Replace the first-run placeholder seed with an onboarding canvas

src/app/App.module.css

@@ -117,3 +117,12 @@
   overflow: hidden;
   background: var(--bg);
 }
+
+/* Onboarding canvas fills the whole panes area when the library is empty (it
+   replaces the entire chrome, not just editor+preview); it scrolls internally. */
+.paneOnboarding {
+  flex: 1 1 0;
+  min-width: 0;
+  overflow: hidden;
+  background: var(--bg);
+}

src/app/App.tsx

@@ -2,6 +2,7 @@ import { useEffect, useRef } from 'react';
 import { ConfirmDialog } from './components/ConfirmDialog';
 import { LivePreview } from './components/LivePreview';
 import { ModalShell } from './components/ModalShell';
+import { Onboarding } from './components/Onboarding';
 import { PaneToggleStrip } from './components/PaneToggleStrip';
 import { ResizeHandle } from './components/ResizeHandle';
 import { SnippetLibrary } from './components/SnippetLibrary';
@@ -11,6 +12,7 @@ import { Toaster } from './components/Toaster';
 import { openModal, setConfirm } from './modals/ModalCoordinator';
 import { confirm } from './stores/ConfirmStore';
 import { usePanesStore } from './stores/PanesStore';
+import { useSnippetStore } from './stores/SnippetStore';
 import { exportWorkspace, importWorkspace } from './services/transfer';
 import styles from './App.module.css';
 
@@ -20,9 +22,12 @@ import styles from './App.module.css';
  *
  * The center editor flexes; the library and preview carry remembered widths and
  * are resized via the drag handles between them (spec §01A). Each pane can be
- * shown/hidden from the always-present toggle strip (the leftmost rail); a hidden
- * pane frees its space and the rest redistribute — when the editor is hidden the
- * two side panes flex proportionally to their remembered widths.
+ * shown/hidden from the toggle strip (the leftmost rail); a hidden pane frees its
+ * space and the rest redistribute — when the editor is hidden the two side panes
+ * flex proportionally to their remembered widths.
+ *
+ * When the library is empty, this whole pane chrome (strip + panes) is replaced
+ * by the full-width onboarding canvas (spec §02 → First-Run & Empty Workspace).
  */
 export function App() {
   const libraryWidth = usePanesStore((s) => s.libraryWidth);
@@ -30,6 +35,10 @@ export function App() {
   const libraryVisible = usePanesStore((s) => s.libraryVisible);
   const editorVisible = usePanesStore((s) => s.editorVisible);
   const previewVisible = usePanesStore((s) => s.previewVisible);
+  // An empty library is the onboarding surface: the whole pane chrome (toggle
+  // strip, library list, editor, preview) is replaced by the full-width Onboarding
+  // canvas (spec §02 → First-Run & Empty Workspace).
+  const hasSnippets = useSnippetStore((s) => s.snippets.length > 0);
 
   // Side-pane sizing: fixed remembered width while the editor (the flex filler) is
   // present; when it's hidden, the side panes grow proportionally to those widths
@@ -120,38 +129,50 @@ export function App() {
 
       {/* tabIndex -1 makes the landmark a focus target for the skip link. */}
       <main id="main" className={styles.panes} tabIndex={-1}>
-        {/* Always-present rail: shows/hides panes and shortcuts to Datasets (§01A). */}
-        <PaneToggleStrip />
-        {libraryVisible && (
-          <section
-            id="pane-library"
-            className={styles.pane}
-            style={sideStyle(libraryWidth)}
-            aria-label="Snippet library"
-          >
-            <SnippetLibrary />
-          </section>
-        )}
-        {/* A resize handle only sits between two visible panes that flank the editor. */}
-        {libraryVisible && editorVisible && (
-          <ResizeHandle side="library" label="Resize snippet library" />
-        )}
-        {editorVisible && (
-          <section id="pane-editor" className={styles.paneEditor} aria-label="Spec editor">
-            <SpecEditor />
-          </section>
-        )}
-        {editorVisible && previewVisible && (
-          <ResizeHandle side="preview" label="Resize live preview" />
-        )}
-        {previewVisible && (
-          <section
-            id="pane-preview"
-            className={styles.pane}
-            style={sideStyle(previewWidth)}
-            aria-label="Live preview"
-          >
-            <LivePreview />
+        {hasSnippets ? (
+          <>
+            {/* Always-present rail: shows/hides panes and shortcuts to Datasets (§01A). */}
+            <PaneToggleStrip />
+            {libraryVisible && (
+              <section
+                id="pane-library"
+                className={styles.pane}
+                style={sideStyle(libraryWidth)}
+                aria-label="Snippet library"
+              >
+                <SnippetLibrary />
+              </section>
+            )}
+            {/* A resize handle only sits between two visible panes that flank the editor. */}
+            {libraryVisible && editorVisible && (
+              <ResizeHandle side="library" label="Resize snippet library" />
+            )}
+            {editorVisible && (
+              <section id="pane-editor" className={styles.paneEditor} aria-label="Spec editor">
+                <SpecEditor />
+              </section>
+            )}
+            {editorVisible && previewVisible && (
+              <ResizeHandle side="preview" label="Resize live preview" />
+            )}
+            {previewVisible && (
+              <section
+                id="pane-preview"
+                className={styles.pane}
+                style={sideStyle(previewWidth)}
+                aria-label="Live preview"
+              >
+                <LivePreview />
+              </section>
+            )}
+          </>
+        ) : (
+          // Empty library → the onboarding canvas takes the full workspace. The
+          // pane chrome (toggle strip, library list, editor, preview) is hidden:
+          // with no snippets, Create/Search/Sort/Storage and the pane toggles have
+          // nothing to act on, so the welcome gets the whole width (spec §02).
+          <section className={styles.paneOnboarding} aria-label="Getting started">
+            <Onboarding />
           </section>
         )}
       </main>

