diff --git a/scripts/format-scope.json b/scripts/format-scope.json
index ff876cef9..7f3542bae 100644
--- a/scripts/format-scope.json
+++ b/scripts/format-scope.json
@@ -1464,5 +1464,6 @@
   "src/ui/styles/scope-off-shadows.css",
   "src/ui/styles/cockpit-panels.css",
   "src/ui/styles/layer-section-index.css",
-  "src/ui/styles/layer-finder.css"
+  "src/ui/styles/layer-finder.css",
+  "src/ui/layerFinder.test.mjs"
 ]
diff --git a/src/ui/layerFinder.test.mjs b/src/ui/layerFinder.test.mjs
new file mode 100644
index 000000000..8cd61ff1a
--- /dev/null
+++ b/src/ui/layerFinder.test.mjs
@@ -0,0 +1,200 @@
+// src/ui/layerFinder.test.mjs — the Data Layers finder and section index work
+// on the rows LayerRows renders: search, the On/Off and category filter,
+// Escape, the clear request voice sends, and the group ticks.
+import '../testSupport/registerDom.mjs';
+import test from 'node:test';
+import assert from 'node:assert/strict';
+import { createApp, h, nextTick } from 'vue';
+import LayerFinder, {
+  LAYER_FINDER_CLEAR_EVENT,
+} from './views/panels/LayerFinder.vue';
+import LayerSectionIndex from './views/panels/LayerSectionIndex.vue';
+
+const ROWS = [
+  { group: 'movement', heading: 'Movement' },
+  { id: 'flights', name: 'Live Flights', english: 'Live Flights', on: true },
+  { id: 'ships', name: 'Ships', english: 'Ships', on: false },
+  { group: 'weather', heading: 'Weather' },
+  { id: 'radar', name: 'Radar météo', english: 'Weather Radar', on: false },
+];
+
+const flush = async () => {
+  await nextTick();
+  await new Promise((resolve) => setTimeout(resolve, 0));
+  await nextTick();
+};
+
+function fixture(t) {
+  document.body.replaceChildren();
+  // Frames run at once, so the observers' batching does not hold a test up.
+  globalThis.requestAnimationFrame = (fn) => setTimeout(fn, 0);
+  globalThis.cancelAnimationFrame = (id) => clearTimeout(id);
+  const panel = document.body.appendChild(document.createElement('section'));
+  panel.id = 'data-panel';
+  const header = panel.appendChild(document.createElement('div'));
+  const bar = panel.appendChild(document.createElement('div'));
+  const list = panel.appendChild(document.createElement('div'));
+  list.id = 'data-toggles';
+  for (const row of ROWS) {
+    if (row.heading) {
+      const heading = list.appendChild(document.createElement('h3'));
+      heading.className = 'data-layer-group-heading';
+      heading.dataset.group = row.group;
+      heading.textContent = row.heading;
+      continue;
+    }
+    const el = list.appendChild(document.createElement('div'));
+    el.className = 'data-toggle-row';
+    el.dataset.layerId = row.id;
+    el.dataset.layerName = row.english;
+    el.innerHTML = `<span class="data-name">${row.name}</span><button class="data-toggle-btn${row.on ? ' active' : ''}"></button>`;
+  }
+  const index = panel.appendChild(document.createElement('div'));
+  const apps = [
+    createApp(() => h(LayerFinder, { part: 'buttons' })),
+    createApp(() => h(LayerFinder, { part: 'bar' })),
+    createApp(LayerSectionIndex),
+  ];
+  apps[0].mount(header);
+  apps[1].mount(bar);
+  apps[2].mount(index);
+  t.after(async () => {
+    document.dispatchEvent(new CustomEvent(LAYER_FINDER_CLEAR_EVENT));
+    for (const app of apps) app.unmount();
+  });
+  const shown = () =>
+    [...list.querySelectorAll('.data-toggle-row:not(.is-filtered)')].map(
+      (row) => row.dataset.layerId,
+    );
+  const search = async (text) => {
+    if (!document.getElementById('layer-finder-input')) {
+      document.getElementById('layer-finder-search-btn').click();
+      await flush();
+    }
+    const input = document.getElementById('layer-finder-input');
+    input.value = text;
+    input.dispatchEvent(new Event('input', { bubbles: true }));
+    await flush();
+  };
+  const openFilter = async () => {
+    document.querySelector('[aria-controls="layer-finder-menu"]').click();
+    await flush();
+    return document.getElementById('layer-finder-menu');
+  };
+  return { list, panel, shown, search, openFilter };
+}
+
+test('search finds a layer by the name on screen or its English name', async (t) => {
+  const { shown, search, list } = fixture(t);
+  await search('météo');
+  assert.deepEqual(shown(), ['radar']);
+  await search('weather radar');
+  assert.deepEqual(shown(), ['radar']);
+  // The Movement heading has no rows left, so it is hidden too.
