Swap: quote through SwapPro (keyless, every venue at once)

CLAUDE.md

@@ -122,7 +122,7 @@ NEXT_PUBLIC_ZORA_API_KEY
 COINGECKO_API_KEY
 PINATA_JWT
 NEYNAR_API_KEY
-ZEROX_API_KEY        # 0x Swap API (server-only)
+# (ZEROX_API_KEY retired: /swap quotes through SwapPro, keyless — docs/integrations/swap.md)
 
 # Optional
 USDC_BASE

docs/integrations/swap.md

@@ -1,75 +1,114 @@
-# 0x Swap Integration
+# SwapPro Swap Integration
 
-The `/swap` page lets users trade ETH, WETH, USDC, GNARS, and a few other Base ERC-20s
-through the [0x Swap API v2](https://0x.org/docs/0x-swap-api/introduction). Routing is
-handled by 0x's allowance-holder endpoints, and all transaction signing happens through
-the existing thirdweb wallet layer (`useWriteAccount`).
+The `/swap` page trades ETH, USDC, GNARS and the other tokens in the picker, on six
+chains, through
+the [SwapPro HTTP API](https://www.swaps.pro/docs/api). One `GET /quote` routes across
+0x, CoW, LI.FI, Relay and more and returns a firm quote with the transaction to sign.
+There is no API key. All transaction signing happens through the existing thirdweb
+wallet layer (`useWriteAccount`), exactly as before.
 
 ## Architecture
 
 ```
-src/app/swap/
-  page.tsx          server component — metadata + page chrome
-  SwapWidget.tsx    "use client" — token pickers, debounced price, approve, swap
+src/app/[locale]/swap/
+  SwapWidget.tsx      "use client" — token pickers, debounced price, approve, swap (unchanged UI)
+
+src/lib/
+  swappro.ts          pure: SwapPro request/response ⇄ the shape the widget reads (unit-tested)
+  swapproRoute.ts     the one handler: reads the query, sets the fee from config, calls SwapPro
 
 src/app/api/0x/
-  price/route.ts    GET proxy → api.0x.org/swap/allowance-holder/price
-  quote/route.ts    GET proxy → api.0x.org/swap/allowance-holder/quote
+  price/route.ts      GET → swapproRoute   (kept at its old path so the widget does not change)
+  quote/route.ts      GET → swapproRoute   (same call: every SwapPro answer is firm)
 ```
 
-The proxies exist so the `0x-api-key` header stays server-side, and so the affiliate-fee
-parameters can be injected without exposing the recipient address in the client bundle.
+The routes keep their `/api/0x/*` paths on purpose: the widget's two-step flow (price while
+typing, quote on click) is untouched, and the fee recipient is still set server-side from
+`src/lib/config.ts` rather than in the client bundle.
 
 ## Flow
 
 1. User picks sell/buy tokens and enters an amount.
 2. After 600 ms of idle, `SwapWidget` calls `/api/0x/price` with `chainId`, `sellToken`,
-   `buyToken`, `sellAmount`, `taker`, and (optionally) `fee=1`.
-3. If the response includes `issues.allowance`, the widget shows an "Approve" button.
-   Approval is signed via `prepareContractCall` + `sendTransaction` against the user's
-   active thirdweb account and confirmed via `waitForReceipt`.
-4. Once approved (or for ETH), the "Swap" button calls `/api/0x/quote` to get a firm
-   transaction (`{ to, data, value, gas }`), wraps it with `prepareTransaction`, and
-   sends it via the same thirdweb account.
-5. Wrong-network state shows a "Switch to Base" CTA that calls
-   `wallet.switchChain(thirdwebBase)`.
+   `buyToken`, `sellAmount` (base units), `taker`, `sellDecimals`, `buyDecimals` and
+   (optionally) `fee=1`.
+3. The handler converts base units to human decimals, maps the native sentinel
+   (`0xeeee…`) to the chain's native symbol, and calls
+   `https://www.swaps.pro/api/sdk/v1/quote`. The answer comes back in the widget's shape:
+   `liquidityAvailable`, `buyAmount` / `minBuyAmount` in base units, `issues.allowance`
+   when an ERC-20 approval is needed, `transaction { to, data, value, gas }`, and `route`
+   naming the venue SwapPro chose.
+4. If `issues.allowance` is present, the widget shows "Approve". SwapPro's approval is for
+   the exact amount; the widget's existing approve flow (`prepareContractCall` +
+   `sendTransaction`) is unchanged.
+5. "Swap" calls `/api/0x/quote` — the same call — and sends `transaction` via
+   `prepareTransaction` on the user's thirdweb account.
+6. Wrong-network state shows a "Switch to Base" CTA, as before.
 
