Choose the right framework

Tenchi focuses on backend changes that humans and agents can understand, implement, and verify. Its small application model combines typed contracts, plain use cases, and explicit ports with inspection, generation, and compatibility evidence.

At a glance

Framework	Strongest fit	Main tradeoff
FastAPI	Typed HTTP APIs with interactive documentation	Built-in API ergonomics and dependency injection; application architecture remains a project choice
Starlette	Small ASGI toolkit and low-level control	The application supplies its contract and use-case conventions
Litestar	Typed ASGI applications with integrated capabilities	More built-in features and framework concepts
Django Ninja	Typed APIs inside the Django ecosystem	Uses Django's infrastructure and conventions
Tenchi	Contract-first backends with a shared development workflow for people and agents	Prescribed source structure and explicit wiring; infrastructure integrations remain application-owned

Choose Tenchi when

People and agents need predictable files, mutation previews, structured diagnostics, and reviewable evidence for backend changes.
The server and a Python client should share one executable contract.
API compatibility must be checked in CI against a historical baseline.
Business behavior should be reusable from HTTP, workers, scripts, and direct tests, with input adapters where an entrypoint needs a different function signature.
You want composition-time signature failures and explicit dependency wiring.
You want a small application model while retaining inspection, generation, and verification as part of everyday development.

Choose another framework when

You need WebSockets, HTML templates, an ORM, admin UI, or background runtime as first-class framework features.
You want built-in dependency injection, authentication primitives, or a broader integration surface.
You need to choose your own application layout instead of adopting Tenchi's feature and composition conventions.
You need older Python versions; Tenchi requires Python 3.12 or newer.

Tenchi and Starlette

Tenchi exposes Starlette where that is useful. create_app() returns a Starlette application, accepts Starlette middleware, and allows explicitly declared passthrough responses for streaming, files, and redirects. Tenchi adds contract ownership around those primitives rather than replacing the ASGI ecosystem.

Tenchi and FastAPI

Both frameworks use Python annotations and Pydantic at the boundary. FastAPI optimizes for concise route declaration and ecosystem reach. Tenchi separates the contract from the use case so the same application function is not owned by HTTP, and it includes a contract-driven runtime client and conservative OpenAPI compatibility analysis.

The tradeoff is explicit source structure and application-owned wiring. Evaluate it by making a representative change: find the affected behavior, change its contract, implement and test it, then review the compatibility evidence. That shows whether the conventions help your team more clearly than the size of the first endpoint example.