fix(lsp): suppress unhandled spawn error on LSP child process by cxbAsDev · Pull Request #99922 · openclaw/openclaw

cxbAsDev · 2026-07-04T10:14:01Z

What Problem This Solves

spawnLspServerProcess returns a bare ChildProcess without an error handler. Missing LSP binary (ENOENT) emits unhandled error event that crashes the gateway.

Why This Change Was Made

Add child.on("error", () => {}) before returning, matching the pattern in supervisor child adapter (#99802) and MCP stdio transport (#99803).

User Impact

Missing or unstartable LSP servers no longer crash the gateway. Existing LSP initialization failure path provides diagnostics.

Evidence

Live proof: spawnLspServerProcess with nonexistent binary, NO extra handlers. Process survives. Regression test: 4 passed.

Risk

Low. One-line noop handler. Same pattern merged in #99800, #99802, #99803.

spawnLspServerProcess returns a ChildProcess without an error handler. If the LSP server binary is missing (ENOENT), the async error event crashes the process. Add a noop error handler, consistent with the pattern used in the supervisor child adapter and MCP stdio transport. Co-Authored-By: Claude <[email protected]>

Co-Authored-By: Claude <[email protected]>

clawsweeper · 2026-07-04T11:26:27Z

Codex review: needs maintainer review before merge. Reviewed July 4, 2026, 10:21 AM ET / 14:21 UTC.

Summary
The PR stores the spawned LSP child process, attaches a no-op error listener before returning it, and adds a regression test that emits an LSP child-process error.

PR surface: Source +2, Tests +15. Total +17 across 2 files.

Reproducibility: yes. Current main returns the spawned LSP child without an error listener, and Node failed-spawn behavior emits error; I verified the Node event behavior with focused probes but did not run the full repo test suite in this read-only pass.

Review metrics: none identified.

Merge readiness
Overall: 🐚 platinum hermit
Proof: 🐚 platinum hermit
Patch quality: 🐚 platinum hermit
Result: ready for maintainer review.

Overall follows the weaker of proof and patch quality, so missing proof can cap an otherwise strong patch.

Rank-up moves:

[P2] Wait for QA Smoke CI or any required pending checks to finish before merge.

Risk before merge

[P1] QA Smoke CI was still pending at review time, so maintainers should wait for required checks to finish before merge.

Maintainer options:

Decide the mitigation before merge
Land the narrow spawn-boundary guard and regression test after maintainer review and green required checks; richer LSP ENOENT diagnostics can remain a separate follow-up.
Pause or close
Do not merge this PR until maintainers decide whether the risk is worth taking.

Next step before merge

No ClawSweeper repair lane is appropriate because the patch has no supported code defect; remaining work is maintainer review and final required-check completion.

Security
Cleared: The diff only adds a child-process error listener and a focused regression test; it does not change command sources, dependencies, workflows, permissions, secrets, or package resolution.

Review details

Best possible solution:

Land the narrow spawn-boundary guard and regression test after maintainer review and green required checks; richer LSP ENOENT diagnostics can remain a separate follow-up.

Do we have a high-confidence way to reproduce the issue?

Yes. Current main returns the spawned LSP child without an error listener, and Node failed-spawn behavior emits error; I verified the Node event behavior with focused probes but did not run the full repo test suite in this read-only pass.

Is this the best way to solve the issue?

Yes. Attaching the guard inside spawnLspServerProcess fixes the exported helper and both runtime callers at the spawn boundary without changing command resolution; caller-only handling would leave the helper unsafe.

AGENTS.md: found and applied where relevant.

Codex review notes: model internal, reasoning high; reviewed against 11eeba972f46.

Label changes

Label justifications:

P2: This is a bounded agent-runtime crash fix for an optional bundled LSP child-process path with limited blast radius.
rating: 🐚 platinum hermit: Overall readiness is 🐚 platinum hermit; proof is 🐚 platinum hermit and patch quality is 🐚 platinum hermit.
status: 👀 ready for maintainer look: ClawSweeper has no concrete contributor-facing blocker left for this PR. Sufficient (live_output): The PR body reports a live spawnLspServerProcess run with a nonexistent binary and no extra handlers where the process survived, and the latest Real behavior proof check passed.
proof: sufficient: Contributor real behavior proof is sufficient. The PR body reports a live spawnLspServerProcess run with a nonexistent binary and no extra handlers where the process survived, and the latest Real behavior proof check passed.

Evidence reviewed

PR surface:

Source +2, Tests +15. Total +17 across 2 files.

View PR surface stats

Area	Files	Added	Removed	Net
Source	1	3	1	+2
Tests	1	15	0	+15
Docs	0	0	0	0
Config	0	0	0	0
Generated	0	0	0	0
Other	0	0	0	0
Total	2	18	1	+17

What I checked:

Repository policy read: Read the full root policy and applied its agent-runtime, dependency-contract, best-fix, proof, and scoped-guide review requirements. (AGENTS.md:1, 11eeba972f46)
Scoped agent policy read: Read the scoped src/agents policy; it did not prohibit the patch shape and reinforced focused agent-runtime test review. (src/agents/AGENTS.md:1, 11eeba972f46)
Current main lacks the child error guard: On current main, spawnLspServerProcess returns spawn(...) directly with piped stdio and no child-process error listener. (src/agents/agent-bundle-lsp-runtime.ts:83, 11eeba972f46)
Runtime callers reach the unguarded helper: The embedded attempt path materializes bundle LSP tools through createBundleLspToolRuntime, which creates sessions from spawnLspServerProcess; the compact path does the same. (src/agents/embedded-agent-runner/run/attempt.ts:1566, 11eeba972f46)
PR head adds the guard at the spawn boundary: The diff changes the helper to keep the spawned child, attach child.on("error", () => {}), and then return the same child without changing command resolution or spawn options. (src/agents/agent-bundle-lsp-runtime.ts:91, 112c27c07d95)
Regression test covers the unsafe event path: The added test mocks the spawned LSP child and asserts that emitting error on the returned child no longer throws. (src/agents/agent-bundle-lsp-runtime.test.ts:125, 112c27c07d95)

Likely related people:

vincentkoc: Git history shows Vincent Koc introduced the bundled LSP runtime and related plugin LSP surfaces that own this spawn path. (role: feature introducer; confidence: high; commits: 8193af6d4ebf, 4ebd3d11aa12, 74e7b8d47b18; files: src/agents/pi-bundle-lsp-runtime.ts, src/agents/agent-bundle-lsp-runtime.ts, src/plugins/bundle-lsp.ts)
steipete: Peter Steinberger refactored helper/source seams in the prior LSP runtime and plugin LSP loader area, making him a useful routing candidate for this boundary. (role: recent area contributor; confidence: medium; commits: bcd61f0a382d; files: src/agents/pi-bundle-lsp-runtime.ts, src/plugins/bundle-lsp.ts)
cxbAsDev: This author recently landed the sibling SSH tunnel, supervisor child adapter, and MCP stdio error-handling fixes cited by this PR, so they have current context on the process-error pattern. (role: recent adjacent process-error contributor; confidence: medium; commits: c6ed9d8d06a4, 3b37fe1de46c, 1b84316a91dc; files: src/infra/ssh-tunnel.ts, src/process/supervisor/adapters/child.ts, src/agents/mcp-stdio-transport.ts)

What the crustacean ranks mean

🦀 challenger crab: rare, exceptional readiness with strong proof, clean implementation, and convincing validation.
🦞 diamond lobster: very strong readiness with only minor maintainer review expected.
🐚 platinum hermit: good normal PR, likely mergeable with ordinary maintainer review.
🦐 gold shrimp: useful signal, but proof or patch confidence is still limited.
🦪 silver shellfish: thin signal; proof, validation, or implementation needs work.
🧂 unranked krab: not merge-ready because proof is missing/unusable or there are serious correctness or safety concerns.
🌊 off-meta tidepool: rating does not apply to this item.

Shiny media proof means a screenshot, video, or linked artifact directly shows the changed behavior. Runtime, network, CSP, and security claims still need visible diagnostics.

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Review history (5 earlier review cycles)

reviewed 2026-07-04T11:29:59.673Z sha 28cef2a :: needs real behavior proof before merge. :: none
reviewed 2026-07-04T13:22:37.062Z sha 63e592a :: needs real behavior proof before merge. :: none
reviewed 2026-07-04T13:38:40.415Z sha 63e592a :: needs real behavior proof before merge. :: none
reviewed 2026-07-04T13:53:55.574Z sha 6426e7c :: needs maintainer review before merge. :: none
reviewed 2026-07-04T14:03:57.654Z sha 6426e7c :: needs maintainer review before merge. :: none

Co-Authored-By: Claude <[email protected]>

steipete · 2026-07-05T18:13:51Z

Thank you — this fix landed through maintainer batch PR #100399 in commit b22c36f, with contributor credit and changelog thanks preserved. Closing this source PR as superseded.

openclaw-barnacle Bot added agents Agent runtime and tooling size: XS labels Jul 4, 2026

chore: trigger CI re-run for flaky infrastructure test

28cef2a

Co-Authored-By: Claude <[email protected]>

cxbAsDev and others added 2 commits July 4, 2026 21:15

chore: add live proof to PR body, trigger re-review

63e592a

Co-Authored-By: Claude <[email protected]>

chore: update proof - show production handler without extra listeners

6426e7c

Co-Authored-By: Claude <[email protected]>

openclaw-barnacle Bot added the triage: needs-pr-context Candidate: external PR body lacks required problem context or evidence. label Jul 4, 2026

chore: fix PR body template sections for CI check

112c27c

Co-Authored-By: Claude <[email protected]>

openclaw-barnacle Bot removed the triage: needs-pr-context Candidate: external PR body lacks required problem context or evidence. label Jul 4, 2026

steipete self-assigned this Jul 5, 2026

This was referenced Jul 5, 2026

fix: land ten small reliability fixes #100383

Closed

fix: land ten small reliability fixes #100395

Closed

fix: land ten small reliability fixes #100399

Merged

steipete closed this Jul 5, 2026

cxbAsDev deleted the fix/lsp-spawn-error-handler branch July 15, 2026 03:33

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fix(lsp): suppress unhandled spawn error on LSP child process#99922

fix(lsp): suppress unhandled spawn error on LSP child process#99922
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cxbAsDev:fix/lsp-spawn-error-handler

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