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

mvp.py

@@ -52,6 +52,16 @@ sys.path.append(os.path.join(REPO_ROOT, "vggt"))
 MK_PATH = os.path.join(REPO_ROOT, "MaskClustering")
 DETECTRON2_ROOT = os.path.join(REPO_ROOT, "MaskClustering", "third_party", "detectron2")
 
+# Ensure local detectron2 is installed at runtime if postBuild didn't run
+try:
+    import detectron2  # noqa: F401
+except Exception:
+    print("[runtime] detectron2 not found. Installing local detectron2 (editable, no build isolation)...")
+    os.system("python -m pip install --no-build-isolation -e ./MaskClustering/third_party/detectron2")
+    import importlib
+    importlib.invalidate_caches()
+    import detectron2  # noqa: F401
+
 # If detectron2 isn't installed as a package, allow importing from vendored source.
 if os.path.isdir(DETECTRON2_ROOT) and DETECTRON2_ROOT not in sys.path:
     sys.path.append(DETECTRON2_ROOT)