diff --git a/package.json b/package.json
index 58917e8c..61db937b 100644
--- a/package.json
+++ b/package.json
@@ -63,6 +63,7 @@
     "@typescript-eslint/parser": "^8.30.1",
     "@vitest/browser-playwright": "4.1.10",
     "@vitest/coverage-v8": "^4.1.10",
+    "@webcomponents/scoped-custom-element-registry": "0.0.10",
     "conventional-changelog-conventionalcommits": "^8.0.0",
     "docsify-cli": "^4.4.4",
     "es-module-lexer": "^2.3.1",
diff --git a/tests/browser/fake-frigate.browser.test.ts b/tests/browser/fake-frigate.browser.test.ts
new file mode 100644
index 00000000..a4e0c846
--- /dev/null
+++ b/tests/browser/fake-frigate.browser.test.ts
@@ -0,0 +1,299 @@
+import { describe, expect, it } from 'vitest';
+
+import type { FrigateEvent } from '../../src/camera-manager/frigate/types';
+import type { ResolvedMedia } from '../../src/ha/types';
+import { createFrigateEvent } from '../test-utils';
+import {
+  createFrigateCameraDescription,
+  FakeFrigate,
+  FRIGATE_CLIENT_ID,
+  getTestFrigateCameraName,
+  type FrigateMediaType,
+} from './fake-frigate';
+import type { FakeHASS } from './fake-hass';
+import { CAMERA_ENTITY, createCameraHASS } from './test-utils';
+
+const CAMERA_NAME = getTestFrigateCameraName(CAMERA_ENTITY);
+const OTHER_CAMERA_NAME = 'hallway';
+
+// Frigate timestamps are Unix seconds. Only their order matters here.
+const EARLIER = 1000;
+const LATER = 2000;
+
+interface FrigateFixture {
+  hass: FakeHASS;
+  frigate: FakeFrigate;
+}
+
+const createFrigate = (events: FrigateEvent[]): FrigateFixture => {
+  const hass = createCameraHASS([createFrigateCameraDescription()]);
+  const frigate = new FakeFrigate(hass);
+  frigate.setEvents(events);
+  return { hass, frigate };
+};
+
+const createEvent = (id: string, event?: Partial<FrigateEvent>): FrigateEvent =>
+  createFrigateEvent({
+    camera: CAMERA_NAME,
+    id,
+    start_time: EARLIER,
+    end_time: LATER,
+    ...event,
+  });
+
+const queryEvents = async (
+  hass: FakeHASS,
+  parameters?: Record<string, unknown>,
+): Promise<FrigateEvent[]> => {
+  const answer = await hass.getHASS().callWS<string>({
+    type: 'frigate/events/get',
+    instance_id: FRIGATE_CLIENT_ID,
+    ...parameters,
+  });
+  const events: FrigateEvent[] = JSON.parse(answer);
+  return events;
+};
+
+const getEventIDs = async (
+  hass: FakeHASS,
+  parameters?: Record<string, unknown>,
+): Promise<string[]> => (await queryEvents(hass, parameters)).map((event) => event.id);
+
+const createContentID = (
+  eventID: string,
+  mediaType: FrigateMediaType,
+  options?: { clientID?: string; camera?: string },
+): string =>
+  [
+    'media-source://frigate',
+    options?.clientID ?? FRIGATE_CLIENT_ID,
+    'event',
+    mediaType,
+    options?.camera ?? CAMERA_NAME,
+    eventID,
+  ].join('/');
+
+const resolveMedia = async (hass: FakeHASS, contentID: string): Promise<ResolvedMedia> =>
+  await hass.getHASS().callWS<ResolvedMedia>({
+    type: 'media_source/resolve_media',
+    media_content_id: contentID,
+  });
+
+const createThumbnailPath = (eventID: string, clientID = FRIGATE_CLIENT_ID): string =>
+  `/api/frigate/${clientID}/thumbnail/${eventID}`;
+
+describe('FakeFrigate', () => {
+  describe('requests', () => {
+    it('should refuse a request meant for another instance', async () => {
+      const { hass } = createFrigate([]);
+
+      await expect(
+        hass
+          .getHASS()
+          .callWS({ type: 'frigate/events/get', instance_id: 'other-frigate' }),
+      ).rejects.toThrow('FakeFrigate was asked for another instance: other-frigate');
+
+      await expect(
+        hass
+          .getHASS()
+          .callWS({ type: 'frigate/ptz/info', instance_id: 'other-frigate' }),
+      ).rejects.toThrow('FakeFrigate was asked for another instance: other-frigate');
+    });
+
+    it('should refuse a request carrying something it does not read', async () => {
+      const { hass } = createFrigate([]);
+
+      await expect(queryEvents(hass, { camera: CAMERA_NAME })).rejects.toThrow(
+        'FakeFrigate was sent unknown parameters: camera',
+      );
+    });
+
+    it('should refuse a parameter of the wrong type', async () => {
+      const { hass } = createFrigate([]);
+
+      await expect(queryEvents(hass, { cameras: CAMERA_NAME })).rejects.toThrow(
+        `FakeFrigate was sent a 'cameras' that is not a list of strings: "${CAMERA_NAME}"`,
+      );
+      await expect(queryEvents(hass, { has_clip: 'yes' })).rejects.toThrow(
+        `FakeFrigate was sent a 'has_clip' that is not true or false: "yes"`,
+      );
+    });
+  });
+
+  describe('events', () => {
+    it('should return every event when nothing narrows the query', async () => {
+      const { hass } = createFrigate([createEvent('one'), createEvent('two')]);
+
+      expect(await getEventIDs(hass)).toEqual(['one', 'two']);
+    });
+
+    it('should return the newest event first', async () => {
+      const { hass } = createFrigate([
+        createEvent('older', { start_time: EARLIER }),
+        createEvent('newer', { start_time: LATER }),
+      ]);
+
+      expect(await getEventIDs(hass)).toEqual(['newer', 'older']);
+    });
+
+    it('should return only the events for the cameras asked for', async () => {
+      const { hass } = createFrigate([
+        createEvent('here'),
+        createEvent('elsewhere', { camera: OTHER_CAMERA_NAME }),
+      ]);
+
+      expect(await getEventIDs(hass, { cameras: [CAMERA_NAME] })).toEqual(['here']);
+    });
+
+    it('should return only the events holding the media asked for', async () => {
+      const { hass } = createFrigate([
+        createEvent('clip-only', { has_clip: true, has_snapshot: false }),
+        createEvent('snapshot-only', { has_clip: false, has_snapshot: true }),
+      ]);
+
+      expect(await getEventIDs(hass, { has_clip: true })).toEqual(['clip-only']);
+      expect(await getEventIDs(hass, { has_snapshot: true })).toEqual(['snapshot-only']);
+    });
+
+    it('should return only the events within the period asked for', async () => {
+      const { hass } = createFrigate([
+        createEvent('before', { start_time: 100, end_time: 200 }),
+        createEvent('during', { start_time: 400, end_time: 600 }),
+        createEvent('after', { start_time: 800, end_time: 900 }),
+      ]);
+
+      expect(await getEventIDs(hass, { after: 300, before: 700 })).toEqual(['during']);
+    });
+
+    it('should return an event that was still running when the period began', async () => {
+      const { hass } = createFrigate([
+        createEvent('running', { start_time: 100, end_time: 500 }),
+      ]);
+
+      expect(await getEventIDs(hass, { after: 300 })).toEqual(['running']);
+    });
+
+    it('should return only the events for the requested label', async () => {
+      const { hass } = createFrigate([
+        createEvent('person', { label: 'person' }),
+        createEvent('car', { label: 'car' }),
+      ]);
+
+      expect(await getEventIDs(hass, { labels: ['car'] })).toEqual(['car']);
+    });
+
+    it('should return only the events in the requested zones', async () => {
+      const { hass } = createFrigate([
+        createEvent('driveway', { zones: ['driveway'] }),
+        createEvent('garden', { zones: ['garden'] }),
+      ]);
+
+      expect(await getEventIDs(hass, { zones: ['garden'] })).toEqual(['garden']);
+    });
+
+    it('should return the events carrying any of the sub labels asked for', async () => {
+      // Frigate keeps several sub labels on one event as a comma separated
+      // string, so asking for one of them has to reach into it.
+      const { hass } = createFrigate([
+        createEvent('known', { sub_label: 'alice, bob' }),
+        createEvent('stranger', { sub_label: null }),
+      ]);
+
+      expect(await getEventIDs(hass, { sub_labels: ['bob'] })).toEqual(['known']);
+    });
+
+    it('should return only the favorites', async () => {
+      const { hass } = createFrigate([
+        createEvent('kept', { retain_indefinitely: true }),
+        createEvent('ordinary', { retain_indefinitely: false }),
+      ]);
+
+      expect(await getEventIDs(hass, { favorites: true })).toEqual(['kept']);
+    });
+
+    it('should return no more events than the limit asked for', async () => {
+      const { hass } = createFrigate([
+        createEvent('older', { start_time: EARLIER }),
+        createEvent('newer', { start_time: LATER }),
+      ]);
+
+      expect(await getEventIDs(hass, { limit: 1 })).toEqual(['newer']);
+    });
+  });
+
+  describe('media', () => {
+    it('should resolve a clip to a video and a snapshot to an image', async () => {
+      const { hass } = createFrigate([createEvent('one')]);
+
+      expect(await resolveMedia(hass, createContentID('one', 'clips'))).toEqual({
+        url: expect.stringContaining('clip.webm?event=one'),
+        mime_type: 'video/webm',
+      });
+      expect(await resolveMedia(hass, createContentID('one', 'snapshots'))).toEqual({
+        url: expect.stringContaining('still-red.png?event=one'),
+        mime_type: 'image/png',
+      });
+    });
+
+    it('should refuse media for an event it does not have', async () => {
+      const { hass } = createFrigate([createEvent('one')]);
+
+      await expect(resolveMedia(hass, createContentID('two', 'clips'))).rejects.toThrow(
+        'FakeFrigate has no such media',
+      );
+    });
+
+    it('should refuse media the event does not have', async () => {
+      const { hass } = createFrigate([createEvent('one', { has_clip: false })]);
+
+      await expect(resolveMedia(hass, createContentID('one', 'clips'))).rejects.toThrow(
+        'FakeFrigate has no such media',
+      );
+    });
+
+    it('should refuse media asked for under the wrong camera or instance', async () => {
+      const { hass } = createFrigate([createEvent('one')]);
+
+      await expect(
+        resolveMedia(hass, createContentID('one', 'clips', { camera: 'elsewhere' })),
+      ).rejects.toThrow('FakeFrigate has no such media');
+      await expect(
+        resolveMedia(hass, createContentID('one', 'clips', { clientID: 'other' })),
+      ).rejects.toThrow('FakeFrigate has no such media');
+    });
+
+    it('should honor set media URL', async () => {
+      const { hass, frigate } = createFrigate([createEvent('one')]);
+
+      frigate.setMediaURL('one', 'clips', '/somewhere-else.webm');
+
+      expect((await resolveMedia(hass, createContentID('one', 'clips'))).url).toBe(
+        '/somewhere-else.webm',
+      );
+
+      // The snapshot is a separate media item and is left where it was.
+      expect(
+        (await resolveMedia(hass, createContentID('one', 'snapshots'))).url,
+      ).toContain('still-red.png');
+    });
+  });
+
+  describe('thumbnails', () => {
+    it('should serve a picture for an event', async () => {
+      const { hass } = createFrigate([createEvent('one')]);
+
+      const response = await hass.getHASS().fetchWithAuth(createThumbnailPath('one'));
+
+      expect(response.ok).toBe(true);
+      expect(response.headers.get('Content-Type')).toContain('image/png');
+    });
+
+    it('should refuse a thumbnail for an event it does not have', async () => {
+      const { hass } = createFrigate([createEvent('one')]);
+
+      await expect(
+        hass.getHASS().fetchWithAuth(createThumbnailPath('two')),
+      ).rejects.toThrow('FakeFrigate has no thumbnail at');
+    });
+  });
+});
diff --git a/tests/browser/fake-frigate.ts b/tests/browser/fake-frigate.ts
new file mode 100644
index 00000000..365642e4
--- /dev/null
+++ b/tests/browser/fake-frigate.ts
@@ -0,0 +1,402 @@
+import { fromUnixTime } from 'date-fns';
+import type { MessageBase } from 'home-assistant-js-websocket';
+
+import type { NativeFrigateEventQuery } from '../../src/camera-manager/frigate/requests';
+import type { EventSummary, FrigateEvent } from '../../src/camera-manager/frigate/types';
+import type { PartialAdvancedCameraCardConfig } from '../../src/config/types';
+import type { ResolvedMedia } from '../../src/ha/types';
+import { createFrigateEvent } from '../test-utils';
+import type { FakeHASS, WSCommandHandler } from './fake-hass';
+import {
+  CLIP_FIXTURE_FILENAME,
+  createFixtureURL,
+  SNAPSHOT_FIXTURE_FILENAME,
+} from './fixtures';
+import { MountedCardFactory, type MountedCard } from './mounted-card';
+import {
+  CAMERA_ENTITY,
+  createCameraHASS,
+  createStillImageCardConfig,
+  type FakeCameraDescription,
+} from './test-utils';
+
+export const FRIGATE_CLIENT_ID = 'frigate';
+export type FrigateMediaType = 'clips' | 'snapshots';
+const FRIGATE_CONFIG_ENTRY_ID = 'frigate-config-entry';
+
+/**
+ * Frigate's name for a test camera, which this harness keeps equal to the
+ * entity's object ID.
+ */
+export const getTestFrigateCameraName = (cameraEntity: string): string =>
+  cameraEntity.split('.')[1];
+
+/**
+ * A camera belonging to Frigate.
+ */
+export const createFrigateCameraDescription = (
+  entityID: string = CAMERA_ENTITY,
+): FakeCameraDescription => ({
+  entityID,
+  entity: { state: 'idle', attributes: { client_id: FRIGATE_CLIENT_ID } },
+  registry: {
+    platform: 'frigate',
+    unique_id: `${FRIGATE_CLIENT_ID}:camera:${getTestFrigateCameraName(entityID)}`,
+    config_entry_id: FRIGATE_CONFIG_ENTRY_ID,
+  },
+});
+
+// Frigate timestamps are UNIX seconds. Two of them, so a test can have an event
+// on each side of the other.
+export const EVENT_TIME_OLDER = 1754300000;
+export const EVENT_TIME_NEWER = 1754310000;
+
+const EVENT_DURATION_SECONDS = 10;
+
+export const createTestFrigateEvent = (
+  id: string,
+  startTime: number,
+  event?: Partial<FrigateEvent>,
+): FrigateEvent =>
+  createFrigateEvent({
+    camera: getTestFrigateCameraName(CAMERA_ENTITY),
+    id,
+    start_time: startTime,
+    end_time: startTime + EVENT_DURATION_SECONDS,
+    ...event,
+  });
+
+export interface CardWithFrigate {
+  card: MountedCard;
+  frigate: FakeFrigate;
+}
+
+/**
+ * A card whose camera is Frigate's, with the given events already detected.
+ */
+export const mountCardWithFrigate = async (
+  events: FrigateEvent[],
+  config?: PartialAdvancedCameraCardConfig,
+): Promise<CardWithFrigate> => {
+  const hass = createCameraHASS([createFrigateCameraDescription()]);
+  const frigate = new FakeFrigate(hass);
+  frigate.setEvents(events);
+
+  const card = await MountedCardFactory.createFromSource(
+    createStillImageCardConfig(config),
+    hass,
+  );
+
+  return { card, frigate };
+};
+
+// An event's media content ID, as `getEventMediaContentID` builds it:
+// media-source://frigate/<client>/event/<clips|snapshots>/<camera>/<id>
+const EVENT_CONTENT_ID =
+  /^media-source:\/\/frigate\/(?<clientID>[^/]+)\/event\/(?<mediaType>[^/]+)\/(?<camera>[^/]+)\/(?<eventID>[^/]+)$/;
+
+// An event's thumbnail, as `getEventThumbnailURL` asks for it:
+// /api/frigate/<client>/thumbnail/<id>
+const THUMBNAIL_PATH =
+  /^\/api\/frigate\/(?<clientID>[^/]+)\/thumbnail\/(?<eventID>[^/]+)$/;
+
+const isStringArray = (value: unknown): value is string[] =>
+  Array.isArray(value) && value.every((entry) => typeof entry === 'string');
+
+const isBoolean = (value: unknown): value is boolean => typeof value === 'boolean';
+
+const isNumber = (value: unknown): value is number => typeof value === 'number';
+
+// Read a request parameter, refusing a value of the wrong type.
+const readParameter = <T>(
+  message: MessageBase,
+  name: string,
+  isExpected: (value: unknown) => value is T,
+  expected: string,
+): T | undefined => {
+  const value: unknown = message[name];
+  if (value === undefined) {
+    return undefined;
+  }
+  if (!isExpected(value)) {
+    throw new Error(
+      `FakeFrigate was sent a '${name}' that is not ${expected}: ` +
+        JSON.stringify(value),
+    );
+  }
+  return value;
+};
+
+const EVERY_REQUEST_PARAMETERS = ['type'];
+
+// Refuse a request carrying a parameter this Frigate does not recognize.
+const requireKnownParameters = (message: MessageBase, parameters: string[]): void => {
+  const known = [...EVERY_REQUEST_PARAMETERS, ...parameters];
+  const unknown = Object.keys(message).filter((name) => !known.includes(name));
+
+  if (unknown.length) {
+    throw new Error(`FakeFrigate was sent unknown parameters: ${unknown}`);
+  }
+};
+
+// Frigate keeps every sub label an event has in one comma separated string.
+const getSubLabels = (event: FrigateEvent): string[] =>
+  event.sub_label?.split(',').map((subLabel) => subLabel.trim()) ?? [];
+
+// The day an event falls on. Always UTC, the only time zone a `FakeHASS` reports,
+// so `formatDate` cannot be used: it renders in local time.
+const getEventDay = (event: FrigateEvent): string =>
+  fromUnixTime(event.start_time).toISOString().slice(0, 'YYYY-MM-DD'.length);
+
+interface FrigateMediaReference {
+  clientID: string;
+  mediaType: FrigateMediaType;
+  camera: string;
+  eventID: string;
+}
+
+// The event media a request is asking for, read out of its media content ID.
+const parseContentID = (contentID: string): FrigateMediaReference | null => {
+  const groups = EVENT_CONTENT_ID.exec(contentID)?.groups;
+  if (!groups) {
+    return null;
+  }
+
+  const mediaType = groups['mediaType'];
+  if (mediaType !== 'clips' && mediaType !== 'snapshots') {
+    return null;
+  }
+
+  return {
+    clientID: groups['clientID'],
+    mediaType,
+    camera: groups['camera'],
+    eventID: groups['eventID'],
+  };
+};
+
+// The instance is separate from the actual query.
+type EventQuery = Omit<NativeFrigateEventQuery, 'instance_id'>;
+
+// Read the whole query before applying any of it. A request carrying nonsense is
+// then refused even when no event would have matched anyway.
+const readEventQuery = (message: MessageBase): EventQuery => {
+  const getList = (name: string): string[] | undefined =>
+    readParameter(message, name, isStringArray, 'a list of strings');
+  const getBoolean = (name: string): boolean | undefined =>
+    readParameter(message, name, isBoolean, 'true or false');
+  const getCount = (name: string): number | undefined =>
+    readParameter(message, name, isNumber, 'a number');
+
+  return {
+    cameras: getList('cameras'),
+    labels: getList('labels'),
+    sub_labels: getList('sub_labels'),
+    zones: getList('zones'),
+    after: getCount('after'),
+    before: getCount('before'),
+    favorites: getBoolean('favorites'),
+    has_clip: getBoolean('has_clip'),
+    has_snapshot: getBoolean('has_snapshot'),
+    limit: getCount('limit'),
+  };
+};
+
+// Whether an event is one the request asked for.
+const matchesEventQuery = (event: FrigateEvent, query: EventQuery): boolean =>
+  (!query.cameras || query.cameras.includes(event.camera)) &&
+  (!query.labels || query.labels.includes(event.label)) &&
+  (!query.sub_labels ||
+    getSubLabels(event).some((subLabel) => query.sub_labels?.includes(subLabel))) &&
+  (!query.zones || query.zones.some((zone) => event.zones.includes(zone))) &&
+  // An event that began before the period and was still running when it started
+  // counts as falling within it.
+  (query.after === undefined || (event.end_time ?? Infinity) >= query.after) &&
+  (query.before === undefined || event.start_time <= query.before) &&
+  (!query.favorites || !!event.retain_indefinitely) &&
+  (!query.has_clip || event.has_clip) &&
+  (!query.has_snapshot || event.has_snapshot);
+
+/**
+ * A Frigate instance behind a `FakeHASS`. Holds the events a test wants a camera
+ * to have detected, and answers what the card asks about them.
+ *
+ * Any missing functionality returns an error.
+ */
+export class FakeFrigate {
+  private _events: FrigateEvent[] = [];
+  private _mediaURLs = new Map<string, string>();
+
+  constructor(hass: FakeHASS) {
+    hass.registerCommand(
+      'frigate/events/get',
+      this._answerAsFrigate(
+        [
+          'after',
+          'before',
+          'cameras',
+          'favorites',
+          'has_clip',
+          'has_snapshot',
+          'labels',
+          'limit',
+          'sub_labels',
+          'zones',
+        ],
+        (message) => this._queryEvents(message),
+      ),
+    );
+    hass.registerCommand(
+      'frigate/events/summary',
+      this._answerAsFrigate(['timezone'], () => this._summariseEvents()),
+    );
+
+    // This Frigate keeps no recordings and cannot be given any. The media filter
+    // and the viewer's seek still ask, and an unanswered request is an error.
+    hass.registerCommand(
+      'frigate/recordings/summary',
+      this._answerAsFrigate(['camera', 'timezone'], () => []),
+    );
+    hass.registerCommand(
+      'frigate/recordings/get',
+      this._answerAsFrigate(['after', 'before', 'camera'], () => []),
+    );
+
+    // Fake Frigate has no review items and cannot be given any. The live view
+    // asks for them on startup, so leaving this unanswered would raise a media
+    // query issue on every card.
+    hass.registerCommand(
+      'frigate/reviews/get',
+      this._answerAsFrigate(
+        [
+          'after',
+          'before',
+          'cameras',
+          'labels',
+          'limit',
+          'reviewed',
+          'severity',
+          'zones',
+        ],
+        () => [],
+      ),
+    );
+    hass.registerCommand(
+      'frigate/ptz/info',
+      this._answerAsFrigate(['camera'], () => ({})),
+    );
+    hass.registerPath(THUMBNAIL_PATH, (path) => this._serveThumbnail(path));
+
+    hass.registerMediaSource(EVENT_CONTENT_ID, (contentID) =>
+      this._resolveMedia(contentID),
+    );
+  }
+
+  /**
+   * The events this Frigate instance has. Held newest first, as Frigate returns them.
+   */
+  public setEvents(events: FrigateEvent[]): void {
+    this._events = [...events].sort((a, b) => b.start_time - a.start_time);
+  }
+
+  /**
+   * Set the URL for a media item.
+   */
+  public setMediaURL(eventID: string, mediaType: FrigateMediaType, url: string): void {
+    this._mediaURLs.set(this._getMediaKey(eventID, mediaType), url);
+  }
+
+  // Answer a command addressed to this instance, refusing one meant for
+  // another. Frigate answers with JSON.
+  private _answerAsFrigate(
+    parameters: string[],
+    handler: (message: MessageBase) => unknown,
+  ): WSCommandHandler {
+    return (message: MessageBase): string => {
+      const instanceID: unknown = message['instance_id'];
+      if (instanceID !== FRIGATE_CLIENT_ID) {
+        throw new Error(
+          `FakeFrigate was asked for another instance: ${String(instanceID)}`,
+        );
+      }
+      requireKnownParameters(message, ['instance_id', ...parameters]);
+
+      return JSON.stringify(handler(message));
+    };
+  }
+
+  private _getMediaKey(eventID: string, mediaType: FrigateMediaType): string {
+    return `${eventID}/${mediaType}`;
+  }
+
+  private _getEvent(eventID: string): FrigateEvent | null {
+    return this._events.find((event) => event.id === eventID) ?? null;
+  }
+
+  private _queryEvents(message: MessageBase): FrigateEvent[] {
+    const query = readEventQuery(message);
+    const matching = this._events.filter((event) => matchesEventQuery(event, query));
+
+    return query.limit === undefined ? matching : matching.slice(0, query.limit);
+  }
+
+  // What the media filter offers to filter by: every camera, day, label and zone
+  // combination the events cover.
+  private _summariseEvents(): EventSummary {
+    const summaries = new Map<string, EventSummary[number]>();
+
+    for (const event of this._events) {
+      const summary = {
+        camera: event.camera,
+        day: getEventDay(event),
+        label: event.label,
+        sub_label: event.sub_label,
+        zones: event.zones,
+      };
+      summaries.set(JSON.stringify(summary), summary);
+    }
+
+    return [...summaries.values()];
+  }
+
+  // Where an event's media is served from. The URL names the event, so a test can
+  // tell which media is on screen without looking at the picture.
+  private _resolveMedia(contentID: string): ResolvedMedia {
+    const media = parseContentID(contentID);
+    const event = media ? this._getEvent(media.eventID) : null;
+    const isClip = media?.mediaType === 'clips';
+
+    if (
+      !media ||
+      !event ||
+      media.clientID !== FRIGATE_CLIENT_ID ||
+      media.camera !== event.camera ||
+      !(isClip ? event.has_clip : event.has_snapshot)
+    ) {
+      throw new Error(`FakeFrigate has no such media: ${contentID}`);
+    }
+
+    const filename = isClip ? CLIP_FIXTURE_FILENAME : SNAPSHOT_FIXTURE_FILENAME;
+
+    return {
+      url:
+        this._mediaURLs.get(this._getMediaKey(media.eventID, media.mediaType)) ??
+        `${createFixtureURL(filename)}?event=${media.eventID}`,
+      mime_type: isClip ? 'video/webm' : 'image/png',
+    };
+  }
+
+  private async _serveThumbnail(path: string): Promise<Response> {
+    const groups = THUMBNAIL_PATH.exec(path)?.groups;
+
+    if (
+      !groups ||
+      groups['clientID'] !== FRIGATE_CLIENT_ID ||
+      !this._getEvent(groups['eventID'])
+    ) {
+      throw new Error(`FakeFrigate has no thumbnail at: ${path}`);
+    }
+
+    return await fetch(createFixtureURL(SNAPSHOT_FIXTURE_FILENAME));
+  }
+}
diff --git a/tests/browser/fake-hass.test.ts b/tests/browser/fake-hass.test.ts
index 2bad579b..a0c18955 100644
--- a/tests/browser/fake-hass.test.ts
+++ b/tests/browser/fake-hass.test.ts
@@ -148,6 +148,70 @@ describe('FakeHASS', () => {
     });
   });
 
