diff --git a/CHANGELOG.md b/CHANGELOG.md
index dad60b0..4086232 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -29,6 +29,20 @@ auto-generated per-PR notes; this file is the curated, human-readable history.
   per-tile controls, and export arrive in later phases (#149 D2–D7). Known
   limitation: two tabs independently refreshing a *rotating* OAuth refresh token
   can race (BroadcastChannel sync deferred).
+- **Dashboard (phase 2): Arrange / Report layout switcher** (#149). A toolbar
+  below the dashboard header (the future filter bar) adds a primary **Arrange |
+  Report** segmented control: **Arrange** is the uniform multi-column grid, and
+  **Report** lays the tiles out as a single full-width scrolling column with
+  taller charts. A secondary **Columns 2 | 3** control tunes the Arrange grid
+  (hidden in Report's single column). Both are presentation-only — switching
+  reshapes the grid and the chart tiles resize themselves, with no tile re-query
+  — and the choice is persisted per browser (`asb:dashLayout` / `asb:dashCols`),
+  surviving reloads and Refresh. Chart tiles were also brought closer to the
+  design: the saved query **description** shows as a subtitle under the tile
+  name, the chart now draws on the **tile's own background** (instead of the
+  darker results-table background), and the value-axis **gridlines are hidden**
+  on tiles (they read as noisy light lines on a dark panel). Drag-to-reorder and
+  1/2-column tile spans arrive in the next phase (#149 D3).
 - **Schema-aware, FROM-driven autocompletion** (#84) — column completion now
   fires *while you type*, driven by the statement's `FROM`/`JOIN` clause, so you
   no longer have to expand a table in the sidebar first. A new pure module
diff --git a/src/core/chart-data.js b/src/core/chart-data.js
index a464fff..05498fc 100644
--- a/src/core/chart-data.js
+++ b/src/core/chart-data.js
@@ -313,9 +313,12 @@ const withAlpha = (hex, frac) => {
 /**
  * Build a complete Chart.js config object (type + data + themed options) from a
  * result and the user's `cfg`. Pure: returns a plain object (Chart.js draws it).
- * `colors` is a resolved token bundle from `chartColors`.
+ * `colors` is a resolved token bundle from `chartColors`. `opts.hideGrid`
+ * suppresses the value-axis gridlines (dashboard tiles draw on the panel
+ * background where a light gridline reads as noise — #149; the tick labels
+ * stay), keeping the chart body clean like the design's tiles.
  */
-export function chartJsConfig(columns, rows, cfg, colors) {
+export function chartJsConfig(columns, rows, cfg, colors, opts = {}) {
   const { labels, datasets } = buildChartData(columns, rows, cfg);
   const pal = colors.palette;
   const horizontal = cfg.type === 'hbar';
@@ -336,7 +339,7 @@ export function chartJsConfig(columns, rows, cfg, colors) {
   });
 
   const multi = datasets.length > 1;
-  const grid = { color: colors.borderFaint, drawBorder: false };
+  const grid = { color: colors.borderFaint, drawBorder: false, display: !opts.hideGrid };
   const ticks = { color: colors.fgMute, font: { family: colors.mono, size: 10 } };
   const valueTicks = { ...ticks, callback: (v) => chartNumFmt(typeof v === 'number' ? v : Number(v)) };
 
diff --git a/src/core/dashboard.js b/src/core/dashboard.js
index 5ed5ecb..faaff34 100644
--- a/src/core/dashboard.js
+++ b/src/core/dashboard.js
@@ -31,6 +31,26 @@ export function configBase(pathname) {
   return (pathname || '').replace(/\/dashboard\/?$/, '');
 }
 
+/**
+ * Dashboard layout modes (#149 D2): `arrange` = uniform multi-column grid
+ * (default), `report` = single full-width scrolling column with taller tiles.
+ * Persisted per browser (`asb:dashLayout`).
