PHP Migration Manager (Laravel)

"A migration you cannot roll back is a deployment you cannot reverse."

"Schema changes are the riskiest deploys you make. Treat them that way."

Core Philosophy

Laravel migrations are version control for the database. This skill manages their full lifecycle — create → review → test rollback → apply → verify — with safety gates between each step. A migration is code that runs against production data exactly once per environment; a mistake is not a failed build, it is corrupted or destroyed data.

The central discipline is reversibility. Every up() has a matching down() that returns the schema to its prior state. The central risk is destructive change on a live table: dropping a column, renaming, or adding a non-nullable column with no default while the old code still runs. For those, the expand-contract pattern (a.k.a. parallel change) replaces a single dangerous migration with a safe sequence across multiple deploys.

Non-Negotiable Constraints:

1. Every up() has a tested down() — rollback is verified, not assumed
2. No destructive operation without expand-contract on a table with live traffic
3. migrate:fresh / migrate:refresh / wipe are forbidden against any shared or production DB
4. Review before apply — a migration is read and risk-rated before artisan migrate runs
5. Backfills are batched — never one unbounded UPDATE on a large table
6. Indexes on large tables are added concurrently where the driver supports it

The full domain principles, knowledge-base lookups, and anti-pattern catalog live in references/domain-principles-and-anti-patterns.md. The AI discipline rules and error-recovery procedures live in references/discipline-and-recovery.md.

Workflow

Phase 1: CREATE

php artisan make:migration create_orders_table          # new table
php artisan make:migration add_phone_to_users_table     # alter

Write both up() and down(). Prefer additive, nullable changes. See references/migration-safety-checklist.md for column-by-column guidance.

Phase 2: REVIEW

Read the migration and risk-rate it before applying. Classify each operation as SAFE / CAUTION / DANGEROUS using references/dangerous-operations.md. Produce the Migration Review report (see references/output-templates.md). DANGEROUS operations require an expand-contract plan.

Phase 3: TEST ROLLBACK

Apply and immediately roll back in a scratch database to prove down() works.

php artisan migrate --database=scratch
php artisan migrate:rollback --database=scratch --step=1
php artisan migrate:status --database=scratch

If down() errors or leaves residue, fix it before going further.

Phase 4: APPLY

php artisan migrate --step          # records each migration separately for granular rollback
php artisan migrate:status

Phase 5: VERIFY

Confirm the schema, run the backfill (batched), and re-run the app's test suite. Produce the Post-Apply Verification report (see references/output-templates.md).

State Block

<php-migration-manager-state>
  phase: CREATE | REVIEW | TEST_ROLLBACK | APPLY | VERIFY | COMPLETE
  migration: [migration file]
  laravel_version: [detected]
  operation_class: SAFE | CAUTION | DANGEROUS
  expand_contract_required: true | false
  down_method_present: true | false
  rollback_tested: true | false
  backfill_required: true | false
  applied: true | false
  last_action: [description]
</php-migration-manager-state>

Output Template

Two reports drive the lifecycle gates; full markdown templates are in references/output-templates.md:

• Migration Review — operation(s), risk class, reversibility, findings table, rollback plan, and the apply/backfill/expand-contract decision. Produced in Phase 2 before any apply.
• Post-Apply Verification — a checklist confirming the migration ran, schema matches intent, batched backfill reconciled, tests green, rollback rehearsed, and no long lock observed. Produced in Phase 5.

Integration with Other Skills