src/app/components/Onboarding.module.css

@@ -0,0 +1,170 @@
+/* Onboarding canvas — fills the editor+preview space when the library is empty. */
+.onboarding {
+  height: 100%;
+  overflow: auto;
+  display: flex;
+  justify-content: center;
+  background: var(--bg);
+}
+
+/* A readable, centered column; the gallery grid widens within it. */
+.inner {
+  width: 100%;
+  max-width: 760px;
+  padding: var(--space-7) var(--space-6);
+}
+
+.title {
+  margin: 0 0 var(--space-2);
+  font-size: 22px;
+  font-weight: 600;
+  letter-spacing: 0.01em;
+}
+
+.tagline {
+  margin: 0 0 var(--space-6);
+  max-width: 56ch;
+  color: var(--text-secondary);
+  line-height: 1.5;
+}
+
+/* Primary call to action — the accent button, matching the library's Create. */
+.primary {
+  display: inline-flex;
+  align-items: center;
+  gap: var(--space-2);
+  height: 40px;
+  padding: 0 var(--space-5);
+  border: var(--border-width) solid transparent;
+  border-radius: var(--radius);
+  background: var(--accent);
+  color: var(--accent-contrast);
+  font: inherit;
+  font-weight: 600;
+  cursor: pointer;
+  transition: background var(--dur-fast) var(--ease);
+}
+.primary:hover {
+  background: var(--accent-hover);
+}
+.primary:focus-visible {
+  outline: 2px solid var(--focus);
+  outline-offset: 2px;
+}
+
+/* The "or start from an example" header row, with Add all pushed to the end. */
+.galleryHead {
+  display: flex;
+  align-items: baseline;
+  justify-content: space-between;
+  gap: var(--space-4);
+  margin: var(--space-7) 0 var(--space-4);
+  padding-top: var(--space-5);
+  border-top: var(--border-width) solid var(--border);
+}
+
+.galleryTitle {
+  margin: 0;
+  font-size: 14px;
+  font-weight: 600;
+  color: var(--text-secondary);
+}
+
+/* Secondary button — bordered, transparent (like the header actions). */
+.addAll {
+  flex: 0 0 auto;
+  height: 32px;
+  padding: 0 var(--space-4);
+  border: var(--border-width) solid var(--border-strong);
+  border-radius: var(--radius);
+  background: transparent;
+  color: var(--text);
+  font: inherit;
+  font-size: 13px;
+  font-weight: 500;
+  cursor: pointer;
+  transition: background var(--dur-fast) var(--ease);
+}
+.addAll:hover {
+  background: var(--layer-01);
+}
+.addAll:focus-visible {
+  outline: 2px solid var(--focus);
+  outline-offset: 2px;
+}
+
+/* Responsive gallery: cards as wide as ~240px, filling the column. */
+.gallery {
+  list-style: none;
+  margin: 0;
+  padding: 0;
+  display: grid;
+  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
+  gap: var(--space-4);
+}
+
+.card {
+  display: flex;
+  flex-direction: column;
+  gap: var(--space-3);
+  padding: var(--space-3);
+  border: var(--border-width) solid var(--border);
+  border-radius: var(--radius);
+  background: var(--layer-01);
+}
+
+/* The live chart's host. Width fills the card; height is fixed inline (THUMB_HEIGHT). */
+.thumb {
+  width: 100%;
+  overflow: hidden;
+  border-radius: var(--radius);
+  background: var(--bg);
+  display: flex;
+  align-items: center;
+  justify-content: center;
+}
+
+.cardBody {
+  display: flex;
+  flex-direction: column;
+  gap: var(--space-1);
+  flex: 1 1 auto;
+}
+
+.cardName {
+  font-weight: 600;
+  font-size: 14px;
+  color: var(--text);
+}
+
+.cardDesc {
+  font-size: 13px;
+  color: var(--text-secondary);
+  line-height: 1.4;
+}
+
+/* Per-example Add — small bordered action, aligned to the card's start. */
+.add {
+  align-self: flex-start;
+  display: inline-flex;
+  align-items: center;
+  gap: var(--space-1);
+  height: 30px;
+  padding: 0 var(--space-4);
+  border: var(--border-width) solid var(--border-strong);
+  border-radius: var(--radius);
+  background: var(--bg);
+  color: var(--text);
+  font: inherit;
+  font-size: 13px;
+  font-weight: 500;
+  cursor: pointer;
+  transition: background var(--dur-fast) var(--ease);
+}
+.add:hover {
+  background: var(--layer-02, var(--layer-01));
+}
+.add:focus-visible {
+  outline: 2px solid var(--focus);
+  outline-offset: 2px;
+}