+ */
+export const DASH_LAYOUTS = ['arrange', 'report'];
+
+/** Snap a persisted layout to a known mode, defaulting to `arrange`. Pure. */
+export function normalizeDashLayout(v) {
+  return DASH_LAYOUTS.includes(v) ? v : 'arrange';
+}
+
+/** Column-count options for Arrange mode (persisted `asb:dashCols`). */
+export const DASH_COLS = [2, 3];
+
+/** Snap a persisted column count to 2 or 3, defaulting to 3. Pure. */
+export function normalizeDashCols(n) {
+  return DASH_COLS.includes(n) ? n : 3;
+}
+
 /**
  * A favorite's SQL prepared for a one-shot tile fetch: `FORMAT JSON` appended
  * unless the query already ends in its own trailing `FORMAT` clause (which we
diff --git a/src/state.js b/src/state.js
index 48b718e..b2a530f 100644
--- a/src/state.js
+++ b/src/state.js
@@ -5,6 +5,7 @@
 import { clamp } from './core/format.js';
 import { mergeSaved } from './core/saved-io.js';
 import { cloneChartCfg } from './core/chart-data.js';
+import { normalizeDashLayout, normalizeDashCols } from './core/dashboard.js';
 import { loadJSON, saveJSON, loadStr, saveStr } from './core/storage.js';
 import { signal } from '@preact/signals-core';
 
@@ -28,6 +29,8 @@ export const KEYS = {
   libraryName: 'asb:libraryName',
   resultRowLimit: 'asb:resultRowLimit',
   varValues: 'asb:varValues',
+  dashLayout: 'asb:dashLayout',
+  dashCols: 'asb:dashCols',
 };
 
 /** Row-limit options for the result cap selector (shared between state + UI). */
@@ -74,6 +77,11 @@ export function createState(read = { loadJSON, loadStr }) {
     // One persisted preference, default 500; a non-option stored value snaps
     // back to the default so the selector always reflects a real choice.
     resultRowLimit: normalizeRowLimit(parseInt(read.loadStr(KEYS.resultRowLimit, '500'), 10)),
+    // Dashboard layout prefs (#149 D2), persisted per browser. Plain (non-signal)
+    // like theme/density — the standalone dashboard page reads them at build time
+    // and mutates + re-saves on the Arrange/Report + column-count controls.
+    dashLayout: normalizeDashLayout(read.loadStr(KEYS.dashLayout, 'arrange')),
+    dashCols: normalizeDashCols(parseInt(read.loadStr(KEYS.dashCols, '3'), 10)),
     sidebarPx: clamp(parseInt(read.loadStr(KEYS.sidebarPx, '248'), 10), 180, 420),
     editorPct: num(KEYS.editorPct, 45, 15, 85),
     sideSplitPct: num(KEYS.sideSplitPct, 58, 25, 85),
diff --git a/src/styles.css b/src/styles.css
index ba3e2f6..7fe70cc 100644
--- a/src/styles.css
+++ b/src/styles.css
@@ -1744,11 +1744,29 @@ table.res-table tbody tr:hover td.idx { background: var(--bg-hover); }
 /* The dashboard's own scroll container: #root is a fixed overflow:hidden flex
    column (the workbench shell), so the dashboard fills it and scrolls itself. */
 .dash-page { height: 100%; overflow-y: auto; overflow-x: hidden; background: var(--bg); }
+/* Header + layout toolbar share one sticky top bar (#149 D2) so the
+   Arrange/Report switcher stays visible while the grid scrolls. */
+.dash-topbar { position: sticky; top: 0; z-index: 40; background: var(--bg-header); }
 .dash-header {
-  position: sticky; top: 0; z-index: 40; display: flex; align-items: center;
+  display: flex; align-items: center;
   gap: 12px; padding: 11px 20px; background: var(--bg-header);
   border-bottom: 1px solid var(--border); flex-wrap: wrap;
 }
+/* Layout toolbar (#149 D2) — becomes the filter bar in D4. */
+.dash-toolbar {
+  display: flex; align-items: center; gap: 12px; flex-wrap: wrap;
+  padding: 8px 20px; background: var(--bg-header); border-bottom: 1px solid var(--border);
+}
+.dash-seg { display: inline-flex; background: var(--bg-chip); border: 1px solid var(--border); border-radius: 8px; padding: 2px; }
+.dash-seg-btn {
+  appearance: none; border: none; background: none; cursor: pointer;
+  padding: 4px 12px; border-radius: 6px; font: 500 12px var(--ui); color: var(--fg-mute);