+  describe('authenticated fetches', () => {
+    it('should answer a registered path', async () => {
+      const hass = createFakeHASS();
+      hass.registerPath(/^\/api\/thumbnail\/.+$/, (path) => new Response(path));
+
+      const response = await hass.getHASS().fetchWithAuth('/api/thumbnail/1');
+
+      await expect(response.text()).resolves.toBe('/api/thumbnail/1');
+    });
+
+    it('should reject an unregistered path', async () => {
+      const hass = createFakeHASS();
+
+      await expect(hass.getHASS().fetchWithAuth('/api/thumbnail/1')).rejects.toThrow(
+        'FakeHASS received a request for an unregistered path: /api/thumbnail/1',
+      );
+    });
+  });
+
+  describe('media sources', () => {
+    const resolveMedia = async (hass: FakeHASS, contentID: unknown): Promise<unknown> =>
+      await hass
+        .getHASS()
+        .callWS({ type: 'media_source/resolve_media', media_content_id: contentID });
+
+    it('should resolve a content ID with the source that claims it', async () => {
+      const hass = createFakeHASS();
+      hass.registerMediaSource(/^media-source:\/\/other\//, () => ({
+        url: '/other.mp4',
+        mime_type: 'video/mp4',
+      }));
+      hass.registerMediaSource(/^media-source:\/\/mine\//, (contentID) => ({
+        url: `/mine.mp4?id=${contentID}`,
+        mime_type: 'video/mp4',
+      }));
+
+      // Demonstrate that two sources coexist.
+      expect(await resolveMedia(hass, 'media-source://mine/1')).toEqual({
+        url: '/mine.mp4?id=media-source://mine/1',
+        mime_type: 'video/mp4',
+      });
+      expect(await resolveMedia(hass, 'media-source://other/1')).toEqual({
+        url: '/other.mp4',
+        mime_type: 'video/mp4',
+      });
+    });
+
+    it('should reject a content ID no source claims', async () => {
+      const hass = createFakeHASS();
+
+      await expect(resolveMedia(hass, 'media-source://mine/1')).rejects.toThrow(
+        'FakeHASS has no media source for: media-source://mine/1',
+      );
+    });
+
+    it('should reject a request carrying no content ID', async () => {
+      const hass = createFakeHASS();
+
+      await expect(resolveMedia(hass, undefined)).rejects.toThrow(
+        'FakeHASS was asked to resolve media without a content ID',
+      );
+    });
+  });
+
   describe('unimplemented methods', () => {
     it('should throw rather than quietly do nothing', () => {
       const hass = createFakeHASS().getHASS();
diff --git a/tests/browser/fake-hass.ts b/tests/browser/fake-hass.ts
index 9133f3dc..c2e8ee84 100644
--- a/tests/browser/fake-hass.ts
+++ b/tests/browser/fake-hass.ts
@@ -9,13 +9,22 @@ import {
 import { mock } from 'vitest-mock-extended';
 
