[OrcaWin]

Problem

On Windows, every Codex agent hook failed with hook exited with code 1 starting in v1.4.138:

• SessionStart hook (failed)   error: hook exited with code 1
• UserPromptSubmit hook (failed)  error: hook exited with code 1
• Stop hook (failed)  error: hook exited with code 1

Root cause

PR #8430 rewrote wrapWindowsCmdHookCommand so the hook command became a cmd compound:

if exist "path\." (drain) else if exist "path" (call "path") else (drain)

Codex/Antigravity/Devin launch the hook command as a program (argv[0]), not through cmd.exe. The compound's argv[0] is the cmd builtin if, which is not an executable, so the launch fails every time. Verified empirically on Windows: a bare .cmd is directly spawnable (exit 0) via the CreateProcess family these agents use, while the if-led form throws ENOENT. cmd /c interprets the compound fine — which is exactly why it slipped through (tests exercised it via cmd /c, not direct spawn).

Affected all three direct-spawn agents (Codex, Antigravity, Devin); Codex is just the one that got reported.

Fix

Revert the cmd-safe fast path to the bare, directly-spawnable .cmd path — the proven pre-#8430 form. A cmd-builtin drain and direct-spawnability are mutually exclusive, and nesting cmd.exe /d /c breaks large-payload draining. The missing-script stdin drain stays on the encoded-PowerShell fallback (used for spaced/non-ASCII paths).

Zero-regression review

• Faithful revert: character-for-character the line fix(agent-hooks): drain stdin before hook script early exits so agents never hit EPIPE #8430 changed; bare-path behavior is proven-in-production.
• Upgrade self-heals: startup install() unconditionally rewrites the command + Codex trust entry and sweeps the old compound (matcher is wrapper-agnostic); no user left with a broken hook.
• Scope: Windows-local only; SSH/WSL/remote (POSIX) untouched. Claude (Git Bash) and Copilot/Droid (PowerShell) launchers unaffected.
• Trade-off (accepted): the fast path no longer drains a stale/missing managed script — a rare edge that was itself the regression vector; the encoded fallback still drains.

Tests

• installer-utils.test.ts: bare-path contract + a platform-independent regression guard (launcher must resolve to a real file, never a cmd-builtin fragment).
• Updated the lifecycle test + agent-hook-stdin-lifecycle.md doc, fixed a stale Devin comment.
• tsc + oxlint clean.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro

Run ID: df90699d-c40c-4644-bc1f-fc833f439a39

📥 Commits

Reviewing files that changed from the base of the PR and between d0ad118 and 954b430.

📒 Files selected for processing (5)

• docs/reference/agent-hook-stdin-lifecycle.md
• src/main/agent-hooks/installer-utils.test.ts
• src/main/agent-hooks/installer-utils.ts
• src/main/agent-hooks/managed-hook-stdin-lifecycle.test.ts
• src/main/devin/hook-settings.ts

🚧 Files skipped from review as they are similar to previous changes (5)

• src/main/devin/hook-settings.ts
• src/main/agent-hooks/managed-hook-stdin-lifecycle.test.ts
• src/main/agent-hooks/installer-utils.test.ts
• docs/reference/agent-hook-stdin-lifecycle.md
• src/main/agent-hooks/installer-utils.ts

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📝 Walkthrough

Walkthrough

Updated Windows hook command wrapping so safe .cmd paths are directly spawnable and non-safe paths use the encoded launcher. Removed the Windows drain contract from this wrapper, adjusted missing-script lifecycle tests, and documented that bare .cmd launches surface missing scripts as launch failures while interpreter-based launchers handle stdin draining.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Description check	⚠️ Warning	The description covers the fix and tests, but it misses required template sections and explicit cross-platform/security review details.	Add the missing Screenshots, AI Review Report, Security Audit, and Notes sections, and explicitly confirm macOS/Linux/Windows compatibility checks.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly summarizes the main change: making the Windows cmd hook launcher directly spawnable to fix the regression.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
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.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

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