WRITING / Backend / AI Systems
Why I Keep AI Logic Out of Route Handlers
A practical boundary for keeping model orchestration testable as an AI backend grows.
BackendAI Systems
- FORMAT
- decision
- READ
- 6 min
- PUBLISHED
- Aug 17, 2026
- TOPICS
- Backend · AI Systems
THE TAKEAWAYHTTP is one adapter around a use case; model orchestration belongs in the use-case layer where it can be tested directly.
The convenient beginning
Putting prompts and model calls in a route handler is fast for a prototype. It also binds transport, orchestration, validation, and provider behavior into one function.
- Hard to test
- Hard to reuse
- Provider errors leak into HTTP concerns
The boundary
Routes parse requests and translate outcomes. A use-case service owns orchestration, while provider and persistence adapters sit behind interfaces.
- Transport adapter
- Application use case
- Infrastructure adapters
Why it pays off
The same workflow can run from a job, CLI, or test without pretending to be an HTTP request.