Fix 405 when saving a drawn layer in the deployed build

backend/api/endpoints/chat.py

@@ -47,7 +47,8 @@ class ChatResponse(BaseModel):
     raw_data: list[dict[str, Any]] = []
 
 
-@router.post("/", response_model=ChatResponse)
+@router.post("", response_model=ChatResponse)
+@router.post("/", response_model=ChatResponse, include_in_schema=False)
 async def chat(request: ChatRequest):
     """
     Non-streaming chat endpoint. Routes to the appropriate handler based on

backend/api/endpoints/user_layers.py

@@ -22,7 +22,12 @@ class UserLayerResponse(BaseModel):
     name: str # The table name in DuckDB
     display_name: str
 
-@router.post("/", response_model=UserLayerResponse)
+# Registered with and without the trailing slash. Starlette only redirects
+# "/layers/user" -> "/layers/user/" when nothing else matches, and the
+# catch-all that serves the frontend matches everything — so in the deployed
+# build the redirect never happened and a POST came back 405.
+@router.post("", response_model=UserLayerResponse)
+@router.post("/", response_model=UserLayerResponse, include_in_schema=False)
 async def register_user_layer(request: UserLayerRequest):
     """
     Registers a new user-drawn layer.

backend/main.py

@@ -1,4 +1,4 @@
-from fastapi import FastAPI
+from fastapi import FastAPI, HTTPException
 from fastapi.middleware.cors import CORSMiddleware
 from fastapi.staticfiles import StaticFiles
 from fastapi.responses import FileResponse
@@ -31,6 +31,12 @@ if static_dir.exists():
 
     @app.get("/{full_path:path}")
     async def serve_frontend(full_path: str):
+        # An unknown API path is an error, not a page. Falling through to
+        # index.html here would answer a bad API call with HTML and a 200,
+        # and it makes this route shadow the API for non-GET methods.
+        if full_path.startswith("api/"):
+            raise HTTPException(status_code=404, detail=f"No such API route: /{full_path}")
+
         file_path = static_dir / full_path
         if file_path.exists() and file_path.is_file():
             return FileResponse(file_path)