refactor(daemon): name stale session recovery boundary

[honor2030]

Summary

• Extract the daemon's stale current-session retry check into a named recovery boundary.
• Add tests that make the safe recovery contract explicit: only calls using the daemon's current default session should re-attach and retry.
• Cover the existing re-attach + retry behavior as the first small implementation slice for the lifecycle design proposal.

Refs #352

Test Plan

• RED: uv run --with pytest --with pillow python -m pytest tests/unit/test_daemon.py::test_recoverable_current_session_error_requires_current_default_session -q failed before the implementation with AttributeError: module 'browser_harness.daemon' has no attribute '_is_recoverable_current_session_error'.
• GREEN: uv run --with pytest --with pillow python -m pytest tests/unit/test_daemon.py -q → 11 passed.
• GREEN: uv run --with pytest --with pillow python -m pytest tests -q → 98 passed.
• GREEN: uv run python -m compileall -q src tests.
• GREEN: uv pip check --python .venv/bin/python → all installed packages compatible.
• GREEN: uv run --with ruff python -m ruff check --select B tests/unit/test_daemon.py → all checks passed.

---

Summary by cubic

Named a clear recovery boundary for stale current-session errors in the daemon and added tests to lock down the behavior. Only calls using the daemon’s current default session will auto re-attach and retry, progressing #352.

• Refactors
  • Extracted _is_recoverable_current_session_error with STALE_SESSION_MARKERS.
  • Auto re-attach + retry only when sid matches the current default session; browser-level and explicit session calls surface the original error.
  • Added unit tests to define the contract and cover the re-attach + retry path.

^{Written for commit d0f6578. Summary will update on new commits.}

[cubic-dev-ai]

No issues found across 2 files