Custom FastAPI routes no longer work

[s0l4r]

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Describe the bug After upgrade from 2.0.2 to 2.0.603 I cannot get custom routes to work, for example https://github.com/Chainlit/cookbook/tree/main/custom-frontend/backend. I've been trying to create the custom endpoint /custom-auth, but the route is never reached.

I believe this may have been introduced in https://github.com/Chainlit/chainlit/pull/1723/files?diff=split&w=0

The custom route is now overwritten of routes by the chainlit catch-all route (e.g., /{full_path:path}).

INFO:     127.0.0.1:62200 - "GET /custom-auth HTTP/1.1" 200 OK
Intercepted path: custom-auth

I modified server.py to check if my custom route is activated, but it's caught by the catch all route:

@router.get("/{full_path:path}")
async def serve(full_path: str, request: Request):
    """Serve the UI files."""
    print(f"Intercepted path: {full_path}")
    html_template = get_html_template(request.scope["root_path"])
    response = HTMLResponse(content=html_template, status_code=200)

    return response

This results in that the default html template is being rendered when I try to access /custom-auth.

To Reproduce Steps to reproduce the behavior:

Run the example at https://github.com/Chainlit/cookbook/tree/main/custom-frontend/backend with custom auth.

I tried starting the app using the new root-path parameter, but still doesn't work (also tried without --root-path set)

"args": [
       "run",
        "--root-path=/chainlit",
        "-h",
        "app.py"
]

Expected behavior Custom routes should not be overwritten by Chainlit.

Desktop (please complete the following information):

• OS: MacOS
• Browser Chrome
• Version 131.0.6778.265

Additional context

The error might be in how the sub application is mounted, and the changes done in #1723

mount_chainlit(app=app, target="cl-app.py", path="/chainlit"