Add optional mask parameter to generate function

- Add optional mask_img parameter to generate function for ComfyUI integration
- Implement smart fallback: use provided mask or base image (instead of garment)
- Add logging for mask selection debugging
- Update API payload to use proper mask URL or base image fallback

app.py

@@ -277,7 +277,13 @@ def _public_storage_url(path: str) -> str:
 # Main generate function
 # -----------------------------------------------------------------------------
 
-def generate(base_img: Image.Image, garment_img: Image.Image, workflow_choice: str, request: gr.Request) -> Image.Image:
+def generate(
+    base_img: Image.Image, 
+    garment_img: Image.Image, 
+    workflow_choice: str, 
+    request: gr.Request,
+    mask_img: Optional[Image.Image] = None  # NEW: Optional mask parameter
+) -> Image.Image:
     if base_img is None or garment_img is None:
         raise gr.Error("Please provide both images.")
     
@@ -299,6 +305,18 @@ def generate(base_img: Image.Image, garment_img: Image.Image, workflow_choice: s
 
     base_url = upload_image_to_supabase(base_img, base_path)
     garment_url = upload_image_to_supabase(garment_img, garment_path)
+    
+    # Handle optional mask image (if provided by ComfyUI or future web UI)
+    mask_url = None
+    if mask_img is not None:
+        print(f"[MASK] Processing user-provided mask image")
+        mask_filename = f"{uuid.uuid4().hex}.png"
+        mask_path = f"{folder}/{mask_filename}"
+        mask_img = downscale_image(mask_img)
+        mask_url = upload_image_to_supabase(mask_img, mask_path)
+        print(f"[MASK] Uploaded mask: {mask_url}")
+    else:
+        print(f"[MASK] No mask provided - will use base image fallback")
 
     # 2. Insert new row into processing_jobs (anon key, relies on open RLS)
     token_for_row = str(uuid.uuid4())
@@ -307,7 +325,7 @@ def generate(base_img: Image.Image, garment_img: Image.Image, workflow_choice: s
         "status": "queued",
         "base_image_path": base_url,
         "garment_image_path": garment_url,
-        "mask_image_path": base_url,
+        "mask_image_path": mask_url if mask_url else base_url,  # Track actual mask used
         "access_token": token_for_row,
         "created_at": datetime.utcnow().isoformat(),
     }
@@ -321,11 +339,17 @@ def generate(base_img: Image.Image, garment_img: Image.Image, workflow_choice: s
     fn_payload = {
         "baseImageUrl": base_url,
         "garmentImageUrl": garment_url,
-        # 👉 hack: use garment as placeholder mask until proper mask provided
-        "maskImageUrl": garment_url,
+        # 🎭 Smart fallback: use provided mask OR base image (much better than garment!)
+        "maskImageUrl": mask_url if mask_url else base_url,
         "jobId": job_id,
         "workflowType": workflow_choice,
     }
+    
+    # Log mask selection for debugging
+    if mask_url:
+        print(f"[API] Using user-provided mask: {mask_url}")
+    else:
+        print(f"[API] Using base image as mask fallback: {base_url}")
     headers = {
         "Content-Type": "application/json",
         "apikey": SUPABASE_SECRET_KEY,