameters: PROTOCOL_PARAMS })).rejects.toThrow(/Coin selection failed for/)
   })
 })
diff --git a/packages/evolution/test/TxBuilder.EdgeCases.test.ts b/packages/evolution/test/TxBuilder.EdgeCases.test.ts
index 52adf9b3..d214d0a0 100644
--- a/packages/evolution/test/TxBuilder.EdgeCases.test.ts
+++ b/packages/evolution/test/TxBuilder.EdgeCases.test.ts
@@ -23,9 +23,6 @@ const CHANGE_ADDRESS = TESTNET_ADDRESSES[0]
 const RECEIVER_ADDRESS = TESTNET_ADDRESSES[1]
 
 const baseConfig: TxBuilderConfig = {
-  protocolParameters: PROTOCOL_PARAMS,
-  changeAddress: CHANGE_ADDRESS,
-  availableUtxos: []
 }
 
 describe("TxBuilder P0 Edge Cases - Reselection Loop Boundaries", () => {
@@ -37,7 +34,7 @@ describe("TxBuilder P0 Edge Cases - Reselection Loop Boundaries", () => {
       createTestUtxo({ txHash: "tx4", outputIndex: 0, address: CHANGE_ADDRESS, lovelace: 100_000n })
     ]
 
-    const txBuilder = makeTxBuilder({ ...baseConfig, availableUtxos: utxos })
+    const txBuilder = makeTxBuilder(baseConfig)
 
     // Try to build transaction requiring 5M lovelace (impossible with 400k total)
     await expect(
@@ -46,7 +43,7 @@ describe("TxBuilder P0 Edge Cases - Reselection Loop Boundaries", () => {
           address: RECEIVER_ADDRESS,
           assets: Assets.fromLovelace(5_000_000n)
         })
-        .build({ useV3: true })
+        .build({ changeAddress: CHANGE_ADDRESS, availableUtxos: utxos, useV3: true, protocolParameters: PROTOCOL_PARAMS })
     ).rejects.toThrow()
   })
 
@@ -140,14 +137,14 @@ describe("TxBuilder P0 Edge Cases - Reselection Loop Boundaries", () => {
       [tokenC]: 100n
     }
 
-    const txBuilder = makeTxBuilder({ ...baseConfig, availableUtxos: utxos })
+    const txBuilder = makeTxBuilder(baseConfig)
 
     const signBuilder = await txBuilder
       .payToAddress({
         address: RECEIVER_ADDRESS,
         assets: paymentAssets
       })
-      .build({ useV3: true })
+      .build({ changeAddress: CHANGE_ADDRESS, availableUtxos: utxos, useV3: true, protocolParameters: PROTOCOL_PARAMS })
 
     const tx = await signBuilder.toTransaction()
 
@@ -197,7 +194,7 @@ describe("TxBuilder P0 Edge Cases - MinUTxO Boundary Precision", () => {
       createTestUtxo({ txHash: "tx2", outputIndex: 0, address: CHANGE_ADDRESS, lovelace: 500_000n })
     ]
 
-    const txBuilder = makeTxBuilder({ ...baseConfig, availableUtxos: utxos })
+    const txBuilder = makeTxBuilder(baseConfig)
 
     // Payment that will leave insufficient change with the first UTxO
     const signBuilder = await txBuilder
@@ -205,7 +202,7 @@ describe("TxBuilder P0 Edge Cases - MinUTxO Boundary Precision", () => {
         address: RECEIVER_ADDRESS,
         assets: { lovelace: 1_000_000n }
       })
-      .build({ useV3: true })
+      .build({ changeAddress: CHANGE_ADDRESS, availableUtxos: utxos, useV3: true, protocolParameters: PROTOCOL_PARAMS })
 
     const tx = await signBuilder.toTransaction()
 
@@ -274,7 +271,7 @@ describe("TxBuilder P0 Edge Cases - MinUTxO Boundary Precision", () => {
       })
     ]
 
-    const txBuilder = makeTxBuilder({ ...baseConfig, availableUtxos: utxos })
+    const txBuilder = makeTxBuilder(baseConfig)
 
     // Small payment to leave change with max-length asset names
     const signBuilder = await txBuilder
@@ -282,7 +279,7 @@ describe("TxBuilder P0 Edge Cases - MinUTxO Boundary Precision", () => {
         address: RECEIVER_ADDRESS,
         assets: { lovelace: 2_000_000n }
       })
-      .build({ useV3: true })
+      .build({ changeAddress: CHANGE_ADDRESS, availableUtxos: utxos, useV3: true, protocolParameters: PROTOCOL_PARAMS })
 
     const tx = await signBuilder.toTransaction()
 
@@ -356,7 +353,7 @@ describe("TxBuilder P0 Edge Cases - MinUTxO Boundary Precision", () => {
       createTestUtxo({ txHash: "tx6", outputIndex: 0, address: CHANGE_ADDRESS, lovelace: 200_000n })
     ]
 
-    const txBuilder = makeTxBuilder({ ...baseConfig, availableUtxos: utxos })
+    const txBuilder = makeTxBuilder(baseConfig)
 
     // Payment sized to trigger cascading reselection
     // Initial 2 UTxOs: 4.4M total
@@ -369,7 +366,7 @@ describe("TxBuilder P0 Edge Cases - MinUTxO Boundary Precision", () => {
         address: RECEIVER_ADDRESS,
         assets: { lovelace: 4_000_000n } // 4.0 ADA (no native assets in payment)
       })
-      .build({ useV3: true })
+      .build({ changeAddress: CHANGE_ADDRESS, availableUtxos: utxos, useV3: true, protocolParameters: PROTOCOL_PARAMS })
 
     const tx = await signBuilder.toTransaction()
 
diff --git a/packages/evolution/test/TxBuilder.InsufficientChange.test.ts b/packages/evolution/test/TxBuilder.InsufficientChange.test.ts
index ba64e051..07381d46 100644
--- a/packages/evolution/test/TxBuilder.InsufficientChange.test.ts
+++ b/packages/evolution/test/TxBuilder.InsufficientChange.test.ts
@@ -77,35 +77,34 @@ const createSufficientUtxo = (lovelace: bigint = 100_000_000n): UTxO.UTxO =>
   createTestUtxo({ txHash: "a".repeat(64), outputIndex: 0, address: CHANGE_ADDRESS, lovelace })
 
 const baseConfig: TxBuilderConfig = {
-  protocolParameters: PROTOCOL_PARAMS,
-  changeAddress: CHANGE_ADDRESS,
-  availableUtxos: []
 }
 
 describe("Fallback Tier 3: onInsufficientChange Strategy", () => {
   it("should throw error by default when change is insufficient (safe default)", async () => {
     // Arrange: UTxO with insufficient leftover for change output
     const utxo = createMinimalUtxo()
-    const builder = makeTxBuilder({ ...baseConfig, availableUtxos: [utxo] }).payToAddress({
-      address: RECIPIENT_ADDRESS,
-      assets: Assets.fromLovelace(2_000_000n)
-    })
+    const builder = makeTxBuilder(baseConfig)
+      .payToAddress({
+        address: RECIPIENT_ADDRESS,
+        assets: Assets.fromLovelace(2_000_000n)
+      })
 
     // Act & Assert: Should fail with default 'error' strategy
     // This is the SAFE default - prevents accidental fund loss
-    await expect(builder.build({ useV3: true })).rejects.toThrow()
+    await expect(builder.build({ changeAddress: CHANGE_ADDRESS, availableUtxos: [utxo], useV3: true, protocolParameters: PROTOCOL_PARAMS })).rejects.toThrow()
   })
 
   it("should burn leftover as extra fee when onInsufficientChange='burn'", async () => {
     // Arrange: Same insufficient leftover scenario
     const utxo = createMinimalUtxo()
-    const builder = makeTxBuilder({ ...baseConfig, availableUtxos: [utxo] }).payToAddress({
-      address: RECIPIENT_ADDRESS,
-      assets: Assets.fromLovelace(2_000_000n)
-    })
+    const builder = makeTxBuilder(baseConfig)
+      .payToAddress({
+        address: RECIPIENT_ADDRESS,
+        assets: Assets.fromLovelace(2_000_000n)
+      })
 
     // Act: Explicitly consent to burning leftover
-    const signBuilder = await builder.build({ onInsufficientChange: "burn", useV3: true })
+    const signBuilder = await builder.build({ changeAddress: CHANGE_ADDRESS, availableUtxos: [utxo], onInsufficientChange: "burn", useV3: true, protocolParameters: PROTOCOL_PARAMS })
     const tx = await signBuilder.toTransaction()
     const txWithFakeWitnesses = await signBuilder.toTransactionWithFakeWitnesses()
 
@@ -133,17 +132,21 @@ describe("Fallback Precedence: drainTo before onInsufficientChange", () => {
   it("should use drainTo (Fallback #1) before checking onInsufficientChange (Fallback #2)", async () => {
     // Arrange: Insufficient change + both fallbacks configured
     const utxo = createMinimalUtxo()
-    const builder = makeTxBuilder({ ...baseConfig, availableUtxos: [utxo] }).payToAddress({
-      address: RECIPIENT_ADDRESS,
-      assets: Assets.fromLovelace(2_000_000n)
-    })
+    const builder = makeTxBuilder(baseConfig)
+      .payToAddress({
+        address: RECIPIENT_ADDRESS,
+        assets: Assets.fromLovelace(2_000_000n)
+      })
 
     // Act: Configure both drainTo and onInsufficientChange='error'
     // drainTo should take precedence (Fallback #1 before #2)
     const signBuilder = await builder.build({
+      changeAddress: CHANGE_ADDRESS,
+      availableUtxos: [utxo],
       drainTo: 0, // Fallback #1: Drain into first output
       onInsufficientChange: "error", // Fallback #2: Would error, but shouldn't reach here
-      useV3: true
+      useV3: true,
+      protocolParameters: PROTOCOL_PARAMS
     })
 
     const tx = await signBuilder.toTransaction()
@@ -168,15 +171,19 @@ describe("Normal Path: Sufficient Change (No Fallbacks)", () => {
   it("should create change output when sufficient funds available", async () => {
     // Arrange: UTxO with plenty of ADA
     const utxo = createSufficientUtxo(100_000_000n) // 100 ADA
-    const builder = makeTxBuilder({ ...baseConfig, availableUtxos: [utxo] }).payToAddress({
-      address: RECIPIENT_ADDRESS,
-      assets: Assets.fromLovelace(10_000_000n) // 10 ADA payment
-    })
+    const builder = makeTxBuilder(baseConfig)
+      .payToAddress({
+        address: RECIPIENT_ADDRESS,
+        assets: Assets.fromLovelace(10_000_000n) // 10 ADA payment
+      })
 
     // Act: Build with fallback configured (shouldn't be needed)
     const signBuilder = await builder.build({
+      changeAddress: CHANGE_ADDRESS,
+      availableUtxos: [utxo],
       onInsufficientChange: "error", // Configured but not reached
-      useV3: true
+      useV3: true,
+      protocolParameters: PROTOCOL_PARAMS
     })
 
     const tx = await signBuilder.toTransaction()
@@ -203,13 +210,14 @@ describe("Normal Path: Sufficient Change (No Fallbacks)", () => {
   it("should handle exact amount with drainTo without triggering fallbacks", async () => {
     // Arrange: UTxO with exact amount needed
     const utxo = createMinimalUtxo()
-    const builder = makeTxBuilder({ ...baseConfig, availableUtxos: [utxo] }).payToAddress({
-      address: RECIPIENT_ADDRESS,
-      assets: Assets.fromLovelace(2_000_000n)
-    })
+    const builder = makeTxBuilder(baseConfig)
+      .payToAddress({
+        address: RECIPIENT_ADDRESS,
+        assets: Assets.fromLovelace(2_000_000n)
+      })
 
     // Act: Use drainTo for exact amount scenarios
-    const signBuilder = await builder.build({ drainTo: 0, useV3: true })
+    const signBuilder = await builder.build({ changeAddress: CHANGE_ADDRESS, availableUtxos: [utxo], drainTo: 0, useV3: true, protocolParameters: PROTOCOL_PARAMS })
     const tx = await signBuilder.toTransaction()
     const txWithFakeWitnesses = await signBuilder.toTransactionWithFakeWitnesses()
 