 ## Configuration
 
-| Setting         | Source                                       | Notes                                                                                                     |
-| --------------- | -------------------------------------------- | --------------------------------------------------------------------------------------------------------- |
-| `ZEROX_API_KEY` | env (server-only)                            | 0x API key. Required — proxy returns `500` without it.                                                    |
-| Fee recipient   | `getSwapFeeRecipient` in `src/lib/config.ts` | Base swaps route fees to the Gnars split contract. Non-Base swaps route to the cross-chain fee recipient. |
-| Fee rate        | `SWAP_FEE_BPS` in `src/lib/config.ts`        | Defaults to `50` (0.5%). Edit the constant to change.                                                     |
-
-Only `ZEROX_API_KEY` is read from the environment. Everything else ships with the
-code so the fee destination and rate are auditable in git rather than hidden in
-deploy-time secrets.
-
-## Affiliate fee behaviour
-
-The fee is **opt-in per request**: the client appends `&fee=1` to its proxy call,
-the proxy sees this flag and injects three params before forwarding to 0x:
-
-```
-swapFeeRecipient = getSwapFeeRecipient(chainId)
-swapFeeBps       = SWAP_FEE_BPS  (default 50)
-swapFeeToken     = <buyToken>    (fee is taken on the asset the user receives)
-```
-
-Both `/api/0x/price` and `/api/0x/quote` apply identical logic so the indicative
-price matches the executed quote. The "Support Gnars treasury (0.5% fee)" checkbox
-in `SwapWidget` defaults to **checked** — users can untick it to skip the fee.
-
-## Notes & deviations from the SkateHive reference
-
-- **No multi-chain.** Gnars lives on Base only; the chainId is hardcoded to `8453`
-  client-side.
-- **No Hive / Zora bonding-curve routes.** Standard 0x ERC-20 swaps only.
-- **shadcn / Tailwind, not Chakra.** UI is rebuilt with `Card`, `Button`, `Input`,
-  `Dialog`, `Checkbox`, `Tooltip`, and `sonner` toasts.
-- **thirdweb signing, not wagmi writes.** The widget calls `useWriteAccount()` and
-  uses thirdweb's `prepareContractCall` (approval) + `prepareTransaction` (raw 0x tx)
-  to keep the SA-vs-EOA view-mode toggle working.
-- **Fixed token list.** No dynamic search — we ship ETH, WETH, USDC, GNARS, DEGEN,
-  HIGHER. Adding tokens is a one-line edit in `SwapWidget.tsx`.
+| Setting       | Source                                       | Notes                                                                                                 |
+| ------------- | -------------------------------------------- | ----------------------------------------------------------------------------------------------------- |
+| API key       | none                                         | SwapPro is CORS-open and keyless. `ZEROX_API_KEY` is no longer read.                                  |
+| Fee recipient | `getSwapFeeRecipient` in `src/lib/config.ts` | Sent as SwapPro's `partner`. An EVM address as partner is the opt-in to being paid the partner share. |
+| Fee rate      | `SWAP_FEE_BPS` in `src/lib/config.ts`        | Sent as `partnerFeeBps`. SwapPro caps it at 100 bps (200 with a Pro Pass).                            |
+| Rate limit    | SwapPro                                      | 60 quotes a minute per IP with no credential; the proxy shares the site's server IP.                  |
+
+## Affiliate fee behaviour — read this before merging
+
+The fee is still **opt-in per request** (`fee=1`, the "Support Gnars treasury" checkbox,
+default checked), and it is now also **gated on the chain**. What changes is _how_ it is
+collected, and it depends on the venue SwapPro picks for the quote:
+
+- **0x and CoW** — collected on chain, on top of SwapPro's own 30 bps, and paid to a
+  0xSplits contract derived from `(payout address, bps)` that divides it between the
+  treasury and SwapPro with no invoice and nobody to trust.
+- **LI.FI** — collected, but LI.FI registers one fee wallet per integrator rather than
+  accepting one per request, so it lands in SwapPro's wallet and the response says so
+  (`paidToPartner: false`).
+- **Relay and other Pioneer venues** — cannot carry a partner fee at all.
+
+Every quote returns a `partnerFee` block saying what was requested, what was collected,
+whether it was `paidToPartner` and where it landed. The handler passes it through verbatim.
+
+### The chain gate
+
+`GNARS_SWAP_PAYOUT` in `src/lib/config.ts` lists the chains where the treasury has an
+address that can actually receive. **A chain missing from that map asks for no fee at
+all** and the checkbox is not shown there.
+
+That is not caution, it is measurement: `eth_getCode` on 2026-09-03 found the treasury's
+split holding 89 bytes on Base and **zero** on Ethereum, Arbitrum, BNB Chain, Avalanche
+and Robinhood Chain. Requesting 50 bps on those chains would take the money from the user
+and park it at an address with nothing behind it. Without the gate the user pays 80 bps
+and the treasury receives none of it.
+
+To earn on another chain: deploy the same split there (0xSplits derives the address from
+the configuration, so it carries over unchanged), then add the chain id to the map.
+Robinhood Chain is the exception — 0xSplits has no factory on 4663, so an EOA or a Safe
+is the only option there.
+
+## What the user gains
+
+- Every quote is priced across every venue at once, not just 0x.
+- `minBuyAmount` is the floor the transaction enforces on chain; the wallet receives at
+  least that or the transaction reverts.
+- No API key to rotate, no per-request 0x pricing.
+- Cross-chain and Bitcoin-native routes (THORChain) are one parameter away when the DAO
+  wants them: the same endpoint takes a different `sellChain`.
+
+## Chains
+
+The picker offers exactly the six chains SwapPro routes: Base, Ethereum, Arbitrum,
+BNB Chain, Avalanche and Robinhood Chain.
+
+Optimism was removed. It sat in the picker and every quote on it came back
+`liquidityAvailable: false` with `code: UNSUPPORTED_CHAIN` — a chain offered that could
+never fill an order. `chains.test.ts` now fails when `SWAP_CHAINS` and `SWAPPRO_CHAINS`
+disagree, so a chain SwapPro adds shows up as a failing test rather than as silence, and
+one it drops cannot linger.
+
+Token addresses and decimals come from SwapPro's own `/tokens` registry and were read back
+from chain before being written down. Two that are not guessable: **BNB Chain's USDT and
+USDC carry 18 decimals**, not Ethereum's six, and Avalanche's Tether is `USDt`. Robinhood
+Chain carries tokenised equities (NVDA, TSLA), which is the reason it is worth offering.

