# Contract Delta: 005-postgres-database-replacement

> For the complete documentation index, see [llms.txt](https://deploy-preview-472--lucky-concha-f3599f.netlify.app/llms.txt).

Parent state: `004-containerized-compose-runtime`

## OpenAPI Changes

*   No REST OpenAPI contract changes.

## Event Contract Changes

*   No trade-feed Socket.IO event contract changes in this state.

## Compatibility Notes

*   UI-visible behavior and endpoint contracts are intentionally preserved.
*   Persistence backend contract changes are internal (SQL engine + init process) and do not change REST payload shapes.
*   Account sequence semantics are preserved using PostgreSQL `accounts_seq`.