Imported looks outlive later features: a body's imported colour, opacity and face colours (kernel paint, dropped by operations) are carried to the next version of the body, its faces by persistent name (split faces keep the colour, new faces take the body's); assigned face appearances already follow their faces by name

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AS5Tn3xieewUSg3uxrMVdL

crates/doc/src/eval.rs

@@ -27,11 +27,13 @@ pub struct ModelBody {
     pub(crate) names: crate::naming::NameCell,
     /// The component the body belongs to (set after each feature).
     pub component: u64,
+    /// The look it was imported with, carried through later features.
+    pub imported: Option<Arc<crate::appearance::ImportedLook>>,
 }
 
 impl ModelBody {
     pub fn new(name: String, body: Body, feature: u64) -> Self {
-        ModelBody { name, body, feature, mesh: OnceLock::new(), key: 0, names: Default::default(), component: 0 }
+        ModelBody { name, body, feature, mesh: OnceLock::new(), key: 0, names: Default::default(), component: 0, imported: None }
     }
     /// Display mesh (chord tolerance 1/1000 of the body size), computed once.
     pub fn mesh(&self) -> Arc<Mesh> {
@@ -236,6 +238,13 @@ impl ModelState {
                     (key, &b.name).hash(&mut h);
                     b.key = h.finish();
                     b.names = crate::naming::NameCell::new(Some(origin.clone()));
+                    // An imported look outlives the operations on the body.
+                    if b.body.paint().is_none()
+                        && b.body.color().is_none()
+                        && let Some(old) = before.bodies.iter().find(|x| x.name == b.name)
+                    {
+                        b.imported = crate::appearance::ImportedLook::of(old);
+                    }
                 }
             }
         }