ruff F401 failed the deploy: `import pytest` in test_event_study.py outlived the pytest.approx assertion it was added for. Compiling the migration for Postgres while checking that turned up a second defect worth fixing while the table is still empty. It created a unique constraint *and* a plain index on effective_date, while the model declares `unique=True, index=True` -- one unique index. Both enforce uniqueness, but the pairing left a redundant second index on the column and a permanent diff for autogenerate to keep trying to reconcile. Now renders byte-for-byte what the model declares, matching RegimeSnapshot.date. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>