diff --git a/package-lock.json b/package-lock.json
index 263fd793d..6430491c1 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -24,6 +24,7 @@
         "vue": "^3.5.44"
       },
       "devDependencies": {
+        "@happy-dom/global-registrator": "^20.14.6",
         "@vitejs/plugin-vue": "^5.2.4",
         "@vue/test-utils": "^2.5.1",
         "happy-dom": "^20.14.6",
@@ -588,6 +589,20 @@
         "node": ">=18"
       }
     },
+    "node_modules/@happy-dom/global-registrator": {
+      "version": "20.14.6",
+      "resolved": "https://registry.npmjs.org/@happy-dom/global-registrator/-/global-registrator-20.14.6.tgz",
+      "integrity": "sha512-Xd2FwCdm0cAZ+EG0upp69tpxBT9jtvVxaZv1lnbgWsNaZyEuPs0PojYgvCmtQ1RRdRCYCyWTeLjn3Z0aSxDchA==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@types/node": ">=20.0.0",
+        "happy-dom": "^20.14.6"
+      },
+      "engines": {
+        "node": ">=20.0.0"
+      }
+    },
     "node_modules/@img/colour": {
       "version": "1.1.0",
       "resolved": "https://registry.npmjs.org/@img/colour/-/colour-1.1.0.tgz",
diff --git a/package.json b/package.json
index 138867968..44316183c 100644
--- a/package.json
+++ b/package.json
@@ -71,6 +71,7 @@
     "vue": "^3.5.44"
   },
   "devDependencies": {
+    "@happy-dom/global-registrator": "^20.14.6",
     "@vitejs/plugin-vue": "^5.2.4",
     "@vue/test-utils": "^2.5.1",
     "happy-dom": "^20.14.6",
diff --git a/scripts/format-scope.json b/scripts/format-scope.json
index 2522f91c7..6197aa43c 100644
--- a/scripts/format-scope.json
+++ b/scripts/format-scope.json
@@ -1118,5 +1118,9 @@
   "src/testSupport/shareViewFixtures.mjs",
   "src/ui/shareLinks.test.mjs",
   "src/ui/shareButton.test.mjs",
-  "src/share/shareLinkPath.test.mjs"
+  "src/share/shareLinkPath.test.mjs",
+  "src/ui/kit/UiRail.test.mjs",
+  "src/testSupport/vueDom.mjs",
+  "src/testSupport/vueLoader.mjs",
+  "src/testSupport/registerVue.mjs"
 ]
diff --git a/scripts/format.mjs b/scripts/format.mjs
index 25311ba29..e91cf527b 100644
--- a/scripts/format.mjs
+++ b/scripts/format.mjs
@@ -39,7 +39,7 @@ export async function discoverRuntimeFormatFiles(root) {
   const files = [];
   for (const name of new Set(candidates)) {
     if (
-      !/\.[cm]?js$/.test(name) ||
+      !/\.([cm]?js|vue)$/.test(name) ||
       /\.test\.[cm]?js$/.test(name) ||
       !existsSync(path.join(root, name))
     )
diff --git a/src/materialSymbolsSubset.test.mjs b/src/materialSymbolsSubset.test.mjs
index ec9ffe2f0..e6352502a 100644
--- a/src/materialSymbolsSubset.test.mjs
+++ b/src/materialSymbolsSubset.test.mjs
@@ -14,6 +14,8 @@ const SPAN_TEXT =
 /** A whole `textContent =` statement, across lines, so a multi-line ternary is read once. */
 const TEXT_ASSIGNMENT = /(?:textContent|innerText)\s*=\s*([^;]{0,400})/gs;
 const STRING_LITERAL = /['"`]([a-z0-9_]{2,})['"`]/g;
+/** A rail or menu item's glyph: `{ icon: 'layers' }`, rendered by `UiIcon`. */
+const ICON_PROPERTY = /\bicon:\s*['"]([a-z0-9_]+)['"]/g;
 
 /**
  * Files that SHIP markup. Tests assert on markup, they do not render it.
