Add gas tiering for multiOFA client by dimriou · Pull Request #462 · smartcontractkit/chainlink-evm

dimriou · 2026-05-06T10:43:07Z

SVR needs an easy way to keep track which OFA included the transaction on-chain. To accomplish this we reserve the last two digits of the gas limit and we assign 10 values space for each one of them, for example:

OFA1: 10 - 19
OFA2: 20 - 29
... and so on.
For now only the first position is used, i.e. 10, 20, etc. However in the future we might want to include per-feed tiering across each OFA, so we reserve 10 spaces upfront.

github-actions · 2026-05-06T10:45:28Z

⚠️ API Diff Results - `github.com/smartcontractkit/chainlink-evm`

⚠️ Breaking Changes (1)

`pkg/txm/clientwrappers/dualbroadcast` (1)

FlashbotsTxStore — 🗑️ Removed

✅ Compatible Changes (1)

`pkg/txm/clientwrappers/dualbroadcast` (1)

NewMultiOfaClient — ➕ Added

📄 View full apidiff report

cll-gg · 2026-05-06T10:54:40Z

+		return nil, fmt.Errorf("failed to sign tiered attempt for txID: %v: %w", tx.ID, err)
+	}
+
+	d.lggr.Infow("Intercepting attempt for tx", "txID", tx.ID, "hash", signedTx.Hash(), "toAddress", tx.ToAddress, "gasLimit", tieredGasLimit,


Does this need to be info level?
I'd rather have an info level log after the attempt has been sent to the OFA to print all the context

The existing log has inaccurate information of the transaction since it has the wrong details (gasLimit). This log is the only way to get the hash of the different OFAs accordingly so we can track them on-chain.

What if we would log this directly after a tx gets sent to an OFA? Then the hash and gasLimit would be correct and we wouldn't have to distinguish mentally between intercepted and non-intercepted attempts.

cll-gg · 2026-05-06T10:55:18Z

@@ -38,10 +36,10 @@ type multiOfaClient struct {
 var _ txm.Client = (*multiOfaClient)(nil)

 // newMultiOfaClient builds backends from URLs: index 0 is primary (outcome and nonces); the rest are secondaries.


Suggested change

// newMultiOfaClient builds backends from URLs: index 0 is primary (outcome and nonces); the rest are secondaries.

// NewMultiOfaClient builds backends from URLs: index 0 is primary (outcome and nonces); the rest are secondaries.

We need to be able to import this client for local testing, similar to the rest of the clients.

Ah ok, clear. Can you point me to the way you do local testing for this? Is there a doc/some guidelines?

cll-gg · 2026-05-06T10:56:37Z

+// createAttemptWithTiering creates a tiered attempt that has a different gas limit for each OFA backend, by reserving the last two digits.
+// Each OFA has 10 values spaced 10 units apart for the gas limit so there is room for feed-specific tiers per OFA in the future.
+// Unfortunately, the per-OFA attempts are not tracked by the txm. We can track them by looking at the individual logs per attempt stored.
+func (d *ofaBackend) createAttemptWithTiering(ctx context.Context, tx *types.Transaction, attempt *types.Attempt) (*types.Attempt, error) {


I'd prefer to not use the keyword tiering here since this is more about tracking, and the term might get confused with feed tiering

Any suggestions?

Maybe createAttemptWithAccountability or createAttemptForOFAAccountability?
We can add to the docs that we've reserved space to support feed tiering in the future.

How about createAttemptWithTracedFee

lhmerino

Looks great, thank you!

I have just one safety comment regarding the gas limit.

lhmerino · 2026-05-06T12:00:15Z

+	if suffix >= 100 {
+		return 0, fmt.Errorf("cannot calculate OFA gas limit tier for %s: suffix %d is not two digits", k.name(), suffix)
+	}
+	return gasLimit - gasLimit%100 + suffix, nil


I would suggest bumping the gas limit to the next hundred to ensure the new gas limit is always greater than or equal to the original gas limit for safety reasons.
Could be as simple as the following statement after applying the suffix change tieredLimit := gasLimit - (gasLimit % 100) + suffix:

if tieredLimit < gasLimit { tieredLimit += 100 }

Following on, might also be nice to make 100 be a constant since its used in multiple locations as well.

Copilot

Pull request overview

This PR introduces gas-limit “tiering” for dual-broadcast via the multi-OFA client so downstream systems can infer which OFA relay included a transaction on-chain by inspecting the last two digits of the gas limit.

