Update ghcr.io/element-hq/element-web:develop Docker digest to e66c143

Use non deprecated non unstable names for getRTCTransports.

.github/workflows/blocked.yaml

@@ -14,7 +14,7 @@ permissions:
 jobs:
   prevent-blocked:
     name: Prevent blocked
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-24.04
     permissions:
       pull-requests: read
     steps:

.github/workflows/build-and-publish-docker.yaml

@@ -17,7 +17,7 @@ env:
 jobs:
   build_and_deploy:
     name: Build & publish docker
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-24.04
     permissions:
       contents: write # required to upload release asset
       packages: write # needed for publishing packages to GHCR

.github/workflows/build-element-call.yaml

@@ -29,7 +29,7 @@ on:
 jobs:
   build:
     name: Build Element Call
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-24.04
     steps:
       - name: Checkout code
         uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4

.github/workflows/build.yaml

@@ -25,7 +25,7 @@ jobs:
     # Deploy main branch to call.element.dev after build completes
     if: github.ref == 'refs/heads/main'
     needs: build_full_element_call
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-24.04
     steps:
       - name: Deploy to call.element.dev
         uses: actions/github-script@d7906e4ad0b1822421a7e6a35d5ca353c962f410 # v6
@@ -92,7 +92,7 @@ jobs:
   build_storybook:
     name: Build Storybook
     if: contains(github.event.pull_request.labels.*.name, 'storybook build')
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-24.04
     steps:
       - name: Checkout code
         uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4

.github/workflows/changelog-label.yml

@@ -13,7 +13,7 @@ permissions:
 
 jobs:
   pr-changelog-label:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-24.04
     steps:
       - uses: yogevbd/enforce-label-action@a3c219da6b8fa73f6ba62b68ff09c469b3a1c024 # 2.2.2
         with:

.github/workflows/claude.yaml

@@ -13,7 +13,7 @@ jobs:
     name: Review
     # Only run on labelling and skip forks.
     if: github.event.label.name == 'Claude-Review' && github.event.pull_request.head.repo.full_name == github.repository
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-24.04
     steps:
       - name: Checkout code
         uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4.4.0

.github/workflows/deploy-to-netlify.yaml

@@ -32,7 +32,7 @@ on:
 
 jobs:
   deploy:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-24.04
     permissions:
       deployments: write
     environment: Netlify

.github/workflows/lint.yaml

@@ -10,7 +10,7 @@ on:
 jobs:
   lint:
     name: Lint, format & type check
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-24.04
     steps:
       - name: Checkout code
         uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4

.github/workflows/pr-deploy.yaml

@@ -17,7 +17,7 @@ jobs:
       github.event.workflow_run.conclusion == 'success' &&
       github.event.workflow_run.event == 'pull_request' &&
       github.event.workflow_run.head_repository.full_name == github.repository
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-24.04
     outputs:
       pr_number: ${{ steps.prdetails.outputs.pr_id }}
       pr_data_json: ${{ steps.prdetails.outputs.data }}

.github/workflows/publish-component.yaml

@@ -17,7 +17,7 @@ permissions: {}
 jobs:
   versioning:
     name: Versioning
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-24.04
     outputs:
       DRY_RUN: ${{ steps.dry_run.outputs.DRY_RUN }}
       PREFIXED_VERSION: ${{ steps.prefixed_version.outputs.PREFIXED_VERSION }}
@@ -59,7 +59,7 @@ jobs:
   publish_npm:
     needs: versioning
     name: Publish NPM
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-24.04
     outputs:
       ARTIFACT_VERSION: ${{ steps.artifact_version.outputs.ARTIFACT_VERSION }}
     permissions:
@@ -111,7 +111,7 @@ jobs:
     needs: [versioning, publish_npm]
     if: ${{ needs.versioning.outputs.DRY_RUN == 'false' }}
     name: Update release notes
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-24.04
     # Shared with publish-embedded-packages.yaml, which appends to the same release: two
     # appends at once would each write back the body without the other's section
     concurrency:

