UPDATEFIELD: an undo step on every run

Co-Authored-By: Claude Opus 5.5 <[email protected]>

src/app/commands/count.rs

@@ -546,6 +546,9 @@ impl OpenCADStudio {
     /// its attributes and the texts of its block definition; a table, the
     /// cell texts of its drawing (its `*T` block).
     fn update_fields(&mut self, i: usize, handles: &[Handle]) {
+        // Every run is an undo step, as in the reference, even with nothing
+        // selected, no field found or no value changed.
+        self.push_undo_mark(i, "UPDATEFIELD");
         if handles.is_empty() {
             return;
         }
@@ -588,7 +591,6 @@ impl OpenCADStudio {
         }
         // The reference counts fields, not the texts holding them, and
         // reports every field it evaluated as updated, changed or not.
-        self.push_undo_snapshot(i, "UPDATEFIELD");
         let (changed, found) = self.tabs[i].scene.update_fields(32, Some(&hosts));
         if changed > 0 {
             self.tabs[i].dirty = true;

src/app/document.rs

@@ -901,4 +901,6 @@ pub(super) struct PendingHistorySnapshot {
     pub(super) dirty_before: bool,
     pub(super) structure_before: CadDocument,
     pub(super) recorder: Arc<codec::document::EntityChangeRecorder>,
+    /// Kept as an undo step even when nothing changed.
+    pub(super) keep_empty: bool,
 }

src/app/history.rs

@@ -313,7 +313,8 @@ impl OpenCADStudio {
         let selected_after: Vec<Handle> = self.tabs[i].scene.selected.iter().copied().collect();
         let dirty_after = self.tabs[i].dirty;
         let active_layer_after = self.tabs[i].active_layer.clone();
-        if entities.is_empty()
+        if !pending.keep_empty
+            && entities.is_empty()
             && !structure_changed
             && pending.selected_before == selected_after
             && pending.dirty_before == dirty_after
@@ -365,9 +366,19 @@ impl OpenCADStudio {
             dirty_before,
             structure_before,
             recorder,
+            keep_empty: false,
         });
     }
 
+    /// [`Self::push_undo_snapshot`] for a command that is an undo step even
+    /// when it changes nothing (UNDO and U then name it and undo nothing).
+    pub(super) fn push_undo_mark(&mut self, i: usize, label: impl Into<String>) {
+        self.push_undo_snapshot(i, label);
+        if let Some(pending) = self.tabs[i].history.pending.as_mut() {
+            pending.keep_empty = true;
+        }
+    }
+
     /// Begin undo capture for an entity edit that will touch `touched` entities.
     /// Starts a cheap Scene delta recording and returns the pre-command state to
     /// pass to [`OpenCADStudio::commit_undo_delta`] after the mutation. A command

src/modules/annotate/count_cmd.rs

@@ -434,9 +434,7 @@ impl CadCommand for UpdateFieldCommand {
     }
 
     fn on_enter(&mut self) -> CmdResult {
-        if self.selected.is_empty() {
-            return CmdResult::Cancel;
-        }
+        // An empty selection still runs (the reference keeps an undo step).
         let handles: Vec<String> = self.selected.iter().map(|h| format!("{:X}", h.value())).collect();
         CmdResult::Dispatch(format!("_UPDATEFIELDRUN {}", handles.join(",")))
     }