@@ -246,14 +254,15 @@ describe("Edge Cases", () => {
       }
     ]
 
-    const builder = makeTxBuilder({ ...baseConfig, availableUtxos: utxos }).payToAddress({
-      address: RECIPIENT_ADDRESS,
-      assets: Assets.fromLovelace(2_000_000n)
-    })
+    const builder = makeTxBuilder(baseConfig)
+      .payToAddress({
+        address: RECIPIENT_ADDRESS,
+        assets: Assets.fromLovelace(2_000_000n)
+      })
 
     // Act: Build with drainTo to merge leftover into payment
     // Total: 2.2 ADA - 2.0 payment - 0.17 fee = 0.03 ADA leftover (insufficient for change)
-    const signBuilder = await builder.build({ drainTo: 0, useV3: true })
+    const signBuilder = await builder.build({ changeAddress: CHANGE_ADDRESS, availableUtxos: utxos, drainTo: 0, useV3: true, protocolParameters: PROTOCOL_PARAMS })
     const tx = await signBuilder.toTransaction()
     const txWithFakeWitnesses = await signBuilder.toTransactionWithFakeWitnesses()
 
@@ -274,13 +283,14 @@ describe("Edge Cases", () => {
     // Arrange: Use the standard minimal UTxO (sufficient for tests)
     const utxo = createMinimalUtxo()
 
-    const builder = makeTxBuilder({ ...baseConfig, availableUtxos: [utxo] }).payToAddress({
-      address: RECIPIENT_ADDRESS,
-      assets: Assets.fromLovelace(2_000_000n)
-    })
+    const builder = makeTxBuilder(baseConfig)
+      .payToAddress({
+        address: RECIPIENT_ADDRESS,
+        assets: Assets.fromLovelace(2_000_000n)
+      })
 
     // Act: Burn small leftover
-    const signBuilder = await builder.build({ onInsufficientChange: "burn", useV3: true })
+    const signBuilder = await builder.build({ changeAddress: CHANGE_ADDRESS, availableUtxos: [utxo], onInsufficientChange: "burn", useV3: true, protocolParameters: PROTOCOL_PARAMS })
     const tx = await signBuilder.toTransaction()
     const txWithFakeWitnesses = await signBuilder.toTransactionWithFakeWitnesses()
 
@@ -329,13 +339,14 @@ describe("Multi-Asset minUTxO Calculation", () => {
 
     // Send most lovelace but keep all native assets
     // This creates leftover with: small lovelace + 10 assets
-    const builder = makeTxBuilder({ ...baseConfig, availableUtxos: [multiAssetUtxo] }).payToAddress({
-      address: RECIPIENT_ADDRESS,
-      assets: Assets.fromLovelace(2_500_000n) // Send 2.5 ADA only
-    })
+    const builder = makeTxBuilder(baseConfig)
+      .payToAddress({
+        address: RECIPIENT_ADDRESS,
+        assets: Assets.fromLovelace(2_500_000n) // Send 2.5 ADA only
+      })
 
     // Act: Build transaction
-    const signBuilder = await builder.build({ useV3: true })
+    const signBuilder = await builder.build({ changeAddress: CHANGE_ADDRESS, availableUtxos: [multiAssetUtxo], useV3: true, protocolParameters: PROTOCOL_PARAMS })
     const tx = await signBuilder.toTransaction()
     const txWithFakeWitnesses = await signBuilder.toTransactionWithFakeWitnesses()
 
@@ -401,13 +412,14 @@ describe("Fee Validation: Multiple Witnesses Edge Case", () => {
     }))
 
     // Build transaction that will select all 10 inputs
-    const builder = makeTxBuilder({ ...baseConfig, availableUtxos: utxos }).payToAddress({
-      address: RECIPIENT_ADDRESS,
-      assets: Assets.fromLovelace(45_000_000n) // 45 ADA
-    })
+    const builder = makeTxBuilder(baseConfig)
+      .payToAddress({
+        address: RECIPIENT_ADDRESS,
+        assets: Assets.fromLovelace(45_000_000n) // 45 ADA
+      })
 
     // Act: Build transaction
-    const signBuilder = await builder.build({ useV3: true })
+    const signBuilder = await builder.build({ changeAddress: CHANGE_ADDRESS, availableUtxos: utxos, useV3: true, protocolParameters: PROTOCOL_PARAMS })
     const tx = await signBuilder.toTransaction()
     const txWithFakeWitnesses = await signBuilder.toTransactionWithFakeWitnesses()
 
@@ -452,13 +464,14 @@ describe("Fee Validation: Multiple Witnesses Edge Case", () => {
       })
     }
 
-    const builder = makeTxBuilder({ ...baseConfig, availableUtxos: utxos }).payToAddress({
-      address: RECIPIENT_ADDRESS,
-      assets: Assets.fromLovelace(45_000_000n)
-    })
+    const builder = makeTxBuilder(baseConfig)
+      .payToAddress({
+        address: RECIPIENT_ADDRESS,
+        assets: Assets.fromLovelace(45_000_000n)
+      })
 
     // Act
-    const signBuilder = await builder.build({ useV3: true })
+    const signBuilder = await builder.build({ changeAddress: CHANGE_ADDRESS, availableUtxos: utxos, useV3: true, protocolParameters: PROTOCOL_PARAMS })
     const tx = await signBuilder.toTransaction()
     const txWithFakeWitnesses = await signBuilder.toTransactionWithFakeWitnesses()
 
diff --git a/packages/evolution/test/TxBuilder.Reselection.test.ts b/packages/evolution/test/TxBuilder.Reselection.test.ts
index 882a6d18..23bef814 100644
--- a/packages/evolution/test/TxBuilder.Reselection.test.ts
+++ b/packages/evolution/test/TxBuilder.Reselection.test.ts
@@ -12,11 +12,10 @@ import * as FeeValidation from "../src/utils/FeeValidation.js"
 import { createTestUtxo } from "./utils/utxo-helpers.js"
 
 describe("TxBuilder Re-selection Loop", () => {
-  
   // ============================================================================
   // Test Configuration
   // ============================================================================
-  
+
   const PROTOCOL_PARAMS = {
     minFeeCoefficient: 44n,
     minFeeConstant: 155_381n,
@@ -37,9 +36,8 @@ describe("TxBuilder Re-selection Loop", () => {
   const RECEIVER_ADDRESS = TESTNET_ADDRESSES[1]
 
   const baseConfig: TxBuilderConfig = {
-    protocolParameters: PROTOCOL_PARAMS,
-    changeAddress: CHANGE_ADDRESS,
-    availableUtxos: []
+    // No wallet/provider - using manual mode
+    // changeAddress and availableUtxos provided via build options
   }
 
   // ============================================================================
@@ -59,14 +57,11 @@ describe("TxBuilder Re-selection Loop", () => {
     expect(validation.difference).toBe(0n)
     
     return validation
-  }
-
-  // ============================================================================
+  }  // ============================================================================
   // Basic Re-selection Tests
   // ============================================================================
 
   describe("Basic Re-selection Scenarios", () => {
-    
     it("should build transaction with single UTxO - sufficient funds", async () => {
       const utxo: UTxO.UTxO = createTestUtxo({
         txHash: "a".repeat(64),
@@ -75,28 +70,32 @@ describe("TxBuilder Re-selection Loop", () => {
         lovelace: 10_000_000n
       })
 
-      const builder = makeTxBuilder({ ...baseConfig, availableUtxos: [utxo] })
-        .payToAddress({
-          address: RECEIVER_ADDRESS,
-          assets: Assets.fromLovelace(2_000_000n)
-        })
+      const builder = makeTxBuilder(baseConfig).payToAddress({
+        address: RECEIVER_ADDRESS,
+        assets: Assets.fromLovelace(2_000_000n)
+      })
 
-      const signBuilder = await builder.build({ useV3: true })
+      const signBuilder = await builder.build({
+        useV3: true,
+        changeAddress: CHANGE_ADDRESS,
+        availableUtxos: [utxo],
+        protocolParameters: PROTOCOL_PARAMS
+      })
       const tx = await signBuilder.toTransaction()
       const txWithFakeWitnesses = await signBuilder.toTransactionWithFakeWitnesses()
 
       // Strict expectations - everything is deterministic
       expect(tx.body.inputs.length).toBe(1)
       expect(tx.body.outputs.length).toBe(2) // Payment + change
-      
+
       const validation = await assertFeeValid(txWithFakeWitnesses, PROTOCOL_PARAMS)
       const size = await Effect.runPromise(calculateTransactionSize(txWithFakeWitnesses))
       expect(size).toBeLessThanOrEqual(PROTOCOL_PARAMS.maxTxSize)
-      
+
       // Strict expectations with deterministic values
       expect(size).toBe(294) // Exact transaction size with 1 witness
       expect(validation.actualFee).toBe(168_317n) // Exact deterministic fee
-      
+
       // Verify exact output amounts
       expect(tx.body.outputs[0].amount.coin).toBe(2_000_000n) // Payment output
       // Change: 10M - 2M payment - 168,317 fee = 7,831,683
@@ -126,13 +125,18 @@ describe("TxBuilder Re-selection Loop", () => {
         lovelace: 1_000_000n
       })
 
-      const builder = makeTxBuilder({ ...baseConfig, availableUtxos: [utxo1, utxo2, utxo3] })
-        .payToAddress({
-          address: RECEIVER_ADDRESS,
-          assets: Assets.fromLovelace(2_000_000n) // 2 ADA payment
-        })
+      const builder = makeTxBuilder(baseConfig).payToAddress({
+        address: RECEIVER_ADDRESS,
+        assets: Assets.fromLovelace(2_000_000n) // 2 ADA payment
+      })
 
-      const signBuilder = await builder.build({ drainTo: 0, useV3: true })
+      const signBuilder = await builder.build({
+        drainTo: 0,
+        useV3: true,
+        changeAddress: CHANGE_ADDRESS,
+        availableUtxos: [utxo1, utxo2, utxo3],
+        protocolParameters: PROTOCOL_PARAMS
+      })
       const tx = await signBuilder.toTransaction()
       const txWithFakeWitnesses = await signBuilder.toTransactionWithFakeWitnesses()
 
@@ -141,14 +145,14 @@ describe("TxBuilder Re-selection Loop", () => {
       expect(tx.body.inputs.length).toBe(2) // utxo1 (2.2M) + utxo2 (1M) after reselection
       // Should have 2 outputs: payment + change
       expect(tx.body.outputs.length).toBe(2)
-      
+
       const validation = await assertFeeValid(txWithFakeWitnesses, PROTOCOL_PARAMS)
       const size = await Effect.runPromise(calculateTransactionSize(txWithFakeWitnesses))
       expect(size).toBeLessThanOrEqual(PROTOCOL_PARAMS.maxTxSize)
-      
+
       expect(size).toBe(330) // 2 inputs, 1 witness, 2 outputs
       expect(validation.actualFee).toBe(169_901n) // Fee for 2-input TX
-      
+
       // Verify exact output amounts - reselection creates proper change output
       expect(tx.body.outputs[0].amount.coin).toBe(2_000_000n) // Payment output
       expect(tx.body.outputs[1].amount.coin).toBe(1_030_099n) // Change output (3.2M - 2M - fee)
@@ -162,13 +166,19 @@ describe("TxBuilder Re-selection Loop", () => {
         lovelace: 1_000_000n
       })
 
-      const builder = makeTxBuilder({ ...baseConfig, availableUtxos: [utxo] })
-        .payToAddress({
-          address: RECEIVER_ADDRESS,
-          assets: Assets.fromLovelace(2_000_000n) // Requesting 2 ADA
-        })
+      const builder = makeTxBuilder(baseConfig).payToAddress({
+        address: RECEIVER_ADDRESS,
+        assets: Assets.fromLovelace(2_000_000n) // Requesting 2 ADA
+      })
 
