Refactor code structure for improved readability and maintainability

workers/bg-remove/handler.py

@@ -0,0 +1,66 @@
+"""
+RunPod Serverless worker: background removal (U²-Net via rembg).
+
+Replaces the flaky in-browser @imgly remover. Runs rembg on CPU (U²-Net is tiny,
+~1-3s) so it needs NO CUDA — it can't hit the driver/kernel problems the GPU
+models had, and it's very reliable.
+
+Contract (matches the app's rpRemoveBackground — no app change needed):
+  {"input": {
+     "image": "<base64>",        # required (raw base64 or data: URI)
+     "model_name": "u2net"       # optional: u2net | u2netp | u2net_human_seg | isnet-general-use
+  }}
+Returns: {"image": "<base64 PNG, RGBA with the background transparent>"}.
+"""
+
+import base64
+import io
+import os
+
+_V = "/runpod-volume"
+if os.path.isdir(_V):
+    os.environ.setdefault("U2NET_HOME", os.path.join(_V, "u2net"))
+
+import runpod  # noqa: E402
+from PIL import Image  # noqa: E402
+from rembg import new_session, remove  # noqa: E402
+
+DEFAULT_MODEL = os.environ.get("BG_REMOVE_MODEL", "u2net")
+_sessions = {}
+
+
+def _get_session(name):
+    if name not in _sessions:
+        _sessions[name] = new_session(name)
+    return _sessions[name]
+
+
+def _b64_to_image(data):
+    if "," in data:
+        data = data.split(",", 1)[1]
+    return Image.open(io.BytesIO(base64.b64decode(data))).convert("RGBA")
+
+
+def _image_to_b64(img):
+    buf = io.BytesIO()
+    img.save(buf, format="PNG")
+    return base64.b64encode(buf.getvalue()).decode("utf-8")
+
+
+def handler(event):
+    inp = (event or {}).get("input") or {}
+    image_b64 = inp.get("image")
+    if not image_b64:
+        return {"error": "Missing 'image' (base64)."}
+    name = (inp.get("model_name") or DEFAULT_MODEL).strip() or DEFAULT_MODEL
+    try:
+        img = _b64_to_image(image_b64)
+        out = remove(img, session=_get_session(name))  # RGBA, background alpha=0
+        if out.mode != "RGBA":
+            out = out.convert("RGBA")
+        return {"image": _image_to_b64(out)}
+    except Exception as exc:
+        return {"error": f"{type(exc).__name__}: {exc}"}
+
+
+runpod.serverless.start({"handler": handler})