Must Fix Before Apply

Review the selected migration plan and code for production safety.

Focus on forward compatibility, rollback feasibility, data integrity, and operational risk.
Assume a live system with concurrent reads and writes.

Output exactly in this format:

## Must Fix Before Apply

List migration blockers.

For each item:

- file/section
- failure mode in one sentence
- concrete safe fix

## Should Fix Soon

List non-blocking risks with meaningful impact.

## Rollback Plan Check

- rollback feasible: yes | no | partial
- missing rollback prerequisites
- specific rollback procedure recommendation

## Zero-Downtime Check

- compatible with old and new app versions: yes | no | partial
- lock/contention risk: low | medium | high
- required phased rollout steps

## Test Gaps

List missing migration tests (forward, backward, data invariants, load-sensitive paths).

## Final Recommendation

- apply now | apply after fixes
- biggest remaining risk in one sentence