.github/workflows/publish-embedded-packages.yaml

@@ -14,7 +14,7 @@ on:
 jobs:
   versioning:
     name: Versioning
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-24.04
     outputs:
       DRY_RUN: ${{ steps.dry_run.outputs.DRY_RUN }}
       PREFIXED_VERSION: ${{ steps.prefixed_version.outputs.PREFIXED_VERSION }}
@@ -76,7 +76,7 @@ jobs:
     needs: [build_element_call, versioning]
     if: always()
     name: Publish tarball
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-24.04
     permissions:
       contents: write # required to upload release asset
     steps:
@@ -107,7 +107,7 @@ jobs:
     needs: [build_element_call, versioning]
     if: always()
     name: Publish NPM
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-24.04
     outputs:
       ARTIFACT_VERSION: ${{ steps.artifact_version.outputs.ARTIFACT_VERSION }}
     permissions:
@@ -152,7 +152,7 @@ jobs:
     needs: [build_element_call, versioning]
     if: always()
     name: Publish Android AAR
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-24.04
     outputs:
       ARTIFACT_VERSION: ${{ steps.artifact_version.outputs.ARTIFACT_VERSION }}
     permissions:
@@ -212,7 +212,7 @@ jobs:
     needs: [build_element_call, versioning]
     if: always()
     name: Publish SwiftPM Library
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-24.04
     outputs:
       ARTIFACT_VERSION: ${{ steps.artifact_version.outputs.ARTIFACT_VERSION }}
     permissions:
@@ -282,7 +282,7 @@ jobs:
     needs: [versioning, publish_npm, publish_android, publish_ios]
     if: always()
     name: Update release notes
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-24.04
     # Shared with publish-component.yaml, which appends to the same release: two appends
     # at once would each write back the body without the other's section
     concurrency:

.github/workflows/publish.yaml

@@ -23,7 +23,7 @@ jobs:
     needs: build_element_call
     if: always()
     name: Publish tarball
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-24.04
     permissions:
       contents: write # required to upload release asset
       packages: write
@@ -68,7 +68,7 @@ jobs:
   add_docker_release_note:
     needs: publish_docker
     name: Add docker release note
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-24.04
     steps:
       - name: Add release note
         uses: softprops/action-gh-release@3bb12739c298aeb8a4eeaf626c5b8d85266b0e65 # v2

