Router prefix composition

@pools_router.post("")                        the decorator states ""
pools_router = AirflowRouter(prefix="/pools")
public_router = AirflowRouter(prefix="/api/v2")
public_router.include_router(authenticated_router)
authenticated_router.include_router(pools_router)
                                              ─► POST /api/v2/pools

Added by the M07 remediation. A route's served path is not the path its decorator states, and comparing a frontend's /api/v2/pools against a decorator's "" compares a served path to a fragment.

What composes

A declaration X = <Something>Router(prefix="/p") and a mounting parent.include_router(child, prefix="/q"). Any constructor whose name ends in Router counts, because projects subclass it — Airflow declares every route on AirflowRouter, and requiring the literal APIRouter finds none of them.

Names at an inclusion site are resolved through the project's imports, so a router declared in one module and mounted in another composes correctly.

What refuses

Outcome	When
Unresolved	a prefix= is present but not a string literal
Unresolved	a prefix= at the inclusion site is not a literal
Unresolved	the inclusion chain cycles, or is deeper than twelve
Ambiguous	a router is mounted in more than one parent
—	the receiver names no router this project declares

Composition can only make a path more complete. Every refusal above leaves the route exactly as declared. An unknown prefix never becomes an empty one.

A trailing slash survives composition, because M03 keeps /items and /items/ distinct: @router.post("") under /pools serves /pools, and @router.get("/") serves /pools/.

What is out of scope

Prefixes contributed by a framework at startup through anything other than include_router — Onyx's include_router_with_global_prefix_prepended is a project-local helper, and its global prefix is not composed. Deployment-time rewriting, such as a Next.js rewrites() mapping /api/* onto a backend, is a different mechanism again.