Editor: Vega-Lite expression intelligence; single-home render errors

src/app/components/LivePreview.test.tsx

@@ -1,10 +1,11 @@
 /**
- * LivePreview — busy overlay guard (spec §04; arch §10.2).
+ * LivePreview — busy overlay + render serialization (spec §04; arch §10.2).
  *
- * The render pipeline is integration-heavy (vega-embed, IndexedDB, Monaco); the
- * busy OVERLAY itself is purely a function of `PreviewStore.busy`. These tests
- * set that flag directly and assert the DOM result — no timing, no mocking of the
- * async render path.
+ * The render pipeline is integration-heavy (vega-embed, IndexedDB, Monaco), so
+ * `renderSpec` is mocked to park each embed in `H.pending` — a test decides when
+ * embeds settle. Render status (`error`/`busy`) is the pane's own local state, so
+ * the busy overlay is driven through its real path — a render left in flight past
+ * the ~1s timer — not by poking a flag.
  */
 
 import { afterEach, beforeEach, describe, expect, test, vi } from 'vitest';
@@ -12,7 +13,6 @@ import { act } from 'react';
 import { createRoot, type Root } from 'react-dom/client';
 import { chartConfigForSelection } from '@core/vega-themes';
 import { useAppStore } from '../stores/AppStore';
-import { usePreviewStore } from '../stores/PreviewStore';
 import { useSnippetStore } from '../stores/SnippetStore';
 import { useDatasetStore } from '../stores/DatasetStore';
 import { LivePreview } from './LivePreview';
@@ -71,7 +71,6 @@ beforeEach(() => {
   H.pending.length = 0;
   H.destroyed.length = 0;
   H.configs.length = 0;
-  usePreviewStore.setState({ error: null, busy: false });
   useSnippetStore.getState().reset();
   useDatasetStore.getState().reset();
 
@@ -84,11 +83,12 @@ beforeEach(() => {
 afterEach(() => {
   act(() => root.unmount());
   container.remove();
-  usePreviewStore.setState({ error: null, busy: false });
   vi.clearAllMocks();
 });
 
 describe('LivePreview busy overlay', () => {
+  const tick = (ms = 6000) => act(async () => void (await vi.advanceTimersByTimeAsync(ms)));
+
   // The overlay is the aria-hidden element carrying the "Rendering…" label — a
   // bare [aria-hidden] query would also match decorative bits of the header
   // controls (e.g. the chart-theme select's caret).
@@ -97,33 +97,44 @@ describe('LivePreview busy overlay', () => {
       /rendering/i.test(el.textContent ?? ''),
     ) ?? null;
 
-  test('does not render the busy overlay when busy=false', () => {
-    // The overlay element should not be in the DOM at all during normal operation.
+  // Start a render and leave it parked in `H.pending`; advancing past the debounce
+  // and the ~1s busy timer flips `busy` on — the real (and only) path now that it
+  // is local state.
+  const startSlowRender = async () => {
+    act(() => {
+      useSnippetStore.setState({ draftText: '{"data":{"values":[]},"mark":"point"}' });
+    });
+    await tick();
+  };
+
+  test('no overlay and no aria-busy before a render is in flight', () => {
     expect(overlay()).toBeNull();
-  });
-
-  test('renders the busy overlay when PreviewStore.busy=true', () => {
-    act(() => usePreviewStore.setState({ busy: true }));
-    expect(overlay()).not.toBeNull();
-  });
-
-  test('the preview body carries aria-busy=true when busy', () => {
-    act(() => usePreviewStore.setState({ busy: true }));
-    // The body element has aria-busy when the store says busy.
-    const busyEl = container.querySelector('[aria-busy="true"]');
-    expect(busyEl).not.toBeNull();
-  });
-
-  test('aria-busy is absent when busy=false (no aria-busy="false" noise)', () => {
     // aria-busy="false" is technically valid but needlessly verbose; we omit it.
     expect(container.querySelector('[aria-busy]')).toBeNull();
   });
 
-  test('overlay disappears when busy returns to false', () => {
-    act(() => usePreviewStore.setState({ busy: true }));
-    expect(overlay()).not.toBeNull();
-    act(() => usePreviewStore.setState({ busy: false }));
-    expect(overlay()).toBeNull();
+  test('a render in flight past ~1s shows the overlay and sets aria-busy', async () => {
+    vi.useFakeTimers();
+    try {
+      await startSlowRender();
+      expect(overlay()).not.toBeNull();
+      expect(container.querySelector('[aria-busy="true"]')).not.toBeNull();
+    } finally {
+      vi.useRealTimers();
+    }
+  });
+
+  test('the overlay clears once the render settles', async () => {
+    vi.useFakeTimers();
+    try {
+      await startSlowRender();
+      expect(overlay()).not.toBeNull();
+      act(() => H.pending[0]()); // the parked embed resolves → busy cleared on settle
+      await tick(0);
+      expect(overlay()).toBeNull();
+    } finally {
+      vi.useRealTimers();
+    }
   });
 });