name	migration-writer
description	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

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 → backfill → 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.

name	migration-writer
description	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

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 → backfill → 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.

migration-writer