-      await expect(builder.build({ useV3: true })).rejects.toThrow()
+      await expect(
+        builder.build({
+          useV3: true,
+          changeAddress: CHANGE_ADDRESS,
+          availableUtxos: [utxo],
+          protocolParameters: PROTOCOL_PARAMS
+        })
+      ).rejects.toThrow()
     })
 
     it("should handle exact amount with drainTo", async () => {
@@ -184,28 +194,33 @@ describe("TxBuilder Re-selection Loop", () => {
         lovelace: exactAmount
       })
 
-      const builder = makeTxBuilder({ ...baseConfig, availableUtxos: [utxo] })
-        .payToAddress({
-          address: RECEIVER_ADDRESS,
-          assets: Assets.fromLovelace(paymentAmount)
-        })
+      const builder = makeTxBuilder(baseConfig).payToAddress({
+        address: RECEIVER_ADDRESS,
+        assets: Assets.fromLovelace(paymentAmount)
+      })
 
-      const signBuilder = await builder.build({ drainTo: 0, useV3: true })
+      const signBuilder = await builder.build({
+        drainTo: 0,
+        useV3: true,
+        changeAddress: CHANGE_ADDRESS,
+        availableUtxos: [utxo],
+        protocolParameters: PROTOCOL_PARAMS
+      })
       const tx = await signBuilder.toTransaction()
       const txWithFakeWitnesses = await signBuilder.toTransactionWithFakeWitnesses()
 
       expect(tx.body.inputs.length).toBe(1)
       // Should have 1 output (payment with drained amount)
       expect(tx.body.outputs.length).toBe(1)
-      
+
       const validation = await assertFeeValid(txWithFakeWitnesses, PROTOCOL_PARAMS)
       const size = await Effect.runPromise(calculateTransactionSize(txWithFakeWitnesses))
       expect(size).toBeLessThanOrEqual(PROTOCOL_PARAMS.maxTxSize)
-      
-      // Strict expectations with deterministic values  
+
+      // Strict expectations with deterministic values
       expect(size).toBe(227) // Exact transaction size with 1 witness, drainTo
       expect(validation.actualFee).toBe(165_369n) // Exact fee: 227*44 + 155_381
-      
+
       // Verify exact output amount (payment + drained leftover)
       expect(tx.body.outputs[0].amount.coin).toBe(2_004_631n) // 2_170_000 - 165_369 fee
     })
@@ -213,7 +228,7 @@ describe("TxBuilder Re-selection Loop", () => {
     it("should create change output instead of using drainTo when leftover contains native assets", async () => {
       // Scenario: drainTo is requested, but leftover has native assets
       // Expected: Transaction succeeds by creating proper change output (drainTo fallback skipped for native assets)
-      
+
       const TOKEN_POLICY = "c".repeat(56)
       const TOKEN_NAME_1 = "544f4b454e31" // "TOKEN1" in hex
       const TOKEN_UNIT_1 = `${TOKEN_POLICY}${TOKEN_NAME_1}`
@@ -227,24 +242,29 @@ describe("TxBuilder Re-selection Loop", () => {
         nativeAssets: { [TOKEN_UNIT_1]: 100n }
       })
 
-      const builder = makeTxBuilder({ ...baseConfig, availableUtxos: [utxo] })
-        .payToAddress({
-          address: RECEIVER_ADDRESS,
-          // Payment leaves leftover + token
-          // 3_000_000 - 2_000_000 - fee(~170k) = ~830k leftover + token
-          assets: Assets.fromLovelace(2_000_000n)
-        })
+      const builder = makeTxBuilder(baseConfig).payToAddress({
+        address: RECEIVER_ADDRESS,
+        // Payment leaves leftover + token
+        // 3_000_000 - 2_000_000 - fee(~170k) = ~830k leftover + token
+        assets: Assets.fromLovelace(2_000_000n)
+      })
 
       // DrainTo requested, but should create change output instead (native assets present)
       // Expected: Transaction succeeds with change output preserving native asset
-      const signBuilder = await builder.build({ drainTo: 0, useV3: true })
+      const signBuilder = await builder.build({
+        drainTo: 0,
+        useV3: true,
+        changeAddress: CHANGE_ADDRESS,
+        availableUtxos: [utxo],
+        protocolParameters: PROTOCOL_PARAMS
+      })
       expect(signBuilder).toBeDefined()
-      
+
       const tx = await signBuilder.toTransaction()
-      
+
       // Should have payment + change output (native assets require change, drainTo skipped)
       expect(tx.body.outputs.length).toBe(2)
-      
+
       // Verify we have 1 input
       expect(tx.body.inputs.length).toBe(1)
     })
@@ -255,7 +275,6 @@ describe("TxBuilder Re-selection Loop", () => {
   // ============================================================================
 
   describe("Multi-Asset Re-selection", () => {
-    
     const TOKEN_POLICY = "c".repeat(56)
     const TOKEN_NAME = "544f4b454e" // "TOKEN" in hex
     const TOKEN_UNIT = `${TOKEN_POLICY}${TOKEN_NAME}`
@@ -279,37 +298,41 @@ describe("TxBuilder Re-selection Loop", () => {
       })
 
       // Pay 2 ADA + 50 tokens
-      const builder = makeTxBuilder({ ...baseConfig, availableUtxos: [utxo1, utxo2] })
-        .payToAddress({
-          address: RECEIVER_ADDRESS,
-          assets: {
-            lovelace: 2_000_000n,
-            [TOKEN_UNIT]: 50n
-          }
-        })
+      const builder = makeTxBuilder(baseConfig).payToAddress({
+        address: RECEIVER_ADDRESS,
+        assets: {
+          lovelace: 2_000_000n,
+          [TOKEN_UNIT]: 50n
+        }
+      })
 
-      const signBuilder = await builder.build({ useV3: true })
+      const signBuilder = await builder.build({
+        useV3: true,
+        changeAddress: CHANGE_ADDRESS,
+        availableUtxos: [utxo1, utxo2],
+        protocolParameters: PROTOCOL_PARAMS
+      })
       const tx = await signBuilder.toTransaction()
       const txWithFakeWitnesses = await signBuilder.toTransactionWithFakeWitnesses()
 
       // Should select both inputs
       expect(tx.body.inputs.length).toBe(2)
-      
+
       // Should have payment output + change output with remaining 50 tokens
       expect(tx.body.outputs.length).toBe(2)
-      
+
       // Verify both outputs exist
       expect(tx.body.outputs[0]).toBeDefined()
       expect(tx.body.outputs[1]).toBeDefined()
-      
+
       const validation = await assertFeeValid(txWithFakeWitnesses, PROTOCOL_PARAMS)
       const size = await Effect.runPromise(calculateTransactionSize(txWithFakeWitnesses))
       expect(size).toBeLessThanOrEqual(PROTOCOL_PARAMS.maxTxSize)
-      
+
       // Strict expectations with deterministic values
       expect(size).toBe(513) // Exact transaction size with 2 witnesses, multi-asset
       expect(validation.actualFee).toBe(177_953n) // Exact fee: 513*44 + 155_381
-      
+
       // Verify exact output amounts (payment output)
       expect(tx.body.outputs[0].amount.coin).toBe(2_000_000n)
       // Change output: initially 2,826,799, adjusted by fee increase of 4,752 = 2,822,047
@@ -320,7 +343,7 @@ describe("TxBuilder Re-selection Loop", () => {
       const TOKEN_POLICY = "c".repeat(56)
       const TOKEN_NAME = "544f4b454e" // "TOKEN" in hex
       const TOKEN_UNIT = `${TOKEN_POLICY}${TOKEN_NAME}`
-      
+
       // UTxO with ONLY ADA (no tokens)
       const utxo1: UTxO.UTxO = createTestUtxo({
         txHash: "a".repeat(64),
@@ -328,7 +351,7 @@ describe("TxBuilder Re-selection Loop", () => {
         address: TESTNET_ADDRESSES[0],
         lovelace: 10_000_000n
       })
-      
+
       // UTxO with tokens (available for coin selection)
       const utxo2: UTxO.UTxO = createTestUtxo({
         txHash: "b".repeat(64),
@@ -337,36 +360,39 @@ describe("TxBuilder Re-selection Loop", () => {
         lovelace: 3_000_000n,
         nativeAssets: { [TOKEN_UNIT]: 200n }
       })
-      
+
       // Config with both utxos available for automatic selection
       const builderConfig: TxBuilderConfig = {
-        ...baseConfig,
-        availableUtxos: [utxo1, utxo2]
+        ...baseConfig
       }
-      
+
       // Payment requires tokens that utxo1 doesn't have
-      const builder = makeTxBuilder(builderConfig)
-        .payToAddress({
-          address: RECEIVER_ADDRESS,
-          assets: {
-            lovelace: 2_000_000n,
-            [TOKEN_UNIT]: 100n // Requires tokens!
-          }
-        })
-      
-      const signBuilder = await builder.build({ useV3: true })
+      const builder = makeTxBuilder(builderConfig).payToAddress({
+        address: RECEIVER_ADDRESS,
+        assets: {
+          lovelace: 2_000_000n,
+          [TOKEN_UNIT]: 100n // Requires tokens!
+        }
+      })
+
+      const signBuilder = await builder.build({
+        useV3: true,
+        availableUtxos: [utxo1, utxo2],
+        changeAddress: CHANGE_ADDRESS,
+        protocolParameters: PROTOCOL_PARAMS
+      })
       const tx = await signBuilder.toTransaction()
-      
+
       // Should automatically select utxo2 to cover the token requirement
       expect(tx.body.inputs.length).toBe(2)
-      
+
       // Should have payment + change output
       expect(tx.body.outputs.length).toBe(2)
-      
+
       // Payment output should have the requested amount
       const paymentOutput = tx.body.outputs[0]
       expect(paymentOutput.amount.coin).toBe(2_000_000n)
-      
+
       // Change output should exist with remaining tokens (200 - 100 = 100)
       const _changeOutput = tx.body.outputs[1]
       // Verify the transaction is valid (coin selection worked correctly)
@@ -378,7 +404,6 @@ describe("TxBuilder Re-selection Loop", () => {
   // ============================================================================
 
   describe("Transaction Size Validation", () => {
-    
     it("should pass size check with same address (1 witness)", async () => {
       // Single address = 1 witness
       const utxos: Array<UTxO.UTxO> = Array.from({ length: 5 }, (_, i) =>
@@ -390,24 +415,28 @@ describe("TxBuilder Re-selection Loop", () => {
         })
       )
 
-      const builder = makeTxBuilder({ ...baseConfig, availableUtxos: utxos })
-        .payToAddress({
-          address: RECEIVER_ADDRESS,
-          assets: Assets.fromLovelace(5_000_000n)
-        })
+      const builder = makeTxBuilder(baseConfig).payToAddress({
+        address: RECEIVER_ADDRESS,
+        assets: Assets.fromLovelace(5_000_000n) // 5 ADA
+      })
 
-      const signBuilder = await builder.build({ useV3: true })
+      const signBuilder = await builder.build({
+        useV3: true,
+        changeAddress: CHANGE_ADDRESS,
+        availableUtxos: utxos,
+        protocolParameters: PROTOCOL_PARAMS
+      })
       const txWithFakeWitnesses = await signBuilder.toTransactionWithFakeWitnesses()
-      
+
       const size = await Effect.runPromise(calculateTransactionSize(txWithFakeWitnesses))
       expect(size).toBeLessThanOrEqual(PROTOCOL_PARAMS.maxTxSize)
       const validation = await assertFeeValid(txWithFakeWitnesses, PROTOCOL_PARAMS)
-      
+
       // With automatic coin selection, builder picks 3 UTxOs (6M total) to cover 5M payment + fees
       // Strict expectations with deterministic values
       expect(size).toBe(366) // Exact transaction size with 1 witness, 3 inputs
       expect(validation.actualFee).toBe(171_485n) // Exact fee: 366*44 + 155_381
-      
+
       // Verify transaction structure
       const tx = await signBuilder.toTransaction()
       expect(tx.body.inputs.length).toBe(3) // Coin selection picked 3 UTxOs
@@ -432,23 +461,27 @@ describe("TxBuilder Re-selection Loop", () => {
         lovelace: 5_000_000n
       })
 
