Title a collapsed Variables or Properties node by what it does

Collapsed, the node reads "Set 2 variables", "Get width" or "No properties";
expanded it is always "Variables" / "Properties". The Properties node shows
its object type (and behavior) as a line under the title instead.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

tests/core/variable-node.test.ts

@@ -1,4 +1,5 @@
 import { describe, expect, it } from 'vitest';
+import { CollapseNodesCommand } from '../../src/core/commands/graphCommands';
 import { RemovePortCommand, SetPortWriteCommand } from '../../src/core/commands/portCommands';
 import { AddVariableCommand, RenameVariableCommand } from '../../src/core/commands/variableCommands';
 import { type GraphNode, GraphInterpreter, inlineValue, resolveDef } from '../../src/core/graph';
@@ -238,22 +239,37 @@ describe('Variables node titles', () => {
   const titleOf = (behavior: BehaviorAsset, node: GraphNode) =>
     resolveDef(node, behavior.graph, () => null)!.label;
 
-  it('name a single variable, and stay plain for none or several', () => {
-    const { behavior, edit } = setup();
-    const one = edit.variables(['count'], { write: true });
-    const none = edit.variables([]);
-    const two = edit.variables(['count', 'copy']);
-    expect([one, none, two].map((node) => titleOf(behavior, node))).toEqual([
-      'count',
-      'Variables',
-      'Variables',
-    ]);
-  });
-
-  it('follow a renamed variable', () => {
+  it('follow a renamed variable once collapsed', () => {
     const { fixture, behavior, edit } = setup();
     const node = edit.variables(['count']);
+    fixture.stack.execute(new CollapseNodesCommand(behavior.id, [node.id], true));
     fixture.stack.execute(new RenameVariableCommand(behavior.id, 'count', 'score'));
-    expect(titleOf(behavior, node)).toBe('score');
+    expect(titleOf(behavior, node)).toBe('Get score');
+  });
+
+  it('say what the node does once it is collapsed, and only then', () => {
+    const { fixture, behavior, edit } = setup(['a', 'b', 'c']);
+    const nodes = [
+      edit.variables(['a', 'b', 'c'], { write: ['a', 'b'] }),
+      edit.variables(['a', 'b', 'c'], { write: ['a'] }),
+      edit.variables(['a', 'b'], { write: ['a'] }),
+      edit.variables(['a'], { write: true }),
+      edit.variables(['a']),
+      edit.variables([]),
+    ];
+    const open = nodes.map((node) => titleOf(behavior, node));
+    const ids = nodes.map((node) => node.id);
+    fixture.stack.execute(new CollapseNodesCommand(behavior.id, ids, true));
+    expect(nodes.map((node) => titleOf(behavior, node))).toEqual([
+      'Set 2 variables',
+      'Get 2 variables',
+      'Set a',
+      'Set a',
+      'Get a',
+      'No variables',
+    ]);
+    fixture.stack.undo();
+    expect(nodes.map((node) => titleOf(behavior, node))).toEqual(open);
+    expect(new Set(open)).toEqual(new Set(['Variables']));
   });
 });