Wire eth_subscribe(newHeads) for Autobahn (CON-257) by wen-coding · Pull Request #3419 · sei-protocol/sei-chain

wen-coding · 2026-05-11T20:15:54Z

Summary

Under Autobahn, eth_subscribe("newHeads") is currently broken: the legacy fan-out subscribes to the Tendermint event bus on tm.event = 'NewBlockHeader', but Autobahn drives app.FinalizeBlock from giga_router rather than CometBFT consensus, so PublishEventNewBlockHeader never fires.
This PR adds a direct in-process notifier from giga_router's post-commit point into evmrpc.SubscriptionAPI's fan-out goroutine, scoped strictly to Autobahn mode (notifier is only constructed when tmConfig.AutobahnConfigFile != ""). The legacy CometBFT path is untouched.
Notifier semantics: single-producer, single-consumer, capacity 1, overwrite-on-full — newHeads subscribers care about the latest head, not a backlog, so stale heads are dropped in favor of new ones.

Design notes

A simpler alternative was to keep using the event bus and just have giga_router call eventBus.PublishEventNewBlockHeader(...) after commit. That would have been a ~20-line diff with zero evmrpc changes (the existing consumer would just work). We opted not to because (1) the pubsub layer isn't doing anything load-bearing for this use case — one fixed query, one subscriber — and (2) we plan to drop the cosmos event bus entirely once external consumers move off tm.event='Tx' and friends. A direct channel is the end-state design; this PR lands it now to avoid carrying the stopgap.

hash on the published header is the autobahn lane-block header hash (the same value the EVM receipt store records as blockHash), not a hash over the synthesized Tendermint header. parentHash / receiptsRoot / transactionsRoot are zero under Autobahn — the lane-block path doesn't compute a Tendermint-style hash chain, and surfacing fakes would be worse than zeros. Subscribers that chain-validate the head stream will need a different mechanism going forward; this is called out in the encoder's doc.

Test plan

gofmt -s -l clean on all modified files; go build ./... clean.
go test ./evmrpc/ — 249 PASS, 8 SKIP, 0 FAIL (22s). Includes:
- existing TestSubscribeNewHeads (legacy event-bus path) — unchanged behaviour.
- new TestSubscribeNewHeadsAutobahn (notifier path, in-process WS server end-to-end).
- new unit tests for BlockHeaderNotifier (deliver, overwrite-on-full, nil-safe) and encodeCommittedBlock (happy path + nil ConsensusParamUpdates).
evm_rpc_tests.sh (HTTP-method fixtures) against a real non-Autobahn cluster — 160/160 pass, no regressions on the request/response RPC surface.
New integration_test/evm_module/ws_test/ — consensus-mode-agnostic, gated on SEI_EVM_WS_RUN_INTEGRATION=1, wired into evm_rpc_tests.sh. Run end-to-end against both cluster modes:
- Non-Autobahn cluster: PASS (number=0x2b, hash 0xe0dd089b...)
- Autobahn cluster: PASS (number=0xf5, hash 0xc4d1bc59..., GigaRouter initialized confirmed in all 4 node logs)
Reviewer: confirm non-app-hash-breaking label is correct — this PR only adds a notification side-effect after commit; no state machine or app-hash-relevant logic changes.

🤖 Generated with Claude Code

Note

Medium Risk
Adds a new post-commit callback on Autobahn’s block execution hot path and changes eth_subscribe("newHeads") delivery to use an in-process channel when enabled; mistakes could drop notifications or affect performance, though legacy CometBFT behavior is preserved.

Overview
Fixes eth_subscribe("newHeads") under Autobahn by bypassing the Tendermint event bus and instead pushing committed block headers through a new in-process BlockHeaderNotifier.

giga_router now invokes an optional types.BlockHeaderListener after successful Commit, the app wires this to the notifier only when Autobahn is enabled, and evmrpc.SubscriptionAPI switches between the legacy event-bus subscription and the notifier-fed fanout. The Autobahn encoder uses the Autobahn-provided block hash, derives gasUsed from tx results, reads gasLimit from current consensus params, and fixes baseFeePerGas selection to use the parent height.

Adds unit + WS end-to-end tests for notifier semantics (overwrite-on-full) and Autobahn newHeads delivery, plus a gated integration WS test and script updates to run it.