-      const builder = makeTxBuilder({ ...baseConfig, availableUtxos: [utxo1, utxo2] })
-        .payToAddress({
-          address: RECEIVER_ADDRESS,
-          assets: Assets.fromLovelace(6_000_000n)
-        })
+      const builder = makeTxBuilder(baseConfig).payToAddress({
+        address: RECEIVER_ADDRESS,
+        assets: Assets.fromLovelace(6_000_000n)
+      })
 
-      const signBuilder = await builder.build({ useV3: true })
+      const signBuilder = await builder.build({
+        useV3: true,
+        changeAddress: CHANGE_ADDRESS,
+        availableUtxos: [utxo1, utxo2],
+        protocolParameters: PROTOCOL_PARAMS
+      })
       const txWithFakeWitnesses = await signBuilder.toTransactionWithFakeWitnesses()
-      
+
       const size = await Effect.runPromise(calculateTransactionSize(txWithFakeWitnesses))
       expect(size).toBeLessThanOrEqual(PROTOCOL_PARAMS.maxTxSize)
       const validation = await assertFeeValid(txWithFakeWitnesses, PROTOCOL_PARAMS)
-      
+
       // Strict expectations with deterministic values
       expect(size).toBe(431) // Exact transaction size with 2 witnesses, 2 inputs
       expect(validation.actualFee).toBe(174_345n) // Exact fee: 431*44 + 155_381
-      
+
       // Verify transaction structure
       const tx = await signBuilder.toTransaction()
       expect(tx.body.inputs.length).toBe(2)
@@ -463,10 +496,10 @@ describe("TxBuilder Re-selection Loop", () => {
       // With 150+ unique payment credentials, we'll need 150+ witnesses
       // Each witness ~130 bytes, so 150 witnesses = ~19.5KB of witnesses alone
       // Plus transaction body ~3-4KB = should exceed 16KB limit
-      
+
       // Generate 200 unique addresses using KeyHash.arbitrary for payment credentials
       // This ensures payment key addresses (not script addresses)
-      const uniqueAddresses = FastCheck.sample(KeyHash.arbitrary, { seed: 42, numRuns: 200 }).map(keyHash => {
+      const uniqueAddresses = FastCheck.sample(KeyHash.arbitrary, { seed: 42, numRuns: 200 }).map((keyHash) => {
         // Create payment key address structure
         const addressStruct = AddressStructure.AddressStructure.make({
           networkId: 0, // Testnet
@@ -476,7 +509,7 @@ describe("TxBuilder Re-selection Loop", () => {
         // Convert to bech32 string
         return Schema.encodeSync(AddressStructure.FromBech32)(addressStruct)
       })
-      
+
       // Create 150 UTxOs with truly unique addresses
       // This will require 150 unique witnesses when selected
       const utxos: Array<UTxO.UTxO> = uniqueAddresses.slice(0, 150).map((address, i) => {
@@ -488,17 +521,23 @@ describe("TxBuilder Re-selection Loop", () => {
         })
       })
 
-      const builder = makeTxBuilder({ ...baseConfig, availableUtxos: utxos })
-        .payToAddress({
-          address: RECEIVER_ADDRESS,
-          // Request 280M to force selection of 140+ UTxOs (each 2M), which will create 140+ witnesses
-          // This will exceed the 16KB transaction size limit
-          assets: Assets.fromLovelace(280_000_000n)
-        })
+      const builder = makeTxBuilder({ ...baseConfig }).payToAddress({
+        address: RECEIVER_ADDRESS,
+        // Request 280M to force selection of 140+ UTxOs (each 2M), which will create 140+ witnesses
+        // This will exceed the 16KB transaction size limit
+        assets: Assets.fromLovelace(280_000_000n)
+      })
 
       // Should throw error due to transaction size exceeding limit
       // With 140+ unique addresses selected, we get 140+ fake witnesses pushing size over 16384 bytes
-      await expect(builder.build({ useV3: true })).rejects.toThrow(/Transaction size.*16384|Build failed/)
+      await expect(
+        builder.build({
+          useV3: true,
+          changeAddress: CHANGE_ADDRESS,
+          availableUtxos: utxos,
+          protocolParameters: PROTOCOL_PARAMS
+        })
+      ).rejects.toThrow(/Transaction size.*16384|Build failed/)
     })
   })
 
@@ -508,39 +547,37 @@ describe("TxBuilder Re-selection Loop", () => {
 
   describe("Multiple Reselection Attempts", () => {
     it("should trigger multiple reselection attempts with incremental coin selection", async () => {
-
       // Create a mix of UTxO sizes - largest-first will pick bigger ones initially
       const utxos: Array<UTxO.UTxO> = [
         // Large UTxOs (selected first)
         createTestUtxo({ txHash: "a".repeat(64), outputIndex: 0, address: CHANGE_ADDRESS, lovelace: 1_500_000n }),
         createTestUtxo({ txHash: "b".repeat(64), outputIndex: 0, address: CHANGE_ADDRESS, lovelace: 1_200_000n }),
-        
+
         // Medium UTxOs (for reselection)
         createTestUtxo({ txHash: "c".repeat(64), outputIndex: 0, address: CHANGE_ADDRESS, lovelace: 600_000n }),
         createTestUtxo({ txHash: "d".repeat(64), outputIndex: 0, address: CHANGE_ADDRESS, lovelace: 600_000n }),
         createTestUtxo({ txHash: "e".repeat(64), outputIndex: 0, address: CHANGE_ADDRESS, lovelace: 600_000n }),
-        
+
         // Small UTxOs (for additional reselections if needed)
         createTestUtxo({ txHash: "f".repeat(64), outputIndex: 0, address: CHANGE_ADDRESS, lovelace: 400_000n }),
         createTestUtxo({ txHash: "g".repeat(64), outputIndex: 0, address: CHANGE_ADDRESS, lovelace: 400_000n }),
         createTestUtxo({ txHash: "h".repeat(64), outputIndex: 0, address: CHANGE_ADDRESS, lovelace: 400_000n })
       ]
 
-      // Use makeTxBuilder with availableUtxos to enable coin selection
-      const builderConfig: TxBuilderConfig = {
-        ...baseConfig,
-        availableUtxos: utxos
-      }
-
-      const builder = makeTxBuilder(builderConfig)
-        .payToAddress({
-          address: RECEIVER_ADDRESS,
-          assets: Assets.fromLovelace(2_500_000n) // 2.5 ADA payment
-        })
+      const builder = makeTxBuilder(baseConfig).payToAddress({
+        address: RECEIVER_ADDRESS,
+        assets: Assets.fromLovelace(2_500_000n) // 2.5 ADA payment
+      })
 
       // Build uses default largest-first algorithm
       // Use drainTo since the change will be small (33K < minUTxO)
-      const signBuilder = await builder.build({ drainTo: 0, useV3: true })
+      const signBuilder = await builder.build({
+        drainTo: 0,
+        useV3: true,
+        changeAddress: CHANGE_ADDRESS,
+        availableUtxos: utxos,
+        protocolParameters: PROTOCOL_PARAMS
+      })
       const tx = await signBuilder.toTransaction()
       const txWithFakeWitnesses = await signBuilder.toTransactionWithFakeWitnesses()
 
@@ -556,10 +593,10 @@ describe("TxBuilder Re-selection Loop", () => {
 
       // 2 outputs: payment + change (change now sufficient for minUTxO)
       expect(tx.body.outputs.length).toBe(2)
-      
+
       // Payment output is exactly 2.5M
       expect(tx.body.outputs[0].amount.coin).toBe(2_500_000n)
-      
+
       // Change output: 3.3M total - 2.5M payment - 171K fee = 628K
       expect(tx.body.outputs[1].amount.coin).toBe(628_515n)
     })
@@ -567,7 +604,7 @@ describe("TxBuilder Re-selection Loop", () => {
     it("should trigger multiple reselection attempts with cascading fee increases", async () => {
       /**
        * Edge Case: Cascading Fee Increases
-       * 
+       *
        * Create many tiny UTxOs where each selection barely covers the payment,
        * causing the algorithm to naturally trigger multiple reselection attempts
        * as fees cascade upward with more inputs.
@@ -575,7 +612,7 @@ describe("TxBuilder Re-selection Loop", () => {
 
       // Create 20 small UTxOs, each with just enough to pass minUTxO
       // Using ~350K lovelace each (slightly above minUTxO of ~280K)
-      const tinyUtxos: Array<UTxO.UTxO> = Array.from({ length: 20 }, (_, i) => 
+      const tinyUtxos: Array<UTxO.UTxO> = Array.from({ length: 20 }, (_, i) =>
         createTestUtxo({
           txHash: i.toString().padStart(64, "0"),
           outputIndex: 0,
@@ -587,17 +624,18 @@ describe("TxBuilder Re-selection Loop", () => {
       // Request a payment that will require multiple UTxOs
       // Each UTxO contributes 350K, minus ~2K fee overhead = ~348K net
       // To get 3M payment, need ~9 UTxOs initially, but fee will increase
-      const builder = makeTxBuilder({
-        ...baseConfig,
-        availableUtxos: tinyUtxos
+      const builder = makeTxBuilder(baseConfig).payToAddress({
+        address: RECEIVER_ADDRESS,
+        assets: Assets.fromLovelace(3_000_000n) // 3 ADA
       })
-        .payToAddress({
-          address: RECEIVER_ADDRESS,
-          assets: Assets.fromLovelace(3_000_000n) // 3 ADA
-        })
 
       // Build should succeed after multiple reselection attempts
-      const signBuilder = await builder.build({ useV3: true })
+      const signBuilder = await builder.build({
+        useV3: true,
+        changeAddress: CHANGE_ADDRESS,
+        availableUtxos: tinyUtxos,
+        protocolParameters: PROTOCOL_PARAMS
+      })
       const tx = await signBuilder.toTransaction()
       const txWithFakeWitnesses = await signBuilder.toTransactionWithFakeWitnesses()
 
@@ -623,7 +661,6 @@ describe("TxBuilder Re-selection Loop", () => {
     })
 
     it("should handle reselection with mixed-size UTxOs", async () => {
-
       const utxos: Array<UTxO.UTxO> = [
         // First pass: Large UTxO insufficient by itself
         createTestUtxo({ txHash: "a".repeat(64), outputIndex: 0, address: CHANGE_ADDRESS, lovelace: 1_500_000n }),
@@ -638,16 +675,17 @@ describe("TxBuilder Re-selection Loop", () => {
         createTestUtxo({ txHash: "f".repeat(64), outputIndex: 0, address: CHANGE_ADDRESS, lovelace: 400_000n })
       ]
 
-      const builder = makeTxBuilder({
-        ...baseConfig,
-        availableUtxos: utxos
+      const builder = makeTxBuilder(baseConfig).payToAddress({
+        address: RECEIVER_ADDRESS,
+        assets: Assets.fromLovelace(2_500_000n) // 2.5 ADA - requires reselection
       })
-        .payToAddress({
-          address: RECEIVER_ADDRESS,
-          assets: Assets.fromLovelace(2_500_000n) // 2.5 ADA - requires reselection
-        })
 
-      const signBuilder = await builder.build({ useV3: true })
+      const signBuilder = await builder.build({
+        useV3: true,
+        changeAddress: CHANGE_ADDRESS,
+        availableUtxos: utxos,
+        protocolParameters: PROTOCOL_PARAMS
+      })
       const tx = await signBuilder.toTransaction()
       const txWithFakeWitnesses = await signBuilder.toTransactionWithFakeWitnesses()
 
@@ -658,7 +696,7 @@ describe("TxBuilder Re-selection Loop", () => {
 
       // Should need at least 2 inputs (1.5M + 0.8M + fee > 2.5M)
       expect(tx.body.inputs.length).toBeGreaterThanOrEqual(2)
-      
+
       // Verify correct payment amount
       expect(tx.body.outputs[0].amount.coin).toBe(2_500_000n)
     })
@@ -673,13 +711,14 @@ describe("TxBuilder Reselection After Change", () => {
     maxTxSize: 16_384
   }
 
