## Summary
- The `MigrateModelIdsToCompositeFormat` migration was setting
`agent.modelId = NULL`, but the column has a `NOT NULL` constraint —
causing the migration to fail on deploy.
- Fixed by setting `modelId` to the `'default-smart-model'` sentinel
value instead of NULL. The runtime already resolves this sentinel
dynamically via `getEffectiveModelConfig` / `isDefaultModelSentinel`, so
agents correctly fall back to the admin-configured smart model.
## Test plan
- [ ] Run `npx nx run twenty-server:database:migrate:prod` — migration
should complete without errors
- [ ] Verify agents still resolve to the correct model at runtime
(sentinel → `getDefaultPerformanceModel()`)
Made with [Cursor](https://cursor.com)