+}
+.dash-seg-btn:hover { color: var(--fg); }
+.dash-seg-btn.is-active { background: var(--bg); color: var(--fg); box-shadow: 0 1px 2px rgba(0,0,0,.12); }
+.dash-cols-wrap { display: inline-flex; align-items: center; gap: 8px; }
+.dash-seg-cols .dash-seg-btn { padding: 4px 10px; font-family: var(--mono); }
+.dash-seg-label { font-size: 11px; color: var(--fg-faint); }
 .dash-icobtn {
   width: 30px; height: 30px; display: inline-flex; align-items: center; justify-content: center;
   background: var(--bg-chip); color: var(--fg-mute); border: 1px solid var(--border);
@@ -1779,16 +1797,19 @@ table.res-table tbody tr:hover td.idx { background: var(--bg-hover); }
 }
 .dash-btn:hover { background: var(--bg-hover); }
 .dash-btn:disabled { opacity: .55; cursor: default; }
-/* Arrange grid: 3 across on wide screens (the design's default), degrading to
-   2 then 1 as width shrinks. A configurable 2/3-column switcher + drag-reorder
-   land in D5. */
+/* Arrange grid: the persisted column count (2 or 3, via `--dash-cols`, default
+   3) on wide screens, degrading to 2 then 1 as width shrinks. The 2/3 switcher
+   lives in the toolbar (#149 D2); drag-reorder + 1/2-col span land in D3. */
 .dash-grid {
   display: grid; gap: 14px; padding: 18px 20px 40px;
-  grid-template-columns: repeat(3, minmax(0, 1fr));
+  grid-template-columns: repeat(var(--dash-cols, 3), minmax(0, 1fr));
   max-width: 1560px; margin: 0 auto;
 }
 @media (max-width: 1100px) { .dash-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); } }
 @media (max-width: 720px) { .dash-grid { grid-template-columns: 1fr; } }
+/* Report mode (#149 D2): one full-width scrolling column with taller tiles. */
+.dash-grid.is-report { grid-template-columns: 1fr; max-width: 1100px; }
+.dash-grid.is-report .dash-tile { min-height: 440px; }
 /* D1 shows charts read-only: renderChart is called with controls:false so the
    Type/X/Y config bar isn't built at all (a settings-popover arrives in D6). */
 .dash-empty { padding: 60px 20px; text-align: center; color: var(--fg-mute); font-size: 13px; }
@@ -1803,8 +1824,18 @@ table.res-table tbody tr:hover td.idx { background: var(--bg-hover); }
   font-size: 13px; font-weight: 600; color: var(--fg);
   overflow: hidden; text-overflow: ellipsis; white-space: nowrap; display: block;
 }
+/* Saved-query description subtitle under the tile name (matches the design). */
+.dash-tile-desc {
+  font-size: 11px; color: var(--fg-mute); margin-top: 2px;
+  overflow: hidden; text-overflow: ellipsis; white-space: nowrap;
+}
 .dash-tile-body { flex: 1; min-height: 0; padding: 6px 8px; display: flex; }
 .dash-tile-body > .chart-view { flex: 1; min-width: 0; }
+/* The chart draws on the tile's own background (--bg-side), not the darker
+   results-table bg the workbench chart view uses; this both matches the design
+   and lets the faint value-axis gridlines recede instead of standing out on a
+   near-black panel in dark mode. */
+.dash-tile .chart-view, .dash-tile .chart-empty { background: transparent; }
 .dash-tile-load {
   display: flex; align-items: center; gap: 8px; margin: auto;
   color: var(--fg-faint); font-size: 12px;
diff --git a/src/ui/dashboard.js b/src/ui/dashboard.js
index 4c26035..43e9d79 100644
--- a/src/ui/dashboard.js
+++ b/src/ui/dashboard.js
@@ -18,6 +18,27 @@ import { formatBytes, formatRows } from '../core/format.js';
 // browser's per-host pool and the cluster) on open and on every Refresh.
 const TILE_CONCURRENCY = 6;
 
+/**
+ * Build a segmented control (`Arrange | Report`, `2 | 3`): a row of buttons of
+ * which exactly one reads active. `getActive` returns the currently-selected
+ * value; `onPick(value)` fires on a click. Returns `{ el, sync }` — `sync()`
+ * repaints the active button from `getActive()` (called after a pick so the
+ * two controls can share one `apply()`).
