feat: implement StateTransitionJsonConvert and fix PlatformAddress map key serialization

packages/rs-dpp/Cargo.toml

@@ -147,6 +147,7 @@ dash-sdk-features = [
   "data-contract-json-conversion",
   "identity-value-conversion",
   "state-transition-value-conversion",
+  "state-transition-json-conversion",
   "state-transition-signing",
   "client",
   "platform-value-cbor",

packages/rs-dpp/src/address_funds/mod.rs

@@ -1,5 +1,7 @@
 pub mod fee_strategy;
 mod platform_address;
+#[cfg(feature = "state-transition-serde-conversion")]
+pub mod platform_address_map_serde;
 mod witness;
 mod witness_verification_operations;
 

packages/rs-dpp/src/address_funds/platform_address_map_serde.rs

@@ -0,0 +1,58 @@
+/// Custom serde serialization for BTreeMap<PlatformAddress, V>
+/// Converts PlatformAddress keys to strings using Display when serializing to JSON
+use crate::address_funds::PlatformAddress;
+use serde::de::{MapAccess, Visitor};
+use serde::ser::SerializeMap;
+use serde::{Deserialize, Deserializer, Serialize, Serializer};
+use std::collections::BTreeMap;
+use std::fmt;
+use std::marker::PhantomData;
+use std::str::FromStr;
+
+pub fn serialize<S, V>(map: &BTreeMap<PlatformAddress, V>, serializer: S) -> Result<S::Ok, S::Error>
+where
+    S: Serializer,
+    V: Serialize,
+{
+    let mut ser_map = serializer.serialize_map(Some(map.len()))?;
+    for (k, v) in map {
+        // Convert PlatformAddress to string using Display
+        ser_map.serialize_entry(&k.to_string(), v)?;
+    }
+    ser_map.end()
+}
+
+pub fn deserialize<'de, D, V>(deserializer: D) -> Result<BTreeMap<PlatformAddress, V>, D::Error>
+where
+    D: Deserializer<'de>,
+    V: Deserialize<'de>,
+{
+    struct MapVisitor<V> {
+        marker: PhantomData<V>,
+    }
+
+    impl<'de, V: Deserialize<'de>> Visitor<'de> for MapVisitor<V> {
+        type Value = BTreeMap<PlatformAddress, V>;
+
+        fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+            formatter.write_str("a map with PlatformAddress keys")
+        }
+
+        fn visit_map<A>(self, mut map: A) -> Result<Self::Value, A::Error>
+        where
+            A: MapAccess<'de>,
+        {
+            let mut result = BTreeMap::new();
+            while let Some((key_str, value)) = map.next_entry::<String, V>()? {
+                let key = PlatformAddress::from_str(&key_str)
+                    .map_err(|e| serde::de::Error::custom(format!("{}", e)))?;
+                result.insert(key, value);
+            }
+            Ok(result)
+        }
+    }
+
+    deserializer.deserialize_map(MapVisitor {
+        marker: PhantomData,
+    })
+}

packages/rs-dpp/src/state_transition/json_conversion.rs

@@ -0,0 +1,31 @@
+use crate::state_transition::{
+    JsonStateTransitionSerializationOptions, StateTransition, StateTransitionJsonConvert,
+};
+use crate::ProtocolError;
+use serde_json::Value as JsonValue;
+
+#[cfg(feature = "state-transition-json-conversion")]
+impl StateTransitionJsonConvert<'_> for StateTransition {
+    fn to_json(
+        &self,
+        options: JsonStateTransitionSerializationOptions,
+    ) -> Result<JsonValue, ProtocolError> {
+        match self {
+            StateTransition::DataContractCreate(st) => st.to_json(options),
+            StateTransition::DataContractUpdate(st) => st.to_json(options),
+            StateTransition::Batch(st) => st.to_json(options),
+            StateTransition::IdentityCreate(st) => st.to_json(options),
+            StateTransition::IdentityTopUp(st) => st.to_json(options),
+            StateTransition::IdentityCreditWithdrawal(st) => st.to_json(options),
+            StateTransition::IdentityUpdate(st) => st.to_json(options),
+            StateTransition::IdentityCreditTransfer(st) => st.to_json(options),
+            StateTransition::MasternodeVote(st) => st.to_json(options),
+            StateTransition::IdentityCreditTransferToAddresses(st) => st.to_json(options),
+            StateTransition::IdentityCreateFromAddresses(st) => st.to_json(options),
+            StateTransition::IdentityTopUpFromAddresses(st) => st.to_json(options),
+            StateTransition::AddressFundsTransfer(st) => st.to_json(options),
+            StateTransition::AddressFundingFromAssetLock(st) => st.to_json(options),
+            StateTransition::AddressCreditWithdrawal(st) => st.to_json(options),
+        }
+    }
+}

