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

mvp.py

@@ -51,7 +51,7 @@ REPO_ROOT = os.path.dirname(os.path.abspath(__file__))
 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")
-sys
+os.environ["PYTHONPATH"] = os.environ.get("PYTHONPATH", "") + ":" + os.path.join(REPO_ROOT, "MaskClustering", "third_party")
 
 # Ensure local detectron2 is installed at runtime if postBuild didn't run
 try:
@@ -674,10 +674,8 @@ def reconstruct(
             check=True,
             env={
                 **os.environ,
-                # Ensure local vendored detectron2 is importable via PYTHONPATH
-                "PYTHONPATH": DETECTRON2_ROOT
-                + os.pathsep
-                + MK_PATH
+                # Use installed detectron2; avoid shadowing it with partial local tree
+                "PYTHONPATH": MK_PATH
                 + (os.pathsep + os.environ["PYTHONPATH"] if os.environ.get("PYTHONPATH") else ""),
             },
         )
@@ -697,12 +695,7 @@ def reconstruct(
         )
 
         env = dict(os.environ)
-        env["PYTHONPATH"] = (
-            DETECTRON2_ROOT
-            + os.pathsep
-            + MK_PATH
-            + (os.pathsep + env["PYTHONPATH"] if env.get("PYTHONPATH") else "")
-        )
+        env["PYTHONPATH"] = MK_PATH + (os.pathsep + env["PYTHONPATH"] if env.get("PYTHONPATH") else "")
         subprocess.run(
             [
                 sys.executable,