-  const CHANGE_ADDRESS = "addr_test1qz2fxv2umyhttkxyxp8x0dlpdt3k6cwng5pxj3jhsydzer3n0d3vllmyqwsx5wktcd8cc3sq835lu7drv2xwl2wywfgs68faae"
-  const RECEIVER_ADDRESS = "addr_test1qpw0djgj0x59ngrjvqthn7enhvruxnsavsw5th63la3mjel3tkc974sr23jmlzgq5zda4gtv8k9cy38756r9y3qgmkqqjz6aa7"
+  const CHANGE_ADDRESS =
+    "addr_test1qz2fxv2umyhttkxyxp8x0dlpdt3k6cwng5pxj3jhsydzer3n0d3vllmyqwsx5wktcd8cc3sq835lu7drv2xwl2wywfgs68faae"
+  const RECEIVER_ADDRESS =
+    "addr_test1qpw0djgj0x59ngrjvqthn7enhvruxnsavsw5th63la3mjel3tkc974sr23jmlzgq5zda4gtv8k9cy38756r9y3qgmkqqjz6aa7"
 
   const baseConfig: TxBuilderConfig = {
-    protocolParameters: PROTOCOL_PARAMS,
-    changeAddress: CHANGE_ADDRESS,
-    availableUtxos: []
+    // No wallet/provider - using manual mode
+    // changeAddress and availableUtxos provided via build options
   }
 
   /**
@@ -694,13 +733,18 @@ describe("TxBuilder Reselection After Change", () => {
       lovelace: 10_000_000n // 10 ADA
     })
 
-    const builder = makeTxBuilder({ ...baseConfig, availableUtxos: [largeUtxo] })
-      .payToAddress({
-        address: RECEIVER_ADDRESS,
-        assets: Assets.fromLovelace(5_000_000n) // 5 ADA payment
-      })
+    const builder = makeTxBuilder(baseConfig).payToAddress({
+      address: RECEIVER_ADDRESS,
+      assets: Assets.fromLovelace(5_000_000n) // 5 ADA payment
+    })
 
-    const signBuilder = await builder.build({ useStateMachine: true, useV3: true })
+    const signBuilder = await builder.build({
+      useStateMachine: true,
+      useV3: true,
+      changeAddress: CHANGE_ADDRESS,
+      availableUtxos: [largeUtxo],
+      protocolParameters: PROTOCOL_PARAMS
+    })
     const tx = await signBuilder.toTransaction()
 
     // Verify transaction structure
@@ -728,17 +772,37 @@ describe("TxBuilder Reselection After Change", () => {
    * Verifies that UTxO reselection uses accurate fee calculation that includes change output size.
    */
   it("should reselect UTxOs based on actual fee (after change creation)", async () => {
-    const utxo1: UTxO.UTxO = createTestUtxo({ txHash: "a", outputIndex: 0, address: CHANGE_ADDRESS, lovelace: 2_000_000n })
-    const utxo2: UTxO.UTxO = createTestUtxo({ txHash: "b", outputIndex: 0, address: CHANGE_ADDRESS, lovelace: 2_000_000n })
-    const utxo3: UTxO.UTxO = createTestUtxo({ txHash: "c", outputIndex: 0, address: CHANGE_ADDRESS, lovelace: 2_000_000n })
+    const utxo1: UTxO.UTxO = createTestUtxo({
+      txHash: "a",
+      outputIndex: 0,
+      address: CHANGE_ADDRESS,
+      lovelace: 2_000_000n
+    })
+    const utxo2: UTxO.UTxO = createTestUtxo({
+      txHash: "b",
+      outputIndex: 0,
+      address: CHANGE_ADDRESS,
+      lovelace: 2_000_000n
+    })
+    const utxo3: UTxO.UTxO = createTestUtxo({
+      txHash: "c",
+      outputIndex: 0,
+      address: CHANGE_ADDRESS,
+      lovelace: 2_000_000n
+    })
 
-    const builder = makeTxBuilder({ ...baseConfig, availableUtxos: [utxo1, utxo2, utxo3] })
-      .payToAddress({
-        address: RECEIVER_ADDRESS,
-        assets: Assets.fromLovelace(3_500_000n) // Needs 2 UTxOs
-      })
+    const builder = makeTxBuilder(baseConfig).payToAddress({
+      address: RECEIVER_ADDRESS,
+      assets: Assets.fromLovelace(3_500_000n) // Needs 2 UTxOs
+    })
 
-    const signBuilder = await builder.build({ useStateMachine: true, useV3: true })
+    const signBuilder = await builder.build({
+      useStateMachine: true,
+      useV3: true,
+      changeAddress: CHANGE_ADDRESS,
+      availableUtxos: [utxo1, utxo2, utxo3],
+      protocolParameters: PROTOCOL_PARAMS
+    })
     const tx = await signBuilder.toTransaction()
 
     // With coin selection: 2 UTxOs (4M) is sufficient for payment (3.5M) + fee (~170K) + change (~330K)
@@ -761,7 +825,7 @@ describe("TxBuilder Reselection After Change", () => {
   it("should account for change output size when it contains native assets", async () => {
     const policyId = "a".repeat(56)
     const assetName = "544f4b454e" // "TOKEN" in hex
-    
+
     const utxoWithAssets: UTxO.UTxO = createTestUtxo({
       txHash: "c",
       outputIndex: 0,
@@ -770,28 +834,33 @@ describe("TxBuilder Reselection After Change", () => {
       nativeAssets: { [`${policyId}${assetName}`]: 1000n } // Native assets increase change size
     })
 
-    const builder = makeTxBuilder({ ...baseConfig, availableUtxos: [utxoWithAssets] })
-      .payToAddress({
-        address: RECEIVER_ADDRESS,
-        assets: Assets.fromLovelace(3_000_000n) // Send only lovelace
-      })
+    const builder = makeTxBuilder(baseConfig).payToAddress({
+      address: RECEIVER_ADDRESS,
+      assets: Assets.fromLovelace(3_000_000n) // Send only lovelace
+    })
 
-    const signBuilder = await builder.build({ useStateMachine: true, useV3: true })
+    const signBuilder = await builder.build({
+      useStateMachine: true,
+      useV3: true,
+      changeAddress: CHANGE_ADDRESS,
+      availableUtxos: [utxoWithAssets],
+      protocolParameters: PROTOCOL_PARAMS
+    })
     const tx = await signBuilder.toTransaction()
 
     // Payment output: only lovelace
     expect(tx.body.outputs[0].amount.coin).toBe(3_000_000n)
-    
+
     // Change output: remaining lovelace + ALL native assets
     const changeOutput = tx.body.outputs[1]
-    
+
     // Verify native assets are in change (not burned)
     if (changeOutput.amount._tag === "WithAssets") {
       expect(changeOutput.amount.assets.size).toBeGreaterThan(0)
     } else {
       throw new Error("Expected change output to have native assets")
     }
-    
+
     // Balance equation with native assets
     const expectedChange = 10_000_000n - 3_000_000n - tx.body.fee
     expect(changeOutput.amount.coin).toBe(expectedChange)
@@ -804,16 +873,31 @@ describe("TxBuilder Reselection After Change", () => {
    * Verifies correct fee calculation when using multiple small UTxOs and change output affects transaction size.
    */
   it("should handle case where change output affects fee calculation", async () => {
-    const utxo1: UTxO.UTxO = createTestUtxo({ txHash: "a", outputIndex: 0, address: CHANGE_ADDRESS, lovelace: 2_000_000n })
-    const utxo2: UTxO.UTxO = createTestUtxo({ txHash: "b", outputIndex: 0, address: CHANGE_ADDRESS, lovelace: 2_000_000n })
+    const utxo1: UTxO.UTxO = createTestUtxo({
+      txHash: "a",
+      outputIndex: 0,
+      address: CHANGE_ADDRESS,
+      lovelace: 2_000_000n
+    })
+    const utxo2: UTxO.UTxO = createTestUtxo({
+      txHash: "b",
+      outputIndex: 0,
+      address: CHANGE_ADDRESS,
+      lovelace: 2_000_000n
+    })
 
-    const builder = makeTxBuilder({ ...baseConfig, availableUtxos: [utxo1, utxo2] })
-      .payToAddress({
-        address: RECEIVER_ADDRESS,
-        assets: Assets.fromLovelace(3_000_000n)
-      })
+    const builder = makeTxBuilder(baseConfig).payToAddress({
+      address: RECEIVER_ADDRESS,
+      assets: Assets.fromLovelace(3_000_000n)
+    })
 
-    const signBuilder = await builder.build({ useStateMachine: true, useV3: true })
+    const signBuilder = await builder.build({
+      useStateMachine: true,
+      useV3: true,
+      changeAddress: CHANGE_ADDRESS,
+      availableUtxos: [utxo1, utxo2],
+      protocolParameters: PROTOCOL_PARAMS
+    })
     const tx = await signBuilder.toTransaction()
 
     // Should successfully build
@@ -830,4 +914,4 @@ describe("TxBuilder Reselection After Change", () => {
     expect(changeOutput.amount.coin).toBeGreaterThan(0n)
     expect(changeOutput.amount.coin).toBeLessThan(1_000_000n) // Reasonable change amount
   })
-})
\ No newline at end of file
+})
diff --git a/packages/evolution/test/TxBuilder.UnfrackChangeHandling.test.ts b/packages/evolution/test/TxBuilder.UnfrackChangeHandling.test.ts
index 791478fa..1a05c7f9 100644
--- a/packages/evolution/test/TxBuilder.UnfrackChangeHandling.test.ts
+++ b/packages/evolution/test/TxBuilder.UnfrackChangeHandling.test.ts
@@ -58,9 +58,6 @@ describe("TxBuilder: Unfrack Change Handling Integration", () => {
       ]
 
       const builder = makeTxBuilder({
-        protocolParameters: PROTOCOL_PARAMS,
-        changeAddress: CHANGE_ADDRESS,
-        availableUtxos: additionalUtxos // Available for re-selection
       })
         .collectFrom({ inputs: [initialUtxo] })
         .payToAddress({
@@ -69,8 +66,11 @@ describe("TxBuilder: Unfrack Change Handling Integration", () => {
         })
 
       const signBuilder = await builder.build({
+        changeAddress: CHANGE_ADDRESS,
+        availableUtxos: additionalUtxos, // Available for re-selection
         useV3: true,
         useStateMachine: true,
+        protocolParameters: PROTOCOL_PARAMS,
         unfrack: {
           ada: {
             subdivideThreshold: 500_000n,
@@ -135,9 +135,6 @@ describe("TxBuilder: Unfrack Change Handling Integration", () => {
       ]
 
       const builder = makeTxBuilder({
-        protocolParameters: PROTOCOL_PARAMS,
-        changeAddress: CHANGE_ADDRESS,
-        availableUtxos: tinyUtxos // Available but won't be used
       })
         .collectFrom({ inputs: [initialUtxo] })
         .payToAddress({
@@ -146,8 +143,11 @@ describe("TxBuilder: Unfrack Change Handling Integration", () => {
         })
 
       const signBuilder = await builder.build({
+        changeAddress: CHANGE_ADDRESS,
+        availableUtxos: tinyUtxos, // Available but won't be used
         useV3: true,
         useStateMachine: true,
+        protocolParameters: PROTOCOL_PARAMS,
         unfrack: {
           ada: {
             subdivideThreshold: 500_000n,
@@ -198,9 +198,6 @@ describe("TxBuilder: Unfrack Change Handling Integration", () => {
       }
 
       const builder = makeTxBuilder({
-        protocolParameters: PROTOCOL_PARAMS,
-        changeAddress: CHANGE_ADDRESS,
-        availableUtxos: [] // No more UTxOs available
       })
         .collectFrom({ inputs: [initialUtxo] })
         .payToAddress({
@@ -211,8 +208,11 @@ describe("TxBuilder: Unfrack Change Handling Integration", () => {
       // Expect build to throw error
       await expect(async () => {
         await builder.build({
+          changeAddress: CHANGE_ADDRESS,
+          availableUtxos: [], // No more UTxOs available
           useV3: true,
           useStateMachine: true,
+          protocolParameters: PROTOCOL_PARAMS,
           unfrack: {
             ada: {
               subdivideThreshold: 500_000n,
@@ -239,9 +239,6 @@ describe("TxBuilder: Unfrack Change Handling Integration", () => {
       }
 