env.example

@@ -70,7 +70,7 @@ NEYNAR_API_KEY=your_neynar_api_key_here
 # The affiliate fee recipients (Gnars split on Base, cross-chain wallet elsewhere)
 # and rate (SWAP_FEE_BPS) live in src/lib/config.ts; only the API key is read
 # from the environment.
-ZEROX_API_KEY=your_0x_api_key_here
+# ZEROX_API_KEY is no longer read: /swap quotes through SwapPro (keyless). See docs/integrations/swap.md
 
 # ===========================================
 # Rounds (community contests) — Postgres

src/app/[locale]/swap/SwapWidget.tsx

@@ -25,7 +25,7 @@ import { useUserAddress } from "@/hooks/use-user-address";
 import { useWriteAccount } from "@/hooks/use-write-account";
 import { Link } from "@/i18n/navigation";
 import { prepareContractCall, prepareTransaction } from "@/lib/builder-code";
-import { DAO_ADDRESSES } from "@/lib/config";
+import { chainPaysTreasury, DAO_ADDRESSES } from "@/lib/config";
 import { ipfsToHttp } from "@/lib/ipfs";
 import { getThirdwebClient } from "@/lib/thirdweb";
 import { ensureOnChain, normalizeTxError } from "@/lib/thirdweb-tx";
@@ -411,6 +411,11 @@ export function SwapWidget() {
   const [buyToken, setBuyToken] = React.useState<SwapToken>(initialPair.buy);
   const [sellAmount, setSellAmount] = React.useState("");
   const [supportFee, setSupportFee] = React.useState(true);
+  // The treasury can only be paid where it has an address that can receive.
+  // On any other chain the checkbox would collect 0.5% and send it nowhere,
+  // so it is not shown and no fee is requested. See GNARS_SWAP_PAYOUT.
+  const canPayTreasury = chainPaysTreasury(chain.id);
+  const feeRequested = supportFee && canPayTreasury;
 
   const [price, setPrice] = React.useState<ZeroExPriceResponse | null>(null);
   // Distinct from `price === null`, which also means "nothing typed yet". Without
@@ -499,8 +504,11 @@ export function SwapWidget() {
           buyToken: buyToken.address,
           sellAmount: rawAmount,
           taker,
+          // SwapPro quotes in human decimals; the proxy converts both ways.
+          sellDecimals: String(sellToken.decimals),
+          buyDecimals: String(buyToken.decimals),
         });
-        if (supportFee) params.set("fee", "1");
+        if (feeRequested) params.set("fee", "1");
 
