Implement tx write in Autobahn rpc-only node (CON-309)

[wen-coding]

Summary

Adds an autobahn-role config (validator | rpc-only). With autobahn-role="rpc-only", a non-validator RPC node loads the committee from autobahn.json as a routing table only — no consensus participation, no block execution, no validator key required.

eth_sendRawTransaction submitted to such a node is recovered, sender-shard-mapped via Committee.EvmShard, and forwarded over HTTP to the shard owner's EVM RPC. The rest of the giga stack (consensus, producer, data, service) stays nil; Run is a no-op; block-read methods return a sentinel error.

InitRPCOnly bootstraps the app once at startup so x/evm params (chain ID, signer config) are populated. app.go pre-fires the EVM HTTP/WS start gate since rpc-only nodes don't call ProcessBlock in the current write-only milestone — see TODO(autobahn-read-path) in NewGigaRouter for the read-side scope.

Test plan

• go vet + gofmt -s -l clean
• go test ./sei-tendermint/internal/p2p/ -run TestGigaRouter_RPCOnly passes
• make autobahn-integration-test locally: all 6 sub-tests pass (BlockProduction, BankTransfer, RPCOnlyForwarding, LivenessUnderMaxFaults, HaltsBeyondMaxFaults, Recovery)
• CI autobahn-integration-tests job green

Follow-up

Read-path milestone: rpc-only nodes subscribe to finalized blocks and serve receipts/logs locally. At that point the autobahnRPCOnly gate-bypass in app.go, the read-path sentinel errors in giga_router.go, and the data/consensus skips in NewGigaRouter can be partially reverted — see the single TODO(autobahn-read-path) in NewGigaRouter for the consolidated plan.

🤖 Generated with Claude Code

[cursor]

PR Summary

Medium Risk
Touches Autobahn routing, node startup, and EVM RPC readiness timing; rpc-only path intentionally skips block reads and full consensus, so misconfiguration could affect tx submission or listener behavior until the read-path milestone lands.

Overview
Introduces autobahn-role="rpc-only" so a non-validator RPC node can join Autobahn with only the committee routing table: no validator key, no consensus/producer/data stack, and eth_sendRawTransaction forwarded to the shard owner’s EVM RPC via GigaRouter.EvmProxy.

Tendermint / node: New AutobahnRole config and validation; buildRPCOnlyGigaConfig and a slim NewGigaRouter path with InitRPCOnly (genesis InitChain when needed). Rpc-only Run is idle; block read APIs return a sentinel error. node.go skips remote-signer checks and optional validator key for rpc-only; calls InitRPCOnly after startup.

App: Replaces racy HTTP/WS start flags with sync.Once and signalEVMRPCReady, plus an Info override so rpc-only nodes (which don’t run ProcessBlock) still open EVM listeners on restart without firing during Comet handshake replay on validators.

Docker / CI: Rpc init script generates autobahn.json and rpc-only role when AUTOBAHN=true; Makefile passes AUTOBAHN, CLUSTER_SIZE, and uses DOCKER_PLATFORM for rpc images. New autobahn-integration-tests job and RPCOnlyForwarding integration test (sidecar + eth_sendRawTransaction end-to-end).

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[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	May 31, 2026, 12:53 AM

[codecov]

Codecov Report

❌ Patch coverage is 54.80769% with 47 lines in your changes missing coverage. Please review.
✅ Project coverage is 58.27%. Comparing base (0ce9176) to head (e25d6b1).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
sei-tendermint/node/setup.go	28.57%	25 Missing ⚠️
sei-tendermint/internal/p2p/giga_router.go	70.00%	7 Missing and 5 partials ⚠️
sei-tendermint/config/config.go	33.33%	4 Missing ⚠️
sei-tendermint/node/node.go	60.00%	2 Missing and 2 partials ⚠️
app/app.go	84.61%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3525      +/-   ##
==========================================
- Coverage   59.12%   58.27%   -0.85%     
==========================================
  Files        2204     2131      -73     
  Lines      182630   174339    -8291     
==========================================
- Hits       107983   101599    -6384     
+ Misses      64942    63707    -1235     
+ Partials     9705     9033     -672     

Flag	Coverage Δ
sei-chain-pr	60.84% <54.80%> (?)
sei-db	70.41% <ø> (ø)
sei-db-state-db	?

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

Files with missing lines	Coverage Δ
sei-tendermint/config/toml.go	55.00% <ø> (ø)
app/app.go	69.26% <84.61%> (-0.01%)	⬇️
sei-tendermint/config/config.go	72.66% <33.33%> (-0.51%)	⬇️
sei-tendermint/node/node.go	65.22% <60.00%> (-0.15%)	⬇️
sei-tendermint/internal/p2p/giga_router.go	69.83% <70.00%> (+0.07%)	⬆️
sei-tendermint/node/setup.go	66.16% <28.57%> (-3.07%)	⬇️

... and 73 files with indirect coverage changes

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[cursor]

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