diff --git a/scripts/test-suites.mjs b/scripts/test-suites.mjs
index 9bb675c1f..4145cfc83 100644
--- a/scripts/test-suites.mjs
+++ b/scripts/test-suites.mjs
@@ -162,6 +162,7 @@ export const SUITES = {
           'tests/live-svelte-component-accept.test.mjs',
           'tests/live-tanstack-adapter.test.mjs',
           'tests/live-target-context.test.mjs',
+          'tests/live-ui-surfaces.test.mjs',
           'tests/live-wrap.test.mjs',
           'tests/live-wrap-buffer-aware.test.mjs',
         ],
diff --git a/skill/scripts/live-browser.js b/skill/scripts/live-browser.js
index aa9bd759b..918dfe093 100644
--- a/skill/scripts/live-browser.js
+++ b/skill/scripts/live-browser.js
@@ -97,23 +97,20 @@
     return { value: c.value, label: c.label };
   });
 
-  const LIVE_CHROME_MOUNT_CONTRACT = ['root', 'transport', 'state', 'actions'];
-  const LIVE_UI_SURFACES = [
-    { key: 'global-bottom-bar', ids: [PREFIX + '-global-bar', PREFIX + '-global-bar-brand', PREFIX + '-pick-toggle', PREFIX + '-insert-toggle', PREFIX + '-detect-toggle', PREFIX + '-detect-badge', PREFIX + '-design-toggle', PREFIX + '-page-chat', PREFIX + '-page-chat-input', PREFIX + '-page-chat-voice', PREFIX + '-page-chat-send'] },
-    { key: 'pending-copy-edit-dock', ids: [PREFIX + '-pending-dock'] },
-    { key: 'element-selection-chrome', ids: [PREFIX + '-highlight', PREFIX + '-tooltip', PREFIX + '-bar', PREFIX + '-selection-pill', PREFIX + '-input', PREFIX + '-configure-voice', PREFIX + '-configure-bar-tooltip'] },
-    { key: 'action-picker', ids: [PREFIX + '-picker'] },
-    { key: 'edit-chrome', ids: [PREFIX + '-edit-badge'] },
-    { key: 'generating-row', ids: [PREFIX + '-bar', PREFIX + '-shader'] },
-    { key: 'variant-cycling-row', ids: [PREFIX + '-bar', PREFIX + '-params-panel'] },
-    { key: 'variant-params-panel', ids: [PREFIX + '-params-panel'] },
-    { key: 'saving-confirmed-rows', ids: [PREFIX + '-bar'] },
-    { key: 'insert-mode-chrome', ids: [PREFIX + '-insert-line', PREFIX + '-insert-placeholder', PREFIX + '-placeholder-resize', PREFIX + '-insert-input', PREFIX + '-insert-voice', PREFIX + '-insert-create', PREFIX + '-insert-create-tooltip'] },
-    { key: 'annotation-chrome', ids: [PREFIX + '-annot', PREFIX + '-annot-svg', PREFIX + '-annot-pins', PREFIX + '-annot-clear'] },
-    { key: 'design-system-panel', ids: [PREFIX + '-design-host'] },
-    { key: 'toasts-and-errors', ids: [PREFIX + '-toast', PREFIX + '-mount-error'] },
-    { key: 'css-isolation-boundary', ids: [PREFIX + '-root'] },
-  ];
+  // The Live chrome inventory (which surfaces exist, and the element ids each
+  // one owns) comes from the canonical source, skill/scripts/live/ui-surfaces.mjs,
+  // which the /live.js assembler serializes into these globals alongside the
+  // token/port/vocabulary. This file is served raw and injected as a classic
+  // script, so it cannot import that module; the private impeccable-site repo
+  // imports it directly to check its Live UI lab holds a snapshot for every
+  // surface, which only works while the list has exactly one definition.
+  // Add a surface in ui-surfaces.mjs, not here.
