fix(cursor): a closed-stream write in the Cursor SDK no longer stops the server #22897 · pingdotgg/t3code

MmacroscopeappBotapproved these changes25d ago

Approvability

Verdict: Approved at dcec962

Macroscope's review found this PR approvable — This is a small, self-contained Cursor server bug fix that prevents one identified closed-stream SDK rejection from terminating the process while preserving existing handling for other rejections. A focused regression test covers both behaviors, with no API, schema, or product-default changes.

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Ggithub-actionsBot25d ago

Thread transfer impact

✅ Thread transfer remains within every enforced ceiling.

Provider	Metric	Main baseline	This PR	Impact	PR ceiling
Codex	Total thread wire	4.9 KiB	5.0 KiB	+23 B (+0.5%)	6.8 KiB	✅
Codex	Thread snapshot wire	3.8 KiB	3.8 KiB	0 B (0.0%)	4.9 KiB	✅
Codex	Live turn WebSocket wire	1.2 KiB	1.2 KiB	+23 B (+1.9%)	2.0 KiB	✅
Codex	Live turn WebSocket decoded	20.8 KiB	20.9 KiB	+41 B (+0.2%)	29.3 KiB	✅
Codex	Live turn messages	1	2	+1 (+100.0%)	8	✅
Claude	Total thread wire	5.0 KiB	5.0 KiB	+7 B (+0.1%)	6.8 KiB	✅
Claude	Thread snapshot wire	3.8 KiB	3.8 KiB	0 B (0.0%)	4.9 KiB	✅
Claude	Live turn WebSocket wire	1.2 KiB	1.2 KiB	+7 B (+0.6%)	2.0 KiB	✅
Claude	Live turn WebSocket decoded	21.2 KiB	21.2 KiB	0 B (0.0%)	29.3 KiB	✅
Claude	Live turn messages	2	2	0 (0.0%)	8	✅

Baseline: e822ba7 · PR result: dcec962 · Source CI: success

Scenario and decoded snapshot size

10 historical turns, 5 command tools per turn, 878.9 KiB retained MCP result per historical turn, and a 1.05 MiB retained result in the measured turn.

Codex decoded thread snapshot: 108.5 KiB
Claude decoded thread snapshot: 108.8 KiB

Updated in place by a trusted workflow. PR artifacts are strictly validated and never executed.

CcoderabbitaiBot25d ago

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📥 Commits

Reviewing files that changed from the base of the PR and between e822ba78ea23612f57093235f84813f385cf6431 and dcec9629a1ff0102971e89b3aeb72de0aa0f2b8d.

📒 Files selected for processing: 2

packages/provider-cursor/src/server/CursorSdk.test.ts
packages/provider-cursor/src/server/CursorSdk.ts

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📝 Walkthrough

The Cursor server now handles SDK-shaped WriteIterableClosedError unhandled rejections without exiting. Tests verify that other errors with the same message still cause an exit with status 1.

Changes: Cursor rejection handling

Layer / File(s)	Summary
Closed-stream rejection handling `packages/provider-cursor/src/server/CursorSdk.ts`, `packages/provider-cursor/src/server/CursorSdk.test.ts`	The handler detects errors named `WriteIterableClosedError`, logs the error, and returns instead of terminating the server. Tests check this behavior and confirm that a generic error with the same message still exits with status 1.

Priority: ➖ Normal

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Bug fix · Severity of issue fixed: Medium

Suggested reviewers: maria-rcks

Merge Risk: ⚪ Minimal · up to dcec9

The Cursor closed-stream guard appears mergeable after normal checks; no actionable merge-blocking risk is established.

Pre-merge checks: ^Passed 4

Check name	Status	Explanation
Title check	Passed	The title clearly and concisely describes the primary fix: preventing a closed-stream Cursor SDK error from stopping the server.
Description check	Passed	The description covers the problem, implementation, scope, issue reference, verification results, untested conditions, and agent disclosure. It does not use the template headings or include an explici…
Linked Issues check	Passed	Issue `#21418` requires containment of the Cursor SDK's asynchronous `WriteIterableClosedError` so it does not terminate the server with exit code 1. `CursorSdk.ts` adds a process-level rejection guard …
Out of Scope Changes check	Passed	The whole-PR diff contains only the Cursor server guard and its focused automated tests. Both changes support issue `#21418`. The guard remains limited to the Cursor provider and does not change web, de…

Full details: Description check

Explanation

The description covers the problem, implementation, scope, issue reference, verification results, untested conditions, and agent disclosure. It does not use the template headings or include an explicit maintainer approval comment, but it is otherwise mostly complete and directly related to the change.

Full details: Linked Issues check

Explanation

Issue #21418 requires containment of the Cursor SDK's asynchronous WriteIterableClosedError so it does not terminate the server with exit code 1. CursorSdk.ts adds a process-level rejection guard that accepts only an Error with the exact name WriteIterableClosedError, logs a fixed message, and returns without calling process.exit. Other rejections retain the existing exit behavior. CursorSdk.test.ts verifies both the non-exit case and the exit-on-other-errors case.

Full details: Out of Scope Changes check

Explanation

The whole-PR diff contains only the Cursor server guard and its focused automated tests. Both changes support issue #21418. The guard remains limited to the Cursor provider and does not change web, desktop-client, mobile-client, or unrelated provider behavior.

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fix(cursor): a closed-stream write in the Cursor SDK no longer stops the server#22897

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Approvability

Thread transfer impact