.github/workflows/test.yaml

@@ -25,7 +25,7 @@ on:
 jobs:
   vitest:
     name: Run unit tests
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-24.04
     steps:
       - name: Checkout code
         uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
@@ -71,10 +71,27 @@ jobs:
           flags: unittests
           fail_ci_if_error: true
   playwright:
-    name: Run end-to-end tests
+    name: Run end-to-end tests (${{ matrix.part }})
     if: ${{ !inputs.disable_e2e_tests }}
     timeout-minutes: 60
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-24.04
+    # We manually shard the tests across runners. Playwright's own shards cut
+    # the list of tests into equal counts in file order, which would leave the
+    # widget suite, the slowest tests by far, together at the end.
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - part: chromium-1
+            args: --project=chromium --shard=1/2
+          - part: chromium-2
+            args: --project=chromium --shard=2/2
+          - part: widget-1
+            args: --project=widget --shard=1/2
+          - part: widget-2
+            args: --project=widget --shard=2/2
+          - part: firefox-mobile
+            args: --project=firefox --project=mobile
     steps:
       - uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
         with:
@@ -107,17 +124,64 @@ jobs:
         run: pnpm playwright install --with-deps
       - name: Run backend components
         run: |
+          # Make sure the directory for the embedded build exists as Docker might
+          # create it with wrong access rights otherwise.
+          mkdir -p embedded/web/dist
           docker compose -f docker-compose-dev.yml -f docker-compose-playwright.yml pull
           docker compose -f docker-compose-dev.yml -f docker-compose-playwright.yml up -d
           docker ps
       - name: Run Playwright tests
         env:
           USE_DOCKER: 1
-        run: pnpm exec playwright test
+          ARGS: ${{ matrix.args }}
+        # Unquoted on purpose: the part's arguments are several words
+        run: pnpm exec playwright test $ARGS
       - uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
         if: ${{ !cancelled() }}
+        with:
+          name: blob-report-${{ matrix.part }}
+          path: blob-report
+          if-no-files-found: error
+          # Only read by the merge below.
+          retention-days: 1
+
+  e2e_report:
+    # Combines the blobs into a single HTML report and blocks PRs on failure.
+    name: Run end-to-end tests
+    needs: playwright
+    if: ${{ always() && !inputs.disable_e2e_tests }}
+    runs-on: ubuntu-24.04
+    steps:
+      - uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4.3.1
+        with:
+          # Inside a called workflow, github.repository is the caller so we need to make sure to still check out the EC repo here.
+          repository: ${{ inputs.matrix-js-sdk-sha && 'element-hq/element-call' || github.repository }}
+          persist-credentials: false
+      - name: Enable Corepack
+        run: corepack enable
+      - uses: actions/setup-node@49933ea5288caeca8642d1e84afbd3f7d6820020 # v4
+        with:
+          cache: "pnpm"
+          node-version-file: ".node-version"
+      - name: Install dependencies
+        run: scripts/layered.sh --ignore-pnpmfile
+        env:
+          PR_HEAD_REPO_OWNER: ${{ github.event.pull_request.head.repo.owner.login }}
+          JS_SDK_GITHUB_BASE_REF: ${{ inputs.matrix-js-sdk-sha }}
+      - name: Download the parts' reports
+        uses: actions/download-artifact@d3f86a106a0bac45b974a628896c90dbdf5c8093 # v4
+        with:
+          pattern: blob-report-*
+          path: all-blob-reports
+          merge-multiple: true
+      - name: Merge into one HTML report
+        run: pnpm exec playwright merge-reports --reporter html ./all-blob-reports
+      - uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
         with:
           name: html-report
           path: playwright-report
           if-no-files-found: error
           retention-days: 4
+      - name: Fail on a failed part
+        if: ${{ needs.playwright.result != 'success' }}
+        run: exit 1

.github/workflows/translations-download.yaml

@@ -7,7 +7,7 @@ on:
 
 jobs:
   download:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-24.04
     permissions:
       contents: read
 

.github/workflows/translations-upload.yaml

@@ -8,7 +8,7 @@ on:
 
 jobs:
   upload:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-24.04
     permissions:
       contents: read
 

.github/workflows/zizmor.yml

@@ -10,7 +10,7 @@ permissions: {}
 jobs:
   zizmor:
     name: Run zizmor 🌈
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-24.04
     permissions:
       security-events: write # Required for upload-sarif (used by zizmor-action) to upload SARIF files.
     steps:

README.md

@@ -221,119 +221,68 @@ See also:
 
 - [Developing with linked packages](./docs/linking.md)
 
-#### Element Call as a component (experimental)
+#### Element Call as a component
 
-Element Call can also be embedded directly into another React application
-rather than being loaded in an iframe as a widget. `pnpm build:component`
-builds it as a library into `component/dist` (the bundle, its stylesheet and
-type declarations), and
+Element Call can be rendered inside another React app instead of an iframe.
+The host supplies its own Matrix client, and the call stays inside the element
+it is mounted in.
 
