fix(test): make subagent sleep hook portable on Windows

[echoVic]

Problem

The Windows CI gate on main has been failing on the subagent_contract test binary (all 12 tests reported failed, e.g. run 30501966908).

Root cause

async_subagent_completes_after_launching_exec_process_exits writes a pre_model_call hook that runs sleep 0.4:

• On Windows the resolved host shell is PowerShell (pwsh/powershell.exe), where sleep is an alias for Start-Sleep.
• Windows PowerShell 5.1's Start-Sleep rejects the fractional 0.4 seconds argument (only PowerShell 6.2+ accepts a double), and cmd.exe has no sleep at all.
• The hook therefore fails → orca exec exits 1 instead of 0 → the test panics (left: Some(1), right: Some(0)).

Because every test in the file shares one static Mutex, that first panic poisons the lock, cascading into all other tests failing with PoisonError and masking the real cause. (Evidence: the suite "finished in 1.70s", proving the 0.4s hook never actually slept.)

Fix

1. Portable hook command — emit sleep {seconds} on Unix and Start-Sleep -Milliseconds {ms} (integer, valid on both PowerShell 5.1 and 7) on Windows, mirroring the existing #[cfg(unix)]/#[cfg(windows)] hook idiom in tests/exec_jsonl.rs.
2. Poison resilience — recover from a poisoned test lock so a single failure is reported on its own merits instead of cascading across the suite.

Verification

• cargo test --test subagent_contract → 12/12 pass on macOS (host).
• The #[cfg(windows)] branch was compiled in isolation and produces Start-Sleep -Milliseconds 400.
• Full cross-compile to x86_64-pc-windows-msvc is blocked locally by ring's C toolchain requirement (no Windows C headers on this Mac); the Windows CI gate on this PR is the authoritative check.

Summary by CodeRabbit

• Bug Fixes
  • Improved test reliability by recovering from locking errors instead of failing immediately.
  • Updated generated hook commands to use platform-appropriate sleep syntax on Unix and Windows.

[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: eaaf4443-ec29-4b03-bc41-f1d8ae46cfe2

📥 Commits

Reviewing files that changed from the base of the PR and between d5a23be and c8fccec.

📒 Files selected for processing (1)

• tests/subagent_contract.rs

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📝 Walkthrough

Walkthrough

The test helpers now recover from poisoned mutex locks and generate operating-system-specific pre-model hook sleep commands for Unix and Windows.

Changes

Subagent contract test robustness

Layer / File(s)	Summary
Poisoned lock recovery tests/subagent_contract.rs	subagent_cli_test_guard recovers the inner mutex guard when the lock is poisoned instead of failing with expect.
Platform-specific sleep hook configuration tests/subagent_contract.rs	write_sleep_hook_config generates Unix sleep commands and Windows PowerShell Start-Sleep commands in config.toml.

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

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly matches the main change: making the subagent sleep hook portable on Windows.
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

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/windows-subagent-hook-flake

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