Runtime fallback: install local detectron2 if import fails (no build isolation)

packages.txt

@@ -1,5 +1,10 @@
 build-essential
 python3-dev
+git
+libgl1
+libglib2.0-0
+build-essential
+python3-dev
 cmake
 ninja-build
 ffmpeg

postBuild

@@ -1,3 +1,56 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+echo "postBuild: starting detectron2 setup"
+python -V || true
+pip --version || true
+
+# Ensure torch is present and print environment info
+python - <<'PY' || true
+import torch, platform, sys
+print("Torch:", torch.__version__)
+print("CUDA available:", torch.cuda.is_available())
+print("torch.version.cuda:", getattr(torch.version, "cuda", None))
+print("Python:", sys.version.split()[0])
+print("Platform:", platform.platform())
+PY
+
+# Determine expected wheel index (CPU or CUDA) based on installed torch
+PYTORCH_MM="$(python - <<'PY'
+import torch
+v = torch.__version__.split('+')[0].split('.')
+print(f"{v[0]}.{v[1]}")
+PY
+)"
+CUDA_TAG="$(python - <<'PY'
+import torch
+cv = getattr(torch.version, "cuda", None)
+print(("cu"+cv.replace(".","")) if cv else "cpu")
+PY
+)"
+
+WHEEL_URL="https://dl.fbaipublicfiles.com/detectron2/wheels/${CUDA_TAG}/torch${PYTORCH_MM}/index.html"
+echo "Attempting detectron2 wheel from: ${WHEEL_URL}"
+
+if pip install --no-cache-dir "detectron2" -f "${WHEEL_URL}"; then
+  echo "detectron2 installed from prebuilt wheel"
+else
+  echo "Prebuilt wheel not available. Building detectron2 from source (CPU-only) ..."
+  export FORCE_CUDA=0
+  pip install --no-cache-dir --no-build-isolation "git+https://github.com/facebookresearch/detectron2.git@fd27788985af0f4ca800bca563acdb700bb890e2"
+fi
+
+# Verify installation
+python - <<'PY'
+import importlib
+spec = importlib.util.find_spec("detectron2")
+if spec is None:
+    raise SystemExit("detectron2 not found after installation")
+import detectron2
+print("detectron2 installed. Version:", getattr(detectron2, "__version__", "unknown"))
+PY
+
+echo "postBuild: detectron2 setup completed"
 #!/bin/sh
 set -e
 

requirements.txt

@@ -20,7 +20,7 @@ scipy
 onnxruntime
 gdown
 # detectron2 runtime deps (needed when importing vendored detectron2 via PYTHONPATH)
-git+https://github.com/facebookresearch/detectron2.git
+
 
 # NOTE (HF Spaces): do not use local-path installs here.
 # HF builds install requirements BEFORE copying the repo into /app.