diff --git a/ai/backend-context.md b/ai/backend-context.md
index 9850c44..7fc2f71 100644
--- a/ai/backend-context.md
+++ b/ai/backend-context.md
@@ -69,6 +69,9 @@ intentionally unclaimed; the built-in health endpoint is `/up`.
   relevant authorization guard instead of duplicating all business branches.
 - Place endpoint tests under `tests/Feature/<Area>/`, extend
   `Tests\TestCase`, and use `RefreshDatabase` when database state is involved.
+- Do not keep tests that only assert an obsolete column or other removed
+  schema detail is absent. Such assertions may verify a removal while it is
+  being developed, but discard them afterward and retain behavioral coverage.
 - Development and runtime use PostgreSQL through the local Unix socket.
   PHPUnit uses SQLite `:memory:` as configured in `phpunit.xml`, so feature
   tests are self-contained and do not need the worktree stack.