+ */
+function buildSeg(cls, options, getActive, onPick) {
+  const btns = options.map(([, label]) =>
+    h('button', { class: 'dash-seg-btn', type: 'button' }, label));
+  const sync = () => btns.forEach((b, i) => {
+    const on = options[i][0] === getActive();
+    b.classList.toggle('is-active', on);
+    b.setAttribute('aria-pressed', String(on));
+  });
+  btns.forEach((b, i) => { b.onclick = () => onPick(options[i][0]); });
+  const el = h('div', { class: 'dash-seg ' + cls, role: 'group' }, ...btns);
+  sync();
+  return { el, sync };
+}
+
 /** Build a tile's footer meta row (rows · ms · bytes), omitting stats CH didn't return. */
 function tileFooter(meta) {
   const parts = [h('span', null, formatRows(meta.rows) + ' rows')];
@@ -55,9 +76,12 @@ async function renderTile(app, q, grid, tiles) {
   const body = h('div', { class: 'dash-tile-body' },
     h('div', { class: 'dash-tile-load' }, Icon.spinner(), h('span', null, 'Loading…')));
   const foot = h('div', { class: 'dash-tile-foot' });
-  const card = h('div', { class: 'dash-tile' },
-    h('div', { class: 'dash-tile-head' }, h('span', { class: 'dash-tile-name', title: q.name }, q.name)),
-    body, foot);
+  // Header: the favorite's name, plus its saved description as a subtitle when it
+  // has one (single line, ellipsized) — mirrors the design mockup's tile header.
+  const head = h('div', { class: 'dash-tile-head' },
+    h('span', { class: 'dash-tile-name', title: q.name }, q.name));
+  if (q.description) head.appendChild(h('div', { class: 'dash-tile-desc', title: q.description }, q.description));
+  const card = h('div', { class: 'dash-tile' }, head, body, foot);
   grid.appendChild(card);
 
   const r = await app.runTile(q.sql);
@@ -78,7 +102,7 @@ async function renderTile(app, q, grid, tiles) {
   const chartTab = { chartKey: schemaKey(r.columns), chartCfg: cls.cfg };
   let inst = null;
   body.replaceChildren(renderChart(app, res, {
-    tab: chartTab, setChart: (c) => { inst = c; }, running: false, controls: false,
+    tab: chartTab, setChart: (c) => { inst = c; }, running: false, controls: false, hideGrid: true,
   }));
   tiles.push({ destroy: () => inst.destroy() });
   foot.replaceChildren(...tileFooter(r.meta));
@@ -125,10 +149,48 @@ export function renderDashboard(app) {
   const empty = h('div', { class: 'dash-empty', style: { display: favorites.length ? 'none' : '' } },
     'No favorites yet — star a query in the Library to add it to the dashboard.');
 
+  // Layout toolbar (#149 D2), the row that becomes the filter bar in D4. The
+  // Arrange|Report switcher is the primary control; the 2/3 column count is a
+  // secondary setting, meaningful only in Arrange (hidden in Report's single
+  // column). Both are presentation-only: `apply()` reshapes the grid and the
+  // tiles' Chart.js instances resize themselves via their ResizeObserver — no
+  // tile re-query. State is mutated + persisted (asb:dashLayout/dashCols) so the
+  // choice survives reloads and Refresh (which rebuilds the grid's children, not
+  // the grid element, so its class/`--dash-cols` persist across a refresh).
