Shader library: fingerprint without node positions, a drag no longer recompiles (#65)

shaderFingerprint(graph) covers node id/type/params/ports and edge endpoints only;
x/y, collapsed, folded and edge ids stay out. ShaderLibrary keys on it and counts
compiles (__gm.shaderCompiles()). Measured before: one compile per preview step of a
node drag (12 for a harness drag); after: 0, a param change exactly +1.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

tests/core/shaders.test.ts

@@ -5,7 +5,14 @@
  */
 import { describe, expect, it } from 'vitest';
 import { CreateAssetCommand, SetAssetPropertyCommand } from '../../src/core/commands/assetCommands';
-import { AddNodeCommand, ConnectCommand } from '../../src/core/commands/graphCommands';
+import {
+  AddNodeCommand,
+  CollapseNodesCommand,
+  ConnectCommand,
+  FoldEdgeCommand,
+  MoveNodeCommand,
+  SetNodeParamCommand,
+} from '../../src/core/commands/graphCommands';
 import { SetOverrideCommand } from '../../src/core/commands/sceneObjectCommands';
 import type { Graph } from '../../src/core/graph';
 import { BUILT_IN_NODES } from '../../src/core/graph/nodes';
@@ -27,7 +34,7 @@ import {
   shaderParamDefs,
 } from '../../src/core/properties/shaders';
 import { inlineInputs } from '../../src/core/graph/NodeRegistry';
-import { compileShader } from '../../src/core/shader/compile';
+import { compileShader, shaderFingerprint } from '../../src/core/shader/compile';
 import {
   SHADER_NODES,
   SHADER_NUMBER,
@@ -567,3 +574,22 @@ describe('a sprite wearing a shader', () => {
     expect(shader.graph.nodes.map((n) => n.id)).toEqual(['o']);
   });
 });
+
+describe('the fingerprint the shader library caches on', () => {
+  it('ignores a move, a collapse and a fold, and changes with a param or an edge', () => {
+    const f = makeProject();
+    const s = shaderEditor(f);
+    const n = buildAdjustColors(s);
+    const before = shaderFingerprint(s.asset().graph);
+    f.stack.execute(new MoveNodeCommand(s.id, n.bright, 300, 200));
+    f.stack.execute(new CollapseNodesCommand(s.id, [n.bright, n.luma], true));
+    f.stack.execute(new FoldEdgeCommand(s.id, s.asset().graph.edges[0]!.id, true));
+    expect(s.asset().graph.nodes.find((x) => x.id === n.bright)).toMatchObject({ x: 300, collapsed: true });
+    expect(shaderFingerprint(s.asset().graph)).toBe(before);
+    f.stack.execute(new SetNodeParamCommand(s.id, n.shifted, 'b', 0.25));
+    const withParam = shaderFingerprint(s.asset().graph);
+    expect(withParam).not.toBe(before);
+    s.link(n.brightness, 'value', n.output, 'alpha');
+    expect(shaderFingerprint(s.asset().graph)).not.toBe(withParam);
+  });
+});