treat WETH->ETH as sametoken trade

[extrawurst]

Skip volume fee on wrapped↔native (WETH→ETH) same-token trades

Same-token trades (sell_token == buy_token) already skip the volume fee unless enable_sell_equals_buy_volume_fee (off by default) is set. This extends "same-token" to native ETH buys: WETH → ETH (buy_token == BUY_ETH_ADDRESS) and the fee is dropped on both the quote and the settlement.

Changes

• shared/fee.rs: get_applicable_volume_fee_factor takes native_token and skips the fee for the native same-token case.
• model/order.rs: extracted is_same_buy_and_sell_token(sell, buy, native), reused by both the fee policy and order validation.
• orderbook (QuoteHandler) and autopilot (ProtocolFees) thread native_token through so quote and settlement agree.

Tests

• Unit: shared::fee::tests::test_same_token_volume_fee_skipped
• E2E: local_node_volume_fee_{dropped_on_same_token, charged_on_same_token_when_enabled, dropped_on_wrapped_to_native_token}

[claude]

Claude encountered an error after 2m 31s —— View job

---

PR Review in progress

• Read changed files & gather context
• Analyze fee logic changes
• Analyze order validation refactor
• Analyze quoter & autopilot integration
• Review tests
• Post final review

[gemini-code-assist]

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[AryanGodara]

LGTM 👌🏼

[nit]native_token could move onto VolumeFeePolicy itself, since both callers (ProtocolFees and QuoteHandler) already construct the policy with the chain's native token immediately after receiving it.

I tried this locally and it works, but is like a 2/10 refactor. So not pushing for it 😅

Tradeoff I think is binding the policy to a specific chain 🤔

[jmg-duarte]

did you test this in staging? and shouldnt the unwraps not even be considered this kind of trade?

[MartinquaXD]

Logic makes sense to me and test coverage is good.

[extrawurst]

tested on base staging now:

{
  "quote": {
    "sellToken": "0x4200000000000000000000000000000000000006",
    "buyToken": "0xeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee",
    "receiver": null,
    "sellAmount": "999999359157841156",
    "buyAmount": "999999359157841156",
    "validTo": 1781791616,
    "appData": "0x0000000000000000000000000000000000000000000000000000000000000000",
    "feeAmount": "640842158844",
    "gasAmount": "115614",
    "gasPrice": "5542946",
    "sellTokenPrice": "1",
    "kind": "sell",
    "partiallyFillable": false,
    "sellTokenBalance": "erc20",
    "buyTokenBalance": "erc20",
    "signingScheme": "eip712"
  },
  "from": "...",
  "expiration": "2026-06-18T13:38:56.649238120Z",
  "id": 1114090,
  "verified": true
}

note: no protocolFeeBps as its null.

without my PR:

{
  "quote": {
    "sellToken": "0x4200000000000000000000000000000000000006",
    "buyToken": "0xeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee",
    "receiver": null,
    "sellAmount": "999999353643515812",
    "buyAmount": "999969353662906507",
    "validTo": 1781791860,
    "appData": "0x0000000000000000000000000000000000000000000000000000000000000000",
    "feeAmount": "646356484188",
    "gasAmount": "115614",
    "gasPrice": "5590642",
    "sellTokenPrice": "1",
    "kind": "sell",
    "partiallyFillable": false,
    "sellTokenBalance": "erc20",
    "buyTokenBalance": "erc20",
    "signingScheme": "eip712"
  },
  "from": "...",
  "expiration": "2026-06-18T13:43:00.668009912Z",
  "id": 1114153,
  "verified": true,
  "protocolFeeBps": "0.3"
}