^{Reviewed by Cursor Bugbot for commit 1cd5600. Bugbot is set up for automated code reviews on this repo. Configure here.}

github-actions · 2026-05-11T20:16:53Z

The latest Buf updates on your PR. Results from workflow Buf / buf (pull_request).

Build	Format	Lint	Breaking	Updated (UTC)
`✅ passed`	`✅ passed`	`✅ passed`	`✅ passed`	May 12, 2026, 7:57 PM

codecov · 2026-05-11T20:21:13Z

Codecov Report

❌ Patch coverage is 71.66667% with 34 lines in your changes missing coverage. Please review.
✅ Project coverage is 59.35%. Comparing base (26636ba) to head (1cd5600).

Files with missing lines	Patch %	Lines
evmrpc/subscribe.go	81.01%	9 Missing and 6 partials ⚠️
sei-tendermint/internal/p2p/giga_router.go	0.00%	8 Missing and 1 partial ⚠️
app/app.go	0.00%	6 Missing and 1 partial ⚠️
evmrpc/notifier.go	88.88%	2 Missing ⚠️
sei-tendermint/node/setup.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3419      +/-   ##
==========================================
+ Coverage   59.34%   59.35%   +0.01%     
==========================================
  Files        2112     2113       +1     
  Lines      174772   174863      +91     
==========================================
+ Hits       103724   103796      +72     
- Misses      62010    62027      +17     
- Partials     9038     9040       +2

Flag	Coverage Δ
sei-chain-pr	`68.42% <71.66%> (?)`
sei-db	`70.41% <ø> (ø)`

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
evmrpc/server.go	`87.79% <100.00%> (ø)`
sei-tendermint/node/node.go	`65.28% <100.00%> (+0.09%)`	⬆️
sei-tendermint/node/public.go	`67.44% <100.00%> (+3.33%)`	⬆️
sei-tendermint/node/seed.go	`48.48% <ø> (ø)`
sei-tendermint/node/setup.go	`69.35% <0.00%> (-0.23%)`	⬇️
evmrpc/notifier.go	`88.88% <88.88%> (ø)`
app/app.go	`68.93% <0.00%> (-0.26%)`	⬇️
sei-tendermint/internal/p2p/giga_router.go	`66.02% <0.00%> (-2.98%)`	⬇️
evmrpc/subscribe.go	`68.69% <81.01%> (+6.84%)`	⬆️

... and 1 file with indirect coverage changes

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encodeCommittedBlock was mirroring the legacy encodeTmHeader, which emits both the typo'd "withdrawlsRoot" and the correctly-spelled "withdrawalsRoot". Since the Autobahn encoder is new code there is no back-compat reason to carry the typo; legacy encodeTmHeader is left untouched. Reported by Cursor Bugbot on #3419. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

ResponseFinalizeBlock.ConsensusParamUpdates is only populated when the app proposes a consensus-param update — nil on the vast majority of blocks. Reading it for newHeads gasLimit means the reported gasLimit would be 0 for nearly every notification under Autobahn. Match the pattern already used in evmrpc/block.go's GetBlockByNumber: pull gasLimit from ctx.ConsensusParams() in the consumer goroutine and pass it as a parameter into encodeCommittedBlock. Reported by Cursor Bugbot on #3419 (high severity). Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

cursor

Cursor Bugbot has reviewed your changes and found 1 potential issue.

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^{Reviewed by Cursor Bugbot for commit 84cd2e6. Configure here.}

Under Autobahn, app.FinalizeBlock is driven by giga_router rather than CometBFT consensus, so the legacy Tendermint event-bus subscription that backs eth_subscribe("newHeads") never fires. This adds a direct in-process notifier from giga_router's commit path into evmrpc's SubscriptionAPI fan-out (overwrite-on-full, capacity 1, so the latest head always wins if a consumer lags). The legacy path is untouched. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

encodeCommittedBlock was mirroring the legacy encodeTmHeader, which emits both the typo'd "withdrawlsRoot" and the correctly-spelled "withdrawalsRoot". Since the Autobahn encoder is new code there is no back-compat reason to carry the typo; legacy encodeTmHeader is left untouched. Reported by Cursor Bugbot on #3419. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