@@ -29,7 +31,7 @@ function sourceFiles(directory = SRC_ROOT) {
     if (entry.isDirectory()) files.push(...sourceFiles(absolute));
     else if (
       entry.isFile() &&
-      /\.(js|mjs|html)$/.test(entry.name) &&
+      /\.(js|mjs|html|vue)$/.test(entry.name) &&
       !entry.name.endsWith('.test.mjs')
     ) {
       files.push(absolute);
@@ -62,6 +64,7 @@ function referencedGlyphs() {
       if (!found.has(glyph)) found.set(glyph, relative);
     };
     for (const match of source.matchAll(SPAN_TEXT)) add(match[1]);
+    for (const match of source.matchAll(ICON_PROPERTY)) add(match[1]);
     for (const match of source.matchAll(TEXT_ASSIGNMENT)) {
       const statement = match[1].replaceAll('?.', '.');
       const assigned = statement.includes('?')
diff --git a/src/testSupport/vueDom.mjs b/src/testSupport/vueDom.mjs
new file mode 100644
index 000000000..3fd138513
--- /dev/null
+++ b/src/testSupport/vueDom.mjs
@@ -0,0 +1,10 @@
+import { GlobalRegistrator } from '@happy-dom/global-registrator';
+
+/**
+ * Give a component test a browser document; returns the teardown.
+ * Call it from `before`/`after`, since other suites assert there is no DOM.
+ */
+export function installVueDom() {
+  GlobalRegistrator.register({ url: 'http://localhost/' });
+  return () => GlobalRegistrator.unregister();
+}
diff --git a/src/ui/kit/UiIcon.vue b/src/ui/kit/UiIcon.vue
new file mode 100644
index 000000000..4f34f29e4
--- /dev/null
+++ b/src/ui/kit/UiIcon.vue
@@ -0,0 +1,16 @@
+<script setup>
+/** A Material Symbols glyph; the name must be in index.html's `icon_names`. */
+defineProps({
+  name: { type: String, required: true },
+  size: { type: Number, default: 18 },
+});
+</script>
+
+<template>
+  <span
+    class="ui-icon material-symbols-outlined"
+    :style="{ fontSize: `${size}px` }"
+    aria-hidden="true"
+    >{{ name }}</span
+  >
+</template>
diff --git a/src/ui/kit/UiRail.test.mjs b/src/ui/kit/UiRail.test.mjs
new file mode 100644
index 000000000..6c443286a
--- /dev/null
+++ b/src/ui/kit/UiRail.test.mjs
@@ -0,0 +1,73 @@
+import { after, before, test } from 'node:test';
+import assert from 'node:assert/strict';
+import { installVueDom } from '../../testSupport/vueDom.mjs';
+
+let mount;
+let UiRail;
+let uninstall;
+before(async () => {
+  uninstall = installVueDom();
+  ({ mount } = await import('@vue/test-utils'));
+  UiRail = (await import('./UiRail.vue')).default;
+});
+after(() => uninstall());
+
+const items = [
+  { id: 'layers', label: 'DATA LAYERS', icon: 'layers' },
+  { id: 'scenes', label: 'AUTHORING', icon: 'movie', separatorBefore: true },
+  { id: 'cctv', label: 'CCTV', icon: 'videocam', disabled: true, badge: 3 },
+];
+
+function mountRail(props = {}) {
+  return mount(UiRail, {
+    props: { items, side: 'left', label: 'Left panels', ...props },
+  });
+}
+
+test('the rail is a named nav with one pressed button per item', () => {
+  const wrapper = mountRail({ active: 'scenes' });
+  const nav = wrapper.get('nav');
+  assert.equal(nav.attributes('aria-label'), 'Left panels');
+  assert.ok(nav.classes().includes('ui-rail--left'));
+  const buttons = wrapper.findAll('button');
+  assert.deepEqual(
+    buttons.map((button) => button.attributes('data-rail-item')),
+    ['layers', 'scenes', 'cctv'],
+  );
+  assert.deepEqual(
+    buttons.map((button) => button.attributes('aria-pressed')),
+    ['false', 'true', 'false'],
+  );
+  assert.equal(buttons[0].attributes('aria-label'), 'DATA LAYERS');
+  assert.equal(buttons[0].get('.material-symbols-outlined').text(), 'layers');
+  assert.ok(buttons[1].classes().includes('ui-rail__item--on'));
+  assert.equal(wrapper.findAll('.ui-rail__sep').length, 1);
+  assert.equal(buttons[2].attributes('disabled'), '');
+  assert.equal(buttons[2].get('.ui-rail__badge').text(), '3');
+});
+
+test('selecting an item emits its id', async () => {
+  const wrapper = mountRail();
+  await wrapper.get('[data-rail-item="scenes"]').trigger('click');
+  assert.deepEqual(wrapper.emitted('select'), [['scenes']]);
+});
+
+test('tips open toward the screen, and not for the open panel', async () => {
+  const wrapper = mountRail({
+    side: 'right',
+    active: 'layers',
+    panelOpen: true,
+  });
+  const [open, other] = wrapper.findAll('.ui-tooltip');
+  await open.trigger('focusin');
+  assert.equal(wrapper.find('[role="tooltip"]').exists(), false);
+  await other.trigger('focusin');
+  // Over an open panel the other tips wait for the pointer to rest.
