- Add batch_id (UUID, nullable, indexed) and target_label (String 255,
nullable) columns to the Session model
- Manual Alembic migration 6e8128ef2aa8 applies both columns
- POST /sessions/batch creates one session per target for maintenance
flows; rejects empty targets (422) and non-maintenance trees (400)
- SessionResponse schema exposes batch_id and target_label
- 3 new integration tests, all 540 tests pass
Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>