fix: honor drawing units in annotation and viewport scales

src/app/commands/layers.rs

@@ -876,6 +876,28 @@ impl OpenCADStudio {
             }
             reframed += 1;
         }
+
+        // Keep the active model-space annotation scale in sync as well.
+        // annotation_scale is drawing/paper, while CANNOSCALEVALUE stores
+        // the reciprocal paper/drawing factor.
+        if self.tabs[i].scene.annotation_scale.abs() > 1.0e-12 {
+            self.tabs[i].scene.annotation_scale *= factor as f32;
+        }
+
+        if self.tabs[i]
+            .scene
+            .document
+            .header
+            .annotation_scale_value
+            .abs()
+            > 1.0e-12
+        {
+            self.tabs[i]
+                .scene
+                .document
+                .header
+                .annotation_scale_value /= factor;
+        }
         // Sizes the drawing keeps as settings rather than as geometry: dash
         // lengths, default heights and widths, the radii the fillet and chamfer
         // commands start from. They are all lengths in the unit that just

src/app/update/command.rs

@@ -1720,12 +1720,29 @@ pub(super) fn on_tab_close(&mut self, idx: usize) -> Task<Message> {
                 Task::none()
     }
 
-    pub(super) fn on_prop_geom_choice_changed(&mut self, field: &'static str, value: String) -> Task<Message> {
-                let i = self.active_tab;
-                let handles = self.property_target_handles(i);
-                if !handles.is_empty() {
-                    self.push_undo_snapshot(i, "CHPROP");
-                    if field == "vp_ucs_name" {
+    pub(super) fn on_prop_geom_choice_changed(
+        &mut self,
+        field: &'static str,
+        value: String,
+    ) -> Task<Message> {
+        let i = self.active_tab;
+        let handles = self.property_target_handles(i);
+
+        if !handles.is_empty() {
+            self.push_undo_snapshot(i, "CHPROP");
+
+            if field == "vscale_std" {
+                for &handle in &handles {
+                    if matches!(
+                        self.tabs[i].scene.document.get_entity(handle),
+                        Some(acadrust::EntityType::Viewport(_))
+                    ) {
+                        let _ = self.tabs[i]
+                            .scene
+                            .set_viewport_scale_named_for(handle, &value);
+                    }
+                }
+            } else if field == "vp_ucs_name" {
                         // Resolve UCS name → cloned data, then mutate viewports.
                         let ucs_data = self.tabs[i]
                             .scene