+  const LIVE_CHROME_MOUNT_CONTRACT = Array.isArray(window.__IMPECCABLE_LIVE_MOUNT_CONTRACT__)
+    ? window.__IMPECCABLE_LIVE_MOUNT_CONTRACT__
+    : ['root', 'transport', 'state', 'actions'];
+  const LIVE_UI_SURFACES = Array.isArray(window.__IMPECCABLE_LIVE_UI_SURFACES__)
+    ? window.__IMPECCABLE_LIVE_UI_SURFACES__
+    : [];
   const LIVE_UI_COMPONENT_IDS = [...new Set(LIVE_UI_SURFACES.flatMap((surface) => surface.ids))];
 
   //
diff --git a/skill/scripts/live/browser-script-parts.mjs b/skill/scripts/live/browser-script-parts.mjs
index 5925136fb..720709a99 100644
--- a/skill/scripts/live/browser-script-parts.mjs
+++ b/skill/scripts/live/browser-script-parts.mjs
@@ -1,6 +1,8 @@
 import fs from 'node:fs';
 import path from 'node:path';
 
+import { LIVE_CHROME_MOUNT_CONTRACT, LIVE_UI_SURFACES } from './ui-surfaces.mjs';
+
 export const LIVE_BROWSER_SCRIPT_PARTS = Object.freeze([
   Object.freeze({ name: 'session-state', file: 'live-browser-session.js' }),
   Object.freeze({ name: 'dom-helpers', file: 'live-browser-dom.js' }),
@@ -32,7 +34,20 @@ export function readLiveBrowserScriptParts(parts, readFile = (filePath) => fs.re
   }));
 }
 
-export function assembleLiveBrowserScript({ token, port, vocabulary, commandPrefix = '/', appRoot = null, parts }) {
+export function assembleLiveBrowserScript({
+  token,
+  port,
+  vocabulary,
+  commandPrefix = '/',
+  appRoot = null,
+  parts,
+  // Defaulted rather than threaded through live-server.mjs: the browser bundle
+  // must always carry the canonical inventory, and a default makes that true by
+  // construction instead of by every caller remembering to pass it. Overridable
+  // so tests can assemble with a stand-in.
+  uiSurfaces = LIVE_UI_SURFACES,
+  mountContract = LIVE_CHROME_MOUNT_CONTRACT,
+}) {
   const prelude =
     `window.__IMPECCABLE_TOKEN__ = '${token}';\n` +
     `window.__IMPECCABLE_PORT__ = ${port};\n` +
@@ -44,7 +59,14 @@ export function assembleLiveBrowserScript({ token, port, vocabulary, commandPref
     `window.__IMPECCABLE_COMMAND_PREFIX__ = ${JSON.stringify(commandPrefix)};\n` +
     // Canonical command vocabulary (values + labels + icons). live-browser.js
     // builds its action picker from this instead of an inline copy.
-    `window.__IMPECCABLE_VOCAB__ = ${JSON.stringify(vocabulary)};\n`;
+    `window.__IMPECCABLE_VOCAB__ = ${JSON.stringify(vocabulary)};\n` +
+    // Canonical Live chrome inventory from live/ui-surfaces.mjs. live-browser.js
+    // is a classic script and cannot import an ES module at runtime, so the list
+    // is serialized here and read off the global there. Node consumers (this
+    // repo's tests, the impeccable-site Live UI lab) import the module directly,
+    // which is what keeps the two from drifting.
+    `window.__IMPECCABLE_LIVE_UI_SURFACES__ = ${JSON.stringify(uiSurfaces)};\n` +
+    `window.__IMPECCABLE_LIVE_MOUNT_CONTRACT__ = ${JSON.stringify(mountContract)};\n`;
 
   const body = parts.map((part) => {
     const file = part.file || path.basename(part.path || '');
diff --git a/skill/scripts/live/ui-surfaces.mjs b/skill/scripts/live/ui-surfaces.mjs
new file mode 100644
index 000000000..b39ca5846
--- /dev/null
+++ b/skill/scripts/live/ui-surfaces.mjs
@@ -0,0 +1,75 @@
+/**
+ * Canonical inventory of the Live overlay's UI surfaces: one entry per piece of
+ * chrome Live mounts on the user's page, with the element ids that make it up.