       const builder = makeTxBuilder({
-        protocolParameters: PROTOCOL_PARAMS,
-        changeAddress: CHANGE_ADDRESS,
-        availableUtxos: []
       })
         .collectFrom({ inputs: [initialUtxo] })
         .payToAddress({
@@ -250,8 +247,11 @@ describe("TxBuilder: Unfrack Change Handling Integration", () => {
         })
 
       const signBuilder = await builder.build({
+        changeAddress: CHANGE_ADDRESS,
+        availableUtxos: [],
         useV3: true,
         useStateMachine: true,
+        protocolParameters: PROTOCOL_PARAMS,
         unfrack: {
           ada: {
             subdivideThreshold: 500_000n,
@@ -282,9 +282,6 @@ describe("TxBuilder: Unfrack Change Handling Integration", () => {
       }
 
       const builder = makeTxBuilder({
-        protocolParameters: PROTOCOL_PARAMS,
-        changeAddress: CHANGE_ADDRESS,
-        availableUtxos: []
       })
         .collectFrom({ inputs: [initialUtxo] })
         .payToAddress({
@@ -293,8 +290,11 @@ describe("TxBuilder: Unfrack Change Handling Integration", () => {
         })
 
       const signBuilder = await builder.build({
+        changeAddress: CHANGE_ADDRESS,
+        availableUtxos: [],
         useV3: true,
         useStateMachine: true,
+        protocolParameters: PROTOCOL_PARAMS,
         unfrack: {
           ada: {
             subdivideThreshold: 500_000n,
@@ -322,9 +322,6 @@ describe("TxBuilder: Unfrack Change Handling Integration", () => {
       }
 
       const builder = makeTxBuilder({
-        protocolParameters: PROTOCOL_PARAMS,
-        changeAddress: CHANGE_ADDRESS,
-        availableUtxos: []
       })
         .collectFrom({ inputs: [initialUtxo] })
         .payToAddress({
@@ -333,9 +330,12 @@ describe("TxBuilder: Unfrack Change Handling Integration", () => {
         })
 
       const signBuilder = await builder.build({
+        changeAddress: CHANGE_ADDRESS,
+        availableUtxos: [],
         useV3: true,
         useStateMachine: true,
         drainTo: 0,
+        protocolParameters: PROTOCOL_PARAMS,
         unfrack: {
           ada: {
             subdivideThreshold: 500_000n,
@@ -364,9 +364,6 @@ describe("TxBuilder: Unfrack Change Handling Integration", () => {
       }
 
       const builder = makeTxBuilder({
-        protocolParameters: PROTOCOL_PARAMS,
-        changeAddress: CHANGE_ADDRESS,
-        availableUtxos: []
       })
         .collectFrom({ inputs: [initialUtxo] })
         .payToAddress({
@@ -375,9 +372,12 @@ describe("TxBuilder: Unfrack Change Handling Integration", () => {
         })
 
       const signBuilder = await builder.build({
+        changeAddress: CHANGE_ADDRESS,
+        availableUtxos: [],
         useV3: true,
         useStateMachine: true,
         onInsufficientChange: "burn",
+        protocolParameters: PROTOCOL_PARAMS,
         unfrack: {
           ada: {
             subdivideThreshold: 500_000n,
diff --git a/packages/evolution/test/TxBuilder.UnfrackDrain.test.ts b/packages/evolution/test/TxBuilder.UnfrackDrain.test.ts
index fe4b1e39..5c9fa292 100644
--- a/packages/evolution/test/TxBuilder.UnfrackDrain.test.ts
+++ b/packages/evolution/test/TxBuilder.UnfrackDrain.test.ts
@@ -123,9 +123,6 @@ const createSimpleAdaWallet = (): Array<UTxO.UTxO> => [
 
 describe("TxBuilder Unfrack + DrainTo Integration", () => {
   const baseConfig: TxBuilderConfig = {
-    protocolParameters: PROTOCOL_PARAMS,
-    changeAddress: DESTINATION_ADDRESS,
-    availableUtxos: []
   }
 
   // ==========================================================================
@@ -138,7 +135,7 @@ describe("TxBuilder Unfrack + DrainTo Integration", () => {
       // Arrange: Simple ADA-only wallet
       const utxos = createSimpleAdaWallet()
 
-      const builder = makeTxBuilder({ ...baseConfig, availableUtxos: utxos })
+      const builder = makeTxBuilder(baseConfig)
         .payToAddress({
           address: DESTINATION_ADDRESS,
           assets: Assets.fromLovelace(1_000_000n) // 1 ADA minimum payment
@@ -146,8 +143,11 @@ describe("TxBuilder Unfrack + DrainTo Integration", () => {
 
       // Act: Drain to output 0 with ADA subdivision
       const signBuilder = await builder.build({
+        changeAddress: SOURCE_ADDRESS,
+        availableUtxos: utxos,
         useV3: true,
         drainTo: 0,
+        protocolParameters: PROTOCOL_PARAMS,
         unfrack: {
           ada: {
             subdivideThreshold: 100_000_000n, // 100 ADA
@@ -193,7 +193,7 @@ describe("TxBuilder Unfrack + DrainTo Integration", () => {
         }
       ]
 
-      const builder = makeTxBuilder({ ...baseConfig, availableUtxos: utxos })
+      const builder = makeTxBuilder(baseConfig)
         .payToAddress({
           address: DESTINATION_ADDRESS,
           assets: Assets.fromLovelace(1_000_000n)
@@ -201,8 +201,11 @@ describe("TxBuilder Unfrack + DrainTo Integration", () => {
 
       // Act: Drain with subdivision threshold of 100 ADA (total is 80 ADA, below threshold)
       const signBuilder = await builder.build({
+        changeAddress: SOURCE_ADDRESS,
+        availableUtxos: utxos,
         useV3: true,
         drainTo: 0,
+        protocolParameters: PROTOCOL_PARAMS,
         unfrack: {
           ada: {
             subdivideThreshold: 100_000_000n // 100 ADA threshold
@@ -247,8 +250,11 @@ describe("TxBuilder Unfrack + DrainTo Integration", () => {
 
       // Act: Drain with token bundling (no isolation or grouping)
       const signBuilder = await builder.build({
+        changeAddress: SOURCE_ADDRESS,
+        availableUtxos: utxos,
         useV3: true,
         drainTo: 0,
+        protocolParameters: PROTOCOL_PARAMS,
         unfrack: {
           tokens: {
             bundleSize: 5 // Bundle tokens in groups of 5
@@ -287,8 +293,11 @@ describe("TxBuilder Unfrack + DrainTo Integration", () => {
 
       // Act: Drain with fungible isolation
       const signBuilder = await builder.build({
+        changeAddress: SOURCE_ADDRESS,
+        availableUtxos: utxos,
         useV3: true,
         drainTo: 0,
+        protocolParameters: PROTOCOL_PARAMS,
         unfrack: {
           tokens: {
             bundleSize: 5,
@@ -328,8 +337,11 @@ describe("TxBuilder Unfrack + DrainTo Integration", () => {
 
       // Act: Drain with NFT policy grouping
       const signBuilder = await builder.build({
+        changeAddress: SOURCE_ADDRESS,
+        availableUtxos: utxos,
         useV3: true,
         drainTo: 0,
+        protocolParameters: PROTOCOL_PARAMS,
         unfrack: {
           tokens: {
             bundleSize: 5,
@@ -369,8 +381,11 @@ describe("TxBuilder Unfrack + DrainTo Integration", () => {
 
       // Act: Drain with full Unfrack.It optimization
       const signBuilder = await builder.build({
+        changeAddress: SOURCE_ADDRESS,
+        availableUtxos: utxos,
         useV3: true,
         drainTo: 0,
+        protocolParameters: PROTOCOL_PARAMS,
         unfrack: {
           tokens: {
             bundleSize: 5,
@@ -424,9 +439,12 @@ describe("TxBuilder Unfrack + DrainTo Integration", () => {
 
       // Act: Drain without any unfracking (standard consolidation)
       const signBuilder = await builder.build({
+        changeAddress: SOURCE_ADDRESS,
+        availableUtxos: utxos,
         useV3: true,
         drainTo: 0,
         // No unfrack options
+        protocolParameters: PROTOCOL_PARAMS,
         useStateMachine: true
       })
 
@@ -462,8 +480,11 @@ describe("TxBuilder Unfrack + DrainTo Integration", () => {
 
       // Act: Drain with empty token options (only ADA subdivision active)
       const signBuilder = await builder.build({
+        changeAddress: SOURCE_ADDRESS,
+        availableUtxos: utxos,
         useV3: true,
         drainTo: 0,
+        protocolParameters: PROTOCOL_PARAMS,
         unfrack: {
           tokens: {
             bundleSize: 10 // Default value, but no tokens present
@@ -515,8 +536,11 @@ describe("TxBuilder Unfrack + DrainTo Integration", () => {
 
       // Act: Drain with subdivision threshold much higher than leftover
       const signBuilder = await builder.build({
+        changeAddress: SOURCE_ADDRESS,
+        availableUtxos: utxos,
         useV3: true,
         drainTo: 0,
+        protocolParameters: PROTOCOL_PARAMS,
         unfrack: {
           ada: {
             subdivideThreshold: 100_000_000n // 100 ADA (leftover is ~5 ADA)
@@ -557,8 +581,11 @@ describe("TxBuilder Unfrack + DrainTo Integration", () => {
 
       // Act: Drain to first output with unfracking
       const signBuilder = await builder.build({
+        changeAddress: SOURCE_ADDRESS,
+        availableUtxos: utxos,
         useV3: true,
         drainTo: 0, // Drain into first payment output
+        protocolParameters: PROTOCOL_PARAMS,
         unfrack: {
           tokens: {
             bundleSize: 5
@@ -608,8 +635,11 @@ describe("TxBuilder Unfrack + DrainTo Integration", () => {
       // Subdividing by [25, 25, 25, 25] would create 4 outputs of ~0.46 ADA each
       // which is BELOW minimum UTxO requirement of ~1.72 ADA
       const signBuilder = await builder.build({
+        changeAddress: SOURCE_ADDRESS,
+        availableUtxos: utxos,
         useV3: true,
         drainTo: 0,
+        protocolParameters: PROTOCOL_PARAMS,
         unfrack: {
           ada: {
             subdivideThreshold: 500_000n, // 0.5 ADA (very low threshold)
@@ -655,8 +685,11 @@ describe("TxBuilder Unfrack + DrainTo Integration", () => {
 
       // Act: Full wallet optimization
       const signBuilder = await builder.build({
+        changeAddress: SOURCE_ADDRESS,
+        availableUtxos: utxos,
         useV3: true,
         drainTo: 0,
+        protocolParameters: PROTOCOL_PARAMS,
         unfrack: {
           tokens: {
             bundleSize: 10, // Larger bundles for efficiency
@@ -701,8 +734,11 @@ describe("TxBuilder Unfrack + DrainTo Integration", () => {
 
       // Act: Migrate everything to destination with optimization
       const signBuilder = await builder.build({
+        changeAddress: SOURCE_ADDRESS,
+        availableUtxos: utxos,
         useV3: true,
         drainTo: 0,
+        protocolParameters: PROTOCOL_PARAMS,
         unfrack: {
           tokens: {
             bundleSize: 5,
diff --git a/packages/evolution/test/TxBuilder.UnfrackMinUTxO.test.ts b/packages/evolution/test/TxBuilder.UnfrackMinUTxO.test.ts
index 09b330cc..40f524c4 100644
--- a/packages/evolution/test/TxBuilder.UnfrackMinUTxO.test.ts
+++ b/packages/evolution/test/TxBuilder.UnfrackMinUTxO.test.ts
@@ -48,9 +48,6 @@ const ASSET_NAME_HEX = "544f4b454e" // "TOKEN" in hex
 
 describe.concurrent("TxBuilder - Unfrack MinUTxO", () => {
   const baseConfig: TxBuilderConfig = {
-    protocolParameters: PROTOCOL_PARAMS,
-    changeAddress: CHANGE_ADDRESS,
-    availableUtxos: []
   }
 
   /**
@@ -82,18 +79,19 @@ describe.concurrent("TxBuilder - Unfrack MinUTxO", () => {
       }
     }
 
