fix: mount Gradio before catch-all route so /gradio/config resolves correctly

app.py

@@ -786,8 +786,11 @@ DIST_DIR = Path(__file__).parent / "dist"
 
 _fastapi = FastAPI()
 
+# Mount Gradio FIRST so its /gradio/* routes have priority over the catch-all.
+os.environ.setdefault("GRADIO_ALLOWED_PATHS", "/tmp")
+app = gr.mount_gradio_app(_fastapi, demo, path="/gradio")
+
 if DIST_DIR.exists():
-    # Static asset folders
     for _subdir in ("assets", "avatars"):
         _path = DIST_DIR / _subdir
         if _path.exists():
@@ -803,18 +806,11 @@ if DIST_DIR.exists():
 
     @_fastapi.get("/{full_path:path}")
     async def _spa_fallback(full_path: str):
-        # Let Gradio handle its own paths
-        if full_path.startswith("gradio"):
-            from fastapi.responses import Response
-            return Response(status_code=404)
         candidate = DIST_DIR / full_path
         if candidate.exists() and candidate.is_file():
             return FileResponse(str(candidate))
         return FileResponse(str(DIST_DIR / "index.html"))
 
-os.environ.setdefault("GRADIO_ALLOWED_PATHS", "/tmp")
-app = gr.mount_gradio_app(_fastapi, demo, path="/gradio")
-
 if __name__ == "__main__":
     import uvicorn
     uvicorn.run(app, host="0.0.0.0", port=7860)