src/app/components/Onboarding.test.tsx

@@ -0,0 +1,96 @@
+/**
+ * Onboarding canvas — the empty-workspace actions (spec §02).
+ *
+ * The live chart rendering is integration (vega-embed) and is mocked away here;
+ * what these tests own is the wiring: each affordance creates the right snippets
+ * in the store. Card previews are exercised only insofar as they don't crash.
+ */
+
+import { afterEach, beforeEach, describe, expect, test, vi } from 'vitest';
+import { act } from 'react';
+import { createRoot, type Root } from 'react-dom/client';
+import { CHART_EXAMPLES, exampleSpecText } from '@core/examples';
+import { sampleSpecText } from '@core/snippet';
+import { useSnippetStore } from '../stores/SnippetStore';
+import { Onboarding } from './Onboarding';
+
+// The gallery renders one chart per card; stub the shared renderer so the test
+// never touches vega-embed. A resolved no-op handle is enough — Onboarding only
+// finalizes it on unmount.
+vi.mock('../services/chart-renderer', () => ({
+  renderSpec: () => Promise.resolve({ destroy() {}, resize() {} }),
+}));
+
+(globalThis as { IS_REACT_ACT_ENVIRONMENT?: boolean }).IS_REACT_ACT_ENVIRONMENT = true;
+
+let container: HTMLDivElement;
+let root: Root;
+
+beforeEach(() => {
+  useSnippetStore.getState().reset();
+  container = document.createElement('div');
+  document.body.appendChild(container);
+  root = createRoot(container);
+  act(() => root.render(<Onboarding />));
+});
+
+afterEach(() => {
+  act(() => root.unmount());
+  container.remove();
+  useSnippetStore.getState().reset();
+  vi.clearAllMocks();
+});
+
+/** Click the button whose accessible name (aria-label, else text) matches. */
+function click(name: string) {
+  const button = Array.from(container.querySelectorAll('button')).find((b) =>
+    (b.getAttribute('aria-label') ?? b.textContent ?? '').includes(name),
+  );
+  if (!button) throw new Error(`button not found: ${name}`);
+  act(() => button.click());
+}
+
+describe('Onboarding', () => {
+  test('greets the user and offers the primary create action', () => {
+    expect(container.textContent).toContain('Welcome to Astrolabe');
+    expect(container.textContent).toContain('Create your first snippet');
+  });
+
+  test('renders one card per example, each with an Add control', () => {
+    for (const example of CHART_EXAMPLES) {
+      expect(container.textContent).toContain(example.name);
+      expect(container.textContent).toContain(example.description);
+      expect(container.querySelector(`button[aria-label="Add ${example.name}"]`)).not.toBeNull();
+    }
+  });
+
+  test('"Create your first snippet" creates one snippet from the sample template', () => {
+    click('Create your first snippet');
+    const { snippets, activeSnippetId } = useSnippetStore.getState();
+    expect(snippets).toHaveLength(1);
+    expect(snippets[0].spec).toBe(sampleSpecText());
+    expect(activeSnippetId).toBe(snippets[0].id);
+  });
+
+  test('an example’s Add creates that snippet, named and active', () => {
+    const scatter = CHART_EXAMPLES.find((e) => e.id === 'scatter')!;
+    click(`Add ${scatter.name}`);
+    const { snippets, activeSnippetId } = useSnippetStore.getState();
+    expect(snippets).toHaveLength(1);
+    expect(snippets[0].name).toBe(scatter.name);
+    expect(snippets[0].spec).toBe(exampleSpecText(scatter));
+    expect(activeSnippetId).toBe(snippets[0].id);
+  });
+
+  test('"Add all" adds every example and makes the bar chart active', () => {
+    click('Add all');
+    const { snippets, activeSnippetId } = useSnippetStore.getState();
+    expect(snippets).toHaveLength(CHART_EXAMPLES.length);
+    // Every example name is present.
+    const names = new Set(snippets.map((s) => s.name));
+    for (const example of CHART_EXAMPLES) expect(names.has(example.name)).toBe(true);
+    // The first example (bar) is the active one (staggered newest).
+    const active = snippets.find((s) => s.id === activeSnippetId);
+    expect(active?.name).toBe(CHART_EXAMPLES[0].name);
+  });
+});