-    const builder = makeTxBuilder({
-      ...baseConfig,
-      availableUtxos: [utxo1, utxo2]
-    })
+    const builder = makeTxBuilder(baseConfig)
       .payToAddress({
         address: RECIPIENT_ADDRESS,
         assets: Assets.fromLovelace(2_000_000n) // 2.0 ADA only
       })
 
     // Act: Build transaction with unfrack enabled
-    const signBuilder = await builder.build({ useV3: true, 
+    const signBuilder = await builder.build({ 
+      changeAddress: CHANGE_ADDRESS,
+      availableUtxos: [utxo1, utxo2],
+      useV3: true, 
       useStateMachine: true,
+      protocolParameters: PROTOCOL_PARAMS,
       unfrack: {
         tokens: {
           bundleSize: 10 // All 5 tokens fit in one bundle
@@ -182,18 +180,19 @@ describe.concurrent("TxBuilder - Unfrack MinUTxO", () => {
       }
     }
 
-    const builder = makeTxBuilder({
-      ...baseConfig,
-      availableUtxos: [utxo1, utxo2, utxo3]
-    })
+    const builder = makeTxBuilder(baseConfig)
       .payToAddress({
         address: RECIPIENT_ADDRESS,
         assets: Assets.fromLovelace(2_000_000n)
       })
 
     // Act: Build transaction with unfrack (bundleSize=5 → 3 bundles for 15 tokens)
-    const signBuilder = await builder.build({ useV3: true, 
+    const signBuilder = await builder.build({ 
+      changeAddress: CHANGE_ADDRESS,
+      availableUtxos: [utxo1, utxo2, utxo3],
+      useV3: true, 
       useStateMachine: true,
+      protocolParameters: PROTOCOL_PARAMS,
       unfrack: {
         tokens: {
           bundleSize: 5 // 15 tokens → 3 bundles
@@ -247,15 +246,19 @@ describe.concurrent("TxBuilder - Unfrack MinUTxO", () => {
       }
     }
 
-    const builder = makeTxBuilder({ ...baseConfig, availableUtxos: [utxo] })
+    const builder = makeTxBuilder(baseConfig)
       .payToAddress({
         address: RECIPIENT_ADDRESS,
         assets: Assets.fromLovelace(2_000_000n)
       })
 
     // Build with drainTo option
-    const signBuilder = await builder.build({ useV3: true, 
+    const signBuilder = await builder.build({ 
+      changeAddress: CHANGE_ADDRESS,
+      availableUtxos: [utxo],
+      useV3: true, 
       useStateMachine: true,
+      protocolParameters: PROTOCOL_PARAMS,
       drainTo: 0 // Request drain into first output
     })
     
@@ -291,7 +294,7 @@ describe.concurrent("TxBuilder - Unfrack MinUTxO", () => {
       }
     }
 
-    const builder = makeTxBuilder({ ...baseConfig, availableUtxos: [utxo] })
+    const builder = makeTxBuilder(baseConfig)
       .payToAddress({
         address: RECIPIENT_ADDRESS,
         assets: Assets.fromLovelace(2_000_000n)
@@ -299,8 +302,12 @@ describe.concurrent("TxBuilder - Unfrack MinUTxO", () => {
 
     // Try with burnAsFee - should fail because of native assets
     await expect(
-      builder.build({ useV3: true, 
+      builder.build({ 
+        changeAddress: CHANGE_ADDRESS,
+        availableUtxos: [utxo],
+        useV3: true, 
         useStateMachine: true,
+        protocolParameters: PROTOCOL_PARAMS,
         onInsufficientChange: "burn"
       })
     ).rejects.toThrow() // Should error about native assets
diff --git a/packages/evolution/test/WalletFromSeed.test.ts b/packages/evolution/test/WalletFromSeed.test.ts
index 06bb4a12..ceb65a3a 100644
--- a/packages/evolution/test/WalletFromSeed.test.ts
+++ b/packages/evolution/test/WalletFromSeed.test.ts
@@ -1,117 +1,99 @@
-import { Either } from "effect"
-import { expect, test } from "vitest"
+import { describe, expect, it } from "@effect/vitest"
+import { Effect } from "effect"
 
 import { walletFromSeed } from "../src/sdk/wallet/Derivation.js"
 
 const seedPhrase =
   "zebra short room flavor rival capital fortune hip profit trust melody office depend adapt visa cycle february link tornado whisper physical kiwi film voyage"
 
-test("WalletFromSeed - Defaults options", () => {
-  const expectedFromSeed = {
-    address: "addr1q98wl3hnya9l94rt58ky533deyqe9t8zz5n9su26k8e5g23yar4q0adtaax9q9g0kphpv2ws7vxqwu6ln6pqx7j29nfqsfy9mg",
-    rewardAddress: "stake1uyjw36s87k477nzsz58mqmsk98g0xrq8wd0eaqsr0f9ze5s48wtl9",
-    paymentKey:
-      "ed25519e_sk1krszcw3ujfs3qnsjwl6wynw7dwudgnq69w9lrrtdf46yqnd25dgv4f5ttaqxr2v6n6azee489c7mryudvhu8n4x4tcvd5hvhtwswsuc4s4c2d",
-    stakeKey:
-      "ed25519e_sk19q4d6fguvncszk6f46fvvep5y5w3877y77t3n3dc446wgja25dg968hm8jxkc9d7p982uls6k8uq0srs69e44lay43hxmdx4nc3rttsn0h2f5"
-  }
-  const result1 = walletFromSeed(seedPhrase, {
-    addressType: "Base",
-    accountIndex: 0,
-    network: "Mainnet"
-  })
-  expect(Either.isRight(result1)).toBe(true)
-  if (Either.isRight(result1)) {
-    expect(expectedFromSeed).toStrictEqual(result1.right)
-  }
+describe("WalletFromSeed", () => {
+  it.effect("Defaults options", () =>
+    Effect.gen(function* () {
+      const result1 = yield* walletFromSeed(seedPhrase, {
+        addressType: "Base",
+        accountIndex: 0,
+        network: "Mainnet"
+      })
+      
+      expect(result1.address).toBe("addr1q98wl3hnya9l94rt58ky533deyqe9t8zz5n9su26k8e5g23yar4q0adtaax9q9g0kphpv2ws7vxqwu6ln6pqx7j29nfqsfy9mg")
+      expect(result1.rewardAddress).toBe("stake1uyjw36s87k477nzsz58mqmsk98g0xrq8wd0eaqsr0f9ze5s48wtl9")
+      expect(result1.paymentKey).toBe("ed25519e_sk1krszcw3ujfs3qnsjwl6wynw7dwudgnq69w9lrrtdf46yqnd25dgv4f5ttaqxr2v6n6azee489c7mryudvhu8n4x4tcvd5hvhtwswsuc4s4c2d")
+      expect(result1.stakeKey).toBe("ed25519e_sk19q4d6fguvncszk6f46fvvep5y5w3877y77t3n3dc446wgja25dg968hm8jxkc9d7p982uls6k8uq0srs69e44lay43hxmdx4nc3rttsn0h2f5")
 
-  const result2 = walletFromSeed(seedPhrase)
-  expect(Either.isRight(result2)).toBe(true)
-  if (Either.isRight(result2)) {
-    expect(expectedFromSeed).toStrictEqual(result2.right)
-  }
-})
+      const result2 = yield* walletFromSeed(seedPhrase)
+      expect(result2.address).toBe(result1.address)
+      expect(result2.rewardAddress).toBe(result1.rewardAddress)
+      expect(result2.paymentKey).toBe(result1.paymentKey)
+      expect(result2.stakeKey).toBe(result1.stakeKey)
+    })
+  )
 
-test("WalletFromSeed - accountIndex 1", () => {
-  const expectedFromSeed = {
-    address: "addr1q8833yrnksyq3v3u582g8pkzzdmg9yge7lftvu8lj6lakmp7e5x8vl3sqdtxra9z9p95k27kx2njgqux86d5mtfc2t8sa7jy78",
-    rewardAddress: "stake1uylv6rrk0ccqx4np7j3zsj6t90tr9feyqwrrax6d45u99nce2rkhr",
-    paymentKey:
-      "ed25519e_sk1tzqvdwc8kr9zk4fmlwhexzpgcgx8t35zls2ckeswehpdsja25dg9j998sp9s2xy0aeyrdquhpljwfgghz9e78wqux8xj9t2p8z59ahc75nyyr",
-    stakeKey:
-      "ed25519e_sk1trauywg7p9x2hg3jgaw2adeyg5ujhax4jfd6exs6hpzakn925dggyvhgrh8kwc9h9n7nh75nwhge9gyxg7vavcwk7mq3r2t03664drcrdegzx"
-  }
-  const result1 = walletFromSeed(seedPhrase, {
-    addressType: "Base",
-    accountIndex: 1,
-    network: "Mainnet"
-  })
-  expect(Either.isRight(result1)).toBe(true)
-  if (Either.isRight(result1)) {
-    expect(expectedFromSeed).toStrictEqual(result1.right)
-  }
+  it.effect("accountIndex 1", () =>
+    Effect.gen(function* () {
+      const result1 = yield* walletFromSeed(seedPhrase, {
+        addressType: "Base",
+        accountIndex: 1,
+        network: "Mainnet"
+      })
+      
+      expect(result1.address).toBe("addr1q8833yrnksyq3v3u582g8pkzzdmg9yge7lftvu8lj6lakmp7e5x8vl3sqdtxra9z9p95k27kx2njgqux86d5mtfc2t8sa7jy78")
+      expect(result1.rewardAddress).toBe("stake1uylv6rrk0ccqx4np7j3zsj6t90tr9feyqwrrax6d45u99nce2rkhr")
+      expect(result1.paymentKey).toBe("ed25519e_sk1tzqvdwc8kr9zk4fmlwhexzpgcgx8t35zls2ckeswehpdsja25dg9j998sp9s2xy0aeyrdquhpljwfgghz9e78wqux8xj9t2p8z59ahc75nyyr")
+      expect(result1.stakeKey).toBe("ed25519e_sk1trauywg7p9x2hg3jgaw2adeyg5ujhax4jfd6exs6hpzakn925dggyvhgrh8kwc9h9n7nh75nwhge9gyxg7vavcwk7mq3r2t03664drcrdegzx")
 
-  const result2 = walletFromSeed(seedPhrase, {
-    accountIndex: 1
-  })
-  expect(Either.isRight(result2)).toBe(true)
-  if (Either.isRight(result2)) {
-    expect(expectedFromSeed).toStrictEqual(result2.right)
-  }
-})
+      const result2 = yield* walletFromSeed(seedPhrase, {
+        accountIndex: 1
+      })
+      expect(result2.address).toBe(result1.address)
+      expect(result2.rewardAddress).toBe(result1.rewardAddress)
+      expect(result2.paymentKey).toBe(result1.paymentKey)
+      expect(result2.stakeKey).toBe(result1.stakeKey)
+    })
+  )
 