 import type { Entity } from '../../src/ha/registry/entity/types';
-import type { HomeAssistant } from '../../src/ha/types';
+import type { HomeAssistant, ResolvedMedia } from '../../src/ha/types';
 import { createRegistryEntity, createStateEntity } from '../test-utils';
 
 // A WebSocket command handler. Returning a rejected promise models a command
 // Home Assistant refuses; throwing models a malformed request.
 export type WSCommandHandler = (message: MessageBase) => Promise<unknown> | unknown;
 
+// A handler for an authenticated HTTP request.
+export type PathHandler = (path: string) => Promise<Response> | Response;
+
+// A handler that turns a media content ID into something playable (i.e. HA
+// media source).
+export type MediaSourceHandler = (
+  contentID: string,
+) => Promise<ResolvedMedia> | ResolvedMedia;
+
 export interface FakeEntityOptions {
   state?: string;
   attributes?: Record<string, unknown>;
@@ -100,6 +109,8 @@ export class FakeHASS {
   private _language: string;
   private _isAdmin: boolean;
   private _handlers = new Map<string, WSCommandHandler>();
+  private _pathHandlers: { pattern: RegExp; handler: PathHandler }[] = [];
+  private _mediaSources: { pattern: RegExp; handler: MediaSourceHandler }[] = [];
   private _commandLog: MessageBase[] = [];
   private _openEventSubscriptions = 0;
 
@@ -130,6 +141,22 @@ export class FakeHASS {
     this._handlers.set(type, handler);
   }
 
+  /**
+   * Register a handler for the paths an authenticated fetch may ask for. The
+   * first pattern registered that matches answers.
+   */
+  public registerPath(pattern: RegExp, handler: PathHandler): void {
+    this._pathHandlers.push({ pattern, handler });
+  }
+
+  /**
+   * Register a handler for the media content IDs an integration can resolve. The
+   * first pattern registered that matches answers.
+   */
+  public registerMediaSource(pattern: RegExp, handler: MediaSourceHandler): void {
+    this._mediaSources.push({ pattern, handler });
+  }
+
   /**
    * Number of event subscriptions not yet released.
    */
@@ -240,12 +267,30 @@ export class FakeHASS {
       ...this._registry.values(),
     ]);
     this.registerCommand('lovelace/resources', () => []);
+    this.registerCommand('media_source/resolve_media', (message) =>
+      this._resolveMedia(message),
+    );
 
     // Not a card command: `ha-nunjucks` fetches the label registry once when a
     // template first renders.
     this.registerCommand('config/label_registry/list', () => []);
   }
 
+  private async _resolveMedia(message: MessageBase): Promise<ResolvedMedia> {
+    const contentID: unknown = message['media_content_id'];
+    if (typeof contentID !== 'string') {
+      throw new Error(
+        `FakeHASS was asked to resolve media without a content ID: ${JSON.stringify(contentID)}`,
+      );
+    }
+
+    const match = this._mediaSources.find(({ pattern }) => pattern.test(contentID));
+    if (!match) {
+      throw new Error(`FakeHASS has no media source for: ${contentID}`);
+    }
+    return await match.handler(contentID);
+  }
+
   private async _callWS<T>(message: MessageBase): Promise<T> {
     this._commandLog.push(message);
     const handler = this._handlers.get(message.type);
@@ -261,6 +306,18 @@ export class FakeHASS {
     return (await handler(message)) as unknown as T;
   }
 
+  private _hassUrl(path?: string): string {
+    return new URL(path ?? '/', window.location.href).href;
+  }
+
+  private async _fetchWithAuth(path: string): Promise<Response> {
+    const match = this._pathHandlers.find(({ pattern }) => pattern.test(path));
+    if (!match) {
+      throw new Error(`FakeHASS received a request for an unregistered path: ${path}`);
+    }
+    return await match.handler(path);
+  }
+
   private _unsupported(name: string): () => never {
     return () => {
       throw new Error(`FakeHASS does not implement ${name}`);
@@ -300,15 +357,15 @@ export class FakeHASS {
       },
 
       callWS: (message) => this._callWS(message),
-      hassUrl: (path?: string) => new URL(path ?? '/', window.location.href).href,
+      hassUrl: (path?: string) => this._hassUrl(path),
       localize: (key: string) => key,
+      fetchWithAuth: (path: string) => this._fetchWithAuth(path),
 