+ *
+ * Single source of truth, consumed by:
+ *   - skill/scripts/live/browser-script-parts.mjs — serializes this into
+ *     window.__IMPECCABLE_LIVE_UI_SURFACES__ in the /live.js prelude.
+ *   - skill/scripts/live-browser.js — publishes it on
+ *     window.__IMPECCABLE_LIVE_CHROME_CORE__ for adapters and E2E probes. That
+ *     file is served raw and injected as a classic <script>, so it cannot
+ *     import this module at runtime; it reads the injected global instead, the
+ *     same path live/vocabulary.mjs already takes for the command palette.
+ *   - the private impeccable-site repo — site/components/LiveUiGallery.astro
+ *     and tests/live-ui-lab.test.mjs import LIVE_UI_SURFACES at build time and
+ *     fail the site build when the Live UI lab has no snapshot for a surface
+ *     defined here. That guard only guards if it reads this list rather than a
+ *     copy the site keeps, so this module must stay importable from Node.
+ *     Renaming a key or the module is a breaking change for that build; the
+ *     list was briefly inlined into live-browser.js and the site had to parse
+ *     it back out with a regex.
+ *
+ * Add a surface here and both the browser bundle and the site lab follow.
+ */
+
+/** Id prefix every Live chrome element carries. Mirrored by PREFIX in live-browser.js. */
+export const LIVE_UI_PREFIX = 'impeccable-live';
+
+const id = (suffix) => `${LIVE_UI_PREFIX}-${suffix}`;
+
+/**
+ * The mount contract every Live chrome adapter (DOM, Svelte, ...) satisfies.
+ * Published alongside the surfaces on __IMPECCABLE_LIVE_CHROME_CORE__.
+ */
+export const LIVE_CHROME_MOUNT_CONTRACT = Object.freeze(['root', 'transport', 'state', 'actions']);
+
+export const LIVE_UI_SURFACES = Object.freeze([
+  {
+    key: 'global-bottom-bar',
+    ids: [
+      id('global-bar'), id('global-bar-brand'), id('pick-toggle'), id('insert-toggle'),
+      id('detect-toggle'), id('detect-badge'), id('design-toggle'), id('page-chat'),
+      id('page-chat-input'), id('page-chat-voice'), id('page-chat-send'),
+    ],
+  },
+  { key: 'pending-copy-edit-dock', ids: [id('pending-dock')] },
+  {
+    key: 'element-selection-chrome',
+    ids: [
+      id('highlight'), id('tooltip'), id('bar'), id('selection-pill'), id('input'),
+      id('configure-voice'), id('configure-bar-tooltip'),
+    ],
+  },
+  { key: 'action-picker', ids: [id('picker')] },
+  { key: 'edit-chrome', ids: [id('edit-badge')] },
+  { key: 'generating-row', ids: [id('bar'), id('shader')] },
+  { key: 'variant-cycling-row', ids: [id('bar'), id('params-panel')] },
+  { key: 'variant-params-panel', ids: [id('params-panel')] },
+  { key: 'saving-confirmed-rows', ids: [id('bar')] },
+  {
+    key: 'insert-mode-chrome',
+    ids: [
+      id('insert-line'), id('insert-placeholder'), id('placeholder-resize'), id('insert-input'),
+      id('insert-voice'), id('insert-create'), id('insert-create-tooltip'),
+    ],
+  },
+  { key: 'annotation-chrome', ids: [id('annot'), id('annot-svg'), id('annot-pins'), id('annot-clear')] },
+  { key: 'design-system-panel', ids: [id('design-host')] },
+  { key: 'toasts-and-errors', ids: [id('toast'), id('mount-error')] },
+  { key: 'css-isolation-boundary', ids: [id('root')] },
+].map((surface) => Object.freeze({ ...surface, ids: Object.freeze(surface.ids) })));
+
+/** Every id any surface owns, de-duplicated, in surface order. */
+export const LIVE_UI_COMPONENT_IDS = Object.freeze([
