Govern task context and advance execution pointer

tools/web/check-nodetree-desktop.py

@@ -0,0 +1,51 @@
+#!/usr/bin/env python3
+import hashlib
+import json
+import os
+import pathlib
+import sys
+import tempfile
+
+import bpy
+
+
+def graph_report():
+    material = bpy.data.materials.get("WebGapNodeTreeMaterial")
+    if material is None or not material.use_nodes:
+        raise RuntimeError("WebGapNodeTreeMaterial is missing")
+    tree = material.node_tree
+    return {
+        "id": "nodetree:WebGapNodeTreeMaterial",
+        "name": tree.name,
+        "nodeTypes": sorted(node.bl_idname for node in tree.nodes),
+        "nodeNames": sorted(node.name for node in tree.nodes),
+        "linkCount": len(tree.links),
+        "links": sorted([[link.from_node.bl_idname, link.from_socket.name, link.to_node.bl_idname, link.to_socket.name] for link in tree.links]),
+    }
+
+
+def main():
+    arguments = sys.argv[sys.argv.index("--") + 1 :]
+    if len(arguments) != 2:
+        raise SystemExit("usage: blender -b --python check-nodetree-desktop.py -- FIXTURE REPORT")
+    fixture, output = (pathlib.Path(value).resolve() for value in arguments)
+    bpy.ops.wm.open_mainfile(filepath=str(fixture), load_ui=False)
+    before = graph_report()
+    descriptor, temporary = tempfile.mkstemp(prefix="m16-nodetree-reopen-", suffix=".blend", dir=fixture.parent)
+    os.close(descriptor)
+    try:
+        bpy.ops.wm.save_as_mainfile(filepath=temporary, check_existing=False, compress=True)
+        bpy.ops.wm.open_mainfile(filepath=temporary, load_ui=False)
+        after = graph_report()
+    finally:
+        pathlib.Path(temporary).unlink(missing_ok=True)
+    if before != after:
+        raise RuntimeError(f"node tree save/reopen drift: {before} != {after}")
+    report = {"schemaVersion": 1, "task": "M16-GAP-00016", "operation": "NODETREE_DATABLOCK_DESKTOP", "fixture": str(fixture), "fixtureSha256": hashlib.sha256(fixture.read_bytes()).hexdigest(), "nodeTree": after, "saveReopen": "EXACT", "blenderVersion": bpy.app.version_string}
+    output.parent.mkdir(parents=True, exist_ok=True)
+    output.write_text(json.dumps(report, indent=2, sort_keys=True) + "\n", encoding="utf-8")
+    print(f"nodetree-desktop-ok id={after['id']} nodes={len(after['nodeTypes'])} links={after['linkCount']} saveReopen=exact")
+
+
+if __name__ == "__main__":
+    main()