ef-migration

name	ef-migration
description	Create, review, and apply an EF Core migration safely. Use when the user wants to add a migration, change the database schema, add/modify entity properties, or asks about database changes.
argument-hint	[MigrationName]
allowed-tools	Bash(dotnet ef *), Bash(dotnet build*), Read, Grep, Glob

EF Core Migration Procedure

Follow every step in order. Never skip the review step.

1. Verify the model change first. Confirm the entity and its IEntityTypeConfiguration<T> are updated and the solution builds: dotnet build --nologo
2. Check for pending migrations that were never applied: dotnet ef migrations list --project src-or-Data-project. If unapplied migrations exist, ask the user whether to apply or fold changes before adding another.
3. Generate the migration with a PascalCase, intent-revealing name (e.g. AddBookRatingTable, not Update1): dotnet ef migrations add $ARGUMENTS --project <Data project> --startup-project <Api project>
4. Review the generated migration — read the new file and check for:
   • Unintended column drops or renames (EF sees renames as drop+add; use RenameColumn manually only via a new migration, never by editing)
   • Missing max lengths on new string columns
   • Cascade delete behavior you did not intend
   • Data loss warnings emitted by the tool
5. Report the review findings to the user before applying anything.
6. Apply only with explicit user confirmation: dotnet ef database update --project <Data project> --startup-project <Api project>
7. Never hand-edit existing migration files or the model snapshot. To fix a bad unapplied migration: dotnet ef migrations remove, fix the model, regenerate.

Rollback

To revert the database to a previous state: dotnet ef database update <PreviousMigrationName>, then dotnet ef migrations remove for each unapplied migration on top.