       // Everything the card can call has to either work or fail loudly. A
       // method that quietly returns nothing would let a card start depending on
       // it without any test noticing.
       callService: this._unsupported('callService'),
       callApi: this._unsupported('callApi'),
-      fetchWithAuth: this._unsupported('fetchWithAuth'),
       sendWS: this._unsupported('sendWS'),
     };
   }
diff --git a/tests/browser/fixtures.ts b/tests/browser/fixtures.ts
new file mode 100644
index 00000000..b3ede94c
--- /dev/null
+++ b/tests/browser/fixtures.ts
@@ -0,0 +1,14 @@
+// The media the browser tests use, served by the Vite dev server from where it
+// sits in the tree. Two consumers build URLs to it and a third serves copies of
+// it (`test-media.ts`), so the path and the names are kept in one place.
+const FIXTURES_PATH = '/tests/browser/fixtures';
+
+// A still red image, standing in for anything a camera hands over as a picture:
+// a snapshot, or a live view drawn from stills.
+export const SNAPSHOT_FIXTURE_FILENAME = 'still-red.png';
+
+// Ten seconds of red, standing in for an event's clip. See fixtures/README.md .
+export const CLIP_FIXTURE_FILENAME = 'clip.webm';
+
+export const createFixtureURL = (filename: string): string =>
+  `${FIXTURES_PATH}/${filename}`;
diff --git a/tests/browser/fixtures/README.md b/tests/browser/fixtures/README.md
new file mode 100644
index 00000000..68b4c7f3
--- /dev/null
+++ b/tests/browser/fixtures/README.md
@@ -0,0 +1,36 @@
+# Browser test fixtures
+
+The media the browser tests serve to the card, at the paths and names built by
+`tests/browser/fixtures.ts`. Most requests reach them directly from the Vite dev
+server. A test that needs a camera to misbehave gets copies from
+`tests/browser/test-media.ts` instead.
+
+## `still-red.png`
+
+A 320x180 red image, 16:9. Everything the card draws as a still image: a
+snapshot in the viewer, or a live view built from stills.
+
+## `clip.webm`
+
+Ten seconds of red at 64x48, VP8. Ten seconds so a test can watch it play
+without it ending under the assertion.
+
+WebM rather than the MP4 (what a real camera integration likely serves), because
+nothing available offline encodes H.264: Playwright's bundled `ffmpeg` has
+libvpx only. This does not change what is under test -- every non-HLS video
+takes the same branch.
+
+Rebuild it with ImageMagick and the `ffmpeg` Playwright installs alongside its
+browsers:
+
+```sh
+convert tests/browser/fixtures/still-red.png -resize 64x48! /tmp/frame.jpg
+
+for i in $(seq 100);
+do
+  cat /tmp/frame.jpg;
+done > /tmp/frames.mjpeg
+
+~/.cache/ms-playwright/ffmpeg-*/ffmpeg-linux -f image2pipe -vcodec mjpeg -r 10 \
+  -i /tmp/frames.mjpeg -c:v libvpx -b:v 50k tests/browser/fixtures/clip.webm
+```
diff --git a/tests/browser/fixtures/clip.webm b/tests/browser/fixtures/clip.webm
new file mode 100644
index 00000000..8bac6f99
Binary files /dev/null and b/tests/browser/fixtures/clip.webm differ
diff --git a/tests/browser/scoped-custom-element-registry.ts b/tests/browser/scoped-custom-element-registry.ts
new file mode 100644
index 00000000..d42526d0
--- /dev/null
+++ b/tests/browser/scoped-custom-element-registry.ts
@@ -0,0 +1,11 @@
+// The card renders a few elements that give their shadow root a registry of its
+// own (`ScopedRegistryHost` from `@lit-labs/scoped-registry-mixin`, used by the
+// media filter and the select). That is not something a browser can do
+// natively: it needs this polyfill, which Home Assistant loads for the whole
+// frontend. Without it, rendering one of those elements throws "importNode is
+// not a function" as Lit tries to clone a template into a registry that has no
+// document behind it.
+//
+// It replaces `customElements` and `attachShadow`, so it has to be the first
+// thing the page runs -- hence its own setup file, ahead of every other.
+import '@webcomponents/scoped-custom-element-registry/scoped-custom-element-registry.min';
diff --git a/tests/browser/test-media.ts b/tests/browser/test-media.ts
index 3dd05528..5363685d 100644
--- a/tests/browser/test-media.ts
+++ b/tests/browser/test-media.ts
@@ -2,8 +2,13 @@ import { delay, http, HttpResponse } from 'msw';
 import { setupWorker } from 'msw/browser';
 import { beforeAll } from 'vitest';
 
+import { createFixtureURL, SNAPSHOT_FIXTURE_FILENAME } from './fixtures';
+
 const HTTP_OK = 200;
 
+// Where this worker answers.
+const TEST_MEDIA_PATH = '/test-media';
+
 // Requests answered per token, so `responses` can be read as a sequence. One
 // page runs one test file, so nothing here is shared with another file.
 const requestCounts = new Map<string, number>();
@@ -12,7 +17,32 @@ const requestCounts = new Map<string, number>();
 // the worker can answer cannot be built without it.
 let inUse = false;
 
-export const isTestMediaInUse = (): boolean => inUse;
+/**
+ * See the worker below for what `responses` and `repeat` ask it to do.
+ */
+export const createTestMediaURL = (
+  responses: number[],
+  repeat = false,
+  filename: string = SNAPSHOT_FIXTURE_FILENAME,
+): string => {
+  if (!inUse) {
+    throw new Error(
+      'Media that misbehaves must be served in a file using useTestMedia().',
+    );
+  }
+
+  return (
+    // TEST_MEDIA_PATH is intercepted by MSW to allow off-wire testing --
+    // without the potential for consuming connections which the browser might
+    // need for loading JS itself.
+    `${TEST_MEDIA_PATH}/${filename}?` +
+    new URLSearchParams({
+      token: crypto.randomUUID(),
+      responses: responses.join(','),
+      repeat: String(repeat),
+    }).toString()
+  );
+};
 
 /**
  * Serves a fixture at `/test-media/<file>`, behaving as the query asks:
@@ -21,9 +51,9 @@ export const isTestMediaInUse = (): boolean => inUse;
  *              behaviour does not depend on what ran before it.
  *   responses  The status to answer each request with, in order: `200` serves
  *              the file and anything else is sent as an empty error.
- *              repeat     What to do once the `responses` list is exhausted:
- *              answer every request after it as the last one was, or never
- *              answer again (i.e. camera going quiet).
+ *   repeat     What to do once the `responses` list is exhausted: answer every
+ *              request after it as the last one was, or never answer again
+ *              (i.e. camera going quiet).
  *
  * Answered from within the page rather than by a server, because a request the
  * page is still waiting on holds one of the handful of connections a browser
@@ -37,7 +67,7 @@ export const isTestMediaInUse = (): boolean => inUse;
  * it would not.
  */
 const worker = setupWorker(
-  http.get('/test-media/:file', async ({ request, params }) => {
+  http.get(`${TEST_MEDIA_PATH}/:file`, async ({ request, params }) => {
     const url = new URL(request.url);
     const token = url.searchParams.get('token');
     if (!token) {
@@ -64,7 +94,7 @@ const worker = setupWorker(
 
     // The fixture itself is served by the dev server. A name is sent rather
     // than a path, so nothing outside the fixtures themselves is reachable.
-    const fixture = await fetch(`/tests/browser/fixtures/${String(params.file)}`);
+    const fixture = await fetch(createFixtureURL(String(params.file)));
 
     return fixture.ok
       ? new HttpResponse(await fixture.arrayBuffer(), {
diff --git a/tests/browser/test-utils.ts b/tests/browser/test-utils.ts
index be1ad92a..da6a8ec2 100644
--- a/tests/browser/test-utils.ts
+++ b/tests/browser/test-utils.ts
@@ -1,19 +1,24 @@
 import { userEvent } from 'vitest/browser';
 
-import type { RawAdvancedCameraCardConfig } from '../../src/config/types';
+import type {
+  PartialAdvancedCameraCardConfig,
+  RawAdvancedCameraCardConfig,
+} from '../../src/config/types';
+import type { Entity } from '../../src/ha/registry/entity/types';
 import type { MediaLoadedInfoEventDetail } from '../../src/types';
 import { createLogAction } from '../../src/utils/action';
+import { isTruthy } from '../../src/utils/basic';
 import { FakeHASS, type FakeEntityOptions } from './fake-hass';
-import { isTestMediaInUse } from './test-media';
+import { createFixtureURL, SNAPSHOT_FIXTURE_FILENAME } from './fixtures';
+import type { MountedCard } from './mounted-card';
+import { createTestMediaURL } from './test-media';
 
-export const STILL_CAMERA_ENTITY = 'camera.office';
-
-const STILL_FIXTURE_FILENAME = 'still-red.png';
+export const CAMERA_ENTITY = 'camera.office';
 
 // A same-origin still red image, served by the Vite dev server. The same image
 // is handed on by the worker in test-media.ts, which can be asked to misbehave
 // in useful ways.
-const STILL_FIXTURE_URL = `/tests/browser/fixtures/${STILL_FIXTURE_FILENAME}`;
+const STILL_FIXTURE_URL = createFixtureURL(SNAPSHOT_FIXTURE_FILENAME);
 
 /**
  * A card showing one still image and nothing else: no stream, no transport and
@@ -24,7 +29,7 @@ const STILL_FIXTURE_URL = `/tests/browser/fixtures/${STILL_FIXTURE_FILENAME}`;
  * configuration error instead of the image.
  */
 export const createStillImageCameraConfig = (
-  cameraEntity: string = STILL_CAMERA_ENTITY,
+  cameraEntity: string = CAMERA_ENTITY,
   url: string = STILL_FIXTURE_URL,
 ): RawAdvancedCameraCardConfig => ({
   camera_entity: cameraEntity,
@@ -39,62 +44,53 @@ export const createStillImageCameraConfig = (
 const HTTP_NOT_FOUND = 404;
 const HTTP_OK = 200;
 
-/**
- * A media URL answered with the given statuses in order. Once they run out
- * every request after them is answered as the last one was, or, if the camera
- * is meant to go quiet, never answered at all.
- *
- * Every URL carries its own counter, since one worker serves every test in a
- * file and a shared counter would make a test depend on what ran before it.
- */
-const createMediaURL = (responses: number[], repeat = false): string => {
-  if (!isTestMediaInUse()) {
-    throw new Error(
-      'Media that misbehaves must be served in a file using useTestMedia().',
-    );
-  }
-
-  return (
-    `/test-media/${STILL_FIXTURE_FILENAME}?` +
-    new URLSearchParams({
-      token: crypto.randomUUID(),
-      responses: responses.join(','),
-      repeat: String(repeat),
-    }).toString()
-  );
-};
-
 /**
  * A media URL that fails the given number of times and then works from there
  * on, so a test can make a camera recover rather than only fail.
  */
-export const createTemporarilyFailingMediaURL = (failures: number): string =>
-  createMediaURL([...Array(failures).fill(HTTP_NOT_FOUND), HTTP_OK], true);
+export const createTemporarilyFailingMediaURL = (
+  failures: number,
+  filename?: string,
+): string =>
+  createTestMediaURL([...Array(failures).fill(HTTP_NOT_FOUND), HTTP_OK], true, filename);
 
 /**
  * A media URL that never works, for a camera that is simply broken.
  */
 export const createFailingMediaURL = (): string =>
-  createMediaURL([HTTP_NOT_FOUND], true);
+  createTestMediaURL([HTTP_NOT_FOUND], true);
 
 /**
  * A media URL that is never answered, for a camera that accepts the request and
  * then says nothing. Silence is a different failure from a refusal, and the
  * only one that can run a loading timeout out.
  */
-export const createUnansweredMediaURL = (): string => createMediaURL([]);
+export const createUnansweredMediaURL = (): string => createTestMediaURL([]);
 
 /**
  * A media URL that answers once and is then never answered again, for a camera
  * that delivers a picture and goes quiet behind it.
  */
-export const createStallingMediaURL = (): string => createMediaURL([HTTP_OK]);
+export const createStallingMediaURL = (filename?: string): string =>
+  createTestMediaURL([HTTP_OK], false, filename);
+
+export interface FakeCameraDescription {
+  entityID: string;
+  entity: FakeEntityOptions;
+  registry: Partial<Entity>;
+}
+
+const createGenericCameraDescription = (
+  entityID: string = CAMERA_ENTITY,
+): FakeCameraDescription => ({
+  entityID,
+  entity: { state: 'idle' },
+  registry: {},
+});
 
 export interface CameraHASSOptions {
-  // Camera entities beyond the default one.
-  cameras?: string[];
-
-  // Anything else the card should be able to see, as entity ID to state.
+  // Anything that is not a camera the card should be able to see, such as a
+  // motion sensor. These get a state and no entity registry entry.
   entities?: Record<string, FakeEntityOptions | string>;
 