+  assert.equal(wrapper.find('[role="tooltip"]').exists(), false);
+  await new Promise((resolve) => setTimeout(resolve, 450));
+  const tip = wrapper.get('[role="tooltip"]');
+  assert.equal(tip.text(), 'AUTHORING');
+  assert.ok(tip.classes().includes('ui-tooltip__tip--left'));
+  await other.trigger('focusout');
+  assert.equal(wrapper.find('[role="tooltip"]').exists(), false);
+});
diff --git a/src/ui/kit/UiRail.vue b/src/ui/kit/UiRail.vue
new file mode 100644
index 000000000..af740aae3
--- /dev/null
+++ b/src/ui/kit/UiRail.vue
@@ -0,0 +1,52 @@
+<script setup>
+import UiIcon from './UiIcon.vue';
+import UiTooltip from './UiTooltip.vue';
+import { RAIL_PANEL_OPEN_TOOLTIP_DELAY_MS } from './rail.js';
+
+defineProps({
+  /** @type {import('vue').PropType<import('./rail.js').UiRailItem[]>} */
+  items: { type: Array, required: true },
+  /** The selected item's id, or null. */
+  active: { type: String, default: null },
+  /** `left` or `right`: the screen edge the rail sits on. */
+  side: { type: String, required: true },
+  /** The nav's accessible name. */
+  label: { type: String, required: true },
+  /**
+   * A panel is open beside the rail: the open item's tip is redundant with the
+   * panel's title, and the other tips wait for the pointer to rest.
+   */
+  panelOpen: { type: Boolean, default: false },
+});
+const emit = defineEmits(['select']);
+</script>
+
+<template>
+  <nav class="ui-rail" :class="`ui-rail--${side}`" :aria-label="label">
+    <template v-for="item in items" :key="item.id">
+      <i v-if="item.separatorBefore" class="ui-rail__sep" aria-hidden="true" />
+      <UiTooltip
+        :text="item.label"
+        :side="side === 'left' ? 'right' : 'left'"
+        :disabled="panelOpen && item.id === active"
+        :delay="panelOpen ? RAIL_PANEL_OPEN_TOOLTIP_DELAY_MS : 0"
+      >
+        <button
+          type="button"
+          class="ui-rail__item"
+          :class="{ 'ui-rail__item--on': item.id === active }"
+          :data-rail-item="item.id"
+          :aria-label="item.label"
+          :aria-pressed="item.id === active"
+          :disabled="item.disabled"
+          @click="emit('select', item.id)"
+        >
+          <UiIcon :name="item.icon" />
+          <span v-if="item.badge !== undefined" class="ui-rail__badge">{{
+            item.badge
+          }}</span>
+        </button>
+      </UiTooltip>
+    </template>
+  </nav>
+</template>
diff --git a/src/ui/kit/UiTooltip.vue b/src/ui/kit/UiTooltip.vue
new file mode 100644
index 000000000..4c63f2316
--- /dev/null
+++ b/src/ui/kit/UiTooltip.vue
@@ -0,0 +1,50 @@
+<script setup>
+import { onBeforeUnmount, ref } from 'vue';
+
+const props = defineProps({
+  text: { type: String, required: true },
+  /** Which side of the trigger the tip opens on. */
+  side: { type: String, default: 'right' },
+  disabled: { type: Boolean, default: false },
+  /** Milliseconds the pointer rests before the tip shows. */
+  delay: { type: Number, default: 0 },
+});
+
+const open = ref(false);
+let timer = null;
+
+function show() {
+  if (props.disabled) return;
+  clearTimeout(timer);
+  if (props.delay > 0)
+    timer = setTimeout(() => (open.value = true), props.delay);
+  else open.value = true;
+}
+
+function hide() {
+  clearTimeout(timer);
+  timer = null;
+  open.value = false;
+}
+
+onBeforeUnmount(hide);
+</script>
+
+<template>
+  <span
+    class="ui-tooltip"
+    @pointerenter="show"
+    @pointerleave="hide"
+    @focusin="show"
+    @focusout="hide"
+  >
+    <slot />
+    <span
+      v-if="open && !disabled"
+      class="ui-tooltip__tip"
+      :class="`ui-tooltip__tip--${side}`"
+      role="tooltip"
+      >{{ text }}</span
+    >
+  </span>
+</template>
diff --git a/src/ui/kit/rail.js b/src/ui/kit/rail.js
new file mode 100644
index 000000000..498628770
--- /dev/null
+++ b/src/ui/kit/rail.js
@@ -0,0 +1,12 @@
+/**
+ * @typedef {object} UiRailItem
+ * @property {string} id Item identity, emitted on selection.