src/app/components/Onboarding.tsx

@@ -0,0 +1,160 @@
+/**
+ * Onboarding canvas — the empty-workspace surface (spec §02 → First-Run & Empty
+ * Workspace).
+ *
+ * Shown by `App` in place of the editor + preview whenever the library is empty
+ * (first run, or after the last snippet is deleted). Rather than seeding a
+ * placeholder snippet, it greets the user and offers two deliberate ways in: a
+ * primary "Create your first snippet" (the sample template) and a gallery of
+ * example snippets, each previewed live and addable on its own or all at once.
+ *
+ * The previews render through the shared `chart-renderer` — the one place that
+ * touches vega-embed — so there is no parallel embed path. Each card's chart
+ * lives in its own node and owns its handle's lifecycle (finalized on unmount),
+ * independent of `LivePreview`'s single-host render serialization.
+ */
+
+import { useEffect, useRef } from 'react';
+import type { VisualizationSpec } from 'vega-embed';
+import { CHART_EXAMPLES, exampleSpecText, type ChartExample } from '@core/examples';
+import { createSnippet as createSnippetRecord } from '@core/snippet';
+import { chartConfigFor } from '@core/vega-themes';
+import { renderSpec, type RenderHandle } from '../services/chart-renderer';
+import { useAppStore } from '../stores/AppStore';
+import { usePanesStore } from '../stores/PanesStore';
+import { useSnippetStore } from '../stores/SnippetStore';
+import { Icon } from './Icon';
+import styles from './Onboarding.module.css';
+
+/** Fixed thumbnail height; width fills the card via Vega's `container` sizing. */
+const THUMB_HEIGHT = 140;
+
+/**
+ * Live preview of one example. Renders the example spec at card width through the
+ * shared renderer, finalizing the Vega view on unmount or when the spec/theme
+ * changes — a chart that isn't finalized leaks its timers and listeners.
+ */
+function ExampleThumbnail({ spec }: { spec: Record<string, unknown> }) {
+  const hostRef = useRef<HTMLDivElement>(null);
+  const uiTheme = useAppStore((s) => s.uiTheme);
+
+  useEffect(() => {
+    const node = hostRef.current;
+    if (!node) return;
+    // TODO: thumbnails render once at mount width and don't call handle.resize(),
+    // so a `width: 'container'` chart won't re-fit when the window resizes and the
+    // grid reflows the card. Cosmetic only (the card clips/letterboxes via overflow
+    // hidden) on a brief first-run surface; wire a resize observer if it ever shows.
+    let handle: RenderHandle | null = null;
+    let cancelled = false;
+    // `container` width fits the card; a fixed height keeps every card uniform.
+    // Spread onto a copy so the shared example object is never mutated.
+    const sized = { ...spec, width: 'container', height: THUMB_HEIGHT } as VisualizationSpec;
+    void renderSpec(node, sized, chartConfigFor(uiTheme))
+      .then((h) => {
+        if (cancelled) h.destroy();
+        else handle = h;
+      })
+      .catch(() => {
+        // Examples are schema-validated (examples.test.ts), but a thumbnail that
+        // somehow fails to render must never break onboarding — leave the card
+        // image blank and let the name + description carry it.
+      });
+    return () => {
+      cancelled = true;
+      handle?.destroy();
+    };
+  }, [spec, uiTheme]);
+
+  // Decorative: the name, description, and Add button carry the meaning, so a
+  // screen reader hears "Bar chart … Add", not a tree of chart SVG nodes (arch §10).
+  return (
+    <div
+      ref={hostRef}
+      className={styles.thumb}
+      style={{ height: THUMB_HEIGHT }}
+      aria-hidden="true"
+    />
+  );
+}
+
+export function Onboarding() {
+  const createSnippet = useSnippetStore((s) => s.createSnippet);
+  const addSnippets = useSnippetStore((s) => s.addSnippets);
+  const applyOnboardingSplit = usePanesStore((s) => s.applyOnboardingSplit);
+
+  // Leaving onboarding lays the workspace out at the default 25·25·50 split, so
+  // the first chart opens with a generous preview (spec §02). The canvas fills
+  // the window here, so its width is a good proxy for the panes container.
+  const layoutWorkspace = () => applyOnboardingSplit(window.innerWidth);
+
+  // Primary path and per-example add both go through the normal create action,
+  // so an added example opens in the editor exactly like any new snippet.
+  const handleCreate = () => {
+    createSnippet();
+    layoutWorkspace();
+  };
+  const handleAdd = (example: ChartExample) => {
+    createSnippet({ name: example.name, spec: exampleSpecText(example) });
+    layoutWorkspace();
+  };
+
+  const handleAddAll = () => {
+    // Stagger the timestamps so the first example (the bar chart) is the newest:
+    // it then sorts to the top of the library and `addSnippets` makes it active
+    // (it selects the newest when nothing is active — true during onboarding).
+    const base = Date.now();
+    const records = CHART_EXAMPLES.map((example, i) =>
+      createSnippetRecord({
+        name: example.name,
+        spec: exampleSpecText(example),
+        now: new Date(base - i * 1000),
+      }),
+    );
+    addSnippets(records);
+    layoutWorkspace();
+  };
+
+  return (
+    <div className={styles.onboarding}>
+      <div className={styles.inner}>
+        <h2 className={styles.title}>Welcome to Astrolabe</h2>
+        <p className={styles.tagline}>
+          A local library for your Vega-Lite charts — authored as JSON, rendered live, and kept on
+          your device.
+        </p>
+
+        <button type="button" className={styles.primary} onClick={handleCreate}>
+          <Icon name="add" /> Create your first snippet
+        </button>
+
+        <div className={styles.galleryHead}>
+          <h3 className={styles.galleryTitle}>Or start from an example</h3>
+          <button type="button" className={styles.addAll} onClick={handleAddAll}>
+            Add all
+          </button>
+        </div>
+
+        <ul className={styles.gallery}>
+          {CHART_EXAMPLES.map((example) => (
+            <li key={example.id} className={styles.card}>
+              <ExampleThumbnail spec={example.spec} />
+              <div className={styles.cardBody}>
+                <span className={styles.cardName}>{example.name}</span>
+                <span className={styles.cardDesc}>{example.description}</span>
+              </div>
+              <button
+                type="button"
+                className={styles.add}
+                aria-label={`Add ${example.name}`}
+                onClick={() => handleAdd(example)}
+              >
+                <Icon name="add" /> Add
+              </button>
+            </li>
+          ))}
+        </ul>
+      </div>
+    </div>
+  );
+}

