Checkpoint web parity through Chromium input tasks

tools/web/check-obj-web-roundtrip.py

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+"""Import a browser-produced OBJ in pinned Blender 5.2 and emit a semantic report."""
+
+import hashlib
+import json
+import sys
+from pathlib import Path
+
+import bpy
+
+
+def sha256_file(path):
+    digest = hashlib.sha256()
+    with open(path, "rb") as handle:
+        for chunk in iter(lambda: handle.read(1024 * 1024), b""):
+            digest.update(chunk)
+    return digest.hexdigest()
+
+
+def report_scene():
+    objects = []
+    for obj in sorted((item for item in bpy.context.scene.objects if item.type == "MESH"), key=lambda item: item.name):
+        mesh = obj.data
+        mesh.calc_loop_triangles()
+        uv_layers = sorted(layer.name for layer in mesh.uv_layers)
+        objects.append({
+            "name": obj.name,
+            "vertexCount": len(mesh.vertices),
+            "polygonCount": len(mesh.polygons),
+            "triangleCount": len(mesh.loop_triangles),
+            "normalCount": len(mesh.vertices),
+            "uvLayers": uv_layers,
+            "uvLoopCount": len(mesh.uv_layers.active.data) if mesh.uv_layers.active else 0,
+            "materials": sorted(material.name for material in mesh.materials if material),
+        })
+    return {"objects": objects, "objectCount": len(objects), "meshCount": len(objects)}
+
+
+def main(obj_path, report_path):
+    obj_path = Path(obj_path).resolve()
+    report_path = Path(report_path).resolve()
+    bpy.ops.wm.read_factory_settings(use_empty=True)
+    result = bpy.ops.wm.obj_import(
+        filepath=str(obj_path),
+        directory=str(obj_path.parent),
+        forward_axis="NEGATIVE_Z",
+        up_axis="Y",
+        global_scale=1.0,
+        use_split_objects=True,
+        use_split_groups=True,
+        validate_meshes=True,
+        import_vertex_groups=False,
+    )
+    if "FINISHED" not in result:
+        raise RuntimeError("Blender OBJ import did not finish: %s" % (result,))
+    report = {
+        "schemaVersion": 1,
+        "operation": "DESKTOP_IMPORT_WEB_OBJ",
+        "sourceObjSha256": sha256_file(obj_path),
+        "sourceObjBytes": obj_path.stat().st_size,
+        **report_scene(),
+    }
+    report_path.parent.mkdir(parents=True, exist_ok=True)
+    report_path.write_text(json.dumps(report, indent=2, sort_keys=True) + "\n", encoding="utf-8")
+    print("obj-web-roundtrip-desktop-imported objects=%s triangles=%s" % (report["objectCount"], sum(item["triangleCount"] for item in report["objects"])))
+
+
+if __name__ == "__main__":
+    args = sys.argv[sys.argv.index("--") + 1 :] if "--" in sys.argv else []
+    if len(args) != 2:
+        raise SystemExit("usage: blender --background --python check-obj-web-roundtrip.py -- OBJ REPORT")
+    main(args[0], args[1])