   // The language Home Assistant is set to for translation tests.
@@ -105,22 +101,48 @@ export interface CameraHASSOptions {
  * A Home Assistant holding the cameras a card is about to be given, which is
  * the minimum any browser test needs before it can mount anything.
  */
-export const createCameraHASS = (options?: CameraHASSOptions): FakeHASS => {
-  const cameras = [STILL_CAMERA_ENTITY, ...(options?.cameras ?? [])];
-
-  return new FakeHASS({
+export const createCameraHASS = (
+  cameras: FakeCameraDescription[],
+  options?: CameraHASSOptions,
+): FakeHASS =>
+  new FakeHASS({
     entities: {
-      ...Object.fromEntries(cameras.map((camera) => [camera, { state: 'idle' }])),
+      ...Object.fromEntries(cameras.map((camera) => [camera.entityID, camera.entity])),
       ...options?.entities,
     },
-    registry: Object.fromEntries(cameras.map((camera) => [camera, {}])),
+    registry: Object.fromEntries(
+      cameras.map((camera) => [camera.entityID, camera.registry]),
+    ),
     ...(options?.language && { language: options.language }),
   });
+
+export interface GenericCameraHASSOptions extends CameraHASSOptions {
+  // Camera entities beyond `CAMERA_ENTITY`, which is always present. Each gets
+  // a state and an entity registry entry, which is what the card reads to
+  // resolve a camera and choose its engine.
+  cameras?: string[];
+}
+
+/**
+ * A Home Assistant whose cameras all belong to no named integration, for a test
+ * that is about the card rather than about where its media comes from.
+ */
+export const createGenericCameraHASS = (
+  options?: GenericCameraHASSOptions,
+): FakeHASS => {
+  const { cameras, ...hassOptions } = options ?? {};
+
+  return createCameraHASS(
+    [CAMERA_ENTITY, ...(cameras ?? [])].map((camera) =>
+      createGenericCameraDescription(camera),
+    ),
+    hassOptions,
+  );
 };
 
 export const createStillImageCardConfig = (
-  overrides?: Partial<RawAdvancedCameraCardConfig>,
-): RawAdvancedCameraCardConfig => ({
+  overrides?: PartialAdvancedCameraCardConfig,
+): PartialAdvancedCameraCardConfig => ({
   type: 'custom:advanced-camera-card',
   cameras: [createStillImageCameraConfig()],
 
@@ -224,6 +246,149 @@ export const isLiveMediaShowing = (root: ParentNode): boolean =>
     (provider) => !!deepQuery(provider, MEDIA_SELECTOR),
   );
 
+/**
+ * Wait until the card has been told an element is on screen.
+ *
+ * Parts of the card only begin work once an element becomes visible, being
+ * notified by an `IntersectionObserver`. A test cannot reach those observers,
+ * but it can make one of its own: a document notifies its observers in the
+ * order they were created, so one created after the card's is strictly called
+ * after them. As such, by the time this function reports the element, the
+ * card's intersection observer callback has already run and whatever it started
+ * is deterministically under way.
+ *
+ * Name the element the card is itself watching, e.g.
+ * `advanced-camera-card-live-provider` for liveness detection. It is waited for
+ * rather than taken as an element, since the card makes its observer when the
+ * element connects: observing beforehand would make this the earlier of the two
+ * and run the ordering above the other way.
+ */
+export const waitUntilObservedVisible = async (
+  card: MountedCard,
+  selector: string,
+): Promise<void> => {
+  const element = await card.waitForSelector(selector);
+
+  await new Promise<void>((resolve) => {
+    const observer = new IntersectionObserver((entries) => {
+      if (entries.some((entry) => entry.isIntersecting)) {
+        observer.disconnect();
+        resolve();
+      }
+    });
+    observer.observe(element);
+  });
+};
+
+/**
+ * Where a media element is being served from.
+ */
+const getMediaURL = (media: Element): string | null => {
+  if (media instanceof HTMLImageElement || media instanceof HTMLMediaElement) {
+    return media.currentSrc || media.getAttribute('src') || null;
+  }
+  return null;
+};
+
+/**
+ * Every media the media viewer has loaded, in the order it rendered them. The
+ * viewer holds a provider per media item and each loads once it has been on
+ * screen, so this is one entry per media a test has visited.
+ */
+export const getMediaViewerMediaURLs = (root: ParentNode): string[] =>
+  deepQueryAll(root, 'advanced-camera-card-viewer-provider')
+    .map((provider) => deepQuery(provider, MEDIA_SELECTOR))
+    .map((media) => (media ? getMediaURL(media) : null))
+    .filter((url) => url !== null);
+
+/**
+ * The thumbnails on screen.
+ */
+export const getThumbnails = (root: ParentNode): HTMLElement[] =>
+  deepQueryAll<HTMLElement>(root, 'advanced-camera-card-thumbnail');
+
+export const getSelectedThumbnail = (root: ParentNode): HTMLElement | null =>
+  deepQuery<HTMLElement>(root, 'advanced-camera-card-thumbnail.slide-selected');
+
+export const clickThumbnail = async (root: ParentNode, index: number): Promise<void> => {
+  const thumbnail = getThumbnails(root)[index];
+  if (!thumbnail) {
+    throw new Error(`There is no thumbnail at index ${index} to click`);
+  }
+  await clickElement(thumbnail);
+};
+
+export const waitForThumbnails = async (
+  card: MountedCard,
+  count: number,
+): Promise<void> => {
+  await card.waitForRender(
+    () => (getThumbnails(card.card).length >= count ? true : null),
+    `${count} thumbnail(s)`,
+  );
+};
+
+/**
+ * Wait until the media viewer has loaded a media whose URL contains the given
+ * text, which is how a test waits for the media it asked for to arrive.
+ */
+export const waitForMediaViewerMedia = async (
+  card: MountedCard,
+  url: string,
+): Promise<void> => {
+  await card.waitForRender(
+    () =>
+      getMediaViewerMediaURLs(card.card).some((shown) => shown.includes(url)) || null,
+    `the media viewer showing ${url}`,
+  );
+};
+
+/**
+ * Move the media viewer to the next or previous media.
+ *
+ * A next/previous control has no size of its own: what is drawn and positioned
+ * is within it, so that is what a real pointer can reach.
+ */
+export const clickNextPreviousMedia = async (
+  root: ParentNode,
+  side: 'left' | 'right',
+): Promise<void> => {
+  const control = deepQuery(
+    root,
+    `advanced-camera-card-next-previous-control[slot="${side}"]`,
+  );
+  const clickable = control ? deepQuery(control, '.controls') : null;
+  if (!clickable) {
+    throw new Error(`The media viewer is showing no ${side} control`);
+  }
+  await clickElement(clickable);
+};
+
+// Everything the status bar is displaying gets this class, whether it is a
+// string, an icon or an image.
+const STATUS_BAR_ITEM_SELECTOR = '.item';
+
+const getStatusBarItems = (root: ParentNode): Element[] => [
+  ...(deepQuery(root, 'advanced-camera-card-status-bar')?.shadowRoot?.querySelectorAll(
+    STATUS_BAR_ITEM_SELECTOR,
+  ) ?? []),
+];
+
+/**
+ * What the status bar is displaying, one entry per item, in the order shown.
+ * Items with no text of their own (an icon, an image) are omitted.
+ */
+export const getStatusBarStrings = (root: ParentNode): string[] =>
+  getStatusBarItems(root)
+    .map((item) => (item.textContent ?? '').trim())
+    .filter(isTruthy);
+
+/**
+ * Get a status bar item by the title it carries.
+ */
+export const getStatusBarItem = (root: ParentNode, title: string): Element | null =>
+  getStatusBarItems(root).find((item) => item.getAttribute('title') === title) ?? null;
+
 // `userEvent.keyboard` is given one string naming every key to press, in which
 // a name of more than one character is wrapped in braces (`{Escape}`) and a
 // single character stands for itself.
diff --git a/tests/camera-manager/manager.browser.test.ts b/tests/camera-manager/manager.browser.test.ts
index 5d4c051b..f20d2253 100644
--- a/tests/camera-manager/manager.browser.test.ts
+++ b/tests/camera-manager/manager.browser.test.ts
@@ -3,7 +3,7 @@ import { describe, expect, it, vi } from 'vitest';
 import type { RawAdvancedCameraCardConfig } from '../../src/config/types';
 import { MountedCardFactory, type MountedCard } from '../browser/mounted-card';
 import {
-  createCameraHASS,
+  createGenericCameraHASS,
   createStillImageCameraConfig,
   createStillImageCardConfig,
   getBlockNotificationText,
@@ -43,7 +43,7 @@ describe('CameraManager', () => {
         ],
         view: { issues: { retry_seconds: 0 } },
       }),
-      createCameraHASS({
+      createGenericCameraHASS({
         cameras: [TRIGGERING_CAMERA_ENTITY, OTHER_TRIGGERING_CAMERA_ENTITY],
       }),
     );
@@ -64,7 +64,7 @@ describe('CameraManager', () => {
       createStillImageCardConfig({
         cameras: [createSubscribingCameraConfig(TRIGGERING_CAMERA_ENTITY)],
       }),
-      createCameraHASS({ cameras: [TRIGGERING_CAMERA_ENTITY] }),
+      createGenericCameraHASS({ cameras: [TRIGGERING_CAMERA_ENTITY] }),
     );
 
     await vi.waitFor(() => expect(card.getOpenEventSubscriptionCount()).toBe(1));
diff --git a/tests/card-controller/automations-manager.browser.test.ts b/tests/card-controller/automations-manager.browser.test.ts
index defffaf2..070da35f 100644
--- a/tests/card-controller/automations-manager.browser.test.ts
+++ b/tests/card-controller/automations-manager.browser.test.ts
@@ -1,12 +1,15 @@
 import { describe, expect, it } from 'vitest';
 
 import { MountedCardFactory, type MountedCard } from '../browser/mounted-card';
-import { createCameraHASS, createStillImageCardConfig } from '../browser/test-utils';
+import {
+  createGenericCameraHASS,
+  createStillImageCardConfig,
+} from '../browser/test-utils';
 
 const TRIGGER_ENTITY = 'input_boolean.zoom';
 
 const mount = async (): Promise<MountedCard> => {
-  const hass = createCameraHASS({ entities: { [TRIGGER_ENTITY]: 'off' } });
+  const hass = createGenericCameraHASS({ entities: { [TRIGGER_ENTITY]: 'off' } });
   return await MountedCardFactory.createFromSource(
     createStillImageCardConfig({
       automations: [
diff --git a/tests/card-controller/card-element-manager.browser.test.ts b/tests/card-controller/card-element-manager.browser.test.ts
index 2babb9d0..6babbbf5 100644
--- a/tests/card-controller/card-element-manager.browser.test.ts
+++ b/tests/card-controller/card-element-manager.browser.test.ts
@@ -4,7 +4,7 @@ import { createLogAction } from '../../src/utils/action';
 import { MountedCardFactory, type MountedCard } from '../browser/mounted-card';
 import {
   CARD_INITIALIZED_MESSAGE,
-  createCameraHASS,
+  createGenericCameraHASS,
   createInitializedAutomation,
   createStillImageCardConfig,
   deepQueryAll,
@@ -28,7 +28,7 @@ const mountCard = async (): Promise<MountedCard> => {
         },
       ],
     }),
-    createCameraHASS(),
+    createGenericCameraHASS(),
   );
 
   await card.events.waitForFirst('advanced-camera-card:media:loaded');
diff --git a/tests/card-controller/initialization/session-manager.browser.test.ts b/tests/card-controller/initialization/session-manager.browser.test.ts
index 78511053..39faddbe 100644
--- a/tests/card-controller/initialization/session-manager.browser.test.ts
+++ b/tests/card-controller/initialization/session-manager.browser.test.ts
@@ -4,7 +4,7 @@ import type { RawAdvancedCameraCardConfig } from '../../../src/config/types';
 import { MountedCardFactory, type MountedCard } from '../../browser/mounted-card';
 import {
   CARD_INITIALIZED_MESSAGE,
-  createCameraHASS,
+  createGenericCameraHASS,
   createInitializedAutomation,
   createStillImageCameraConfig,
   createStillImageCardConfig,
@@ -26,7 +26,7 @@ const mount = async (
 ): Promise<MountedCard> =>
   await MountedCardFactory.createFromSource(
     createConfig(overrides),
-    createCameraHASS({ cameras: [OTHER_CAMERA_ENTITY] }),
+    createGenericCameraHASS({ cameras: [OTHER_CAMERA_ENTITY] }),
   );
 
