fix(server): restore Windows terminal startup after node-pty upgrade

[SegFaultZero]

Why

Terminals on Windows are broken after the node-pty upgrade: opening a terminal displays "[terminal] The environment request failed." instead of a usable shell.

After #13748 upgraded node-pty from 1.1.0 to 1.2.0-beta.15, Windows spawn initially returns PID 0 while process creation is pending. T3 stored that value before node-pty assigned the real PID. Clients rejected the terminal snapshots because the contract accepts only a positive PID or null.

What changed

The node-pty adapter waits for a valid Windows PID before completing spawn. It uses the private ready_datapipe event introduced by microsoft/node-pty#885, which deferred Windows process creation to avoid blocking on named pipes. This supports silent processes without polling or waiting for output. Unix spawning does not perform this readiness wait.

The adapter captures exits immediately after native spawn and replays them to late subscribers, preserving exits across the readiness handoff. The manager establishes the running state before subscribing and publishes startup before draining replayed events. Its existing PID-based event guards are unchanged.

Startup failures remain PtySpawnError. Cancellation uses the private Windows agent because public kill() waits for output. Cleanup exceptions are logged without replacing the original failure or interruption. JSDoc explains the compatibility hooks and links their upstream changes.

Validation

• 103 focused tests passed: vp test run src/terminal/NodePtyAdapter.test.ts src/terminal/Manager.test.ts from apps/server, including forced scheduler yielding, exit replay, event ordering, cancellation, and cleanup failures.
• Server typecheck and adapter lint passed. Broader targeted lint reported one existing warning in Manager.test.ts.
• Native Windows cleanup checks confirmed that cancellation before readiness stops the worker without creating a child, and cleanup after creation terminates the captured child PID.
• The earlier desktop build succeeded on Windows, and the reporter confirmed working terminals in that build. The latest review fixes have focused test and typecheck coverage; the desktop build was not repeated.

Implemented with GPT-6-Astra through the Codex harness.

Closes #13937.

Summary by CodeRabbit

• Bug Fixes
  • Improved the reliability of Windows terminal startup when process information is delayed.
  • Terminal startup now handles early connection or process failures more cleanly, including stopping pending startup when it is canceled.

[macroscopeapp]

Approvability

Verdict: Approved at 6c680ef

Macroscope's review found this PR approvable — This is a focused Windows-only compatibility fix in the node-pty adapter that waits for deferred PTY readiness and cleans up failed or cancelled startup, while leaving Unix behavior unchanged. Targeted tests cover readiness, failures, cancellation, and existing termination semantics.

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📒 Files selected for processing (4)

• apps/server/src/terminal/Manager.test.ts
• apps/server/src/terminal/Manager.ts
• apps/server/src/terminal/NodePtyAdapter.test.ts
• apps/server/src/terminal/NodePtyAdapter.ts

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📝 Walkthrough

Walkthrough

The PTY adapter retains exit events that occur during Windows startup readiness and replays them to later subscribers. The terminal manager queues events received during listener setup until after it publishes the startup or restart event.

Changes

PTY exit handling and startup ordering

Layer / File(s)	Summary
Retain PTY exits across startup readiness apps/server/src/terminal/NodePtyAdapter.ts, apps/server/src/terminal/NodePtyAdapter.test.ts	The adapter wraps the native PTY before Windows PID readiness checks. The wrapper retains the first exit event, replays it to late subscribers, and disposes its native exit subscription. Startup cancellation failures are logged. Tests cover readiness failures, exit handoff, late subscription, and cleanup.
Publish startup before draining PTY events apps/server/src/terminal/Manager.ts, apps/server/src/terminal/Manager.test.ts	The manager queues events received during listener setup and drains them after publishing the startup or restart event. A regression test checks that a replayed exit follows started and appears in the attach snapshot.

Priority: ➖ Normal

Estimated code review effort: 3 (Moderate) | ~25 minutes

Change: Bug fix

Suggested reviewers: juliusmarminge

Merge Risk: ⚪ Minimal · up to 9d6bd

The startup and exit-ordering paths appear ready to merge after normal checks.

Security Architecture Review

Security architecture risk: 🔵 Low · up to 9d6bd

The change addresses a Windows terminal startup failure while preserving the existing terminal interface. No new access path or privilege was identified. The main remaining uncertainty is how process cleanup behaves when native cancellation fails.

Retained concerns
No architecture-level concerns identified.

Security review details

Security Blast Radius

• inferred — The affected production boundary is the server-owned terminal process lifecycle and the events delivered to its existing consumers. The inspected changes do not add an exported process API or a new privilege-bearing dependency; the full external terminal authorization chain was not traced.

Trust Boundaries and Controls

• observed — The adapter requires a positive integer Windows PID before returning a process. The manager checks session status and expected PID before accepting process events, limiting stale callbacks after ownership changes.

Resilience and Maintainability Implications

• inferred — If the private Windows cancellation call throws while a child remains alive, source-level cleanup provides no second termination path or retained owner. That conditional failure path predates this PR; whether it leaves a live child in production is unverified.

Hardening Proposals

• proposed — Validate native process liveness after a cancellation exception and, if a child can remain alive, add a bounded fallback or cleanup owner. This addresses the pre-existing conditional failure path rather than a verified regression.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 2 functions across 4 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Title check	✅ Passed	The title clearly and concisely describes the main change: restoring Windows terminal startup after the node-pty upgrade.
Description check	✅ Passed	The description explains why the issue occurred, what changed, how the change was validated, and includes a UI screenshot for the reported terminal failure. It does not include the template checklist,…

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Actionable comments posted: 1

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Inline comments:
In @apps/server/src/terminal/NodePtyAdapter.ts:
- Around line 109-110: Update NodePtyAdapter.spawn’s readiness handoff to retain
any exit event received before the returned process is subscribed to. Make
NodePtyProcess.onExit replay the retained exit state to new subscribers, while
preserving normal node-pty exit delivery.

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• apps/server/src/terminal/NodePtyAdapter.test.ts
• apps/server/src/terminal/NodePtyAdapter.ts

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[SegFaultZero]

Follow-up to the review summary, addressed in 9d6bd81:

• Cleanup exceptions now produce a warning with PID and cause while preserving the original spawn error or interruption. Tests cover both paths. Native Windows checks verified that pre-readiness cancellation stops the worker without creating a child, and cleanup after creation terminates the captured PID. Cleanup remains best-effort if native termination itself fails.
• The PID-based manager guards already existed in the PR base and remain unchanged. This PR did not replace process-object guards with PID guards. The latest manager changes establish state before subscribing and preserve startup/exit ordering.
• The readiness and cancellation helpers now have JSDoc, retaining the upstream links.

All 103 focused tests pass, as do server typecheck and adapter lint.