fix(history): preserve native networks during unrelated undo

Synchronize the native parametric graph only when replay changes constraints or named parameters. Geometry and visibility history preserve existing imported network identities and ownership. Add a regression for a rejected block copy followed by local undo and redo.

src/app/block_editor_tests.rs

@@ -54,6 +54,46 @@ fn main_depth(app: &OpenCADStudio) -> usize {
         .unwrap_or(tab.history.undo_stack.len())
 }
 
+#[test]
+fn local_undo_preserves_imported_native_networks_when_constraints_are_unchanged() {
+    use codec::objects::{AssocNetwork, AssociativeData, AssociativeObject, Dictionary, ObjectType};
+    let (mut app, reference) = fixture();
+    let i = app.active_tab;
+    let doc = &mut app.tabs[i].scene.document;
+    let owner = doc.block_records.get("EDIT_ME").unwrap().handle;
+    let dictionary_handle = doc.allocate_handle();
+    let network_handle = doc.allocate_handle();
+    let mut dictionary = Dictionary::new();
+    dictionary.handle = dictionary_handle;
+    dictionary.owner = owner;
+    dictionary.hard_owner = true;
+    dictionary.add_entry("ACAD_ASSOCNETWORK", network_handle);
+    doc.objects
+        .insert(dictionary_handle, ObjectType::Dictionary(dictionary));
+    let network = AssociativeObject {
+        handle: network_handle,
+        owner: dictionary_handle,
+        reactors: vec![dictionary_handle],
+        dxf_name: "ASSOCNETWORK".into(),
+        cpp_class_name: "AcDbAssocNetwork".into(),
+        data: AssociativeData::Network(AssocNetwork::default()),
+        ..Default::default()
+    };
+    doc.objects
+        .insert(network_handle, ObjectType::Associative(network));
+    begin(&mut app, reference);
+    let original_objects = app.tabs[i].scene.document.objects.clone();
+    circle(&mut app, 1.0);
+    assert!(!app.save_block_edit_as(i, "COPY"));
+    assert_eq!(app.tabs[i].scene.document.objects, original_objects);
+    app.undo_steps(1);
+    assert_eq!(members(&app).len(), 1);
+    assert_eq!(app.tabs[i].scene.document.objects, original_objects);
+    app.redo_steps(1);
+    assert_eq!(members(&app).len(), 2);
+    assert_eq!(app.tabs[i].scene.document.objects, original_objects);
+}
+
 #[test]
 fn save_as_forks_unsaved_edits_and_undoes_as_one_drawing_step() {
     let (mut app, reference) = fixture();