+ * @property {string} label Translated name, shown as the tooltip and accessible name.
+ * @property {string} icon Material Symbols glyph.
+ * @property {boolean} [disabled] Shown but not selectable.
+ * @property {boolean} [separatorBefore] Draw a divider above this item.
+ * @property {string|number} [badge] Small count or marker on the icon.
+ */
+
+/** How long the pointer rests on an item before its tip shows over an open panel. */
+export const RAIL_PANEL_OPEN_TOOLTIP_DELAY_MS = 400;
diff --git a/src/ui/styles/kit.css b/src/ui/styles/kit.css
new file mode 100644
index 000000000..ef65c1215
--- /dev/null
+++ b/src/ui/styles/kit.css
@@ -0,0 +1,100 @@
+/* Generic components in src/ui/kit. Names follow Halfpixel's ui-vue kit; the
+   surfaces use this application's glass, accent and type tokens. */
+
+.ui-icon {
+  display: inline-block;
+  line-height: 1;
+  font-variation-settings:
+    'FILL' 0,
+    'wght' 400,
+    'GRAD' 0,
+    'opsz' 20;
+  user-select: none;
+}
+
+.ui-tooltip {
+  position: relative;
+  display: inline-flex;
+}
+.ui-tooltip__tip {
+  position: absolute;
+  top: 50%;
+  z-index: 1;
+  padding: 4px 8px;
+  border: 1px solid var(--glass-border);
+  border-radius: 6px;
+  background: var(--menu-bg);
+  color: var(--dock-label-color);
+  font: var(--dock-label-font-weight) var(--dock-label-font-size) / 1.4
+    var(--font-sans);
+  letter-spacing: var(--dock-label-letter-spacing);
+  white-space: nowrap;
+  pointer-events: none;
+  transform: translateY(-50%);
+}
+.ui-tooltip__tip--right {
+  left: calc(100% + 10px);
+}
+.ui-tooltip__tip--left {
+  right: calc(100% + 10px);
+}
+
+.ui-rail {
+  display: flex;
+  flex-direction: column;
+  gap: 2px;
+  padding: 4px;
+  border: 1px solid var(--glass-border);
+  border-radius: calc(var(--btn-radius) + 4px);
+  background: var(--glass-bg);
+  backdrop-filter: blur(20px);
+  -webkit-backdrop-filter: blur(20px);
+  pointer-events: auto;
+}
+.ui-rail__sep {
+  height: 1px;
+  margin: 3px 6px;
+  background: var(--glass-border);
+}
+.ui-rail__item {
+  position: relative;
+  display: grid;
+  place-items: center;
+  width: 32px;
+  height: 32px;
+  border: 1px solid transparent;
+  border-radius: var(--btn-radius);
+  background: transparent;
+  color: var(--text-secondary);
+  cursor: pointer;
+  transition:
+    color var(--transition-fast),
+    background var(--transition-fast),
+    border-color var(--transition-fast);
+}
+.ui-rail__item:hover:not(:disabled) {
+  color: var(--text-primary);
+  background: rgba(255, 255, 255, 0.05);
+}
+.ui-rail__item--on,
+.ui-rail__item--on:hover:not(:disabled) {
+  border-color: var(--accent-dim);
+  background: var(--accent-dim);
+  color: var(--accent);
+}
+.ui-rail__item:disabled {
+  opacity: 0.35;
+  cursor: default;
+}
+.ui-rail__badge {
+  position: absolute;
+  top: 1px;
+  right: 1px;
+  min-width: 14px;
+  padding: 0 3px;
+  border-radius: 7px;
+  background: var(--accent);
+  color: var(--bg-dark);
+  font: 600 9px/14px var(--font-mono);
+  text-align: center;
+}
diff --git a/style.css b/style.css
index 1b55c459f..f887debb1 100644
--- a/style.css
+++ b/style.css
@@ -32,6 +32,7 @@
 @import './src/ui/styles/weather.css';
 @import './src/ui/styles/panel-surfaces.css';
 @import './src/ui/styles/segmented-control.css';
+@import './src/ui/styles/kit.css';
 @import './src/ui/styles/cjk.css';
 @import './src/ui/styles/mobile-shell.css';
 @import './src/ui/styles/cyber.css';