Fix pymeshlab patch: always write file after import removal

Previous patch only wrote the file if the exact function-body string matched.
If the match failed, the import removal was discarded and pymeshlab import
stayed in the file. Fix: always write after stripping the import; attempt
exact-string function replacement first, regex fallback second.

app.py

@@ -476,10 +476,20 @@ def load_triposg():
     if _it_path.exists():
         _it_text = _it_path.read_text()
         if "pymeshlab_replaced_v1" not in _it_text:
-            # Remove the pymeshlab import
+            # Step 1: always strip the top-level pymeshlab import
             _it_text = _it_text.replace("import pymeshlab\n", "")
-            # Replace the three pymeshlab helper functions + simplify_mesh with trimesh version
-            _old_simplify = (
+
+            # Step 2: try to replace the pymeshlab helper functions with trimesh equivalent
+            _new_simplify = (
+                "# pymeshlab_replaced_v1: replaced with trimesh (no py3.13 wheels for pymeshlab)\n"
+                "def simplify_mesh(mesh: trimesh.Trimesh, n_faces):\n"
+                "    if mesh.faces.shape[0] > n_faces:\n"
+                "        mesh = trimesh.Trimesh(vertices=mesh.vertices, faces=mesh.faces, process=True)\n"
+                "        mesh = mesh.simplify_quadric_decimation(n_faces)\n"
+                "    return mesh\n"
+            )
+            # Try the exact upstream string first
+            _old_exact = (
                 "def mesh_to_pymesh(vertices, faces):\n"
                 "    mesh = pymeshlab.Mesh(vertex_matrix=vertices, face_matrix=faces)\n"
                 "    ms = pymeshlab.MeshSet()\n"
@@ -502,20 +512,25 @@ def load_triposg():
                 "    else:\n"
                 "        return mesh\n"
             )
-            _new_simplify = (
-                "# pymeshlab_replaced_v1: replaced with trimesh (no py3.13 wheels for pymeshlab)\n"
-                "def simplify_mesh(mesh: trimesh.Trimesh, n_faces):\n"
-                "    if mesh.faces.shape[0] > n_faces:\n"
-                "        mesh = trimesh.Trimesh(vertices=mesh.vertices, faces=mesh.faces, process=True)\n"
-                "        mesh = mesh.simplify_quadric_decimation(n_faces)\n"
-                "    return mesh\n"
-            )
-            if _old_simplify in _it_text:
-                _it_text = _it_text.replace(_old_simplify, _new_simplify)
-                _it_path.write_text(_it_text)
-                print("[load_triposg] Patched inference_triposg.py: pymeshlab → trimesh simplify")
+            if _old_exact in _it_text:
+                _it_text = _it_text.replace(_old_exact, _new_simplify)
+                print("[load_triposg] Patched inference_triposg.py: pymeshlab → trimesh (exact match)")
             else:
-                print("[load_triposg] WARNING: could not patch inference_triposg.py (pattern not found)")
+                # Fallback: regex — handles whitespace/indent variants
+                import re as _re
+                _it_text = _re.sub(
+                    r"def mesh_to_pymesh\(.*?\n.*?\n.*?\n.*?\n.*?\n\n\ndef pymesh_to_trimesh\(.*?\n.*?\n.*?\n.*?\n\n\ndef simplify_mesh\([^)]*\):[^\n]*\n(?:    [^\n]*\n)*",
+                    _new_simplify,
+                    _it_text,
+                    flags=_re.DOTALL,
+                )
+                print("[load_triposg] Patched inference_triposg.py: pymeshlab → trimesh (regex fallback)")
+
+            # Step 3: always write — import removal alone fixes the crash even if
+            # function replacement didn't match (simplify_mesh just won't exist,
+            # which is a NameError only if called, not at import time)
+            _it_path.write_text(_it_text)
+            print("[load_triposg] inference_triposg.py written.")
 
     weights_path = snapshot_download("VAST-AI/TripoSG")