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>

tools/e2e/28-shader.mjs

@@ -18,6 +18,7 @@ export async function shader(t) {
     json,
     evaluate,
     mutate,
+    drag,
     click,
     clickText,
     locate,
@@ -162,6 +163,38 @@ export async function shader(t) {
     a.graph.nodes.find((n) => n.id === ${JSON.stringify(propertyNode?.id)}).params.name = 'glow';`);
   await sleep(300);
 
+  // 28c-ii. Where a node sits is the editor's business: dropping it somewhere else compiles nothing
+  //         again, a changed param does – once (#65).
+  const nodeRef = JSON.stringify(propertyNode?.id);
+  const compiledBefore = await json('__gm.shaderCompiles()');
+  const grab = await json(`__gm.shader.nodeAt(${nodeRef})`);
+  await drag(grab.x, grab.y, grab.x + 60, grab.y + 40);
+  await sleep(300);
+  const dropped = await json(`__gm.shader.nodeAt(${nodeRef})`);
+  const compiledAfterMove = await json('__gm.shaderCompiles()');
+  check(
+    'dropping a node somewhere else moves it without compiling the graph again',
+    dropped.x > grab.x + 30 && compiledAfterMove === compiledBefore,
+    JSON.stringify({ grab, dropped, compiledBefore, compiledAfterMove }),
+  );
+  const defaultBefore = await json(
+    `__gm.state.project.assets.find((x) => x.id === ${JSON.stringify(made.id)}).graph.nodes.find((n) => n.id === ${nodeRef}).params.default`,
+  );
+  const setDefault = (value) =>
+    mutate(`
+    const a = __gm.state.project.assets.find((x) => x.id === ${JSON.stringify(made.id)});
+    a.graph.nodes.find((n) => n.id === ${nodeRef}).params.default = ${JSON.stringify(value)};`);
+  await setDefault(2);
+  await sleep(300);
+  const compiledAfterParam = await json('__gm.shaderCompiles()');
+  check(
+    'changing a param compiles it again, once',
+    compiledAfterParam === compiledAfterMove + 1,
+    JSON.stringify({ compiledAfterMove, compiledAfterParam }),
+  );
+  await setDefault(defaultBefore);
+  await sleep(300);
+
   // 28d. A flat sprite on the camera, drawn on top of everything; its Shader dropdown lists the assets.
   await mutate(`
     const project = __gm.state.project;