 // The cameras the card has actually loaded media for, in order. Media that
diff --git a/tests/card-controller/issues/issues/initialization.browser.test.ts b/tests/card-controller/issues/issues/initialization.browser.test.ts
index ea9a8586..0674b7ab 100644
--- a/tests/card-controller/issues/issues/initialization.browser.test.ts
+++ b/tests/card-controller/issues/issues/initialization.browser.test.ts
@@ -3,7 +3,7 @@ import { describe, expect, it, vi } from 'vitest';
 import { MountedCardFactory, type MountedCard } from '../../../browser/mounted-card';
 import {
   CARD_INITIALIZED_MESSAGE,
-  createCameraHASS,
+  createGenericCameraHASS,
   createInitializedAutomation,
   createStillImageCameraConfig,
   createStillImageCardConfig,
@@ -40,7 +40,7 @@ const mountBrokenCard = async (): Promise<MountedCard> =>
       view: { issues: { retry_seconds: 0 } },
       automations: [createInitializedAutomation()],
     }),
-    createCameraHASS(),
+    createGenericCameraHASS(),
   );
 
 describe('InitializationIssue', () => {
diff --git a/tests/card-controller/issues/issues/media-unavailable.browser.test.ts b/tests/card-controller/issues/issues/media-unavailable.browser.test.ts
index f5a95aa0..03c2a9d3 100644
--- a/tests/card-controller/issues/issues/media-unavailable.browser.test.ts
+++ b/tests/card-controller/issues/issues/media-unavailable.browser.test.ts
@@ -12,8 +12,9 @@ import {
 } from '../../../browser/mounted-card';
 import { useTestMedia } from '../../../browser/test-media';
 import {
-  createCameraHASS,
+  CAMERA_ENTITY,
   createFailingMediaURL,
+  createGenericCameraHASS,
   createStallingMediaURL,
   createStillImageCameraConfig,
   createStillImageCardConfig,
@@ -22,9 +23,11 @@ import {
   deepQuery,
   deepQueryAll,
   getBlockNotificationText,
+  getStatusBarItem,
   isLiveMediaShowing,
-  STILL_CAMERA_ENTITY,
+  waitUntilObservedVisible,
   type CameraHASSOptions,
+  type GenericCameraHASSOptions,
 } from '../../../browser/test-utils';
 
 const SECOND_CAMERA_ENTITY = 'camera.hallway';
@@ -38,12 +41,15 @@ const MEDIA_ISSUE_TITLE = 'Media unavailable';
 const IRIS_CONTROL = 'Iris / Default View / Unhide menu';
 
 const findIssue = (card: MountedCard): Element | null =>
-  deepQuery(card.card, 'advanced-camera-card-status-bar')?.shadowRoot?.querySelector(
-    `[title="${MEDIA_ISSUE_TITLE}"]`,
-  ) ?? null;
+  getStatusBarItem(card.card, MEDIA_ISSUE_TITLE);
 
 const isIssueReported = (card: MountedCard): boolean => !!findIssue(card);
 
+const getIssueReason = (detail: unknown): string | null =>
+  detail && typeof detail === 'object' && 'reason' in detail
+    ? String(detail.reason)
+    : null;
+
 // Resolve once `image` holds a picture that actually loaded. A failed load also
 // marks the element complete, so the decoded size is what separates the two.
 const waitForImageLoaded = async (image: HTMLImageElement): Promise<void> =>
@@ -69,7 +75,7 @@ const waitForIssueCleared = async (card: MountedCard): Promise<void> => {
   );
 };
 
-interface MountCardOptions extends MountOptions, CameraHASSOptions {}
+interface MountCardOptions extends MountOptions, GenericCameraHASSOptions {}
 
 /**
  * Every test here needs the status bar rendered, since that is where an issue
@@ -83,7 +89,7 @@ const mountCard = async (
 
   return await MountedCardFactory.createFromSource(
     createStillImageCardConfig({ status_bar: { style: 'outside' }, ...config }),
-    createCameraHASS({ cameras, entities, language }),
+    createGenericCameraHASS({ cameras, entities, language }),
     mountOptions,
   );
 };
@@ -159,7 +165,7 @@ describe('MediaUnavailableIssue', () => {
   it('should wait out the grace period before reporting an unavailable camera', async () => {
     const card = await mountCardSingleCamera();
 
-    card.setEntityState(STILL_CAMERA_ENTITY, 'unavailable');
+    card.setEntityState(CAMERA_ENTITY, 'unavailable');
 
     // Just short of the grace period: reporting here would alarm on a camera
     // that is about to come back.
@@ -173,10 +179,10 @@ describe('MediaUnavailableIssue', () => {
   it('should never report a camera that recovers within the grace period', async () => {
     const card = await mountCardSingleCamera();
 
-    card.setEntityState(STILL_CAMERA_ENTITY, 'unavailable');
+    card.setEntityState(CAMERA_ENTITY, 'unavailable');
     await card.advanceSeconds(LIVENESS_ENTITY_UNAVAILABLE_GRACE_SECONDS - 1);
 
-    card.setEntityState(STILL_CAMERA_ENTITY, 'idle');
+    card.setEntityState(CAMERA_ENTITY, 'idle');
 
     // Well past the point the issue report would have appeared had the blip not
     // ended. Nothing should ever have been shown.
@@ -357,9 +363,7 @@ describe('MediaUnavailableIssue', () => {
 
   it('should report a camera whose media fails to load', async () => {
     const card = await mountCard({
-      cameras: [
-        createStillImageCameraConfig(STILL_CAMERA_ENTITY, createFailingMediaURL()),
-      ],
+      cameras: [createStillImageCameraConfig(CAMERA_ENTITY, createFailingMediaURL())],
     });
 
     // The entity is present and healthy, so the failed fetch is the only thing
@@ -369,16 +373,13 @@ describe('MediaUnavailableIssue', () => {
     await waitForIssueReported(card);
 
     expect(getBlockNotificationText(card.card)).toContain('Could not load image');
-    expect(getBlockNotificationText(card.card)).toContain(STILL_CAMERA_ENTITY);
+    expect(getBlockNotificationText(card.card)).toContain(CAMERA_ENTITY);
   });
 
   it('should clear the issue report once the camera delivers media again', async () => {
     const card = await mountCard({
       cameras: [
-        createStillImageCameraConfig(
-          STILL_CAMERA_ENTITY,
-          createTemporarilyFailingMediaURL(1),
-        ),
+        createStillImageCameraConfig(CAMERA_ENTITY, createTemporarilyFailingMediaURL(1)),
       ],
     });
 
@@ -400,9 +401,7 @@ describe('MediaUnavailableIssue', () => {
 
   it('should wait out the loading timeout before reporting a slow camera', async () => {
     const card = await mountCard({
-      cameras: [
-        createStillImageCameraConfig(STILL_CAMERA_ENTITY, createUnansweredMediaURL()),
-      ],
+      cameras: [createStillImageCameraConfig(CAMERA_ENTITY, createUnansweredMediaURL())],
     });
 
     // Nothing is waited on until there is a player asking for media, so let one
@@ -424,7 +423,7 @@ describe('MediaUnavailableIssue', () => {
   it('should keep retrying a camera that is still broken', async () => {
     // Must use the real clock: fake time moves the card's timers instantly, so
     // a request would never get a chance to answer between one retry and the
-    // next.
+    // next, and the card would call the attempt slow instead of failed.
     vi.useRealTimers();
 
     const card = await mountCard({
@@ -437,10 +436,7 @@ describe('MediaUnavailableIssue', () => {
       // the test runtime.
       view: { issues: { retry_seconds: 0.1 } },
       cameras: [
-        createStillImageCameraConfig(
-          STILL_CAMERA_ENTITY,
-          createTemporarilyFailingMediaURL(2),
-        ),
+        createStillImageCameraConfig(CAMERA_ENTITY, createTemporarilyFailingMediaURL(2)),
       ],
     });
 
@@ -449,15 +445,20 @@ describe('MediaUnavailableIssue', () => {
     await card.events.waitForCount('advanced-camera-card:issue:trigger', 2);
     await waitForIssueReported(card);
 
-    // The third attempt is served.
+    // The third attempt is served. Clearing the issue is a render that follows
+    // the media arriving rather than accompanying it, so it is waited for.
     await card.events.waitForFirst('advanced-camera-card:media:loaded');
+    await waitForIssueCleared(card);
 
-    expect(isIssueReported(card)).toBe(false);
     expect(isLiveMediaShowing(card.card)).toBe(true);
 
     // Exactly the two attempts that failed, so the retry ran once rather than
     // spinning until something happened to work.
-    expect(card.events.getEntries('advanced-camera-card:issue:trigger')).toHaveLength(2);
+    expect(
+      card.events
+        .getEntries('advanced-camera-card:issue:trigger')
+        .map((entry) => getIssueReason(entry.detail)),
+    ).toEqual(['not_loading', 'not_loading']);
   });
 
   it('should re-attempt when the retry control is used', async () => {
@@ -465,10 +466,7 @@ describe('MediaUnavailableIssue', () => {
       // Automatic retries switched off.
       view: { issues: { retry_seconds: 0 } },
       cameras: [
-        createStillImageCameraConfig(
-          STILL_CAMERA_ENTITY,
-          createTemporarilyFailingMediaURL(1),
-        ),
+        createStillImageCameraConfig(CAMERA_ENTITY, createTemporarilyFailingMediaURL(1)),
       ],
     });
 
@@ -489,9 +487,7 @@ describe('MediaUnavailableIssue', () => {
   it('should not report while a non-media view is showing', async () => {
     const card = await mountCard({
       menu: { style: 'outside' },
-      cameras: [
-        createStillImageCameraConfig(STILL_CAMERA_ENTITY, createFailingMediaURL()),
-      ],
+      cameras: [createStillImageCameraConfig(CAMERA_ENTITY, createFailingMediaURL())],
     });
 
     await card.events.waitForFirst('advanced-camera-card:issue:trigger');
@@ -517,15 +513,10 @@ describe('MediaUnavailableIssue', () => {
   it('should report media that stalls after it has loaded', async () => {
     const refreshSeconds = 2;
 
-    // Double the window the watchdog itself is using. The second half is slack:
-    // the watchdog begins watching in real time, so the loop below can step the
-    // clock a few times before that window has even begun.
-    const reportSecondsAllowed = (refreshSeconds + FRAME_STALL_SECONDS) * 2;
-
     const card = await mountCard({
       cameras: [
         {
-          camera_entity: STILL_CAMERA_ENTITY,
+          camera_entity: CAMERA_ENTITY,
           live_provider: 'image',
           image: {
             mode: 'url',
@@ -543,22 +534,16 @@ describe('MediaUnavailableIssue', () => {
     await card.events.waitForFirst('advanced-camera-card:media:loaded');
     expect(card.events.getEntries('advanced-camera-card:issue:trigger')).toHaveLength(0);
 
-    // Advance a second at a time rather than in one jump. The watchdog only
-    // starts counting once the player has begun watching for images, which
-    // happens in real time. A jump would spend the whole allowance before that
-    // point, and the counting would then start from the end of it: no stall
-    // would ever be reported and this test would fail. Stepping lets the player
-    // begin watching, after which the clock moves through a window that is
-    // actually being counted.
-    for (
-      let second = 0;
-      second < reportSecondsAllowed && !isIssueReported(card);
-      second++
-    ) {
-      await card.advanceSeconds(1);
-    }
+    // The card only starts its stall timer once the player has both loaded and
+    // come on screen. The load is waited for above, so waiting for the provider
+    // to be seen means the timer is running and the clock can be jumped through
+    // it.
+    await waitUntilObservedVisible(card, 'advanced-camera-card-live-provider');
 