src/app/components/SnippetLibrary.test.tsx

@@ -159,16 +159,6 @@ describe('SnippetLibrary metadata panel (spec §02)', () => {
     expect(container.textContent).toContain('No snippets match your search');
   });
 
-  test('shows the empty-library state when there are no snippets', () => {
-    useSnippetStore.getState().hydrate([], null);
-
-    act(() => {
-      root.render(<SnippetLibrary />);
-    });
-
-    expect(container.textContent).toContain('No snippets yet');
-  });
-
   test('Duplicate adds an independent copy and makes it active', async () => {
     const s = createSnippet({ id: 'a', name: 'Chart', now: new Date('2026-01-01T00:00:00Z') });
     useSnippetStore.getState().hydrate([s], 'a');

src/app/components/SnippetLibrary.tsx

@@ -199,8 +199,10 @@ export function SnippetLibrary() {
     [snippets, searchQuery, sortBy, sortOrder],
   );
 
-  // Empty-state copy splits two cases (council EMPTY STATES; Carbon two types):
-  // a genuinely empty library vs. a search that matched nothing.
+  // The list owes a single empty state: a search that matched nothing (council
+  // EMPTY STATES). A genuinely empty library is handled one level up — App replaces
+  // the whole pane chrome with the onboarding canvas (spec §02 → First-Run & Empty
+  // Workspace), so this component never renders with zero snippets.
   const searching = searchQuery.trim() !== '';
   const noMatches = ordered.length === 0;
 
@@ -299,19 +301,14 @@ export function SnippetLibrary() {
 
       <ul className={styles.list}>
         {noMatches && searching && (
-          // Empty state (b): a search that matched nothing (council EMPTY STATES).
+          // The list's one empty state: a search that matched nothing (council
+          // EMPTY STATES). A genuinely empty library never reaches here — App shows
+          // the onboarding canvas in place of this pane (spec §02).
           <li className={styles.empty}>
             <span className={styles.emptyTitle}>No snippets match your search</span>
             <span className={styles.emptyHint}>Try a different term.</span>
           </li>
         )}
-        {noMatches && !searching && (
-          // Empty state (a): a genuinely empty library — guide to Create.
-          <li className={styles.empty}>
-            <span className={styles.emptyTitle}>No snippets yet</span>
-            <span className={styles.emptyHint}>Create your first one with the button above.</span>
-          </li>
-        )}
         {ordered.map((s) => {
           // Size is omitted under ~1 KB per spec §02; null collapses the suffix.
           const size = formatSnippetSize(snippetSizeBytes(s));

src/app/orchestration/startup.ts

@@ -1,15 +1,16 @@
 /**
  * App startup orchestration.
  *
- * Loads the snippet library from IndexedDB into the store, seeds a sample
- * snippet on first run (spec §02 → "On first run … seed one sample bar-chart
- * snippet"), then wires the persistence subscribers. Called once from main.tsx;
- * the UI renders immediately and fills in when hydration completes.
+ * Loads the snippet library from IndexedDB into the store, then wires the
+ * persistence subscribers. Called once from main.tsx; the UI renders immediately
+ * and fills in when hydration completes. An empty library is NOT seeded with a
+ * placeholder — the workspace shows the onboarding canvas instead (spec §02 →
+ * First-Run & Empty Workspace).
  */
 