+  const apply = () => {
+    grid.classList.toggle('is-report', state.dashLayout === 'report');
+    grid.style.setProperty('--dash-cols', String(state.dashCols));
+    colsWrap.style.display = state.dashLayout === 'report' ? 'none' : '';
+    layoutSeg.sync();
+    colsSeg.sync();
+  };
+  const layoutSeg = buildSeg('dash-seg-layout', [['arrange', 'Arrange'], ['report', 'Report']],
+    () => state.dashLayout, (v) => {
+      if (v === state.dashLayout) return;
+      state.dashLayout = v;
+      app.savePref('dashLayout', v);
+      apply();
+    });
+  const colsSeg = buildSeg('dash-seg-cols', [[2, '2'], [3, '3']],
+    () => state.dashCols, (v) => {
+      if (v === state.dashCols) return;
+      state.dashCols = v;
+      app.savePref('dashCols', v);
+      apply();
+    });
+  const colsWrap = h('div', { class: 'dash-cols-wrap' },
+    h('span', { class: 'dash-seg-label' }, 'Columns'), colsSeg.el);
+  const toolbar = h('div', { class: 'dash-toolbar' },
+    layoutSeg.el,
+    h('div', { class: 'dash-spacer', style: { flex: '1' } }),
+    colsWrap);
+  apply();
+
   // #root is a fixed, overflow:hidden flex column (the workbench layout), so the
   // dashboard needs its own scroll container — otherwise a tall grid clips with
-  // no vertical scroll. The sticky header lives inside it.
-  app.root.replaceChildren(h('div', { class: 'dash-page' }, header, empty, grid));
+  // no vertical scroll. The header + toolbar share one sticky top bar inside it.
+  app.root.replaceChildren(h('div', { class: 'dash-page' },
+    h('div', { class: 'dash-topbar' }, header, toolbar), empty, grid));
 
   // Chart.js instances of the tiles currently in the grid, torn down before the
   // next Refresh rebuilds them (grid.replaceChildren() alone would orphan them,
diff --git a/src/ui/results.js b/src/ui/results.js
index 29b047d..c7b1b4e 100644
--- a/src/ui/results.js
+++ b/src/ui/results.js
@@ -962,6 +962,7 @@ export function installChartZoomFix(chart, canvas) {
  * `opts.running` overrides the run-state gate — a detached snapshot's `r` is
  * always already-complete, independent of whatever the live tab is doing.
  * `opts.controls === false` omits the Type/X/Y config bar (read-only tiles).
+ * `opts.hideGrid` suppresses the value-axis gridlines (dashboard tiles — #149).
  */
 export function renderChart(app, r, opts = {}) {
   const tab = opts.tab || app.activeTab();
@@ -1019,7 +1020,7 @@ export function renderChart(app, r, opts = {}) {
   // contradicting the "first N rows" note. It would also sort up to VIS_CAP
   // rows just to discard all but the first `cap`.
   const chart = installChartZoomFix(
-    new app.Chart(canvas, chartJsConfig(r.columns, r.rows, cfg, chartColors(app.cssVar))),
+    new app.Chart(canvas, chartJsConfig(r.columns, r.rows, cfg, chartColors(app.cssVar), { hideGrid: opts.hideGrid })),
     canvas);
   setChart(chart);
   // Chart.js's own responsive sizing reads layout through APIs (getComputedStyle,
diff --git a/tests/unit/chart-data.test.js b/tests/unit/chart-data.test.js
index 88f9e3e..e634c9a 100644
--- a/tests/unit/chart-data.test.js
+++ b/tests/unit/chart-data.test.js
@@ -287,6 +287,15 @@ describe('chartJsConfig', () => {
     expect(cfg.options.scales.y.grid.display).toBe(false); // category axis
     expect(cfg.data.datasets[0].backgroundColor).toBe(colors.palette[0]);
   });
+  it('shows value-axis gridlines by default, hides them with opts.hideGrid (#149)', () => {
+    const shown = chartJsConfig(cols, rows, { type: 'bar', x: 0, y: [1], series: null }, colors);
+    expect(shown.options.scales.y.grid.display).toBe(true);
+    const hidden = chartJsConfig(cols, rows, { type: 'bar', x: 0, y: [1], series: null }, colors, { hideGrid: true });
+    expect(hidden.options.scales.y.grid.display).toBe(false);
+    // the horizontal-bar value axis (x) is hidden too, not just the category axis
+    const hbar = chartJsConfig(cols, rows, { type: 'hbar', x: 0, y: [1], series: null }, colors, { hideGrid: true });
+    expect(hbar.options.scales.x.grid.display).toBe(false);
+  });
   it('vertical column keeps indexAxis x', () => {
     const cfg = chartJsConfig(cols, rows, { type: 'bar', x: 0, y: [1], series: null }, colors);
     expect(cfg.type).toBe('bar');
diff --git a/tests/unit/dashboard.test.js b/tests/unit/dashboard.test.js
index 95de434..6070867 100644