-    expect(isIssueReported(card)).toBe(true);
+    // A refreshing picture is allowed a whole refresh interval on top of the
+    // standard window, so that one slow fetch is not called a stall.
+    await card.advanceSeconds(refreshSeconds + FRAME_STALL_SECONDS);
+    await waitForIssueReported(card);
 
     // Stalled rather than failed: the picture on screen is real but frozen, and
     // saying so is the difference between "this is old" and "this is broken".
@@ -575,15 +560,15 @@ describe('MediaUnavailableIssue', () => {
         status_bar: { style: 'outside' },
         cameras: [
           {
-            camera_entity: STILL_CAMERA_ENTITY,
+            camera_entity: CAMERA_ENTITY,
             live_provider: 'image',
             image: { mode: 'camera' },
           },
         ],
       }),
-      createCameraHASS({
+      createGenericCameraHASS({
         entities: {
-          [STILL_CAMERA_ENTITY]: {
+          [CAMERA_ENTITY]: {
             state: 'idle',
             attributes: { entity_picture: createFailingMediaURL() },
           },
@@ -608,7 +593,7 @@ describe('MediaUnavailableIssue', () => {
       // A provider given nothing to play. It reports that it failed without
       // saying why, which is what a playback error is: every other reason
       // here is one the card was able to name.
-      cameras: [{ camera_entity: STILL_CAMERA_ENTITY, live_provider: 'go2rtc' }],
+      cameras: [{ camera_entity: CAMERA_ENTITY, live_provider: 'go2rtc' }],
     });
 
     await card.events.waitForFirst('advanced-camera-card:issue:trigger');
diff --git a/tests/card-controller/keyboard-state-manager.browser.test.ts b/tests/card-controller/keyboard-state-manager.browser.test.ts
index 0f00ac42..51036e0f 100644
--- a/tests/card-controller/keyboard-state-manager.browser.test.ts
+++ b/tests/card-controller/keyboard-state-manager.browser.test.ts
@@ -10,7 +10,7 @@ import {
 import {
   CARD_INITIALIZED_MESSAGE,
   clickElement,
-  createCameraHASS,
+  createGenericCameraHASS,
   createInitializedAutomation,
   createStillImageCardConfig,
   dispatchPointerDown,
@@ -106,7 +106,7 @@ const mountCard = async (options?: MountCardOptions): Promise<MountedCard> => {
         },
       ],
     }),
-    createCameraHASS({ entities: { [ZOOM_ENTITY]: 'off' } }),
+    createGenericCameraHASS({ entities: { [ZOOM_ENTITY]: 'off' } }),
     mountOptions,
   );
 
diff --git a/tests/card-controller/style-manager.browser.test.ts b/tests/card-controller/style-manager.browser.test.ts
index d16b6ddc..785e9f84 100644
--- a/tests/card-controller/style-manager.browser.test.ts
+++ b/tests/card-controller/style-manager.browser.test.ts
@@ -1,17 +1,21 @@
 import { describe, expect, it } from 'vitest';
 
+import type { ThemeName } from '../../src/config/schema/view';
 import { MountedCardFactory } from '../browser/mounted-card';
-import { createCameraHASS, createStillImageCardConfig } from '../browser/test-utils';
+import {
+  createGenericCameraHASS,
+  createStillImageCardConfig,
+} from '../browser/test-utils';
 
 // A colour the dark theme sets and the card carries no other way. Reading it
 // back proves the stylesheet reached the card rather than merely compiling.
 // See src/scss/themes/dark.scss .
 const DARK_PRIMARY_BACKGROUND = '#111111';
 
-const mountThemed = async (themes: string[]) =>
+const mountThemed = async (themes: ThemeName[]) =>
   await MountedCardFactory.createFromSource(
     createStillImageCardConfig({ view: { theme: { themes } } }),
-    createCameraHASS(),
+    createGenericCameraHASS(),
   );
 
 describe('themes', () => {
diff --git a/tests/components/gallery/gallery.browser.test.ts b/tests/components/gallery/gallery.browser.test.ts
new file mode 100644
index 00000000..becc806c
--- /dev/null
+++ b/tests/components/gallery/gallery.browser.test.ts
@@ -0,0 +1,128 @@
+import { describe, expect, it } from 'vitest';
+
+import type { FrigateEvent } from '../../../src/camera-manager/frigate/types';
+import type { PartialAdvancedCameraCardConfig } from '../../../src/config/types';
+import {
+  createTestFrigateEvent,
+  EVENT_TIME_NEWER,
+  EVENT_TIME_OLDER,
+  mountCardWithFrigate,
+} from '../../browser/fake-frigate';
+import type { MountedCard } from '../../browser/mounted-card';
+import {
+  clickThumbnail,
+  deepQuery,
+  getBlockNotificationText,
+  getMediaViewerMediaURLs,
+  getThumbnails,
+  waitForThumbnails,
+} from '../../browser/test-utils';
+
+const NO_MEDIA_TEXT = 'No media to display';
+
+const mountCard = async (
+  events: FrigateEvent[],
+  config?: PartialAdvancedCameraCardConfig,
+): Promise<MountedCard> =>
+  (await mountCardWithFrigate(events, { view: { default: 'clips' }, ...config })).card;
+
+describe('AdvancedCameraCardGallery', () => {
+  it('should show a thumbnail for every event the camera detected', async () => {
+    const card = await mountCard([
+      createTestFrigateEvent('older', EVENT_TIME_OLDER),
+      createTestFrigateEvent('newer', EVENT_TIME_NEWER),
+    ]);
+
+    await waitForThumbnails(card, 2);
+
+    expect(getThumbnails(card.card)).toHaveLength(2);
+  });
+
+  it('should show the picture Frigate has of each event', async () => {
+    const card = await mountCard([createTestFrigateEvent('newer', EVENT_TIME_NEWER)]);
+
+    await waitForThumbnails(card, 1);
+    const thumbnail = getThumbnails(card.card)[0];
+
+    // A thumbnail that never arrives is drawn as an icon and nothing else says
+    // so, so counting thumbnails says nothing about whether there is a picture
+    // in them. The card fetches one with the user's credentials and embeds what
+    // comes back, which is why the result is a data URL rather than the path
+    // asked for.
+    const image = await card.waitForRender(
+      () => deepQuery<HTMLImageElement>(thumbnail, 'img'),
+      'the thumbnail picture',
+    );
+
+    expect(image.src).toMatch(/^data:image\/png/);
+  });
+
+  it('should say there is nothing to view when the camera has no events', async () => {
+    const card = await mountCard([]);
+
+    // The element renders before its text, so waiting for the element alone can
+    // read it while it is still empty.
+    await card.waitForRender(
+      () => getBlockNotificationText(card.card).includes(NO_MEDIA_TEXT) || null,
+      `the "${NO_MEDIA_TEXT}" notification`,
+    );
+
+    expect(getThumbnails(card.card)).toHaveLength(0);
+  });
+
+  it('should open the clips gallery from the live view', async () => {
+    const card = await mountCard([createTestFrigateEvent('newer', EVENT_TIME_NEWER)], {
+      view: { default: 'live' },
+
+      // The clips button is hidden by default.
+      menu: { style: 'outside', buttons: { clips: { enabled: true } } },
+    });
+
+    await card.events.waitForFirst('advanced-camera-card:media:loaded');
+
+    await card.clickControl('Clips gallery');
+    await card.waitForSelector('advanced-camera-card-gallery');
+
+    await waitForThumbnails(card, 1);
+    expect(getThumbnails(card.card)).toHaveLength(1);
+  });
+
+  it('should open the viewer on the media that was clicked', async () => {
+    const card = await mountCard([
+      createTestFrigateEvent('older', EVENT_TIME_OLDER),
+      createTestFrigateEvent('newer', EVENT_TIME_NEWER),
+    ]);
+
+    await waitForThumbnails(card, 2);
+
+    // The newest event is shown first, so index 1 is the older of the two.
+    await clickThumbnail(card.card, 1);
+    await card.events.waitForFirst('advanced-camera-card:media:loaded');
+
+    await card.waitForSelector('advanced-camera-card-viewer-carousel');
+
+    expect(getMediaViewerMediaURLs(card.card)).toEqual([
+      expect.stringContaining('clip.webm?event=older'),
+    ]);
+  });
+
+  it('should show the media filter', async () => {
+    const card = await mountCard([createTestFrigateEvent('newer', EVENT_TIME_NEWER)]);
+
+    await card.waitForSelector('advanced-camera-card-media-filter');
+
+    expect(deepQuery(card.card, 'advanced-camera-card-media-filter')).not.toBeNull();
+  });
+
+  it('should not show the media filter when its mode is none', async () => {
+    const card = await mountCard([createTestFrigateEvent('newer', EVENT_TIME_NEWER)], {
+      media_gallery: { controls: { filter: { mode: 'none' } } },
+    });
+
+    await waitForThumbnails(card, 1);
+
+    // The gallery still renders, so a missing filter is not a missing gallery.
+    expect(deepQuery(card.card, 'advanced-camera-card-gallery')).not.toBeNull();
+    expect(deepQuery(card.card, 'advanced-camera-card-media-filter')).toBeNull();
+  });
+});
diff --git a/tests/components/image-updating-player.browser.test.ts b/tests/components/image-updating-player.browser.test.ts
index fd5d834c..9a79d452 100644
--- a/tests/components/image-updating-player.browser.test.ts
+++ b/tests/components/image-updating-player.browser.test.ts
@@ -3,10 +3,10 @@ import { describe, expect, it } from 'vitest';
 import type { MediaLoadedInfoEventDetail } from '../../src/types';
 import { MountedCardFactory, type MountedCard } from '../browser/mounted-card';
 import {
-  createCameraHASS,
+  CAMERA_ENTITY,
+  createGenericCameraHASS,
   createStillImageCardConfig,
   isMediaLoadedInfoEventDetail,
-  STILL_CAMERA_ENTITY,
 } from '../browser/test-utils';
 
 const UNRELATED_ENTITY = 'input_boolean.unrelated';
@@ -22,7 +22,7 @@ interface RenderedElement extends Element {
 }
 
 const mount = async (): Promise<MountedCard> => {
-  const hass = createCameraHASS({ entities: { [UNRELATED_ENTITY]: 'off' } });
+  const hass = createGenericCameraHASS({ entities: { [UNRELATED_ENTITY]: 'off' } });
   return await MountedCardFactory.createFromSource(createStillImageCardConfig(), hass);
 };
 