packages/rs-dpp/src/state_transition/mod.rs

@@ -38,10 +38,16 @@ pub mod errors;
 use crate::util::hash::ripemd160_sha256;
 use crate::util::hash::{hash_double_to_vec, hash_single};
 
+#[cfg(feature = "state-transition-json-conversion")]
+mod json_conversion;
 pub mod proof_result;
 mod serialization;
 pub mod state_transitions;
+#[cfg(test)]
+mod test_json_serde_integration;
 mod traits;
+#[cfg(feature = "state-transition-value-conversion")]
+mod value_conversion;
 
 // pub mod state_transition_fee;
 
@@ -383,6 +389,26 @@ impl OptionallyAssetLockProved for StateTransition {
     }
 }
 
+impl StateTransitionFieldTypes for StateTransition {
+    fn signature_property_paths() -> Vec<&'static str> {
+        // The top-level enum doesn't have fixed signature paths
+        // Each variant has its own specific paths
+        vec![]
+    }
+
+    fn identifiers_property_paths() -> Vec<&'static str> {
+        // The top-level enum doesn't have fixed identifier paths
+        // Each variant has its own specific paths
+        vec![]
+    }
+
+    fn binary_property_paths() -> Vec<&'static str> {
+        // The top-level enum doesn't have fixed binary paths
+        // Each variant has its own specific paths
+        vec![]
+    }
+}
+
 /// The state transition signing options
 #[derive(Debug, Clone, Copy, Default, Eq, PartialEq)]
 pub struct StateTransitionSigningOptions {

packages/rs-dpp/src/state_transition/state_transitions/address_funds/address_credit_withdrawal_transition/v0/mod.rs

@@ -27,6 +27,10 @@ use crate::{identity::core_script::CoreScript, withdrawal::Pooling, ProtocolErro
 )]
 #[derive(Default)]
 pub struct AddressCreditWithdrawalTransitionV0 {
+    #[cfg_attr(
+        feature = "state-transition-serde-conversion",
+        serde(with = "crate::address_funds::platform_address_map_serde")
+    )]
     pub inputs: BTreeMap<PlatformAddress, (AddressNonce, Credits)>,
     /// Optional output for change
     pub output: Option<(PlatformAddress, Credits)>,

packages/rs-dpp/src/state_transition/state_transitions/address_funds/address_funding_from_asset_lock_transition/v0/mod.rs

@@ -44,12 +44,20 @@ mod property_names {
 pub struct AddressFundingFromAssetLockTransitionV0 {
     pub asset_lock_proof: AssetLockProof,
     /// Inputs from existing platform addresses (optional, for combining funds)
+    #[cfg_attr(
+        feature = "state-transition-serde-conversion",
+        serde(with = "crate::address_funds::platform_address_map_serde")
+    )]
     pub inputs: BTreeMap<PlatformAddress, (AddressNonce, Credits)>,
     /// Outputs to fund platform addresses.
     /// - `Some(credits)` = explicit amount to send to this address
     /// - `None` = this address receives everything remaining after explicit outputs and fees
     ///   Exactly one output must be `None` to receive the remainder
     ///   (ensures full asset lock consumption).
+    #[cfg_attr(
+        feature = "state-transition-serde-conversion",
+        serde(with = "crate::address_funds::platform_address_map_serde")
+    )]
     pub outputs: BTreeMap<PlatformAddress, Option<Credits>>,
     pub fee_strategy: AddressFundsFeeStrategy,
     pub user_fee_increase: UserFeeIncrease,

packages/rs-dpp/src/state_transition/state_transitions/address_funds/address_funds_transfer_transition/v0/mod.rs

