fix(acp): bound git attribution branch lookup

[KonghaYao]

Summary by CodeRabbit

• Bug Fixes

  • Prevented prompts from silently hanging when Git branch detection is slow or unresponsive.
  • Added a one-second limit for branch detection, allowing the agent to continue if it times out.
  • Ensured stalled branch-detection processes are terminated safely.

• Documentation

  • Updated middleware documentation with the revised attribution and branch-detection behavior.
  • Added a Windows-specific issue record and verification details.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 3083470c-b990-4d0e-87b2-f42f49e4619c

📥 Commits

Reviewing files that changed from the base of the PR and between dea290e and cdc6ded.

📒 Files selected for processing (4)

• docs/code-index/peri-middlewares.md
• peri-middlewares/src/attribution/mod.rs
• peri-middlewares/src/attribution/mod_test.rs
• spec/issues/2026-08-29-windows-acp-prompt-silently-hangs.md

Included review availability: Your plan provides up to 2 included reviews per hour; 0 remain after this review.

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📝 Walkthrough

Walkthrough

The change adds a one-second asynchronous timeout to Git branch detection. It configures subprocess cleanup on timeout, adds cross-platform lifecycle tests, and updates the middleware index and issue specification.

Changes

Git branch timeout

Layer / File(s)	Summary
Bounded branch probe peri-middlewares/src/attribution/mod.rs	The Git branch probe uses null stdin, piped output and error streams, kill_on_drop(true), and a one-second timeout.
Branch probe regression coverage peri-middlewares/src/attribution/mod_test.rs, docs/code-index/peri-middlewares.md, spec/issues/2026-08-29-windows-acp-prompt-silently-hangs.md	Tests verify trimmed output and termination of a timed-out subprocess. The code index and issue specification describe the updated behavior.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Merge Risk: ⚪ Minimal · up to cdc6d

The PR bounds Git branch detection so a hanging lookup no longer blocks attribution indefinitely, while preserving the existing fallback behavior. No actionable merge-blocking risk remains after normal checks and review.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 50.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 14 functions across 2 files. (2 skipped: …	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: adding a time bound to the Git attribution branch lookup to prevent hangs.
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.

Full details: Docstring Coverage

Explanation

Docstring coverage is 50.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 14 functions across 2 files. (2 skipped: 2 unsupported.)

• Fix all pre-merge checks with AI

✨ Finishing Touches 💡 1

📝 Generate docstrings 💡

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch codex/fix-windows-acp-git-attribution-hang

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