- Move mid-file pydantic/uuid imports to top of sessions.py
- Add can_access_tree, is_active, and draft status guards to batch_launch_sessions
- Remove notes field from _BatchTarget to keep API clean
- Add max_length=100 cap to targets list in _BatchLaunchRequest
- Hoist tree_snapshot computation above the session creation loop
- Replace N db.refresh() calls with a single bulk select after flush
- Add test_batch_launch_requires_auth and test_batch_launch_rejects_draft_tree tests
- Fix trailing slash on /api/v1/trees/ URL in new test (caused 307 redirect)
Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>