Ecto Migration Playbook

HARD-GATE

• A migration plan and rollback story are documented before any migration is written.
• Schema changes and data backfill are never combined in the same migration.
• A test that depends on the new schema/constraint fails before the migration is applied and passes after.
• The mix ecto.migrate → mix ecto.rollback → mix ecto.migrate cycle must succeed.
• mix format --check-formatted, mix credo --strict, and the full mix test suite are green.
• HITL approval is obtained for production-impacting locks.

When to use

Any schema change: tables, columns, indexes, constraints.

Atomic skills this playbook loads