+  ...new Set(LIVE_UI_SURFACES.flatMap((surface) => surface.ids)),
+]);
diff --git a/tests/live-browser-regression.test.mjs b/tests/live-browser-regression.test.mjs
index 04688c3b3..bcd26bd71 100644
--- a/tests/live-browser-regression.test.mjs
+++ b/tests/live-browser-regression.test.mjs
@@ -18,6 +18,8 @@ import fs from 'node:fs';
 import path from 'node:path';
 import { fileURLToPath } from 'node:url';
 
+import { LIVE_UI_COMPONENT_IDS, LIVE_UI_PREFIX } from '../skill/scripts/live/ui-surfaces.mjs';
+
 const __dirname = path.dirname(fileURLToPath(import.meta.url));
 const LIVE_BROWSER = path.resolve(
   __dirname,
@@ -1280,9 +1282,12 @@ describe('live-browser.js regression guards', () => {
       /if \(e\.key === 'Enter'\) \{\s*e\.preventDefault\(\);\s*submitSteerMessage\(\);/,
       'keyboard submit stays',
     );
-    assert.match(
-      SOURCE,
-      /PREFIX \+ '-page-chat-send'\] \}/,
+    // The inventory used to be an inline literal here, so this used to be a
+    // source-text match on the surface entry. It now lives in
+    // live/ui-surfaces.mjs (importable, one definition), so assert membership
+    // in the real list instead of the shape of the line that declares it.
+    assert.ok(
+      LIVE_UI_COMPONENT_IDS.includes(`${LIVE_UI_PREFIX}-page-chat-send`),
       'the Send control must be registered as live UI chrome so it is excluded from capture',
     );
   });
diff --git a/tests/live-server.test.mjs b/tests/live-server.test.mjs
index d4556649e..c350c517d 100644
--- a/tests/live-server.test.mjs
+++ b/tests/live-server.test.mjs
@@ -200,6 +200,17 @@ describe('live-server integration', () => {
     assert.deepEqual(injected, LIVE_COMMANDS);
   });
 
+  it('/live.js injects the canonical Live UI surface inventory', async () => {
+    // Same path as the vocabulary: live-browser.js is a classic script and
+    // cannot import live/ui-surfaces.mjs, so the served bundle must carry the
+    // module's list. Node consumers (including the impeccable-site Live UI lab)
+    // import the module, and this is what keeps the two the same list.
+    const { LIVE_UI_SURFACES } = await import('../skill/scripts/live/ui-surfaces.mjs');
+    const body = await (await fetch(`http://localhost:${server.port}/live.js?token=${server.token}`)).text();
+    const injected = JSON.parse(body.match(/window\.__IMPECCABLE_LIVE_UI_SURFACES__\s*=\s*(\[.*?\]);\n/s)[1]);
+    assert.deepEqual(injected, JSON.parse(JSON.stringify(LIVE_UI_SURFACES)));
+  });
+
   it('/status returns durable recovery state', async () => {
     await drainPolls(server);
     const eventRes = await fetch(`http://localhost:${server.port}/events`, {
diff --git a/tests/live-ui-surfaces.test.mjs b/tests/live-ui-surfaces.test.mjs
new file mode 100644
index 000000000..f4b1d4c46
--- /dev/null
+++ b/tests/live-ui-surfaces.test.mjs
@@ -0,0 +1,94 @@
+/**
+ * The Live chrome inventory has exactly one definition, and it is importable.
+ *
+ * live-browser.js is served raw as a classic script and cannot import an ES
+ * module, which is why the list was once inlined there as a function-scope
+ * const. That put it out of reach of every Node consumer: this repo's own
+ * tooling, and the private impeccable-site repo, whose Live UI lab fails its
+ * build when a surface defined here has no snapshot. That guard is only a guard
+ * while it reads Live's real list, so these tests pin both halves: the module
+ * stays the definition, and the browser bundle still receives it at runtime.