-import { createSnippet, type Snippet } from '@core/snippet';
+import type { Snippet } from '@core/snippet';
 import type { Dataset } from '@core/dataset';
-import { loadSnippets, saveSnippet } from '../infrastructure/snippet-store';
+import { loadSnippets } from '../infrastructure/snippet-store';
 import { loadDatasets } from '../infrastructure/dataset-store';
 import { storageErrorNotification } from '../services/storage-errors';
 import { notify } from '../stores/NotificationStore';
@@ -28,31 +29,15 @@ export async function initApp(): Promise<void> {
 
   // If storage can't be opened (private-browsing, blocked storage), don't fail
   // startup silently: warn, then run this session in memory so the app is still
-  // usable. `storageOk` gates the seed-save below — there's no point trying to
-  // persist a seed into storage we just failed to read.
+  // usable. An empty result — whether genuinely empty or a failed read — leaves
+  // the library empty and the onboarding canvas takes over (spec §02).
   let snippets: Snippet[] = [];
-  let storageOk = true;
   try {
     snippets = await loadSnippets();
   } catch (err) {
-    storageOk = false;
     notify(storageErrorNotification('load', err));
   }
 
-  if (snippets.length === 0) {
-    const sample = createSnippet();
-    snippets = [sample];
-    if (storageOk) {
-      // Ensure the seed survives even before the first edit; a failure here is
-      // surfaced, not swallowed.
-      try {
-        await saveSnippet(sample);
-      } catch (err) {
-        notify(storageErrorNotification('save', err));
-      }
-    }
-  }
-
   // Load the dataset library too (no first-run seed — datasets are user-created).
   // A failure here is surfaced; the app stays usable with an empty dataset library.
   let datasets: Dataset[] = [];

src/app/stores/PanesStore.test.ts

@@ -138,3 +138,26 @@ describe('pane visibility (§01A)', () => {
     expect(store().libraryWidth).toBe(250);
   });
 });
+
+describe('applyOnboardingSplit (spec §02 → First-Run & Empty Workspace)', () => {
+  test('lays out 25·25·50 on a roomy container', () => {
+    const W = 1600;
+    store().applyOnboardingSplit(W);
+    expect(store().libraryWidth).toBe(W * 0.25); // 400
+    expect(store().previewWidth).toBe(W * 0.5); // 800 → editor flexes to the remaining ~25%
+  });
+
+  test('shows all three panes, even ones that were hidden', () => {
+    store().hydrate({}, { library: false, editor: false, preview: false });
+    store().applyOnboardingSplit(1600);
+    expect(store().libraryVisible).toBe(true);
+    expect(store().editorVisible).toBe(true);
+    expect(store().previewVisible).toBe(true);
+  });
+
+  test('never drops a pane below its minimum on a narrow container', () => {
+    store().applyOnboardingSplit(600);
+    expect(store().libraryWidth).toBeGreaterThanOrEqual(PANE_MIN.library);
+    expect(store().previewWidth).toBeGreaterThanOrEqual(PANE_MIN.preview);
+  });
+});

src/app/stores/PanesStore.ts

@@ -99,6 +99,15 @@ export interface PanesState {
   previewVisible: boolean;
   /** Set a side pane's width (already clamped by the caller). */
   setWidth: (side: PaneSide, width: number) => void;
+  /**
+   * Lay the workspace out at the onboarding default split — library 25% · editor
+   * 25% · preview 50% of `containerWidth` — and show all three panes. Applied when
+   * the user leaves the empty/onboarding state by creating their first snippet(s),
+   * so the first chart opens with a generous preview rather than the generic
+   * remembered widths (spec §02 → First-Run & Empty Workspace). Widths are clamped
+   * to keep every pane at least its minimum.
+   */
+  applyOnboardingSplit: (containerWidth: number) => void;
   /** Show/hide one pane. Hiding all panes is permitted (§01A) — the strip stays. */
   togglePane: (pane: PaneName) => void;
   /** Restore persisted widths + visibility on startup; missing values keep defaults. */
@@ -124,6 +133,31 @@ export const usePanesStore = create<PanesState>((set) => ({
   setWidth: (side, width) =>
     set(side === 'library' ? { libraryWidth: width } : { previewWidth: width }),
 