@@ -54,7 +54,7 @@ describe('AdvancedCameraCardImageUpdatingPlayer', () => {
 
     const loads = getMediaLoadedInfos(card);
     expect(loads).toHaveLength(1);
-    expect(loads[0].info.targetID).toBe(STILL_CAMERA_ENTITY);
+    expect(loads[0].info.targetID).toBe(CAMERA_ENTITY);
   });
 
   it('should announce the size of the media itself', async () => {
diff --git a/tests/components/viewer/carousel.browser.test.ts b/tests/components/viewer/carousel.browser.test.ts
new file mode 100644
index 00000000..f18f1029
--- /dev/null
+++ b/tests/components/viewer/carousel.browser.test.ts
@@ -0,0 +1,197 @@
+import { assert, describe, expect, it, onTestFinished, vi } from 'vitest';
+
+import { MEDIA_LOADING_TIMEOUT_SECONDS } from '../../../src/components-lib/media-load-watchdog-controller';
+import type { PartialAdvancedCameraCardConfig } from '../../../src/config/types';
+import {
+  createTestFrigateEvent,
+  EVENT_TIME_NEWER,
+  EVENT_TIME_OLDER,
+  mountCardWithFrigate,
+} from '../../browser/fake-frigate';
+import type { MountedCard } from '../../browser/mounted-card';
+import { useTestMedia } from '../../browser/test-media';
+import {
+  clickElement,
+  clickNextPreviousMedia,
+  clickThumbnail,
+  createFailingMediaURL,
+  deepQuery,
+  getMediaViewerMediaURLs,
+  getSelectedThumbnail,
+  getStatusBarItem,
+  getStatusBarStrings,
+  getThumbnails,
+  waitForMediaViewerMedia,
+  waitForThumbnails,
+} from '../../browser/test-utils';
+
+const EVENTS = [
+  createTestFrigateEvent('older', EVENT_TIME_OLDER),
+  createTestFrigateEvent('newer', EVENT_TIME_NEWER),
+];
+
+// What the status bar calls a media failure, which is where the viewer shows
+// the issue: the media it cannot show is still on screen behind the carousel.
+const MEDIA_ISSUE_TITLE = 'Media unavailable';
+
+// The thumbnail carousel sits in a drawer by default, which is harder to click.
+const CONFIG_THUMBNAILS_BELOW: PartialAdvancedCameraCardConfig = {
+  media_viewer: { controls: { thumbnails: { mode: 'below' } } },
+};
+
+interface ViewerOptions {
+  config?: PartialAdvancedCameraCardConfig;
+
+  // Which gallery thumbnail to open the viewer on. The newest event is first.
+  thumbnail?: number;
+}
+
+const mountViewer = async (
+  events = EVENTS,
+  options?: ViewerOptions,
+): Promise<MountedCard> => {
+  const { card } = await mountCardWithFrigate(events, {
+    view: { default: 'clips' },
+    ...options?.config,
+  });
+
+  await waitForThumbnails(card, events.length);
+  await clickThumbnail(card.card, options?.thumbnail ?? 0);
+  await card.events.waitForFirst('advanced-camera-card:media:loaded');
+
+  return card;
+};
+
+// One test here has a clip that never loads, which is served from within the
+// page rather than by the dev server.
+useTestMedia();
+
+describe('AdvancedCameraCardViewerCarousel', () => {
+  it('should play the clip that was opened', async () => {
+    const card = await mountViewer();
+
+    expect(getMediaViewerMediaURLs(card.card)).toEqual([
+      expect.stringContaining('clip.webm?event=newer'),
+    ]);
+    expect(deepQuery(card.card, 'advanced-camera-card-video-player')).not.toBeNull();
+  });
+
+  it('should show a snapshot as a still image', async () => {
+    const card = await mountViewer(EVENTS, {
+      config: { view: { default: 'snapshots' } },
+    });
+
+    expect(getMediaViewerMediaURLs(card.card)).toEqual([
+      expect.stringContaining('still-red.png?event=newer'),
+    ]);
+    expect(deepQuery(card.card, 'advanced-camera-card-image-player')).not.toBeNull();
+    expect(deepQuery(card.card, 'advanced-camera-card-video-player')).toBeNull();
+  });
+
+  it('should show the next media when the next control is used', async () => {
+    // Opened on the older event, so there is a newer one to move on to.
+    const card = await mountViewer(EVENTS, { thumbnail: 1 });
+
+    await clickNextPreviousMedia(card.card, 'right');
+
+    await waitForMediaViewerMedia(card, 'clip.webm?event=newer');
+    expect(getSelectedThumbnail(card.card)).toBe(getThumbnails(card.card)[1]);
+  });
+
+  it('should show the media selected in the thumbnail carousel', async () => {
+    const card = await mountViewer(EVENTS, { config: CONFIG_THUMBNAILS_BELOW });
+
+    // The viewer runs oldest first (gallery is the opposite). This is the oldest.
+    await clickThumbnail(card.card, 0);
+
+    await waitForMediaViewerMedia(card, 'clip.webm?event=older');
+    expect(getSelectedThumbnail(card.card)).toBe(getThumbnails(card.card)[0]);
+  });
+
+  it('should name the media being viewed in the status bar', async () => {
+    const card = await mountViewer(
+      [
+        createTestFrigateEvent('older', EVENT_TIME_OLDER, { label: 'car' }),
+        createTestFrigateEvent('newer', EVENT_TIME_NEWER, { label: 'person' }),
+      ],
+      { config: { status_bar: { style: 'outside' }, ...CONFIG_THUMBNAILS_BELOW } },
+    );
+
+    expect(getStatusBarStrings(card.card).join(' ')).toContain('Person');
+
+    await clickThumbnail(card.card, 0);
+    await waitForMediaViewerMedia(card, 'clip.webm?event=older');
+
+    expect(getStatusBarStrings(card.card).join(' ')).toContain('Car');
+  });
+
+  it('should play the clip when a snapshot is clicked', async () => {
+    const card = await mountViewer(EVENTS, {
+      config: { view: { default: 'snapshots' } },
+    });
+
+    const snapshot = deepQuery(card.card, 'advanced-camera-card-image-player');
+    assert(snapshot);
+
+    await clickElement(snapshot);
+
+    await waitForMediaViewerMedia(card, 'clip.webm?event=newer');
+  });
+
+  it('should pause the media that is moved away from', async () => {
+    // Opened on the older event, so there is a newer one to move on to.
+    const card = await mountViewer(EVENTS, { thumbnail: 1 });
+
+    // `auto_play` covers the selected media, so the clip starts on its own.
+    await card.events.waitForFirst('advanced-camera-card:media:play');
+
+    await clickNextPreviousMedia(card.card, 'right');
+
+    // Leaving a clip playing behind the one on screen would have two videos
+    // running at once, and the user hearing the one they cannot see.
+    await card.events.waitForFirst('advanced-camera-card:media:pause');
+  });
+
+  it('should report media that cannot be loaded', async () => {
+    vi.useFakeTimers();
+    onTestFinished(() => {
+      vi.useRealTimers();
+    });
+
+    const { card, frigate } = await mountCardWithFrigate(EVENTS, {
+      view: { default: 'clips' },
+      status_bar: { style: 'outside' },
+    });
+    frigate.setMediaURL('newer', 'clips', createFailingMediaURL());
+
+    await waitForThumbnails(card, EVENTS.length);
+    await clickThumbnail(card.card, 0);
+
+    // The card starts its load timer when the player is rendered, so waiting for
+    // the player means the timer is running and the clock can be jumped.
+    await card.waitForSelector('video');
+
+    // A clip that refuses to load says nothing of its own, so the card has only
+    // silence to go on and triggers an issue once it has waited long enough.
+    await card.advanceSeconds(MEDIA_LOADING_TIMEOUT_SECONDS);
+
+    await card.waitForRender(
+      () => getStatusBarItem(card.card, MEDIA_ISSUE_TITLE),
+      `the ${MEDIA_ISSUE_TITLE} issue being reported`,
+    );
+  });
+
+  it('should return to the gallery from the viewer', async () => {
+    const card = await mountViewer(EVENTS, {
+      config: {
+        // The clips button is hidden by default.
+        menu: { style: 'outside', buttons: { clips: { enabled: true } } },
+      },
+    });
+
+    await card.clickControl('Clips gallery');
+
+    await card.waitForSelector('advanced-camera-card-gallery');
+    expect(deepQuery(card.card, 'advanced-camera-card-viewer-carousel')).toBeNull();
+  });
+});
diff --git a/tests/dist/dist.browser.test.ts b/tests/dist/dist.browser.test.ts
index a3274c44..b4667803 100644
--- a/tests/dist/dist.browser.test.ts
+++ b/tests/dist/dist.browser.test.ts
@@ -11,7 +11,7 @@ import {
   type MountOptions,
 } from '../browser/mounted-card';
 import {
-  createCameraHASS,
+  createGenericCameraHASS,
   createStillImageCardConfig,
   isLiveMediaShowing,
 } from '../browser/test-utils';
@@ -99,7 +99,7 @@ class BuildMountedCardFactory extends MountedCardFactory {
  * rather than from `src/`.
  */
 const mountBuiltCard = async (
-  hass: FakeHASS = createCameraHASS(),
+  hass: FakeHASS = createGenericCameraHASS(),
 ): Promise<MountedCard> =>
   await BuildMountedCardFactory.createFromBuild(
     `/${PUBLIC_ENTRY}?hacstag=${HACSTAG}`,
@@ -243,7 +243,7 @@ describe('the built card', () => {
     // Clear resource timings to only measure the impact of mounting the card.
     performance.clearResourceTimings();
 
-    const mounted = await mountBuiltCard(createCameraHASS({ language: 'de' }));
+    const mounted = await mountBuiltCard(createGenericCameraHASS({ language: 'de' }));
     await mounted.events.waitForFirst('advanced-camera-card:media:loaded');
 
     expect(getLanguageChunks()).toEqual([expect.stringMatching(/^lang-de-/)]);
diff --git a/vitest.browser.config.ts b/vitest.browser.config.ts
index 4c80263b..47e7dc3c 100644
--- a/vitest.browser.config.ts
+++ b/vitest.browser.config.ts
@@ -67,13 +67,23 @@ export default defineConfig({
     name: 'browser',
     include: ['tests/**/*.browser.test.ts'],
 
+    // One file at a time. Files otherwise share a browser, in which only one of
+    // them can hold focus, so a test driving the keyboard loses it to whichever
+    // sibling clicks next. Measured no slower than running in parallel.
+    fileParallelism: false,
+
     // The tests under `tests/dist` need a card build to exist (in dist/), which
     // this suite does not require. They have their own config, see
     // vitest.dist.config.ts .
     exclude: ['tests/dist/**'],
 
-    // Cosmetic: Style the pages as HA does for screenshots.
-    setupFiles: ['./tests/browser/style.ts'],
+    setupFiles: [
+      // Must run before anything defines an element.
+      './tests/browser/scoped-custom-element-registry.ts',
+
+      // Cosmetic: Style the pages as HA does for screenshots.
+      './tests/browser/style.ts',
+    ],
 
     // A failing test leaves a screenshot and any attachments behind. Both
     // default to somewhere else -- a `__screenshots__` directory next to the
@@ -85,6 +95,11 @@ export default defineConfig({
     // past the default of 300ms.
     slowTestThreshold: 10000,
 
+    // How long a test may take before it is called a hang. Mounting a real card
+    // in three browsers at once is expensive, and a machine running something
+    // else alongside can push a healthy test past the default of 5 seconds.
+    testTimeout: 30000,
+
     server: {
       deps: {
         // These dependencies import without extensions.
diff --git a/yarn.lock b/yarn.lock
index 24f29950..7814194a 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -2465,6 +2465,13 @@ __metadata:
   languageName: node
   linkType: hard
 
+"@webcomponents/scoped-custom-element-registry@npm:0.0.10":
+  version: 0.0.10
+  resolution: "@webcomponents/scoped-custom-element-registry@npm:0.0.10"
+  checksum: 10c0/97fdb174f6795b20a3f6e8af9018b6c3e48c6a2bf40b87ef606d9b4616df32b0dc67a085f8ca1fda0e4327b3237ae76626bf1bbea3cfea0e03ce743f915a39cc
+  languageName: node
+  linkType: hard
+
 "a-sync-waterfall@npm:^1.0.0":
   version: 1.0.1
   resolution: "a-sync-waterfall@npm:1.0.1"
@@ -2552,6 +2559,7 @@ __metadata:
     "@use-gesture/vanilla": "npm:^10.3.1"
     "@vitest/browser-playwright": "npm:4.1.10"
     "@vitest/coverage-v8": "npm:^4.1.10"
+    "@webcomponents/scoped-custom-element-registry": "npm:0.0.10"
     any-date-parser: "npm:^2.2.0"
     component-emitter: "npm:^1.3.1"
     compute-scroll-into-view: "npm:^3.1.1"