-```sh
-pnpm dev:component
-```
-
-serves a harness on port 3001 that stands in for such an application: it signs
-in twice against the development backend and shows two calls side by side, in
-resizable boxes, with page furniture of its own around them. Use it to see how
-Element Call behaves when it does not own the page — the size it is given,
-whether it stays inside its container, and what it says to its host, which is
-logged along the bottom. The harness is served with the same development
-certificate as the app, so unless the development CA is trusted, the browser
-needs a certificate exception for `https://localhost:3001` as well (see the
-note under [Backend](#backend)). It reads the same `public/config.json` as
-`pnpm dev` if one exists, and runs with Element Call's defaults otherwise.
-
-The call lays itself out for the size of the element it is mounted in, not the
-window: a host that shrinks the container to a corner of its page gets the
-picture-in-picture layout, just as a host that shrank the whole iframe used to.
-The breakpoints in the stylesheets the component uses are
-`@container element-call` queries against its root element for the same reason;
-for the standalone app the root is the page, so they mean what the media queries
-they replaced did. (The standalone-only views, such as the home and login pages,
-still use plain media queries, since the component never shows them.)
-
-The component's stylesheet is confined to the element it is mounted in: the
-build rewrites every selector so that it matches only Element Call's root or
-what is inside it, with `html`, `body` and `:root` standing for that root (see
-`component/build/scopeStylesToRoot.ts`). A host's own page keeps its styles,
-and Element Call brings its own fonts and design tokens along.
-
-The component speaks every language the app does. English is bundled in; the
-other locales are split into chunks the host's bundler loads the first time
-they are needed. It starts in the browser's language, and follows the host's
-own language setting through the `language` prop (`supportedLanguages` lists
-the tags it accepts, and anything else falls back to its base language or to
-English). The `theme` prop works the same way and takes the same values as the
-widget's `theme` URL parameter: `light`, `dark`, `light-high-contrast` or
-`dark-high-contrast`. Both can change while a call is running without
-disturbing it.
-
-A host must call and await `initializeElementCall(config)` once before
-rendering the component: it loads the `Intl` polyfills, applies the
-deployment-wide `config.json`-style configuration and sets up translations.
-The component itself takes the host's `client` and the `roomId` to call in, an
-`intent` saying what the user asked for (which decides whether to show the
-lobby, ring, and so on), an optional `config` overriding what the intent
-implies, and an optional `hostBridge` through which Element Call tells the host
-that the user has joined or hung up, that it wants to stay on screen, and so
-on. The host makes its own requests (`join`, `hangUp`, `setDeviceMute`) through
-the handle exposed on `ref`. The full API is documented in the type declarations
-(`component/index.tsx` and `component/host.ts`).
-
-A few things differ from the widget on purpose: the component draws a solid
-background rather than a gradient unless told otherwise, never offers to edit
-the user's profile (the account is the host's), scopes its keyboard shortcuts to
-its own root element so that several instances can share a page, and only shows
-its own post-call and error screens when the host has not supplied a `close()`
-callback; with one, it asks the host to unmount it instead. The
-[global JS controls](./docs/controls.md) on `window` are unchanged and remain
-page-wide, so with several instances on one page they apply to all of them.
-
-Each release publishes the package to npm, with the same version as the release:
+##### Install
 
 ```sh
 npm install @element-hq/element-call-component
 ```
 
-To use an unreleased commit, a host can instead install it as a git dependency
-on the `component` directory of this repository,
+Releases publish the package with the same version as Element Call. For an
+unreleased commit, depend on this repository directly:
 
 ```json
 "@element-hq/element-call-component": "github:element-hq/element-call#main&path:/component"
 ```
 
-whose `prepare` script runs the build on install. That build needs pnpm (via
-Corepack) on the host's machine, runs a full `pnpm install` of this repository,
-since it inherits the `--max-old-space-size` setting of
-the app build; the host's pnpm also has to allow it to run at all
-(`allowBuilds` in its `pnpm-workspace.yaml`). Note that `component/` is a pnpm
-project of its own for this reason, so pnpm commands run from inside that
-directory target it rather than the repository; run them from the repository
-root. The host imports the component from
-`@element-hq/element-call-component` and the stylesheet from
-`@element-hq/element-call-component/style.css`, and has to provide `react`,
-`react-dom`, `matrix-js-sdk`, `@vector-im/compound-web` and
-`@vector-im/compound-design-tokens` itself, since the bundle leaves them
-external.
-Compound's stylesheet are the host's to load too: the component shares
-the host's copy of Compound, (required for example for tooltips)
+This builds on install, so the host needs pnpm (via Corepack) and must allow
+the build (`allowBuilds` in its `pnpm-workspace.yaml`).
 
