Support autobahn node restart by skipping CometBFT handshaker (CON-252)

[wen-coding]

Summary

Enables an autobahn validator to be stopped and restarted. The CometBFT handshaker used to abort because autobahn never writes to the CometBFT block/state stores, so it observed storeHeight=0 < appHeight=N → ErrAppBlockHeightTooHigh.

• node.go: shouldHandshake = !stateSync && !gigaEnabled — skip the handshaker in giga mode.
• giga_router.go (runExecute): now owns InitChain. Calls it on fresh start (last == 0); skips it on restart (last > 0), where BaseApp.FinalizeBlock's existing nil-check rebuilds deliverState from the committed CMS.
• giga_router_test.go: drop the simulated-handshaker InitChain from TestGigaRouter_FinalizeBlocks; tighten the contract-test doc on TestInitChainCommitThenFinalize.
• integration_test/autobahn/autobahn_test.go: replace the t.Skip in the Recovery subtest with a real restart test. Adds restartNode helper.

Startup paths

	shouldHandshake	InitChain by	FinalizeBlock's deliverState
A (fresh, no giga)	true	handshaker	InitChain
B (fresh, giga)	false	runExecute	InitChain
C (restart, no giga)	true	— (appHeight>0)	handshaker replay if needed, else existing
D (restart, giga)	false	— (last>0)	BaseApp nil-check fallback from committed CMS

Cases B and D are what change. In B, runExecute takes over the InitChain duty the handshaker used to perform. In D, skipping the handshaker is the whole fix: the CometBFT state/block stores are never populated by autobahn, so reconciling against them is vacuous; the app's committed CMS is the source of truth, and BaseApp.FinalizeBlock's existing if deliverState == nil { setDeliverState(header) } fallback picks it up on the first block post-restart.

Scope / TODO

Covers restart with local disk intact (app.Info().LastBlockHeight = N, autobahn WAL has block ≥ N). Does not cover a new validator joining or a disk-wiped node — that needs app state sync + autobahn WAL sync. Tracked via TODO(autobahn-recovery) in node.go.

Test plan

• go build ./... clean; gofmt -s -l . clean
• go test ./internal/p2p/... ./node/... ./internal/consensus/... ./internal/autobahn/... — green
• make autobahn-integration-test — all 5 subtests pass. Recovery: halted @ 482 → resumed @ 537 in 12.4s after restarting a killed node.

🤖 Generated with Claude Code

[github-actions]

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

Build	Format	Lint	Breaking	Updated (UTC)
✅ passed	✅ passed	✅ passed	✅ passed	Apr 23, 2026, 3:27 AM

[codecov]

Codecov Report

❌ Patch coverage is 72.72727% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 58.31%. Comparing base (0ddccd5) to head (1ac271a).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
sei-tendermint/internal/p2p/giga_router.go	83.33%	2 Missing and 1 partial ⚠️
sei-tendermint/node/node.go	25.00%	3 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3300   +/-   ##
=======================================
  Coverage   58.31%   58.31%           
=======================================
  Files        2085     2085           
  Lines      209061   209070    +9     
=======================================
+ Hits       121906   121912    +6     
- Misses      78363    78366    +3     
  Partials     8792     8792           

Flag	Coverage Δ
sei-chain-pr	69.86% <72.72%> (?)
sei-db	69.36% <ø> (ø)

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

Files with missing lines	Coverage Δ
sei-tendermint/internal/p2p/giga_router.go	64.57% <83.33%> (-0.41%)	⬇️
sei-tendermint/node/node.go	60.28% <25.00%> (-0.38%)	⬇️

... and 1 file with indirect coverage changes

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.