feat(simulation): auto-build source mesh collision

tests/test_gaussian_pipeline_gateway.py

@@ -117,6 +117,28 @@ def test_gateway_uploads_lcc_bundle_with_tus_and_reads_provider_contract(tmp_pat
     assert descriptor.total_byte_length == sum(member.byte_length for member in descriptor.members)
 
 
+def test_folder_discovery_retains_one_nested_xgrids_source_mesh(tmp_path: Path) -> None:
+    root = tmp_path / "export"
+    scene = root / "LCC_Results"
+    mesh = root / "Mesh_Files"
+    scene.mkdir(parents=True)
+    mesh.mkdir()
+    (scene / "scan.lcc").write_text(
+        json.dumps({"fileType": "Portable"}),
+        encoding="utf-8",
+    )
+    (scene / "index.bin").write_bytes(b"index")
+    (scene / "data.bin").write_bytes(b"data")
+    (mesh / "scan.ply").write_bytes(b"ply")
+
+    members = _discover_bundle_members(root, "LCC_Results/scan.lcc", "lcc")
+
+    assert "Mesh_Files/scan.ply" in members
+    (mesh / "duplicate.ply").write_bytes(b"ply")
+    with pytest.raises(GaussianPipelineIntegrityError, match="at most one"):
+        _discover_bundle_members(root, "LCC_Results/scan.lcc", "lcc")
+
+
 def test_gateway_uploads_and_normalizes_archive_with_tus(tmp_path: Path) -> None:
     archive_bytes = b"portable-archive"
     archive_sha = hashlib.sha256(archive_bytes).hexdigest()