-The component is large, and a host will usually load it lazily, only once a
-call is shown. Everything a host needs in order to talk about a call before
-then is also exported
-from `@element-hq/element-call-component/api` (a small entry point that does not
-load the component).
+##### Use
 
-- props and the types they are made of
-- the handle
-- the host bridge
-- `UserIntent`
-- `HeaderStyle`
-- `BackgroundStyle` enums
-- `configurationForIntent`, the defaults each intent implies
-  Import from it wherever a value such as
-  `BackgroundStyle.Solid` is needed on a path that must stay light; the main
-  entry point re-exports all of it too.
+1. Provide the externals yourself: `react`, `react-dom`, `matrix-js-sdk`,
+   `@vector-im/compound-web`, `@vector-im/compound-design-tokens`, and
+   Compound's stylesheet.
+2. Import `@element-hq/element-call-component/style.css`.
+3. Await `initializeElementCall(config)` once before rendering.
+4. Render the component with `client`, `roomId` and an `intent`; optionally
+   pass `config`, `hostBridge`, `language` and `theme` (both can change
+   mid-call). Control it through the `ref` handle (`join`, `hangUp`,
+   `setDeviceMute`).
+
+Load the component lazily. Types, enums and `configurationForIntent` are
+available without it from `@element-hq/element-call-component/api`. The full
+API is in `component/index.tsx`, `component/api.ts` and `component/host.ts`.
+
+##### How it differs from the widget
+
+- It lays out for its container, not the window: a small container gets the
+  picture-in-picture layout.
+- Its styles and keyboard shortcuts are scoped to its root, so the host page is
+  untouched and several instances can share a page. The
+  [global JS controls](./docs/controls.md) stay page-wide.
+- It draws a solid background by default and never offers profile editing.
+- If the host bridge implements `close()`, it asks to be unmounted instead of
+  showing its own post-call and error screens.
+- Sounds, images and the MediaPipe runtime are separate files the host's
+  bundler copies (webpack 5, Vite, Rollup); MediaPipe is fetched only when a
+  background effect is first used.
+
+##### Develop
+
+- `pnpm build:component` builds the library into `component/dist`.
+- `pnpm dev:component` serves a test host on `https://localhost:3001`: two
+  calls side by side in resizable boxes, with host messages logged at the
+  bottom. It uses the development backend, `public/config.json` if present,
+  and needs the same certificate exception as `pnpm dev` (see
+  [Backend](#backend)).
+- Run pnpm commands from the repository root; `component/` is its own pnpm
+  project.
 
 ### Backend
 

backend/ew.test.config.json

@@ -26,8 +26,7 @@
   "features": {
     "feature_element_call_video_rooms": true,
     "feature_video_rooms": true,
-    "feature_group_calls": true,
-    "feature_release_announcement": false
+    "feature_group_calls": true
   },
   "default_federate": true,
   "default_theme": "light",
@@ -40,7 +39,10 @@
   },
   "setting_defaults": {
     "breadcrumbs": true,
-    "feature_group_calls": true
+    "feature_group_calls": true,
+    "releaseAnnouncementData": {
+      "room_list_section": true
+    }
   },
   "jitsi": {
     "preferred_domain": "meet.element.io"

backend/ew.test.othersite.config.json

@@ -26,8 +26,7 @@
   "features": {
     "feature_element_call_video_rooms": true,
     "feature_video_rooms": true,
-    "feature_group_calls": true,
-    "feature_release_announcement": false
+    "feature_group_calls": true
   },
   "default_federate": true,
   "default_theme": "light",
@@ -40,7 +39,10 @@
   },
   "setting_defaults": {
     "breadcrumbs": true,
-    "feature_group_calls": true
+    "feature_group_calls": true,
+    "releaseAnnouncementData": {
+      "room_list_section": true
+    }
   },
   "jitsi": {
     "preferred_domain": "meet.element.io"

docker-compose-dev.yml

@@ -3,7 +3,7 @@ networks:
 
 services:
   auth-service:
-    image: ghcr.io/element-hq/lk-jwt-service:0.8.0
+    image: ghcr.io/element-hq/lk-jwt-service:0.10.0
     pull_policy: always
     hostname: auth-server
     environment:
@@ -33,7 +33,7 @@ services:
       - ecbackend
 