- Tighten hash field doc in blockHeaderEvent: receipt store records zero blockHash on disk and evmrpc overlays the autobahn hash at read time. The prior wording implied the receipt store stored it directly. - Clarify single-producer assumption in OnBlockCommitted and document multi-producer behaviour (still safe, latest-wins is acceptable). - Move SubscriptionManager construction inside the legacy event-bus branch in NewSubscriptionAPI so the field is nil under Autobahn instead of dead state. - Document the non-nil header/response contract on BlockHeaderListener, and add a defensive guard in runNewHeadsFromNotifier so a single malformed event does not kill the fan-out goroutine for all subscribers. - Annotate the listener call site in giga_router.executeBlock so the fire-after-Commit-before-mempool-update ordering is explicit. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

ResponseFinalizeBlock.ConsensusParamUpdates is only populated when the app proposes a consensus-param update — nil on the vast majority of blocks. Reading it for newHeads gasLimit means the reported gasLimit would be 0 for nearly every notification under Autobahn. Match the pattern already used in evmrpc/block.go's GetBlockByNumber: pull gasLimit from ctx.ConsensusParams() in the consumer goroutine and pass it as a parameter into encodeCommittedBlock. Reported by Cursor Bugbot on #3419 (high severity). Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

GetNextBaseFeePerGas(ctx_at_N) returns the base fee for block N+1, not block N. The previous code passed the current block's ctx, so the newHeads notification for block N reported what should have been attached to N+1. Match the pattern from block.go's GetBlockByNumber: derive baseFee from the parent block's ctx, with a genesis (height==1) fallback to DefaultMinFeePerGas. The legacy CometBFT path has the same bug but is left alone — the more important consistency to restore is between eth_subscribe(newHeads) and eth_getBlockByNumber on the same Autobahn cluster. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

ExecTxResult has both a GasWanted and a GasUsed field with different semantics. The variable was accumulating GasUsed but named "gasWanted", inviting a future field-swap regression. Rename for clarity. Legacy encodeTmHeader carries the same anti-pattern but is left alone. Reported by Cursor Bugbot on #3419 (low severity). Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

amir-deris · 2026-05-12T17:16:32Z

+
+	// First message must be the subscription confirmation. Bound the wait
+	// so a broken handshake fails fast.
+	if err := conn.SetReadDeadline(time.Now().Add(10 * time.Second)); err != nil {


This err shadows definition of err on line 42. Can just reuse it (similarly in other lines):
if err = conn.SetReadDeadline....

@amir-deris

The five `if err := ...` blocks in TestEthSubscribeNewHeads each shadowed the outer err from the initial Dial call. Reuse with `err =` for clarity (the outer err is already in scope and gets overwritten on each call anyway). Reported by @amir-deris on #3419. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

The base-fee selection in runNewHeadsFromNotifier was the actual location of the off-by-one fix (parent ctx vs current ctx) but had no direct test coverage — encodeCommittedBlock takes baseFee as an arg, so testing it only proved the encoder forwards the value it's given, not that the caller picks the right ctx. Extract pickHeadBaseFee as a free function that takes getNextBaseFee as a function pointer (rather than reaching into *keeper.Keeper), then spy on the ctxProvider in tests to verify: - TestPickHeadBaseFee_UsesParentCtx: ctxProvider called with height-1 (NOT height), and result is forwarded. - TestPickHeadBaseFee_GenesisFallback: at height 1 the keeper call is skipped entirely and DefaultMinFeePerGas is returned. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

wen-coding added the non-app-hash-breaking label May 11, 2026

wen-coding changed the title ~~Wire eth_subscribe(newHeads) for Autobahn via in-process notifier~~ Wire eth_subscribe(newHeads) for Autobahn (CON-257) May 11, 2026

cursor Bot reviewed May 11, 2026

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Comment thread evmrpc/subscribe.go

wen-coding requested review from arajasek, codchen, jewei1997, masih and pompon0 May 11, 2026 20:52

codchen approved these changes May 12, 2026

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cursor Bot reviewed May 12, 2026

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Comment thread evmrpc/subscribe.go

wen-coding requested a review from amir-deris May 12, 2026 13:53

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Comment thread evmrpc/subscribe.go

wen-coding and others added 6 commits May 12, 2026 10:02

wen-coding force-pushed the wen/add_eth_subscribe_newhead_for_autobahn branch from 073496b to c8c0d46 Compare May 12, 2026 17:04

amir-deris approved these changes May 12, 2026

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wen-coding and others added 2 commits May 12, 2026 10:37

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Wire eth_subscribe(newHeads) for Autobahn (CON-257)#3419

Wire eth_subscribe(newHeads) for Autobahn (CON-257)#3419
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