@@ -37,7 +37,15 @@ use serde::{Deserialize, Serialize};
 #[platform_serialize(unversioned)]
 #[derive(Default)]
 pub struct AddressFundsTransferTransitionV0 {
+    #[cfg_attr(
+        feature = "state-transition-serde-conversion",
+        serde(with = "crate::address_funds::platform_address_map_serde")
+    )]
     pub inputs: BTreeMap<PlatformAddress, (AddressNonce, Credits)>,
+    #[cfg_attr(
+        feature = "state-transition-serde-conversion",
+        serde(with = "crate::address_funds::platform_address_map_serde")
+    )]
     pub outputs: BTreeMap<PlatformAddress, Credits>,
     pub fee_strategy: AddressFundsFeeStrategy,
     pub user_fee_increase: UserFeeIncrease,

packages/rs-dpp/src/state_transition/state_transitions/identity/identity_create_from_addresses_transition/v0/mod.rs

@@ -39,6 +39,10 @@ pub struct IdentityCreateFromAddressesTransitionV0 {
     // When signing, we don't sign the signatures for keys
     #[platform_signable(into = "Vec<IdentityPublicKeyInCreationSignable>")]
     pub public_keys: Vec<IdentityPublicKeyInCreation>,
+    #[cfg_attr(
+        feature = "state-transition-serde-conversion",
+        serde(with = "crate::address_funds::platform_address_map_serde")
+    )]
     pub inputs: BTreeMap<PlatformAddress, (AddressNonce, Credits)>,
     /// Optional output to send remaining credits to an address
     pub output: Option<(PlatformAddress, Credits)>,
@@ -56,6 +60,10 @@ pub struct IdentityCreateFromAddressesTransitionV0 {
 struct IdentityCreateFromAddressesTransitionV0Inner {
     // Own ST fields
     public_keys: Vec<IdentityPublicKeyInCreation>,
+    #[cfg_attr(
+        feature = "state-transition-serde-conversion",
+        serde(with = "crate::address_funds::platform_address_map_serde")
+    )]
     inputs: BTreeMap<PlatformAddress, (AddressNonce, Credits)>,
     output: Option<(PlatformAddress, Credits)>,
     fee_strategy: AddressFundsFeeStrategy,

packages/rs-dpp/src/state_transition/state_transitions/identity/identity_credit_transfer_to_addresses_transition/v0/mod.rs

@@ -43,6 +43,10 @@ use serde::{Deserialize, Serialize};
 pub struct IdentityCreditTransferToAddressesTransitionV0 {
     // Own ST fields
     pub identity_id: Identifier,
+    #[cfg_attr(
+        feature = "state-transition-serde-conversion",
+        serde(with = "crate::address_funds::platform_address_map_serde")
+    )]
     pub recipient_addresses: BTreeMap<PlatformAddress, Credits>,
     pub nonce: IdentityNonce,
     pub user_fee_increase: UserFeeIncrease,

packages/rs-dpp/src/state_transition/state_transitions/identity/identity_topup_from_addresses_transition/v0/mod.rs

@@ -28,6 +28,10 @@ use crate::ProtocolError;
 )]
 #[derive(Default)]
 pub struct IdentityTopUpFromAddressesTransitionV0 {
+    #[cfg_attr(
+        feature = "state-transition-serde-conversion",
+        serde(with = "crate::address_funds::platform_address_map_serde")
+    )]
     pub inputs: BTreeMap<PlatformAddress, (AddressNonce, Credits)>,
     /// Optional output to send remaining credits to an address
     pub output: Option<(PlatformAddress, Credits)>,

