# flare.openapi.from_router

> A module of flare_mlake's API.

Derive an :class:`OpenApiSpec` from a runtime :class:`Router`.

Walks the router's registered route table -- method + path template +
path-parameter names -- and builds a spec whose ``paths`` group by
template with one operation per method. Path parameters (``:name``
segments) surface as required ``path`` parameters; every operation gets a
default ``200`` response.

ponytail: this derives the *structural* surface the runtime Router
retains (methods, path templates, path params). Request/response body
schemas and query/header parameters live on the typed ``Extracted[H]``
handler, which the Router erases at registration -- deriving those needs
a comptime walk of ``reflect[H]`` at the registration site (the
ComptimeRouter path), not runtime introspection. Mounted sub-routers are
not walked yet (top-level routes only).

## Functions

### `spec_from_router`

```mojo
def spec_from_router(r: Router, title: String, version: String) -> OpenApiSpec
```

Build an :class:`OpenApiSpec` from ``r``'s registered routes.

Operations under the same template are merged into one
:class:`OpenApiPath`; first-seen template order is preserved so the
emitted JSON is deterministic.