   auth-service-1:
-    image: ghcr.io/element-hq/lk-jwt-service:0.8.0
+    image: ghcr.io/element-hq/lk-jwt-service:0.10.0
     pull_policy: always
     hostname: auth-server-1
     environment:

docker-compose-playwright.yml

@@ -19,7 +19,12 @@ services:
       - ./backend/playwright_homeserver-othersite.yaml:/data/cfg/homeserver.yaml:Z
   element-web:
     # Pin to a SHA so that upstream cannot break our tests. Renovate handles regular updates.
-    image: ghcr.io/element-hq/element-web:develop@sha256:a79801206c628a912d57fa6f355d5c5ab9c6c40c2d1b6208d4192678fb6e80c7
+    image: ghcr.io/element-hq/element-web:develop@sha256:e66c143884f9923944f999cd0c6f268b9c1dfde2d8654906063dab869facf2df
   element-web-1:
     # Pin to a SHA so that upstream cannot break our tests. Renovate handles regular updates.
-    image: ghcr.io/element-hq/element-web:develop@sha256:a79801206c628a912d57fa6f355d5c5ab9c6c40c2d1b6208d4192678fb6e80c7
+    image: ghcr.io/element-hq/element-web:develop@sha256:e66c143884f9923944f999cd0c6f268b9c1dfde2d8654906063dab869facf2df
+    volumes:
+      # The other site opens the embedded package under test in place of the
+      # copy its image bundles (the first site opens the dev server's app.
+      # Built by the Playwright run (see build.setup.ts).
+      - ./embedded/web/dist:/app/widgets/element-call:ro,Z

docs/agents/testing.md

@@ -34,6 +34,10 @@ translations. The browser is Playwright's, so a fresh clone needs
 
 ## End-to-end
 
+The Element Web instance `HOST1` opens the app the dev server serves. The instance
+`HOST2` (the other site) opens the embedded package as a host ships it. This package
+is built by the `build-embedded` setup project and mounted in `docker-compose-playwright.yml`.
+
 - `playwright/*.spec.ts` — standalone, on Chromium and Firefox.
 - `playwright/widget/` — widget mode, where cross-context bugs surface.
 - `playwright/component/` — the component in a host page, via the harness on port
@@ -48,6 +52,8 @@ Test what a user observes: the peer sees the change, it survives a reconnect, it
 right after a reload. Reuse `playwright/spa-helpers.ts`,
 `playwright/widget/test-helpers.ts`, `playwright/fixtures/`.
 