+ */
+
+import { describe, it } from 'node:test';
+import assert from 'node:assert/strict';
+import fs from 'node:fs';
+import path from 'node:path';
+import { fileURLToPath } from 'node:url';
+
+import { assembleLiveBrowserScript } from '../skill/scripts/live/browser-script-parts.mjs';
+import {
+  LIVE_CHROME_MOUNT_CONTRACT,
+  LIVE_UI_COMPONENT_IDS,
+  LIVE_UI_PREFIX,
+  LIVE_UI_SURFACES,
+} from '../skill/scripts/live/ui-surfaces.mjs';
+
+const __dirname = path.dirname(fileURLToPath(import.meta.url));
+const LIVE_BROWSER_SOURCE = fs.readFileSync(
+  path.resolve(__dirname, '..', 'skill/scripts/live-browser.js'),
+  'utf-8',
+);
+
+describe('live UI surfaces module', () => {
+  it('exports a non-empty inventory with unique keys', () => {
+    assert.ok(LIVE_UI_SURFACES.length > 0);
+    const keys = LIVE_UI_SURFACES.map((surface) => surface.key);
+    assert.equal(new Set(keys).size, keys.length, 'surface keys must be unique');
+    for (const surface of LIVE_UI_SURFACES) {
+      assert.equal(typeof surface.key, 'string');
+      assert.ok(surface.ids.length > 0, `${surface.key} must own at least one element id`);
+    }
+  });
+
+  it('builds every id from the canonical prefix', () => {
+    for (const id of LIVE_UI_COMPONENT_IDS) {
+      assert.ok(id.startsWith(`${LIVE_UI_PREFIX}-`), `${id} must carry the ${LIVE_UI_PREFIX} prefix`);
+    }
+  });
+
+  it('agrees with the PREFIX live-browser.js hardcodes', () => {
+    // live-browser.js cannot import LIVE_UI_PREFIX, so it declares the string
+    // itself and every id it creates at runtime is built from that. If the two
+    // drift, the inventory names ids that no element on the page ever has.
+    const declared = LIVE_BROWSER_SOURCE.match(/const PREFIX = '([^']+)';/);
+    assert.ok(declared, 'live-browser.js must declare `const PREFIX = ...`');
+    assert.equal(declared[1], LIVE_UI_PREFIX);
+  });
+
+  it('is not redefined inside live-browser.js', () => {
+    // The list living in two places is the failure this module exists to end.
+    assert.doesNotMatch(LIVE_BROWSER_SOURCE, /const LIVE_UI_SURFACES = \[/);
+    assert.match(LIVE_BROWSER_SOURCE, /window\.__IMPECCABLE_LIVE_UI_SURFACES__/);
+  });
+});
+
+describe('live UI surfaces reach the browser bundle', () => {
+  const assemble = () => assembleLiveBrowserScript({
+    token: 'token-a',
+    port: 8421,
+    vocabulary: [],
+    parts: [{ name: 'browser-ui', file: 'live-browser.js', source: LIVE_BROWSER_SOURCE }],
+  });
+
+  it('serializes the canonical inventory into the prelude by default', () => {
+    const script = assemble();
+    const surfaces = JSON.parse(
+      script.match(/window\.__IMPECCABLE_LIVE_UI_SURFACES__ = (\[.*?\]);\n/s)[1],
+    );
+    assert.deepEqual(surfaces, JSON.parse(JSON.stringify(LIVE_UI_SURFACES)));
+
+    const contract = JSON.parse(
+      script.match(/window\.__IMPECCABLE_LIVE_MOUNT_CONTRACT__ = (\[.*?\]);\n/s)[1],
+    );
+    assert.deepEqual(contract, [...LIVE_CHROME_MOUNT_CONTRACT]);
+  });
+
+  it('injects the globals before the script part that reads them', () => {
+    const script = assemble();
+    assert.ok(
+      script.indexOf('window.__IMPECCABLE_LIVE_UI_SURFACES__ =')
+        < script.indexOf('impeccable live script part: browser-ui'),
+    );
+  });
+});