noir-migration

name: noir-migration description: Create an EF Core migration in NOIR with the correct --context flag and output directory. Use when the user asks to add, generate, create, or roll back a database migration. Prevents the common mistake of running dotnet ef migrations add without --context, which creates the migration against the wrong DbContext and corrupts the Migrations/App vs Migrations/Tenant separation.

noir-migration — Safe EF Core migrations

NOIR has two DbContexts and the CLI silently picks one if --context is omitted. Migrations end up in the wrong folder or apply to the wrong database. This skill enforces the correct invocation.

Which context?

Rule of thumb: if you're not sure, it's ApplicationDbContext. Only touch TenantStoreDbContext when modifying the Tenant / TenantStore entities themselves in NOIR.Domain/Tenancy/.

Workflow

1. Confirm with the user

Ask (unless obvious from the conversation):

• Migration name (PascalCase, describe the change): e.g. AddInvoiceEntity, AddIndexToProductSlug, BackfillCustomerTier
• Which context — App (default) or Tenant?
• Is this additive only? If it drops or renames columns, warn the user about production rollback concerns. Review CLAUDE.md Rule 4 (soft delete).

2. Pre-flight checks

# Must pass before generating migration
dotnet build src/NOIR.sln

Verify:

• Entity changes compile cleanly
• {Entity}Configuration includes TenantId in unique indexes (Rule 18)
• Soft delete filter (HasQueryFilter) preserved if entity implements ISoftDeletable

3. Generate the migration

App context (default):

dotnet ef migrations add <MigrationName> \
  --project src/NOIR.Infrastructure \
  --startup-project src/NOIR.Web \
  --context ApplicationDbContext \
  --output-dir Migrations/App

Tenant context:

dotnet ef migrations add <MigrationName> \
  --project src/NOIR.Infrastructure \
  --startup-project src/NOIR.Web \
  --context TenantStoreDbContext \
  --output-dir Migrations/Tenant

4. Review generated SQL

Open {timestamp}_{Name}.cs in the target Migrations folder. Inspect the Up/Down methods. Reject the migration if:

• It drops a column that still has production data (needs a 2-phase migration: nullable column first, backfill, then drop in next release)
• It renames a column without RenameColumn (produces DROP + CREATE which loses data — EF usually infers rename from model config, but verify)
• Foreign key OnDelete is Cascade on a SQL Server path that already has another cascade — SQL Server rejects multiple cascade paths (see gotchas_backend.md)
• Unique index is missing TenantId (Rule 18) — fails silently across tenants

5. Apply to local database

# App
dotnet ef database update \
  --project src/NOIR.Infrastructure \
  --startup-project src/NOIR.Web \
  --context ApplicationDbContext

# Tenant
dotnet ef database update \
  --project src/NOIR.Infrastructure \
  --startup-project src/NOIR.Web \
  --context TenantStoreDbContext

6. Post-apply verification

dotnet test src/NOIR.sln   # all tests must pass — integration tests will catch schema mismatches

Check the snapshot file got updated:

• App: Migrations/App/ApplicationDbContextModelSnapshot.cs
• Tenant: Migrations/Tenant/TenantStoreDbContextModelSnapshot.cs

Rollback

If the migration hasn't been committed/pushed yet:

# Rollback DB first
dotnet ef database update <PreviousMigration> --context ApplicationDbContext \
  --project src/NOIR.Infrastructure --startup-project src/NOIR.Web

# Then remove the migration file
dotnet ef migrations remove --context ApplicationDbContext \
  --project src/NOIR.Infrastructure --startup-project src/NOIR.Web

If already pushed/merged: create a NEW forward migration that reverses the change. Never edit or delete a committed migration.

Common mistakes this skill prevents

• Running dotnet ef migrations add X without --context → picks first DbContext alphabetically, migration lands in wrong folder
• Forgetting --output-dir → migration lands in Migrations/ root instead of App/ or Tenant/ subdirectory
• Unique index without TenantId → silently fails for second tenant with same value (Rule 18)
• Cascade delete conflict on SQL Server multi-path FK
• Dropping a NOT NULL column with existing data — migration applies clean locally but fails in prod
• Renaming a column in the entity without running migration — model snapshot drifts from DB
• Editing a committed migration instead of creating a forward one