diff --git a/ai/backend-context.md b/ai/backend-context.md
index 34729b2..3395a52 100644
--- a/ai/backend-context.md
+++ b/ai/backend-context.md
@@ -40,11 +40,14 @@ intentionally omitted here - update this section as entities land.
 
 ## Migrations
 
-- This project is not in production. By default, schema changes should update
-  the relevant create-table migration so migrations describe the current desired
-  schema from scratch.
-- Do not add alter-table or data-backfill migrations unless the user explicitly
-  asks for production-style migration safety.
+- This project is in production. Never edit, delete, rename, or reorder an
+  existing migration file. Every schema change must use a new forward
+  migration.
+- Production migrations must preserve existing data, include any required
+  backfill, and define a safe rollback.
+- Plan schema changes for the deployment order and for compatibility between
+  the old and new application versions. Use expand/backfill/contract sequencing
+  when a single compatible migration is not safe.
 - Put seed data in seeders, not migrations.
 
 ## PHP rules