Changes:

Re-sign dual-broadcast transactions with a tiered gas limit suffix prior to OFA submission.
Export and refactor NewMultiOfaClient to depend on narrower interfaces and pass keystore support through to Nova.
Update/add unit tests and fixtures to use dynamic-fee transactions and validate tiering behavior.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
pkg/txm/clientwrappers/dualbroadcast/selector.go	Switches to the exported `NewMultiOfaClient` constructor.
pkg/txm/clientwrappers/dualbroadcast/ofa_backend.go	Adds gas-limit tiering via re-signing; refactors keystore/txstore interfaces.
pkg/txm/clientwrappers/dualbroadcast/ofa_backend_test.go	Updates fixtures to dynamic-fee txs, adds tiering tests, introduces a test keystore helper.
pkg/txm/clientwrappers/dualbroadcast/multiofa_client.go	Exports constructor and adjusts dependencies to interfaces; passes keystore to Nova client creation.
pkg/txm/clientwrappers/dualbroadcast/multiofa_client_test.go	Updates tests to use `NewMultiOfaClient` and provide a keystore where needed.

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@@ -38,10 +36,10 @@ type multiOfaClient struct {
 var _ txm.Client = (*multiOfaClient)(nil)

 // newMultiOfaClient builds backends from URLs: index 0 is primary (outcome and nonces); the rest are secondaries.


+	if !attempt.Fee.ValidDynamic() {
+		return nil, errors.New("attempt is not a dynamic fee attempt") // We could potentially support legacy transactions, but dynamic transactions are the default so this is ok.
+	}


+		GasTipCap: attempt.Fee.GasTipCap.ToInt(),
+		Data:      tx.Data,
+	}
+


+func (k ofa) tieredGasLimit(gasLimit uint64) (uint64, error) {
+	suffix := (uint64(k) + 1) * 10
+	if suffix >= tieringSpace {
+		return 0, fmt.Errorf("cannot calculate OFA gas limit tier for %s: suffix %d is not in the range 0-%d", k.name(), suffix, tieringSpace-1)
+	}
+	tieredLimit := gasLimit - gasLimit%tieringSpace + suffix


Add gas tiering for multiOFA client

6bdfb64

cll-gg reviewed May 6, 2026

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Comment thread pkg/txm/clientwrappers/dualbroadcast/ofa_backend.go

cll-gg reviewed May 6, 2026

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Comment thread pkg/txm/clientwrappers/dualbroadcast/multiofa_client.go

cll-gg reviewed May 6, 2026

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Comment thread pkg/txm/clientwrappers/dualbroadcast/ofa_backend.go

cll-gg reviewed May 6, 2026

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Comment thread pkg/txm/clientwrappers/dualbroadcast/ofa_backend.go

lhmerino previously approved these changes May 6, 2026

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Add tieringSpace so we never underestimate

303b092

dimriou dismissed lhmerino’s stale review via 303b092 May 6, 2026 16:06

Remove unused test method

0c2b8da

dimriou marked this pull request as ready for review May 8, 2026 09:06

dimriou requested a review from a team as a code owner May 8, 2026 09:06

Copilot AI review requested due to automatic review settings May 8, 2026 09:06

dimriou requested a review from a team as a code owner May 8, 2026 09:06

product-security-plaid-production Bot requested review from b-s-d and yashnevatia May 8, 2026 09:07

Copilot started reviewing on behalf of dimriou May 8, 2026 09:07 View session

Copilot AI reviewed May 8, 2026

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alejoberardino previously approved these changes May 8, 2026

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Update keystore requirements for nova

2580b10

dimriou dismissed alejoberardino’s stale review via 2580b10 May 11, 2026 08:36

dhaidashenko approved these changes May 11, 2026

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		@@ -38,10 +36,10 @@ type multiOfaClient struct {
		var _ txm.Client = (*multiOfaClient)(nil)

		// newMultiOfaClient builds backends from URLs: index 0 is primary (outcome and nonces); the rest are secondaries.

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dimriou commented May 6, 2026

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⚠️ API Diff Results - github.com/smartcontractkit/chainlink-evm

⚠️ Breaking Changes (1)

pkg/txm/clientwrappers/dualbroadcast (1)

✅ Compatible Changes (1)

pkg/txm/clientwrappers/dualbroadcast (1)

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lhmerino May 6, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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github-actions Bot commented May 6, 2026 •

edited

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⚠️ API Diff Results - `github.com/smartcontractkit/chainlink-evm`

`pkg/txm/clientwrappers/dualbroadcast` (1)

`pkg/txm/clientwrappers/dualbroadcast` (1)

lhmerino May 6, 2026 •

edited

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