Highlight modifier faces from timeline hover and selection

crates/doc/src/eval.rs

@@ -2946,7 +2946,11 @@ pub fn world_state(doc: &Document, st: &ModelState) -> ModelState {
             let bm = doc.body_offsets.get(&b.name).map(|o| crate::mat_mul(&m, o)).unwrap_or(m);
             let body =
                 if crate::is_identity(&bm) { b.body.clone() } else { kernel::transform_matrix(&b.body, bm).unwrap_or_else(|_| b.body.clone()) };
-            out.bodies.push(ModelBody::new(name, body, b.feature));
+            let mut placed = ModelBody::new(name, body, b.feature);
+            // Placement preserves topology: face ownership remains that of the
+            // source model, including modifiers on component instances.
+            placed.names = crate::naming::NameCell::known(crate::naming::face_names(b));
+            out.bodies.push(placed);
         }
         if primary {
             for s in st.sketches.iter().filter(|s| comp_of_feature(s.feature) == comp) {

crates/doc/src/naming.rs

@@ -173,6 +173,13 @@ pub fn face_names(b: &ModelBody) -> Arc<Vec<String>> {
 
 /// Work out a body's face names from the feature that made it and the model before it.
 fn derive(b: &ModelBody, o: &NamingOrigin, nf: usize) -> Vec<String> {
+    // A rigid Move changes coordinates, not topology or face ownership. Geometric
+    // overlap with the unmoved input cannot recover the names at the new position.
+    if matches!(o.feature.kind, FeatureKind::Move { .. })
+        && let Some(input) = o.before.body(&b.name)
+    {
+        return face_names(input).as_ref().clone();
+    }
     let m = b.mesh();
     let size = b.body.size().max(1e-6);
     let tol = (size * 1e-4).max(1e-6);