-test("WalletFromSeed - Custom Network", () => {
-  const expectedFromSeed = {
-    address:
-      "addr_test1qp8wl3hnya9l94rt58ky533deyqe9t8zz5n9su26k8e5g23yar4q0adtaax9q9g0kphpv2ws7vxqwu6ln6pqx7j29nfqnle9hh",
-    rewardAddress: "stake_test1uqjw36s87k477nzsz58mqmsk98g0xrq8wd0eaqsr0f9ze5sjdyfmc",
-    paymentKey:
-      "ed25519e_sk1krszcw3ujfs3qnsjwl6wynw7dwudgnq69w9lrrtdf46yqnd25dgv4f5ttaqxr2v6n6azee489c7mryudvhu8n4x4tcvd5hvhtwswsuc4s4c2d",
-    stakeKey:
-      "ed25519e_sk19q4d6fguvncszk6f46fvvep5y5w3877y77t3n3dc446wgja25dg968hm8jxkc9d7p982uls6k8uq0srs69e44lay43hxmdx4nc3rttsn0h2f5"
-  }
-  const result1 = walletFromSeed(seedPhrase, {
-    addressType: "Base",
-    accountIndex: 0,
-    network: "Custom"
-  })
-  expect(Either.isRight(result1)).toBe(true)
-  if (Either.isRight(result1)) {
-    expect(expectedFromSeed).toStrictEqual(result1.right)
-  }
+  it.effect("Custom Network", () =>
+    Effect.gen(function* () {
+      const result1 = yield* walletFromSeed(seedPhrase, {
+        addressType: "Base",
+        accountIndex: 0,
+        network: "Custom"
+      })
+      
+      expect(result1.address).toBe("addr_test1qp8wl3hnya9l94rt58ky533deyqe9t8zz5n9su26k8e5g23yar4q0adtaax9q9g0kphpv2ws7vxqwu6ln6pqx7j29nfqnle9hh")
+      expect(result1.rewardAddress).toBe("stake_test1uqjw36s87k477nzsz58mqmsk98g0xrq8wd0eaqsr0f9ze5sjdyfmc")
+      expect(result1.paymentKey).toBe("ed25519e_sk1krszcw3ujfs3qnsjwl6wynw7dwudgnq69w9lrrtdf46yqnd25dgv4f5ttaqxr2v6n6azee489c7mryudvhu8n4x4tcvd5hvhtwswsuc4s4c2d")
+      expect(result1.stakeKey).toBe("ed25519e_sk19q4d6fguvncszk6f46fvvep5y5w3877y77t3n3dc446wgja25dg968hm8jxkc9d7p982uls6k8uq0srs69e44lay43hxmdx4nc3rttsn0h2f5")
 
-  const result2 = walletFromSeed(seedPhrase, {
-    network: "Custom"
-  })
-  expect(Either.isRight(result2)).toBe(true)
-  if (Either.isRight(result2)) {
-    expect(expectedFromSeed).toStrictEqual(result2.right)
-  }
-})
+      const result2 = yield* walletFromSeed(seedPhrase, {
+        network: "Custom"
+      })
+      expect(result2.address).toBe(result1.address)
+      expect(result2.rewardAddress).toBe(result1.rewardAddress)
+      expect(result2.paymentKey).toBe(result1.paymentKey)
+      expect(result2.stakeKey).toBe(result1.stakeKey)
+    })
+  )
 
-test("WalletFromSeed - Address Enterprise", () => {
-  const expectedFromSeed = {
-    address: "addr1v98wl3hnya9l94rt58ky533deyqe9t8zz5n9su26k8e5g2srcn4hd",
-    rewardAddress: undefined,
-    paymentKey:
-      "ed25519e_sk1krszcw3ujfs3qnsjwl6wynw7dwudgnq69w9lrrtdf46yqnd25dgv4f5ttaqxr2v6n6azee489c7mryudvhu8n4x4tcvd5hvhtwswsuc4s4c2d",
-    stakeKey: undefined
-  }
-  const result1 = walletFromSeed(seedPhrase, {
-    addressType: "Enterprise",
-    accountIndex: 0,
-    network: "Mainnet"
-  })
-  expect(Either.isRight(result1)).toBe(true)
-  if (Either.isRight(result1)) {
-    expect(expectedFromSeed).toStrictEqual(result1.right)
-  }
+  it.effect("Address Enterprise", () =>
+    Effect.gen(function* () {
+      const result1 = yield* walletFromSeed(seedPhrase, {
+        addressType: "Enterprise",
+        accountIndex: 0,
+        network: "Mainnet"
+      })
+      
+      expect(result1.address).toBe("addr1v98wl3hnya9l94rt58ky533deyqe9t8zz5n9su26k8e5g2srcn4hd")
+      expect(result1.rewardAddress).toBeUndefined()
+      expect(result1.paymentKey).toBe("ed25519e_sk1krszcw3ujfs3qnsjwl6wynw7dwudgnq69w9lrrtdf46yqnd25dgv4f5ttaqxr2v6n6azee489c7mryudvhu8n4x4tcvd5hvhtwswsuc4s4c2d")
+      expect(result1.stakeKey).toBeUndefined()
 
-  const result2 = walletFromSeed(seedPhrase, {
-    addressType: "Enterprise"
-  })
-  expect(Either.isRight(result2)).toBe(true)
-  if (Either.isRight(result2)) {
-    expect(expectedFromSeed).toStrictEqual(result2.right)
-  }
+      const result2 = yield* walletFromSeed(seedPhrase, {
+        addressType: "Enterprise"
+      })
+      expect(result2.address).toBe(result1.address)
+      expect(result2.rewardAddress).toBeUndefined()
+      expect(result2.paymentKey).toBe(result1.paymentKey)
+      expect(result2.stakeKey).toBeUndefined()
+    })
+  )
 })
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 9f759910..5e8cf610 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -156,6 +156,9 @@ importers:
       '@effect/platform-node':
         specifier: ^0.96.0
         version: 0.96.0(@effect/cluster@0.48.2(@effect/platform@0.90.6(effect@3.17.9))(@effect/rpc@0.69.1(@effect/platform@0.90.6(effect@3.17.9))(effect@3.17.9))(@effect/sql@0.44.2(@effect/experimental@0.54.6(@effect/platform@0.90.6(effect@3.17.9))(effect@3.17.9))(@effect/platform@0.90.6(effect@3.17.9))(effect@3.17.9))(@effect/workflow@0.9.2(@effect/platform@0.90.6(effect@3.17.9))(@effect/rpc@0.69.1(@effect/platform@0.90.6(effect@3.17.9))(effect@3.17.9))(effect@3.17.9))(effect@3.17.9))(@effect/platform@0.90.6(effect@3.17.9))(@effect/rpc@0.69.1(@effect/platform@0.90.6(effect@3.17.9))(effect@3.17.9))(@effect/sql@0.44.2(@effect/experimental@0.54.6(@effect/platform@0.90.6(effect@3.17.9))(effect@3.17.9))(@effect/platform@0.90.6(effect@3.17.9))(effect@3.17.9))(effect@3.17.9)
+      '@noble/curves':
+        specifier: ^2.0.1
+        version: 2.0.1
       '@noble/hashes':
         specifier: ^1.8.0
         version: 1.8.0
@@ -180,9 +183,6 @@ importers:
       effect:
         specifier: ^3.17.9
         version: 3.17.9
-      libsodium-wrappers-sumo:
-        specifier: ^0.7.15
-        version: 0.7.15
     devDependencies:
       '@dcspark/cardano-multiplatform-lib-nodejs':
         specifier: ^6.2.0
@@ -190,9 +190,6 @@ importers:
       '@types/dockerode':
         specifier: ^3.3.43
         version: 3.3.43
-      '@types/libsodium-wrappers-sumo':
-        specifier: ^0.7.8
-        version: 0.7.8
       tinybench:
         specifier: ^5.0.0
         version: 5.0.0
@@ -1003,10 +1000,18 @@ packages:
     resolution: {integrity: sha512-gbKGcRUYIjA3/zCCNaWDciTMFI0dCkvou3TL8Zmy5Nc7sJ47a0jtOeZoTaMxkuqRo9cRhjOdZJXegxYE5FN/xw==}
     engines: {node: ^14.21.3 || >=16}
 
+  '@noble/curves@2.0.1':
+    resolution: {integrity: sha512-vs1Az2OOTBiP4q0pwjW5aF0xp9n4MxVrmkFBxc6EKZc6ddYx5gaZiAsZoq0uRRXWbi3AT/sBqn05eRPtn1JCPw==}
+    engines: {node: '>= 20.19.0'}
+
   '@noble/hashes@1.8.0':
     resolution: {integrity: sha512-jCs9ldd7NwzpgXDIf6P3+NrHh9/sD6CQdxHyjQI+h/6rDNo88ypBxxz45UDuZHz9r3tNz7N/VInSVoVdtXEI4A==}
     engines: {node: ^14.21.3 || >=16}
 
+  '@noble/hashes@2.0.1':
+    resolution: {integrity: sha512-XlOlEbQcE9fmuXxrVTXCTlG2nlRXa9Rj3rr5Ue/+tX+nmkgbX720YHh0VR3hBF9xDvwnb8D2shVGOwNx+ulArw==}
+    engines: {node: '>= 20.19.0'}
+
   '@nodelib/fs.scandir@2.1.5':
     resolution: {integrity: sha512-vq24Bq3ym5HEQm2NKCr3yXDwjc7vTsEThRDnkp2DK9p1uqLR+DHurm/NOTo0KG7HYHU7eppKZj3MyqYuMBf62g==}
     engines: {node: '>= 8'}
@@ -1810,12 +1815,6 @@ packages:
   '@types/json5@0.0.29':
     resolution: {integrity: sha512-dRLjCWHYg4oaA77cxO64oO+7JwCwnIzkZPdrrC71jQmQtlhM556pwKo5bUzqvZndkVbeFLIIi+9TC40JNF5hNQ==}
 
-  '@types/libsodium-wrappers-sumo@0.7.8':
-    resolution: {integrity: sha512-N2+df4MB/A+W0RAcTw7A5oxKgzD+Vh6Ye7lfjWIi5SdTzVLfHPzxUjhwPqHLO5Ev9fv/+VHl+sUaUuTg4fUPqw==}
-
-  '@types/libsodium-wrappers@0.7.14':
-    resolution: {integrity: sha512-5Kv68fXuXK0iDuUir1WPGw2R9fOZUlYlSAa0ztMcL0s0BfIDTqg9GXz8K30VJpPP3sxWhbolnQma2x+/TfkzDQ==}
-
   '@types/mdast@4.0.4':
     resolution: {integrity: sha512-kGaNbPh1k7AFzgpud/gMdvIm5xuECykRR+JnWKQno9TAXVa6WIVCGTPvYGekIDL4uwCZQSYbUxNBSb1aUo79oA==}
 
@@ -3669,12 +3668,6 @@ packages:
     resolution: {integrity: sha512-+bT2uH4E5LGE7h/n3evcS/sQlJXCpIp6ym8OWJ5eV6+67Dsql/LaaT7qJBAt2rzfoa/5QBGBhxDix1dMt2kQKQ==}
     engines: {node: '>= 0.8.0'}
 
-  libsodium-sumo@0.7.15:
-    resolution: {integrity: sha512-5tPmqPmq8T8Nikpm1Nqj0hBHvsLFCXvdhBFV7SGOitQPZAA6jso8XoL0r4L7vmfKXr486fiQInvErHtEvizFMw==}
-
-  libsodium-wrappers-sumo@0.7.15:
-    resolution: {integrity: sha512-aSWY8wKDZh5TC7rMvEdTHoyppVq/1dTSAeAR7H6pzd6QRT3vQWcT5pGwCotLcpPEOLXX6VvqihSPkpEhYAjANA==}
-
   lightningcss-darwin-arm64@1.30.1:
     resolution: {integrity: sha512-c8JK7hyE65X1MHMN+Viq9n11RRC7hgin3HhYKhrMyaXflk5GVplZ60IxyoVtzILeKr+xAJwg6zK6sjTBJ0FKYQ==}
     engines: {node: '>= 12.0.0'}
@@ -6322,8 +6315,14 @@ snapshots:
     dependencies:
       '@noble/hashes': 1.8.0
 
+  '@noble/curves@2.0.1':
+    dependencies:
+      '@noble/hashes': 2.0.1
+
   '@noble/hashes@1.8.0': {}
 
+  '@noble/hashes@2.0.1': {}
+
   '@nodelib/fs.scandir@2.1.5':
     dependencies:
       '@nodelib/fs.stat': 2.0.5
@@ -7088,12 +7087,6 @@ snapshots:
 
   '@types/json5@0.0.29': {}
 
-  '@types/libsodium-wrappers-sumo@0.7.8':
-    dependencies:
-      '@types/libsodium-wrappers': 0.7.14
-
-  '@types/libsodium-wrappers@0.7.14': {}
-
   '@types/mdast@4.0.4':
     dependencies:
       '@types/unist': 3.0.3
@@ -9261,12 +9254,6 @@ snapshots:
       prelude-ls: 1.2.1
       type-check: 0.4.0
 
-  libsodium-sumo@0.7.15: {}
-
-  libsodium-wrappers-sumo@0.7.15:
-    dependencies:
-      libsodium-sumo: 0.7.15
-
   lightningcss-darwin-arm64@1.30.1:
     optional: true