feat(canvas): accelerate local previews and harden edge flows

tests/use-node-local-data-order.test.ts

@@ -0,0 +1,95 @@
+// @vitest-environment jsdom
+
+import React, { act, useEffect } from "react";
+import { createRoot, type Root } from "react-dom/client";
+import { afterEach, describe, expect, it, vi } from "vitest";
+
+const canvasGraphMock = vi.hoisted(() => ({
+  clearPreviewNodeDataOverride: vi.fn(),
+  setPreviewNodeDataOverride: vi.fn(),
+}));
+
+vi.mock("@/components/canvas/canvas-graph-context", () => ({
+  useCanvasGraphPreviewOverrides: () => canvasGraphMock,
+}));
+
+import { useNodeLocalData } from "@/components/canvas/nodes/use-node-local-data";
+
+type AdjustmentData = {
+  exposure: number;
+};
+
+const latestHookRef: {
+  current:
+    | {
+        updateLocalData: (updater: (current: AdjustmentData) => AdjustmentData) => void;
+      }
+    | null;
+} = { current: null };
+
+function HookHarness() {
+  const { updateLocalData } = useNodeLocalData<AdjustmentData>({
+    nodeId: "node-1",
+    data: { exposure: 0.2 },
+    normalize: (value) => ({ ...(value as AdjustmentData) }),
+    saveDelayMs: 1000,
+    onSave: async () => undefined,
+    debugLabel: "light-adjust",
+  });
+
+  useEffect(() => {
+    latestHookRef.current = { updateLocalData };
+    return () => {
+      latestHookRef.current = null;
+    };
+  }, [updateLocalData]);
+
+  return null;
+}
+
+(globalThis as typeof globalThis & { IS_REACT_ACT_ENVIRONMENT?: boolean }).IS_REACT_ACT_ENVIRONMENT = true;
+
+describe("useNodeLocalData ordering", () => {
+  let container: HTMLDivElement | null = null;
+  let root: Root | null = null;
+
+  afterEach(async () => {
+    if (root) {
+      await act(async () => {
+        root?.unmount();
+      });
+    }
+    container?.remove();
+    root = null;
+    container = null;
+    latestHookRef.current = null;
+    canvasGraphMock.clearPreviewNodeDataOverride.mockReset();
+    canvasGraphMock.setPreviewNodeDataOverride.mockReset();
+  });
+
+  it("does not write preview overrides from inside the local state updater", async () => {
+    let overrideWriteStack = "";
+
+    canvasGraphMock.setPreviewNodeDataOverride.mockImplementation(() => {
+      overrideWriteStack = new Error().stack ?? "";
+    });
+
+    container = document.createElement("div");
+    document.body.appendChild(container);
+    root = createRoot(container);
+
+    await act(async () => {
+      root?.render(React.createElement(HookHarness));
+    });
+
+    await act(async () => {
+      latestHookRef.current?.updateLocalData((current) => ({
+        ...current,
+        exposure: 0.8,
+      }));
+    });
+
+    expect(overrideWriteStack).not.toContain("basicStateReducer");
+    expect(overrideWriteStack).not.toContain("updateReducerImpl");
+  });
+});