+  applyOnboardingSplit: (containerWidth) =>
+    set(() => {
+      // Clamp preview (the larger share) first, then library against it, so the
+      // editor keeps at least its minimum wherever the window is wide enough.
+      const previewWidth = clampSideWidth(
+        'preview',
+        Math.round(containerWidth * 0.5),
+        containerWidth,
+        Math.round(containerWidth * 0.25),
+      );
+      const libraryWidth = clampSideWidth(
+        'library',
+        Math.round(containerWidth * 0.25),
+        containerWidth,
+        previewWidth,
+      );
+      return {
+        libraryWidth,
+        previewWidth,
+        libraryVisible: true,
+        editorVisible: true,
+        previewVisible: true,
+      };
+    }),
+
   togglePane: (pane) => set((s) => ({ [VISIBLE_KEY[pane]]: !s[VISIBLE_KEY[pane]] })),
 
   hydrate: (layout, visibility) =>

src/core/examples.test.ts

@@ -0,0 +1,49 @@
+import { describe, expect, test } from 'vitest';
+import { compile } from 'vega-lite';
+import { CHART_EXAMPLES, exampleSpecText } from './examples';
+import { SAMPLE_SPEC, VEGA_LITE_SCHEMA_URL } from './snippet';
+
+describe('chart examples', () => {
+  test('the gallery is non-empty and ids are unique', () => {
+    expect(CHART_EXAMPLES.length).toBeGreaterThan(0);
+    const ids = CHART_EXAMPLES.map((e) => e.id);
+    expect(new Set(ids).size).toBe(ids.length);
+  });
+
+  test('the bar example reuses the blank-snippet template (one source of truth)', () => {
+    const bar = CHART_EXAMPLES.find((e) => e.id === 'bar');
+    expect(bar?.spec).toBe(SAMPLE_SPEC);
+  });
+
+  // The whole promise of the gallery is that every card renders. A spec that
+  // doesn't compile would render to an error on first paint — so each example
+  // must be valid, self-contained Vega-Lite.
+  describe.each(CHART_EXAMPLES.map((e) => [e.id, e] as const))('example: %s', (_id, example) => {
+    test('has a name and a one-line description', () => {
+      expect(example.name.trim()).not.toBe('');
+      expect(example.description.trim()).not.toBe('');
+    });
+
+    test('pins the bundled Vega-Lite schema', () => {
+      expect(example.spec.$schema).toBe(VEGA_LITE_SCHEMA_URL);
+    });
+
+    test('carries inline data only (no named/url reference, no dataset coupling)', () => {
+      const data = example.spec.data as { values?: unknown[]; name?: string; url?: string };
+      expect(Array.isArray(data?.values)).toBe(true);
+      expect(data.values?.length ?? 0).toBeGreaterThan(0);
+      expect(data.name).toBeUndefined();
+      expect(data.url).toBeUndefined();
+    });
+
+    test('compiles as valid Vega-Lite', () => {
+      // compile() is pure (produces a Vega spec, no DOM/render); it throws on an
+      // invalid Vega-Lite spec, which is exactly the failure we want to catch.
+      expect(() => compile(example.spec as unknown as Parameters<typeof compile>[0])).not.toThrow();
+    });
+
+    test('serializes to JSON text that round-trips to the spec', () => {
+      expect(JSON.parse(exampleSpecText(example))).toEqual(example.spec);
+    });
+  });
+});

