feat(ai): add emit_progress() calls to all Python AI scripts

packages/ai/python/remove_bg.py

@@ -1,6 +1,12 @@
 """Background removal using rembg with state-of-the-art BiRefNet models."""
 import sys
 import json
+import os
+
+
+def emit_progress(percent, stage):
+    """Emit structured progress to stderr for bridge.ts to capture."""
+    print(json.dumps({"progress": percent, "stage": stage}), file=sys.stderr, flush=True)
 
 
 def main():
@@ -11,23 +17,26 @@ def main():
     model = settings.get("model", "u2net")
     bg_color = settings.get("backgroundColor", "")
 
+    # Redirect stdout to stderr so library download/progress output
+    # cannot contaminate our JSON result on stdout.
+    stdout_fd = os.dup(1)
+    os.dup2(2, 1)
+
     try:
         from rembg import remove, new_session
         import io
 
-        # Progress messages go to stderr (stdout reserved for JSON result)
-        sys.stderr.write(f"Loading model: {model}\n")
-        sys.stderr.flush()
+        emit_progress(10, "Loading model")
 
         session = new_session(model)
 
-        sys.stderr.write("Processing image...\n")
-        sys.stderr.flush()
+        emit_progress(25, "Model loaded")
 
         with open(input_path, "rb") as f:
             input_data = f.read()
 
         # Try with alpha matting for better edges, fall back without
+        emit_progress(30, "Analyzing image")
         try:
             output_data = remove(
                 input_data,
@@ -39,8 +48,11 @@ def main():
         except Exception:
             output_data = remove(input_data, session=session)
 
+        emit_progress(80, "Background removed")
+
         # If a background color is specified, composite onto it
         if bg_color and bg_color.startswith("#"):
+            emit_progress(85, "Compositing background")
             from PIL import Image
 
             img = Image.open(io.BytesIO(output_data)).convert("RGBA")
@@ -54,22 +66,27 @@ def main():
             bg.save(buf, format="PNG")
             output_data = buf.getvalue()
 
+        emit_progress(95, "Saving result")
         with open(output_path, "wb") as f:
             f.write(output_data)
 
-        print(json.dumps({"success": True, "model": model}))
+        result = json.dumps({"success": True, "model": model})
 
     except ImportError:
-        print(
-            json.dumps(
-                {
-                    "success": False,
-                    "error": "rembg is not installed. Install with: pip install rembg[cpu]",
-                }
-            )
+        result = json.dumps(
+            {
+                "success": False,
+                "error": "rembg is not installed. Install with: pip install rembg[cpu]",
+            }
         )
     except Exception as e:
-        print(json.dumps({"success": False, "error": str(e)}))
+        result = json.dumps({"success": False, "error": str(e)})
+
+    # Restore original stdout and write only our JSON result
+    os.dup2(stdout_fd, 1)
+    os.close(stdout_fd)
+    sys.stdout.write(result + "\n")
+    sys.stdout.flush()
 
 
 if __name__ == "__main__":