## Code Review: PASS
### Changes Reviewed
**File: app/models/ticket.rb**
- `approve` event: Now allows transitions from all 7 states (backlog, todo, in_progress, pending_audit, review, pending_approval, blocked) → done
- Excludes: `done`, `cancelled` (correct - cannot approve already done or cancelled tickets)
- Guard: `all_subtasks_completed?` preserved ✓
- After callback: `completed_at` set ✓
- `cancel` event: Now allows transitions from all 8 states (backlog, todo, in_progress, pending_audit, review, pending_approval, done, blocked) → cancelled
- Excludes: `cancelled` (correct - cannot cancel already cancelled tickets)
**File: spec/models/ticket_spec.rb**
- Added 5 new tests for approve from: backlog, todo, in_progress, pending_audit, blocked
- Added 4 new tests for cancel from: pending_audit, review, pending_approval, done
- All 46 tests pass ✓
### Acceptance Criteria Met
- ✓ cancel transition available from all states (except cancelled)
- ✓ approve transition available from all states (except done/cancelled)
- ✓ Tests added for global cancel/approve
- ✓ No breaking changes to existing workflow
### Verification
- State machine correctly covers all 9 possible states
- PO override commands properly bypass normal workflow constraints
- Guard conditions preserved
- All existing tests continue to pass