diff --git a/src/app/document.rs b/src/app/document.rs
index f9bef2bbb..209bd502b 100644
--- a/src/app/document.rs
+++ b/src/app/document.rs
@@ -206,6 +206,12 @@ pub(super) struct DocumentTab {
     pub(super) dyn_active: usize,
     pub(super) history: HistoryState,
     pub(super) active_layer: String,
+    /// Block references whose properties panel shows per-axis Scale X/Y/Z even
+    /// though the three factors are currently equal — the user unchecked the
+    /// "Uniform scale" box for them (#427). Per-tab: fresh documents restart
+    /// handle numbering, so an app-global set keyed by raw handle leaks one
+    /// tab's opt-out into another tab reusing the value (#47).
+    pub(super) props_asym_scale: std::collections::HashSet<u64>,
     /// Node graph shown by the command line's graph button.
     pub(super) graph: crate::ui::node_graph::Graph,
     /// Currently active UCS. `None` means WCS (identity transform).
@@ -649,6 +655,7 @@ impl DocumentTab {
             dyn_active: 0,
             history: HistoryState::default(),
             active_layer: "0".to_string(),
+            props_asym_scale: std::collections::HashSet::new(),
             graph: Default::default(),
             active_ucs: None,
             sketch_session: None,
diff --git a/src/app/mod.rs b/src/app/mod.rs
index cb9aa099d..37a73f74c 100644
--- a/src/app/mod.rs
+++ b/src/app/mod.rs
@@ -419,10 +419,6 @@ pub(super) struct OpenCADStudio {
     discussions: Vec<crate::discussions::DiscussionEntry>,
     /// True while the boot-time Discussions refresh is still in flight.
     discussions_loading: bool,
-    /// Block references whose properties panel shows per-axis Scale X/Y/Z even
-    /// though the three factors are currently equal — the user unchecked the
-    /// "Uniform scale" box for them (#427). Keyed by entity handle.
-    props_asym_scale: std::collections::HashSet<u64>,
     /// Collapsed Properties-panel section titles. This belongs to the app,
     /// rather than an individual document tab, so the same view preference is
     /// used by every currently open drawing/project.
@@ -4110,7 +4106,6 @@ impl OpenCADStudio {
             videos_loading: false,
             discussions: Vec::new(),
             discussions_loading: false,
-            props_asym_scale: std::collections::HashSet::new(),
             collapsed_property_sections: rustc_hash::FxHashSet::default(),
             start_section: StartSection::default(),
             start_action_w: std::sync::Arc::new(std::sync::atomic::AtomicU32::new(0)),
diff --git a/src/app/properties.rs b/src/app/properties.rs
index 3883c7f50..3237203e0 100644
--- a/src/app/properties.rs
+++ b/src/app/properties.rs
@@ -463,7 +463,7 @@ impl OpenCADStudio {
         if let codec::EntityType::Insert(ins) = entity {
             let eq = (ins.x_scale() - ins.y_scale()).abs() < 1e-12
                 && (ins.x_scale() - ins.z_scale()).abs() < 1e-12;
-            let uniform = eq && !self.props_asym_scale.contains(&handle.value());
+            let uniform = eq && !self.tabs[i].props_asym_scale.contains(&handle.value());
             for section in sections.iter_mut() {
                 let Some(xi) = section.props.iter().position(|p| p.field == "x_scale")
                 else {
@@ -4373,6 +4373,45 @@ fn apply_insert_unit_scale(ins: &mut codec::entities::Insert, ratio: f64) -> boo
     true
 }
 
+#[cfg(test)]
+mod asym_scale_tests {
+    // #47: the uniform-scale opt-out must be per-tab. Fresh documents restart
+    // handle numbering (seed 1), so two tabs hand out identical handles — an
+    // app-global set leaks one tab's opt-out into the other.
+    use crate::app::OpenCADStudio;
+
+    fn tab_with_insert(app: &mut OpenCADStudio) -> (usize, codec::Handle) {
+        app.tab_counter += 1;
+        let n = app.tab_counter;
+        app.tabs
+            .push(crate::app::document::DocumentTab::new_drawing(n));
+        let idx = app.tabs.len() - 1;
+        app.active_tab = idx;
+        let ins =
+            codec::entities::Insert::new("B", codec::types::Vector3::ZERO);
+        let h = app
+            .commit_entity_handle(codec::EntityType::Insert(ins))
+            .expect("insert commits");
+        (idx, h)
+    }
+
+    #[test]
+    fn asym_scale_opt_out_does_not_leak_across_tabs() {
+        let mut app = OpenCADStudio::new_for_test();
+        let (a, ha) = tab_with_insert(&mut app);
+        let (b, hb) = tab_with_insert(&mut app);
+        assert_eq!(
+            ha, hb,
+            "premise: identically built fresh docs reuse handle values"
+        );
+        app.tabs[a].props_asym_scale.insert(ha.value());
+        assert!(
+            !app.tabs[b].props_asym_scale.contains(&hb.value()),
+            "tab B must not see tab A's opt-out"
+        );
+    }
+}
+
 #[cfg(test)]
 mod insert_unit_scale_tests {
     use super::{apply_insert_unit_scale, format_unit_factor, insert_unit_scale, insunits_to_mm};
diff --git a/src/app/update/mod.rs b/src/app/update/mod.rs
index 985df0ebb..f3dcbc669 100644
--- a/src/app/update/mod.rs
+++ b/src/app/update/mod.rs
@@ -6895,11 +6895,11 @@ impl OpenCADStudio {
                                 };
                                 let Some((sx, sy, sz)) = scales else { return };
                                 let eq = (sx - sy).abs() < 1e-12 && (sx - sz).abs() < 1e-12;
-                                let checked = eq && !app.props_asym_scale.contains(&handle.value());
+                                let checked = eq && !app.tabs[i].props_asym_scale.contains(&handle.value());
                                 if checked {
-                                    app.props_asym_scale.insert(handle.value());
+                                    app.tabs[i].props_asym_scale.insert(handle.value());
                                 } else {
-                                    app.props_asym_scale.remove(&handle.value());
+                                    app.tabs[i].props_asym_scale.remove(&handle.value());
                                     if let Some(codec::EntityType::Insert(ins)) =
                                         app.tabs[i].scene.document.get_entity_mut(handle)
                                     {
diff --git a/src/ui/overlay.rs b/src/ui/overlay.rs
index e8cd3f062..0b4804fa7 100644
--- a/src/ui/overlay.rs
+++ b/src/ui/overlay.rs
@@ -2961,7 +2961,6 @@ fn draw_axes(
     axes: (Vec3, Vec3, Vec3),
     bg_luminance: f32,
 ) {
-    let (ax, ay, az) = axes;
     let axis_stroke = |r: f32, g: f32, b: f32| canvas::Stroke {
         width: 1.5,
         style: canvas::Style::Solid(Color { r, g, b, a: 0.85 }),