--- a/tests/unit/dashboard.test.js
+++ b/tests/unit/dashboard.test.js
@@ -2,6 +2,7 @@ import { describe, it, expect, vi } from 'vitest';
 import { webcrypto } from 'node:crypto';
 import {
   isDashboardRoute, configBase, dashboardTileSql, parseJsonResult, classifyTile,
+  normalizeDashLayout, normalizeDashCols,
 } from '../../src/core/dashboard.js';
 import {
   AUTH_SS_KEYS, AUTH_REQUEST, AUTH_GRANT,
@@ -107,6 +108,24 @@ describe('classifyTile', () => {
   });
 });
 
+describe('normalizeDashLayout', () => {
+  it('passes through known modes, defaults everything else to arrange', () => {
+    expect(normalizeDashLayout('arrange')).toBe('arrange');
+    expect(normalizeDashLayout('report')).toBe('report');
+    expect(normalizeDashLayout('grid')).toBe('arrange');
+    expect(normalizeDashLayout(undefined)).toBe('arrange');
+  });
+});
+
+describe('normalizeDashCols', () => {
+  it('passes through 2/3, defaults everything else to 3', () => {
+    expect(normalizeDashCols(2)).toBe(2);
+    expect(normalizeDashCols(3)).toBe(3);
+    expect(normalizeDashCols(4)).toBe(3);
+    expect(normalizeDashCols(NaN)).toBe(3);
+  });
+});
+
 // ── core/auth-handoff.js ─────────────────────────────────────────────────────
 function memSession(initial = {}) {
   const m = new Map(Object.entries(initial));
@@ -188,6 +207,19 @@ describe('renderDashboard', () => {
     expect(app.root.querySelector('.dash-tile-foot').textContent).toContain('rows');
   });
 
+  it('renders the saved description as a tile subtitle when present, omits it otherwise', async () => {
+    const favorites = [
+      { id: '1', name: 'With desc', sql: 'a', favorite: true, description: 'Daily totals by category' },
+      { id: '2', name: 'No desc', sql: 'b', favorite: true },
+    ];
+    const app = dashApp(favorites, vi.fn(async () => chartResult()));
+    await renderDashboard(app);
+    const descs = [...app.root.querySelectorAll('.dash-tile-desc')];
+    expect(descs).toHaveLength(1);
+    expect(descs[0].textContent).toBe('Daily totals by category');
+    expect(descs[0].getAttribute('title')).toBe('Daily totals by category');
+  });
+
   it('uses the singular chip label with exactly one favorite', async () => {
     const app = dashApp([{ id: '1', name: 'Q', sql: 'q', favorite: true }], vi.fn(async () => chartResult()));
     await renderDashboard(app);
@@ -286,6 +318,68 @@ describe('renderDashboard', () => {
     expect(app.root.querySelector('.dash-tile .chart-config')).toBeNull(); // controls omitted, not hidden
     expect(app.root.querySelector('.dash-tile .chart-select')).toBeNull();
   });
+
+  // ── D2: layout toolbar (Arrange/Report + column count) ──────────────────────
+  const oneFav = () => dashApp([{ id: '1', name: 'Q', sql: 'q', favorite: true }], vi.fn(async () => chartResult()));
+  const seg = (root, cls, label) =>
+    [...root.querySelectorAll('.' + cls + ' .dash-seg-btn')].find((b) => b.textContent === label);
+
+  it('defaults to Arrange (3 columns), grid not in report mode, column control shown', async () => {
+    const app = oneFav();
+    await renderDashboard(app);
+    const grid = app.root.querySelector('.dash-grid');
+    expect(grid.classList.contains('is-report')).toBe(false);
+    expect(grid.style.getPropertyValue('--dash-cols')).toBe('3');
+    expect(seg(app.root, 'dash-seg-layout', 'Arrange').classList.contains('is-active')).toBe(true);
+    expect(seg(app.root, 'dash-seg-layout', 'Report').classList.contains('is-active')).toBe(false);
+    expect(app.root.querySelector('.dash-cols-wrap').style.display).toBe('');
+    expect(seg(app.root, 'dash-seg-cols', '3').getAttribute('aria-pressed')).toBe('true');
+  });
+
+  it('switching to Report reshapes the grid, hides the column control, and persists', async () => {
+    const app = oneFav();
+    await renderDashboard(app);
+    seg(app.root, 'dash-seg-layout', 'Report').dispatchEvent(new Event('click', { bubbles: true }));
+    const grid = app.root.querySelector('.dash-grid');
+    expect(grid.classList.contains('is-report')).toBe(true);
+    expect(seg(app.root, 'dash-seg-layout', 'Report').classList.contains('is-active')).toBe(true);
+    expect(app.root.querySelector('.dash-cols-wrap').style.display).toBe('none');
+    expect(app.savePref).toHaveBeenCalledWith('dashLayout', 'report');
+    // …and back to Arrange restores the grid + column control.
