fix(tolerance): complete workflow integration

Sync current main and companion codec changes before preserving unsupported frame rows, rendering in the entity plane, and sharing final layout metrics with placement preview.

src/scene/selection.rs

@@ -1,6 +1,9 @@
 // Auto-split from scene/mod.rs. Pure text-move; behaviour unchanged.
 use super::*;
 
+use std::collections::hash_map::DefaultHasher;
+use std::hash::{Hash, Hasher};
+
 impl Scene {
     // ── Selection ─────────────────────────────────────────────────────────
     /// Treat a classic LEADER and its attached annotation as one logical object.
@@ -37,8 +40,11 @@ impl Scene {
     }
     pub fn select_entity(&mut self, handle: Handle, exclusive: bool) {
         let handles = self.handles_expanded_for_leader_annotations(&[handle]);
+        let mut changed = false;
 
         if exclusive {
+            changed = self.selected.len() != handles.len()
+                || handles.iter().any(|handle| !self.selected.contains(handle));
             self.selected.clear();
             self.selected_order.clear();
         }
@@ -46,15 +52,35 @@ impl Scene {
         for handle in handles {
             if self.selected.insert(handle) {
                 self.selected_order.push(handle);
+                changed = true;
             }
         }
-        self.bump_selection();
+        if changed {
+            self.bump_selection_set();
+        }
     }
 
     pub fn deselect_all(&mut self) {
+        if self.selected.is_empty() {
+            return;
+        }
         self.selected.clear();
         self.selected_order.clear();
-        self.bump_selection();
+        self.bump_selection_set();
+    }
+
+    pub(crate) fn selection_fingerprint(&mut self) -> u64 {
+        if self.selection_fingerprint_dirty {
+            let mut fingerprint = self.selected.len() as u64;
+            for handle in &self.selected {
+                let mut hasher = DefaultHasher::new();
+                handle.hash(&mut hasher);
+                fingerprint ^= hasher.finish();
+            }
+            self.selection_fingerprint_cache = fingerprint;
+            self.selection_fingerprint_dirty = false;
+        }
+        self.selection_fingerprint_cache
     }
 
     pub(crate) fn selected_handles_in_order(&self) -> Vec<Handle> {
@@ -103,7 +129,7 @@ impl Scene {
             order.extend(added);
             self.selected = selected;
             self.selected_order = order;
-            self.bump_selection();
+            self.bump_selection_set();
         }
     }
 
@@ -118,7 +144,7 @@ impl Scene {
         }
 
         if changed {
-            self.bump_selection();
+            self.bump_selection_set();
         }
     }
 
@@ -199,7 +225,7 @@ impl Scene {
             }
         }
         if added > 0 {
-            self.bump_selection();
+            self.bump_selection_set();
         }
         added
     }
@@ -223,7 +249,9 @@ impl Scene {
                 self.selected_order.push(h);
             }
         }
-        self.bump_selection();
+        if self.selected != prev {
+            self.bump_selection_set();
+        }
         self.selected.len()
     }
 
@@ -709,7 +737,8 @@ impl Scene {
 
         let mut handle_set: HashSet<Handle> = HashSet::default();
         let mut erased: Vec<(Handle, ChangeKind)> = Vec::new();
-        let mut highlight_changed = false;
+        let mut selection_changed = false;
+        let mut hover_changed = false;
 
         for &h in &erase_handles {
             // Objects on a locked layer can't be erased.
@@ -724,11 +753,11 @@ impl Scene {
             self.delete_solid_history(h);
             self.remember_removed_cache_categories(h);
             self.document.remove_entity_arc(h);
-            highlight_changed |= self.selected.remove(&h);
+            selection_changed |= self.selected.remove(&h);
             self.selected_order.retain(|selected| *selected != h);
             if self.hover_highlight == Some(h) {
                 self.hover_highlight = None;
-                highlight_changed = true;
+                hover_changed = true;
             }
             self.hatches.remove(&h);
             self.images.remove(&h);
@@ -738,7 +767,9 @@ impl Scene {
             handle_set.insert(h);
             erased.push((h, ChangeKind::Removed));
         }
-        if highlight_changed {
+        if selection_changed {
+            self.bump_selection_set();
+        } else if hover_changed {
             self.bump_selection();
         }
         // Capture exactly the group objects that this erase will rewrite, plus
@@ -838,3 +869,29 @@ impl Scene {
         restored
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn selection_fingerprint_tracks_final_set_only() {
+        let mut scene = Scene::default();
+        let first = Handle::new(1);
+        let second = Handle::new(2);
+        scene.select_entity(first, false);
+        scene.select_entity(second, false);
+        let fingerprint = scene.selection_fingerprint();
+        assert!(!scene.selection_fingerprint_dirty);
+
+        scene.deselect_all();
+        scene.select_entity(second, false);
+        scene.select_entity(first, false);
+        assert!(scene.selection_fingerprint_dirty);
+        assert_eq!(scene.selection_fingerprint(), fingerprint);
+
+        scene.set_hover_highlight(Some(Handle::new(3)));
+        assert!(!scene.selection_fingerprint_dirty);
+        assert_eq!(scene.selection_fingerprint(), fingerprint);
+    }
+}