mygit/.agents/skills/create-database-migration/SKILL.md

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Create database migration

Create a database migration to add a table, add columns to an existing table, add a setting, or otherwise change the schema of Ghost's MySQL database. Use this skill whenever the task involves modifying Ghost's database schema — including adding, removing, or renaming columns or tables, adding new settings, creating indexes, updating data, or any change that requires a migration file in ghost/core. Also use when the user references schema.js, knex-migrator, the migrations directory, or asks to "add a field" or "add a column" to any Ghost model/table. Even if the user frames it as a feature or Linear issue, if the implementation requires a schema change, this skill applies.

Create Database Migration

Instructions

1. Create a new, empty migration file: cd ghost/core && pnpm migrate:create <kebab-case-slug>. IMPORTANT: do not create the migration file manually; always use this script to create the initial empty migration file. The slug must be kebab-case (e.g. add-column-to-posts).
2. The above command will create a new directory in ghost/core/core/server/data/migrations/versions if needed, create the empty migration file with the appropriate name, and bump the core and admin package versions to RC if this is the first migration after a release.
3. Update the migration file with the changes you want to make in the database, following the existing patterns in the codebase. Where appropriate, prefer to use the utility functions in ghost/core/core/server/data/migrations/utils/*.
4. Update the schema definition file in ghost/core/core/server/data/schema/schema.js, and make sure it aligns with the latest changes from the migration.
5. Test the migration manually: cd ghost/core && pnpm knex-migrator migrate --v {version directory} --force
6. If adding or dropping a table, update ghost/core/core/server/data/exporter/table-lists.js as appropriate.
7. If adding or dropping a table, also add or remove the table name from the expected tables list in ghost/core/test/integration/exporter/exporter.test.js. This test has a hardcoded alphabetically-sorted array of all database tables — it runs in CI integration tests (not unit tests) and will fail if the new table is missing.
8. Run the schema integrity test, and update the hash: cd ghost/core && pnpm test:single test/unit/server/data/schema/integrity.test.js
9. Run unit tests in Ghost core, and iterate until they pass: cd ghost/core && pnpm test:unit

Examples

See examples.md for example migrations.

Rules

See rules.md for rules that should always be followed when creating database migrations.