Write safe, reversible database migrations for this repo's conventions. Use for any schema change.
Installation
Install with Codex or Claude Copy this prompt, paste it into Codex, Claude, or another assistant, and let it review the skill page and install it for you.
Write safe, reversible database migrations for this repo's conventions. Use for any schema change.
when_to_use
add/alter a table, column, index, or constraint
targets
["*"]
Migration Writer
Read the current schema first. Match the repo's migration tool and naming (NNN_<verb>_<noun>).
Write BOTH up and down. A migration you can't reverse is a migration you can't deploy safely.
Live-safe: on a hot table, adding a NOT NULL column with no default, or an index without CONCURRENTLY, takes a blocking lock. Split into steps: add nullable โ backfill โ add constraint.
Backfill large tables in batches, not one statement.
Never edit an already-merged migration - add a new one.
Test with a dry-run before committing. Output the migration + the exact deploy order.