fix(desktop): restore auto-restart of stale daemon in dev mode

[Kitenite]

Summary

• Restores the mtime-based detection that automatically restarts the terminal daemon when the script is rebuilt in dev mode
• Fixes connection errors that occur when the daemon gets out of sync with the app after code changes
• Partially reverts fix(desktop): remove auto-restart of terminal daemon in dev mode #897, keeping the pty-subprocess.ts fix (waiting for tree-kill callback)

Test plan

• Run desktop app in dev mode
• Make a change to terminal-host code and let it rebuild
• Verify daemon automatically restarts on next terminal connection
• Verify no connection errors occur

Summary by CodeRabbit

• Chores
  • Enhanced daemon restart handling during development to automatically detect and recover from script rebuilds, improving stability when internal components change.

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[coderabbitai]

📝 Walkthrough

Walkthrough

A development mode enhancement that detects when the daemon script has been rebuilt and automatically restarts the daemon. The implementation tracks the daemon script's modification time and triggers a restart during connection attempts if changes are detected.

Changes

Cohort / File(s)	Summary
Daemon Script Staleness Detection apps/desktop/src/main/lib/terminal-host/client.ts	Added SCRIPT_MTIME_PATH constant, isDaemonScriptStale() and saveDaemonScriptMtime() private methods for tracking daemon script modifications. Integrated staleness check into dev-mode connection flow to detect rebuilt daemons, kill via PID file, spawn replacement, and record new mtime. Applied same logic in both dev branches of connect-and-authenticate workflow.

Estimated Code Review Effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

• fix(desktop): remove auto-restart of terminal daemon in dev mode #897 — Removes the SCRIPT_MTIME_PATH and daemon restart logic introduced here, indicating a subsequent revert of this functionality.
• fix(desktop): fix terminal daemon stuck state and add restart button #847 — Implements the identical daemon script staleness detection and restart mechanism in the same file.
• feat(desktop): terminal persistence via daemon process #619 — Introduces foundational TerminalHostClient implementation in the modified file.

Poem

🐰 A daemon grows stale, the script's been rebuilt,
We check its timestamp with whisker-twitched guilt,
If mtime has shifted, we swiftly restart,
A fresh spawn awaits—development's art! 🔄✨

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title 'fix(desktop): restore auto-restart of stale daemon in dev mode' accurately and clearly describes the main change: restoring auto-restart functionality for a stale daemon in development mode.
Description check	✅ Passed	The pull request description includes a clear summary of changes, explains the problem being fixed, and provides a detailed test plan. It adequately covers the purpose and validation approach for the changes.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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✨ Finishing touches

• 📝 Generate docstrings

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[github-actions]

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