Introduction
A working demonstration is not the same as a production-ready RAG system. A full path may succeed from upload to answer while important failures remain hidden in permissions, migrations, concurrency, retrieval quality, event persistence, or model behavior. The correct final stage is not deployment by default. It is systematic validation and an honest assessment of maturity.
Testing should begin early. Waiting until all modules are complete creates a large and expensive regression problem. Each new feature can break an earlier feature, especially when AI coding agents make broad changes across the front end, back end, database, and configuration.
A regression suite should be derived from the requirements and saved implementation plans. Each feature needs explicit acceptance criteria. The suite can cover:
Authentication and identity:
- The login page loads.
- Valid users can sign in and sign out.
- Two users see isolated data.
- Administrator-only settings are unavailable to ordinary users.
Chat and persistence:
- A thread is created.
- A response streams.
- The stream can be cancelled.
- A second message can be sent.
- Messages persist after refresh.
- Dynamic titles are created.
- Older threads reload correctly.
- Tool and subagent events remain visible after reload.