packages/rs-dpp/src/state_transition/test_json_serde_integration.rs

@@ -0,0 +1,125 @@
+#[cfg(all(
+    test,
+    feature = "state-transition-serde-conversion",
+    feature = "state-transition-json-conversion"
+))]
+mod test_serde_json_serialization {
+    use crate::address_funds::PlatformAddress;
+    use crate::state_transition::address_funds_transfer_transition::v0::AddressFundsTransferTransitionV0;
+    use crate::state_transition::address_funds_transfer_transition::AddressFundsTransferTransition;
+    use crate::state_transition::{
+        JsonStateTransitionSerializationOptions, StateTransition, StateTransitionJsonConvert,
+    };
+    use std::collections::BTreeMap;
+
+    /// Recursively search a JSON value for a given key name.
+    fn find_key_recursive<'a>(
+        val: &'a serde_json::Value,
+        key: &str,
+    ) -> Option<&'a serde_json::Value> {
+        match val {
+            serde_json::Value::Object(map) => {
+                if let Some(v) = map.get(key) {
+                    return Some(v);
+                }
+                for v in map.values() {
+                    if let Some(found) = find_key_recursive(v, key) {
+                        return Some(found);
+                    }
+                }
+                None
+            }
+            serde_json::Value::Array(arr) => {
+                for v in arr {
+                    if let Some(found) = find_key_recursive(v, key) {
+                        return Some(found);
+                    }
+                }
+                None
+            }
+            _ => None,
+        }
+    }
+
+    /// Helper: build an AddressFundsTransfer StateTransition with known addresses.
+    fn make_address_funds_transfer() -> StateTransition {
+        let mut inputs = BTreeMap::new();
+        let input_address = PlatformAddress::P2pkh([1u8; 20]);
+        inputs.insert(input_address, (1u32, 1000u64));
+
+        let mut outputs = BTreeMap::new();
+        let output_address = PlatformAddress::P2pkh([2u8; 20]);
+        outputs.insert(output_address, 900u64);
+
+        let v0 = AddressFundsTransferTransitionV0 {
+            inputs,
+            outputs,
+            user_fee_increase: 0,
+            fee_strategy: Default::default(),
+            input_witnesses: vec![],
+        };
+
+        StateTransition::AddressFundsTransfer(AddressFundsTransferTransition::V0(v0))
+    }
+
+    /// Given an AddressFundsTransfer variant with BTreeMap<PlatformAddress, _> fields,
+    /// When calling to_json() on the inner variant directly,
+    /// Then serialization succeeds without "key must be a string" errors.
+    #[test]
+    fn variant_to_json_succeeds() {
+        let st = make_address_funds_transfer();
+        if let StateTransition::AddressFundsTransfer(ref inner) = st {
+            inner
+                .to_json(JsonStateTransitionSerializationOptions::default())
+                .expect("variant to_json should succeed");
+        }
+    }
+
+    /// Given an AddressFundsTransfer wrapped in the top-level StateTransition enum,
+    /// When calling to_json() on the enum and serde_json::to_string_pretty(),
+    /// Then both serialization paths succeed and PlatformAddress map keys are
+    ///   rendered as human-readable strings (e.g. "P2PKH(hex...)"), not complex objects.
+    #[test]
+    fn enum_to_json_succeeds_and_serde_roundtrips() {
+        let st = make_address_funds_transfer();
+
+        // StateTransition::to_json() must succeed (the whole point of the fix).
+        let json = st
+            .to_json(JsonStateTransitionSerializationOptions::default())
+            .expect("StateTransition::to_json should succeed");
+
+        // serde_json must also work now (custom map-key serializer).
+        let serde_json_str = serde_json::to_string_pretty(&st)
+            .expect("serde_json::to_string_pretty should succeed after custom serde fix");
+
+        // The to_json output must contain string keys for PlatformAddress maps.
+        let inputs = json.get("inputs").expect("JSON must have 'inputs' field");
+        assert!(
+            inputs.is_object(),
+            "inputs must be a JSON object (string keys)"
+        );
+        for key in inputs.as_object().unwrap().keys() {
+            assert!(
+                key.starts_with("P2PKH(") || key.starts_with("P2SH("),
+                "map key must be a PlatformAddress Display string, got: {key}"
+            );
+        }
+
+        // The serde output must also have string keys for PlatformAddress maps.
+        // The exact nesting depends on enum repr; find "inputs" anywhere in the tree.
+        let serde_val: serde_json::Value =
+            serde_json::from_str(&serde_json_str).expect("re-parse must succeed");
+        let inputs_field = find_key_recursive(&serde_val, "inputs")
+            .expect("serde JSON must contain an 'inputs' field somewhere");
+        assert!(
+            inputs_field.is_object(),
+            "serde inputs must be a JSON object with string keys"
+        );
+        for key in inputs_field.as_object().unwrap().keys() {
+            assert!(
+                key.starts_with("P2PKH(") || key.starts_with("P2SH("),
+                "serde map key must be a PlatformAddress Display string, got: {key}"
+            );
+        }
+    }
+}