+    seg(app.root, 'dash-seg-layout', 'Arrange').dispatchEvent(new Event('click', { bubbles: true }));
+    expect(grid.classList.contains('is-report')).toBe(false);
+    expect(app.root.querySelector('.dash-cols-wrap').style.display).toBe('');
+  });
+
+  it('the column-count control switches 2/3 and persists', async () => {
+    const app = oneFav();
+    await renderDashboard(app);
+    seg(app.root, 'dash-seg-cols', '2').dispatchEvent(new Event('click', { bubbles: true }));
+    const grid = app.root.querySelector('.dash-grid');
+    expect(grid.style.getPropertyValue('--dash-cols')).toBe('2');
+    expect(seg(app.root, 'dash-seg-cols', '2').classList.contains('is-active')).toBe(true);
+    expect(app.savePref).toHaveBeenCalledWith('dashCols', 2);
+  });
+
+  it('clicking the already-active layout or column is a no-op (no persist)', async () => {
+    const app = oneFav();
+    await renderDashboard(app);
+    seg(app.root, 'dash-seg-layout', 'Arrange').dispatchEvent(new Event('click', { bubbles: true }));
+    seg(app.root, 'dash-seg-cols', '3').dispatchEvent(new Event('click', { bubbles: true }));
+    expect(app.savePref).not.toHaveBeenCalled();
+  });
+
+  it('reflects the persisted layout (Report) and column count (2) on first render', async () => {
+    const app = oneFav();
+    app.state.dashLayout = 'report';
+    app.state.dashCols = 2;
+    await renderDashboard(app);
+    const grid = app.root.querySelector('.dash-grid');
+    expect(grid.classList.contains('is-report')).toBe(true);
+    expect(grid.style.getPropertyValue('--dash-cols')).toBe('2');
+    expect(app.root.querySelector('.dash-cols-wrap').style.display).toBe('none');
+    expect(seg(app.root, 'dash-seg-cols', '2').classList.contains('is-active')).toBe(true);
+  });
 });
 
 // ── app.js: runTile + auth handoff wiring ────────────────────────────────────
diff --git a/tests/unit/state.test.js b/tests/unit/state.test.js
index 19e7dfc..2d6c746 100644
--- a/tests/unit/state.test.js
+++ b/tests/unit/state.test.js
@@ -41,6 +41,8 @@ describe('createState', () => {
     expect(s.expanded.value.size).toBe(0);
     expect(s.libraryName.value).toBe(DEFAULT_LIBRARY_NAME);
     expect(s.libraryDirty.value).toBe(false);
+    expect(s.dashLayout).toBe('arrange');
+    expect(s.dashCols).toBe(3);
   });
   it('reads + clamps persisted prefs', () => {
     const s = createState(reader({
@@ -53,9 +55,13 @@ describe('createState', () => {
       [KEYS.saved]: [{ id: 's1', sql: 'x', name: 'n', starred: true }],
       [KEYS.history]: [{ id: 'h1', sql: 'y', ts: 1, rows: 1, ms: 2 }],
       [KEYS.libraryName]: 'My team queries',
+      [KEYS.dashLayout]: 'report',
+      [KEYS.dashCols]: '2',
     }));
     expect(s.theme).toBe('light');
     expect(s.libraryName.value).toBe('My team queries');
+    expect(s.dashLayout).toBe('report');
+    expect(s.dashCols).toBe(2);
     expect(s.sidebarPx).toBe(420);
     expect(s.editorPct).toBe(15);
     expect(s.sideSplitPct).toBe(85);