feat: one gateway port with path-mounted frontends, markdown chat, collapsible sidebars

src/beaver_gateway/frontends/root.py

@@ -0,0 +1,49 @@
+"""The one ASGI app the gateway listens with.
+
+Every HTTP frontend is mounted under its ``path`` (``/anthropic``,
+``/mcp``, ``/md``, ``/api``, ``/admin``); ``/healthz`` answers for the
+whole process and ``/`` redirects to the landing frontend (the admin
+console) when one is configured.
+"""
+
+from __future__ import annotations
+
+from typing import TYPE_CHECKING
+
+from starlette.applications import Starlette
+from starlette.responses import JSONResponse, RedirectResponse
+from starlette.routing import Mount, Route
+
+if TYPE_CHECKING:
+    from collections.abc import Iterable
+
+    from starlette.requests import Request
+
+    from beaver_gateway.frontends.base import Frontend
+
+__all__ = ["build_root_app"]
+
+
+def build_root_app(frontends: Iterable[Frontend]) -> Starlette:
+    mounted = [fe for fe in frontends if fe.path and fe.app() is not None]
+    landing = next((fe for fe in mounted if fe.landing), None)
+    paths = [fe.path for fe in mounted]
+
+    async def healthz(_request: Request) -> JSONResponse:
+        return JSONResponse({"status": "ok", "frontends": paths})
+
+    async def index(_request: Request) -> JSONResponse | RedirectResponse:
+        if landing is not None:
+            return RedirectResponse(f"{landing.path}/", status_code=307)
+        return JSONResponse({"frontends": paths})
+
+    routes: list[Route | Mount] = [
+        Route("/healthz", healthz, methods=["GET"]),
+        Route("/", index, methods=["GET"]),
+    ]
+    for fe in mounted:
+        app = fe.app()
+        assert app is not None  # noqa: S101 - filtered above; narrows for ty
+        assert fe.path is not None  # noqa: S101
+        routes.append(Mount(fe.path, app=app, name=fe.name or fe.path.strip("/")))
+    return Starlette(routes=routes)