Settle fast-path quote solutions via the existing /settle by AryanGodara · Pull Request #4710 · cowprotocol/services

AryanGodara · 2026-08-06T14:34:12Z

Description

Completes the driver half of BE-58. A fast-path quote already caches its Solution (in #4678). This works on the /settle part. At settle time the driver re-encodes the cached solution against the real signed order and submits via the unchanged mempool path.

Changes

Added an optional real signed order and its native prices to /settle. When the order is present, the driver re-encodes the cached quote solution against it before the (unchanged) settle path submits.
Re-encoding reuses the quote's work instead of re-solving: it swaps the quote's placeholder order for the real signed order, keeps the cached route + clearing prices, and adds the native prices onto the auction's tokens so the settlement gets a slippage buffer.
The resulting settlement is cached by (auction_id, solution_id), so the existing /settle lookup + mempool submission consume it unchanged.

How to test

unit and e2e tests

linear-code · 2026-08-06T14:34:24Z

BE-58

github-actions · 2026-08-06T14:34:27Z

Reminder: Please consider backward compatibility when modifying the API specification.
If breaking changes are unavoidable, ensure:

You explicitly pointed out breaking changes.
You communicate the changes to affected teams (at least Frontend team and SAFE team).
You provide proper versioning and migration mechanisms.

Resolved

claude · 2026-08-06T15:00:31Z

Claude finished @AryanGodara's task in 5m 23s —— View job

PR Review — Settle fast-path quote solutions

The design is sound and, importantly, fail-safe: rebind_quote_order only swaps the order while keeping the cached route/prices, and Fulfillment::new re-validates executed_with_fee == order.target(), so a real order whose amounts/side/tokens/kind don't match the quote is rejected rather than mis-settled. The settle/reveal lookup keys on (auction_id, solution_id), which the re-encoded settlement inherits from the cached quote auction, so the existing mempool path consumes it unchanged. The solve_request.rs change is a clean extract-to-into_domain refactor with no behavior change. Nice test coverage for the happy path, missing-order, and mismatch cases.

Two minor points posted inline (silent dropping of invalid native prices → missing slippage buffer; and all fast-path failures collapsing into Kind::Unknown, hurting prod diagnosability). Both are non-blocking.

One item not inline-able (file not in diff):

crates/driver/openapi.yml — SettleRequest (around line 593) was not updated with the new optional order and prices fields. Given the API-change reminder on this PR, worth adding them (documented as optional / fast-path-only) so the spec stays in sync.

Nothing here blocks merge — the amount-mismatch guard makes the risky part safe. LGTM once the openapi doc is updated.

MartinquaXD

I'm positively surprised. A few things seem more complicated than they need to and some edge cases are not handled but overall the approach seems relatively non invasive. 👍

…rappers

MartinquaXD

Things are more complicated than I thought. Will have to think more about it and do another pass tomorrow.

…stpath-quote # Conflicts: # crates/driver/openapi.yml # crates/driver/src/domain/competition/mod.rs # crates/driver/src/domain/quote.rs # crates/driver/src/infra/api/routes/quote/dto/quote.rs # crates/driver/src/infra/api/routes/quote/mod.rs # crates/driver/src/tests/cases/quote.rs # crates/driver/src/tests/setup/mod.rs

github-actions · 2026-08-10T14:23:15Z

Reminder: Please consider backward compatibility when modifying the API specification.
If breaking changes are unavoidable, ensure:

You explicitly pointed out breaking changes.
You communicate the changes to affected teams (at least Frontend team and SAFE team).
You provide proper versioning and migration mechanisms.

Caused by:

crates/driver/openapi.yml

MartinquaXD · 2026-08-11T08:59:17Z

+            order::Side::Sell => user.buy_amount(&clearing)?.0 >= limit_prices.buy,
+            order::Side::Buy => user.sell_amount(&clearing)?.0 <= limit_prices.sell,


it's not enough to ensure that the original solution is at least as good as the required limit prices.
The driver also has to make sure the order gets executed EXACTLY at that limit price otherwise the circuit breaker will complain that the order did not get filled as it was intended.