+To mark new release announcements as viewed, add them in `backend/ew.test*.config.json`.
+
 ```sh
 pnpm test                   # unit + storybook
 pnpm backend                # Synapse + LiveKit, required for e2e

locales/en/app.json

@@ -3,6 +3,7 @@
     "user_menu": "User menu"
   },
   "action": {
+    "add_background_image": "Add image",
     "close": "Close",
     "copy_link": "Copy link",
     "edit": "Edit",
@@ -98,6 +99,10 @@
   },
   "disconnected_banner": "Connectivity to the server has been lost.",
   "error": {
+    "background_animated": "Animated images cannot be used as a background",
+    "background_not_an_image": "That file is not a supported image",
+    "background_not_kept": "That background could not be saved",
+    "background_undecodable": "That image could not be opened",
     "call_is_not_supported": "Call is not supported",
     "call_not_found": "Call not found",
     "call_not_found_description": "<0>That link doesn't appear to belong to any existing call. Check that you have the right link, or <2>create a new one</2>.</0>",

package.json

@@ -97,6 +97,7 @@
     "copy-to-clipboard": "^3.3.3",
     "eslint-plugin-element-call": "link:eslint",
     "eslint-plugin-storybook": "^10.3.6",
+    "fake-indexeddb": "^6.2.5",
     "fetch-mock": "11.1.5",
     "i18next": "^26.0.0",
     "i18next-browser-languagedetector": "^8.0.0",
@@ -106,7 +107,7 @@
     "livekit-client": "^2.18.1",
     "lodash-es": "^4.17.21",
     "loglevel": "^1.9.1",
-    "matrix-js-sdk": "github:matrix-org/matrix-js-sdk#a9ef09fbf2f1644c8663d0aeaf6a921cd16e7b01",
+    "matrix-js-sdk": "github:matrix-org/matrix-js-sdk#10e4faabbb49baca655492d523b58faa9eea04b9",
     "matrix-widget-api": "^1.18.0",
     "node-stdlib-browser": "^1.3.1",
     "normalize.css": "^8.0.1",

playwright.config.ts

@@ -26,6 +26,19 @@ process.env.NODE_EXTRA_CA_CERTS = join(
   "backend/dev_tls_local-ca.crt",
 );
 
+const desktopChrome = {
+  ...devices["Desktop Chrome"],
+  permissions: ["clipboard-write", "clipboard-read", "microphone", "camera"],
+  ignoreHTTPSErrors: true,
+  launchOptions: {
+    args: [
+      "--use-fake-ui-for-media-stream",
+      "--use-fake-device-for-media-stream",
+      "--mute-audio",
+    ],
+  },
+};
+
 /**
  * See https://playwright.dev/docs/test-configuration.
  */
@@ -43,11 +56,11 @@ export default defineConfig({
    * Reporter to use. See https://playwright.dev/docs/test-reporters
    *
    * On CI, `list` prints a line per test as it finishes, which keeps the job
-   * log moving; `github` annotates failures on the PR; `html` is uploaded as
-   * an artifact and must never try to open a browser there.
+   * log moving; `github` annotates failures on the PR; the `blob` format is
+   * uploaded by sharded CI runs and combined into a HTML report by the workflow.
    */
   reporter: process.env.CI
-    ? [["list"], ["github"], ["html", { open: "never" }]]
+    ? [["list"], ["github"], ["blob"]]
     : [["list"], ["html"]],
   /* Stop a broken run early on CI instead of waiting out every retry. */
   maxFailures: process.env.CI ? 5 : undefined,
@@ -63,29 +76,28 @@ export default defineConfig({
   },
   /* Configure projects for major browsers */
   projects: [
+    {
+      // Builds the embedded package into the directory the other site's
+      // Element Web container serves it from (see docker-compose-playwright.yml).
+      name: "build-embedded",
+      testMatch: "**/widget/embedded/build.setup.ts",
+    },
     {
       name: "chromium",
-      testIgnore: "**/mobile/**",
-      use: {
-        ...devices["Desktop Chrome"],
-        permissions: [
-          "clipboard-write",
-          "clipboard-read",
-          "microphone",
-          "camera",
-        ],
-        ignoreHTTPSErrors: true,
-        launchOptions: {
-          args: [
-            "--use-fake-ui-for-media-stream",
-            "--use-fake-device-for-media-stream",
-            "--mute-audio",
-          ],
-        },
-      },
+      testIgnore: ["**/mobile/**", "**/widget/**"],
+      use: desktopChrome,
+    },
+    {
+      // Element Call as a widget in Element Web, on Chromium. This uses its
+      // own project so that it can be sharded on CI.
+      name: "widget",
+      dependencies: ["build-embedded"],
+      testMatch: "**/widget/**/*.@(spec|test).ts",
+      use: desktopChrome,
     },
     {
       name: "firefox",
+      dependencies: ["build-embedded"],
       testIgnore: "**/mobile/**",
       use: {
         ...devices["Desktop Firefox"],

playwright/background-effects.spec.ts

@@ -5,9 +5,15 @@ SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
 Please see LICENSE in the repository root for full details.
 */
 
-import { expect, test, type Locator, type Page } from "@playwright/test";
+import { expect, test, type Browser, type Page } from "@playwright/test";
 
 import { SpaHelpers } from "./spa-helpers.ts";
+import {
+  averageColour,
+  cameraColour,
+  type Colour,
+  distance,
+} from "./utils/colour.ts";
 
 // