[ShiJie Wu (wsjwu58-cmd)]

Fixes #65089

Analysis

When the async API server disconnects during a request, vscode-jsonrpc closes the connection without rejecting pending responses. Callers can remain blocked until they explicitly close the API. Disposing immediately also risks dropping complete responses still waiting for decoding or dispatch.

Fix

Handle disconnects for socket and spawned-process clients, reject queued work, drain complete responses received before the first close event, then reject unanswered requests. Keep stale connection closures from affecting retries and wait for drained response timings before writing a timing dump.

After a writer-only close, bytes not yet delivered to the reader are discarded so an independently open reader cannot keep requests pending indefinitely. No dependencies or vendored files change.

Validation

• 28 new disconnect regression tests passed.
• Full native API suite: 1048 passed.
• WASM API suites: 381 async and 533 sync passed.
• Type builds, both Go lint modules (0 issues), and formatting passed.

Copilot Checklist

• npx hereby validate --api completed without error. The command exited 1 because Go tests hit Windows paging-file/memory limits, missing symlink privileges, and an fswatch event mismatch. The three memory-related failed packages passed when rerun separately; all API suites passed.
• New tests cover the change.
• Associated issue in the Backlog milestone. Issue Async API requests remain pending after the RPC connection closes #65089 has been filed and is awaiting milestone triage.

Related: #64846 handles the same underlying mechanism only during timing collection on explicit close.

AI assistance

The implementation and tests were authored with Codex using Terra max sub-agents and reviewed with AI assistance. The human operator selected this specific fix. Human code review remains pending.

[ShiJie Wu (wsjwu58-cmd)]

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