I see. Now >= is only a feasibility gate (can the cached route cover the limit?),
so after the check I pin the order's two clearing prices to the signed limit, so it fills at exactly that.
also added a small test for this

jmg-duarte · 2026-08-11T10:58:34Z

+        #[error("invalid fast-path trade: {0:?}")]
+        FastPathTrade(#[from] Trade),


Can we get a reason as to why it was invalid?

jmg-duarte · 2026-08-11T11:09:36Z

+            Kind::InvalidFastPathOrder => {
+                "the settle order does not match the quoted fast-path solution"


If this is the respective error message, the error should be called "FastPathOrderQuoteMismatch" or similar, it's much closer and less general than just "invalid order"

jmg-duarte · 2026-08-11T11:10:27Z

 }

+impl Order {
+    #[expect(deprecated)]


why add a new function if its already deprecated?

it's not deprecated, that attribute is only there because it still maps the old Balancer Internal/External balance variants which are marked deprecated but not removed yet. i pulled it out into its own function so /settle can reuse the same conversion /solve does. (so when those are removed, expect will error out, reminding to remove this attirbute as well)

jmg-duarte · 2026-08-11T11:12:18Z

+    #[error("fast-path order does not match the quoted solution: {0:?}")]
+    FastPathInvalidOrder(solution::Error),


again specific message vs generic error

jmg-duarte · 2026-08-11T11:13:51Z

 impl DataAggregator {
+    /// Resolves the order's app-data hash to the underlying JSON if it isn't
+    /// already resolved.
+    pub async fn resolve_app_data(&self, order: &mut Order) {


not the biggest fan of the mut reference mutation, personally i'd rather take ownership for mutation and returning it afterwards

leaving this to your judgement

keeping &mut for now, as it just updates one field and does nothing when there's nothing to fetch, so passing the whole order in and out didn't seem worth it

jmg-duarte

LGTM

AryanGodara added 6 commits July 28, 2026 17:54

cache fast-path quote solutions in the driver

13bdda9

Merge branch 'main' into aryan/be-58-cache-quote-solutions

a156e8a

address claude bot comments

ffda40e

Merge branch 'main' into aryan/be-58-cache-quote-solutions

46801e7

address review comments

a2b4f96

Merge branch 'main' into aryan/be-58-cache-quote-solutions

c61b07f

AryanGodara self-assigned this Aug 6, 2026

AryanGodara changed the base branch from main to aryan/be-58-cache-quote-solutions August 6, 2026 14:34

AryanGodara added 2 commits August 6, 2026 20:05

Merge branch 'main' into aryan/be-58-cache-quote-solutions

1bd6fe7

settle fast-path quote solutions via the existing /settle

1b8d082

AryanGodara force-pushed the aryan/be-58-settle-fastpath-quote branch from ad645bf to 1b8d082 Compare August 6, 2026 14:41

AryanGodara marked this pull request as ready for review August 6, 2026 14:59

AryanGodara requested a review from a team as a code owner August 6, 2026 14:59

claude Bot reviewed Aug 6, 2026

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Comment thread crates/driver/src/infra/api/routes/settle/mod.rs Outdated

claude Bot reviewed Aug 6, 2026

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Comment thread crates/driver/src/infra/api/error.rs

MartinquaXD reviewed Aug 6, 2026

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AryanGodara added 2 commits August 7, 2026 00:18

address review comments

a256508

resolve order app-data at settle and re-derive fast-path flashloans/w…

258e7b1

…rappers

AryanGodara requested a review from MartinquaXD August 6, 2026 19:56

MartinquaXD reviewed Aug 6, 2026

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Base automatically changed from aryan/be-58-cache-quote-solutions to main August 7, 2026 14:06

AryanGodara added 2 commits August 10, 2026 19:05

addressed all review comments

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MartinquaXD reviewed Aug 11, 2026

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addressed all review comments

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AryanGodara requested a review from MartinquaXD August 11, 2026 11:12

Merge branch 'main' into aryan/be-58-settle-fastpath-quote

823e9f8

jmg-duarte reviewed Aug 11, 2026

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address new review comment

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AryanGodara requested a review from jmg-duarte August 11, 2026 13:46

jmg-duarte approved these changes Aug 11, 2026

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AryanGodara mentioned this pull request Aug 11, 2026

Settle fast-path orders from the autopilot #4729

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MartinquaXD approved these changes Aug 13, 2026

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AryanGodara added this pull request to the merge queue Aug 13, 2026

Merged via the queue into main with commit 623396b Aug 13, 2026
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AryanGodara deleted the aryan/be-58-settle-fastpath-quote branch August 13, 2026 07:09

github-actions Bot locked and limited conversation to collaborators Aug 13, 2026

		order::Side::Sell => user.buy_amount(&clearing)?.0 >= limit_prices.buy,
		order::Side::Buy => user.sell_amount(&clearing)?.0 <= limit_prices.sell,

		#[error("invalid fast-path trade: {0:?}")]
		FastPathTrade(#[from] Trade),

		Kind::InvalidFastPathOrder => {
		"the settle order does not match the quoted fast-path solution"

		#[error("fast-path order does not match the quoted solution: {0:?}")]
		FastPathInvalidOrder(solution::Error),

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AryanGodara commented Aug 6, 2026

Description

Changes

How to test

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PR Review — Settle fast-path quote solutions

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github-actions Bot commented Aug 6, 2026 •

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