fix: select complete circular rims and curved surfaces in 3D

Group kernel pieces across circular rims and hidden surface seams for hovering, selection, dialogs, and measurement. Preserve physical references and cover full-item toggling and picking with regression tests.

Fixes #88

crates/ui-egui/src/selection.rs

@@ -8,6 +8,15 @@ use solvecraft_engine::geom::Vec3;
 
 use crate::viewport::Hit;
 
+/// Model picks retain an on-surface point, but their identity is the body and topology index.
+pub(crate) fn same_item(a: &Sel, b: &Sel) -> bool {
+    match (a, b) {
+        (Sel::Edge { body: a, index: i, .. }, Sel::Edge { body: b, index: j, .. })
+        | (Sel::Face { body: a, index: i, .. }, Sel::Face { body: b, index: j, .. }) => a == b && i == j,
+        _ => a == b,
+    }
+}
+
 /// What a selection input accepts (bit set).
 pub type Accept = u16;
 pub const PROFILES: Accept = 1;
@@ -73,11 +82,11 @@ impl SelInput {
             return;
         }
         // A pick of something already in (or a chain fully in) takes it out.
-        if picked.iter().all(|p| self.items.contains(p)) {
-            self.items.retain(|x| !picked.contains(x));
+        if picked.iter().all(|p| self.items.iter().any(|x| same_item(x, p))) {
+            self.items.retain(|x| !picked.iter().any(|p| same_item(x, p)));
         } else {
             for p in picked {
-                if !self.items.contains(&p) {
+                if !self.items.iter().any(|x| same_item(x, &p)) {
                     self.items.push(p);
                 }
             }