src/core/examples.ts

@@ -0,0 +1,184 @@
+/**
+ * Example snippets — the onboarding gallery (spec §02 → First-Run & Empty
+ * Workspace).
+ *
+ * Portable core: no browser APIs, no React. A small, curated set of simple
+ * Vega-Lite specs that each showcase a distinct capability (a mark type, the
+ * temporal field type, a colour encoding, stacking, a non-cartesian mark, a
+ * data transform). They exist so a first-time user can populate their library
+ * from working examples instead of a blank canvas or a placeholder seed.
+ *
+ * Constraints that keep them safe and self-contained:
+ *   - **Inline data only** — every example carries its own `data.values`, so it
+ *     always renders offline and never couples to the dataset library.
+ *   - **Meaningful names** — added examples become ordinary snippets; they carry
+ *     real names ("Bar chart", "Scatter plot"), never an auto-generated stamp.
+ *   - **Valid Vega-Lite** — each spec compiles (asserted in examples.test.ts).
+ *
+ * The bar-chart example reuses `SAMPLE_SPEC` — the same template `createSnippet`
+ * starts a blank snippet from — so "the starting template" and "the first
+ * example" are one source of truth, not two copies that can drift.
+ */
+
+import { SAMPLE_SPEC, VEGA_LITE_SCHEMA_URL } from './snippet';
+
+export interface ChartExample {
+  /** Stable key — React list key and test identity (not user-visible). */
+  id: string;
+  /** The snippet name applied when this example is added to the library. */
+  name: string;
+  /** One-line gallery description of what the chart shows. */
+  description: string;
+  /** The Vega-Lite spec as a plain object: rendered live, serialized when added. */
+  spec: Record<string, unknown>;
+}
+
+/**
+ * The curated gallery, in pedagogical order (simplest first). Adding an example
+ * = one entry here; the onboarding canvas and the validation test both iterate
+ * this array, so nothing else needs touching.
+ */
+export const CHART_EXAMPLES: ReadonlyArray<ChartExample> = [
+  {
+    id: 'bar',
+    name: 'Bar chart',
+    description: 'Compare a value across categories.',
+    // Reuses the blank-snippet template, so the starting point and the first
+    // example never drift apart.
+    spec: SAMPLE_SPEC,
+  },
+  {
+    id: 'line',
+    name: 'Time-series line',
+    description: 'Trace a value over time (a temporal axis).',
+    spec: {
+      $schema: VEGA_LITE_SCHEMA_URL,
+      description: 'A line chart over time.',
+      data: {
+        values: [
+          { date: '2024-01-01', price: 120 },
+          { date: '2024-02-01', price: 135 },
+          { date: '2024-03-01', price: 128 },
+          { date: '2024-04-01', price: 156 },
+          { date: '2024-05-01', price: 172 },
+          { date: '2024-06-01', price: 165 },
+        ],
+      },
+      mark: 'line',
+      encoding: {
+        x: { field: 'date', type: 'temporal', title: 'Month' },
+        y: { field: 'price', type: 'quantitative', title: 'Price' },
+      },
+    },
+  },
+  {
+    id: 'scatter',
+    name: 'Scatter plot',
+    description: 'Relate two measures, coloured by group.',
+    spec: {
+      $schema: VEGA_LITE_SCHEMA_URL,
+      description: 'A scatter plot with a colour encoding.',
+      data: {
+        values: [
+          { x: 1.2, y: 3.4, group: 'A' },
+          { x: 2.5, y: 1.9, group: 'B' },
+          { x: 3.1, y: 4.7, group: 'A' },
+          { x: 4.0, y: 2.2, group: 'B' },
+          { x: 2.2, y: 3.0, group: 'C' },
+          { x: 3.8, y: 4.1, group: 'C' },
+        ],
+      },
+      mark: 'point',
+      encoding: {
+        x: { field: 'x', type: 'quantitative' },
+        y: { field: 'y', type: 'quantitative' },
+        color: { field: 'group', type: 'nominal' },
+      },
+    },
+  },
+  {
+    id: 'area',
+    name: 'Stacked area',
+    description: 'Stack series totals over time.',
+    spec: {
+      $schema: VEGA_LITE_SCHEMA_URL,
+      description: 'A stacked area chart.',
+      data: {
+        values: [
+          { month: '2024-01-01', series: 'North', sales: 28 },
+          { month: '2024-01-01', series: 'South', sales: 19 },
+          { month: '2024-02-01', series: 'North', sales: 35 },
+          { month: '2024-02-01', series: 'South', sales: 22 },
+          { month: '2024-03-01', series: 'North', sales: 31 },
+          { month: '2024-03-01', series: 'South', sales: 27 },
+        ],
+      },
+      mark: 'area',
+      encoding: {
+        x: { field: 'month', type: 'temporal', title: 'Month' },
+        y: { field: 'sales', type: 'quantitative', stack: 'zero' },
+        color: { field: 'series', type: 'nominal' },
+      },
+    },
+  },
+  {
+    id: 'donut',
+    name: 'Donut',
+    description: 'Show parts of a whole (an arc mark).',
+    spec: {
+      $schema: VEGA_LITE_SCHEMA_URL,
+      description: 'A donut chart.',
+      data: {
+        values: [
+          { category: 'A', value: 40 },
+          { category: 'B', value: 30 },
+          { category: 'C', value: 20 },
+          { category: 'D', value: 10 },
+        ],
+      },
+      mark: { type: 'arc', innerRadius: 50 },
+      encoding: {
+        theta: { field: 'value', type: 'quantitative' },
+        color: { field: 'category', type: 'nominal' },
+      },
+    },
+  },
+  {
+    id: 'histogram',
+    name: 'Histogram',
+    description: 'Bin values to show a distribution.',
+    spec: {
+      $schema: VEGA_LITE_SCHEMA_URL,
+      description: 'A binned histogram.',
+      data: {
+        values: [
+          { value: 12 },
+          { value: 18 },
+          { value: 21 },
+          { value: 22 },
+          { value: 24 },
+          { value: 25 },
+          { value: 27 },
+          { value: 31 },
+          { value: 33 },
+          { value: 35 },
+          { value: 38 },
+          { value: 42 },
+          { value: 45 },
+          { value: 51 },
+          { value: 55 },
+        ],
+      },
+      mark: 'bar',
+      encoding: {
+        x: { field: 'value', type: 'quantitative', bin: true },
+        y: { aggregate: 'count' },
+      },
+    },
+  },
+];
+
+/** The example's spec as pretty-printed JSON text — what a snippet stores. */
+export function exampleSpecText(example: ChartExample): string {
+  return JSON.stringify(example.spec, null, 2);
+}