+  assert.equal(
+    list
+      .querySelector('[data-group="movement"]')
+      .classList.contains('is-filtered'),
+    true,
+  );
+  await search('nothing like it');
+  assert.deepEqual(shown(), []);
+  assert.match(
+    document.querySelector('.layer-finder__empty')?.textContent || '',
+    /No layers match/,
+  );
+});
+
+test('On and Off follow whether the layer is enabled', async (t) => {
+  const { shown, openFilter } = fixture(t);
+  const menu = await openFilter();
+  const on = [...menu.querySelectorAll('button')].find((b) =>
+    b.textContent.trim().endsWith('On'),
+  );
+  on.click();
+  await flush();
+  assert.deepEqual(shown(), ['flights']);
+  assert.equal(on.getAttribute('aria-pressed'), 'true');
+});
+
+test('a chosen category survives its heading being translated', async (t) => {
+  const { shown, openFilter, list } = fixture(t);
+  const menu = await openFilter();
+  [...menu.querySelectorAll('button')]
+    .find((b) => b.textContent.trim().endsWith('Weather'))
+    .click();
+  await flush();
+  assert.deepEqual(shown(), ['radar']);
+  list.querySelector('[data-group="weather"]').textContent = 'Météo';
+  await flush();
+  assert.deepEqual(shown(), ['radar']);
+  assert.match(
+    document.querySelector('.layer-finder__chip').textContent,
+    /Météo/,
+  );
+});
+
+test('Escape in the search field closes it without reaching the panel', async (t) => {
+  const { search, panel } = fixture(t);
+  let reached = false;
+  panel.addEventListener('keydown', () => (reached = true));
+  await search('ships');
+  document
+    .getElementById('layer-finder-input')
+    .dispatchEvent(
+      new KeyboardEvent('keydown', { key: 'Escape', bubbles: true }),
+    );
+  await flush();
+  assert.equal(reached, false);
+  assert.equal(document.getElementById('layer-finder-input'), null);
+  assert.equal(document.activeElement?.id, 'layer-finder-search-btn');
+});
+
+test('the filter menu takes focus, moves with the arrows and closes on Escape', async (t) => {
+  const { openFilter } = fixture(t);
+  const menu = await openFilter();
+  const buttons = [...menu.querySelectorAll('button')];
+  assert.equal(document.activeElement, buttons[0]);
+  menu.dispatchEvent(
+    new KeyboardEvent('keydown', { key: 'ArrowDown', bubbles: true }),
+  );
+  assert.equal(document.activeElement, buttons[1]);
+  menu.dispatchEvent(
+    new KeyboardEvent('keydown', { key: 'End', bubbles: true }),
+  );
+  assert.equal(document.activeElement, buttons.at(-1));
+  menu.dispatchEvent(
+    new KeyboardEvent('keydown', { key: 'Escape', bubbles: true }),
+  );
+  await flush();
+  assert.equal(document.getElementById('layer-finder-menu'), null);
+  assert.equal(
+    document.activeElement,
+    document.querySelector('[aria-controls="layer-finder-menu"]'),
+  );
+});
+
+test('a clear request shows every row again', async (t) => {
+  const { shown, search } = fixture(t);
+  await search('ships');
+  assert.deepEqual(shown(), ['ships']);
+  document.dispatchEvent(new CustomEvent(LAYER_FINDER_CLEAR_EVENT));
+  await flush();
+  assert.deepEqual(shown(), ['flights', 'ships', 'radar']);
+});
+
+test('the section index has a tick per group and drops filtered groups', async (t) => {
+  const { search } = fixture(t);
+  await flush();
+  assert.equal(
+    document.querySelectorAll('.layer-section-index__tick').length,
+    2,
+  );
+  await search('ships');
+  await flush();
+  // One group left: no index.
+  assert.equal(
+    document.querySelectorAll('.layer-section-index__tick').length,
+    0,
+  );
+});