         const res = await fetch(`/api/0x/price?${params.toString()}`);
         const data: ZeroExPriceResponse & { error?: string } = await res.json();
@@ -542,7 +550,7 @@ export function SwapWidget() {
       cancelled = true;
       clearTimeout(timeout);
     };
-  }, [sellAmount, sellToken, buyToken, address, supportFee, chain.id]);
+  }, [sellAmount, sellToken, buyToken, address, feeRequested, chain.id]);
 
   const flip = () => {
     setSellToken(buyToken);
@@ -632,8 +640,10 @@ export function SwapWidget() {
         buyToken: buyToken.address,
         sellAmount: rawAmount,
         taker: address,
+        sellDecimals: String(sellToken.decimals),
+        buyDecimals: String(buyToken.decimals),
       });
-      if (supportFee) params.set("fee", "1");
+      if (feeRequested) params.set("fee", "1");
 
       const res = await fetch(`/api/0x/quote?${params.toString()}`);
       const quote: ZeroExQuoteResponse = await res.json();
@@ -976,8 +986,8 @@ export function SwapWidget() {
 
           <div className="hidden h-px flex-1 bg-border @2xl:block" />
 
-          {/* Fee opt-in */}
-          <div className="flex items-center gap-2">
+          {/* Fee opt-in — only where the treasury can actually be paid. */}
+          <div className={cn("flex items-center gap-2", !canPayTreasury && "hidden")}>
             <Checkbox
               id="support-treasury-fee"
               checked={supportFee}

src/app/[locale]/swap/chains.test.ts

@@ -0,0 +1,65 @@
+import { describe, expect, it } from "vitest";
+import { SWAPPRO_CHAINS } from "@/lib/swappro";
+import { GNARS_SWAP_PAYOUT } from "@/lib/config";
+import { getDefaultPair, NATIVE_TOKEN, SWAP_CHAINS } from "./chains";
+
+/**
+ * The picker and the router have to agree.
+ *
+ * Every failure below was once shipped: Optimism in the picker that SwapPro
+ * cannot route, a default pair naming a token the chain's list does not carry,
+ * and a stablecoin given Ethereum's six decimals on a chain that uses
+ * eighteen. None of them is caught by types.
+ */
+describe("swap chains", () => {
+  it("offers exactly the chains SwapPro routes", () => {
+    const offered = SWAP_CHAINS.map((c) => c.id).sort((a, b) => a - b);
+    const routed = Object.keys(SWAPPRO_CHAINS)
+      .map(Number)
+      .sort((a, b) => a - b);
+    expect(offered).toEqual(routed);
+  });
+
+  it("names the native asset the way SwapPro resolves it", () => {
+    for (const chain of SWAP_CHAINS) {
+      const native = chain.tokens.find((t) => t.address === NATIVE_TOKEN);
+      expect(native, `${chain.name} has no native token`).toBeDefined();
+      expect(native?.symbol).toBe(SWAPPRO_CHAINS[chain.id].native);
+      expect(native?.decimals).toBe(18);
+    }
+  });
+
+  it("resolves both default symbols to real entries in the chain's own list", () => {
+    for (const chain of SWAP_CHAINS) {
+      const { sell, buy } = getDefaultPair(chain);
+      expect(sell.symbol, `${chain.name} default sell`).toBe(chain.defaults.sell);
+      expect(buy.symbol, `${chain.name} default buy`).toBe(chain.defaults.buy);
+      expect(sell.address).not.toBe(buy.address);
+    }
+  });
+
+  it("carries no duplicate symbol or address inside one chain", () => {
+    for (const chain of SWAP_CHAINS) {
+      const symbols = chain.tokens.map((t) => t.symbol);
+      const addresses = chain.tokens.map((t) => t.address.toLowerCase());
+      expect(new Set(symbols).size, `${chain.name} symbols`).toBe(symbols.length);
+      expect(new Set(addresses).size, `${chain.name} addresses`).toBe(addresses.length);
+    }
+  });
+
+  it("gives BNB Chain's stables eighteen decimals, not Ethereum's six", () => {
+    const bnb = SWAP_CHAINS.find((c) => c.id === 56);
+    for (const symbol of ["USDT", "USDC"]) {
+      expect(bnb?.tokens.find((t) => t.symbol === symbol)?.decimals, symbol).toBe(18);
+    }
+  });
+
+  it("only claims a treasury payout on a chain the treasury can be paid on", () => {
+    for (const id of Object.keys(GNARS_SWAP_PAYOUT).map(Number)) {
+      expect(
+        SWAP_CHAINS.some((c) => c.id === id),
+        `payout configured for chain ${id}, which the picker does not offer`,
+      ).toBe(true);
+    }
+  });
+});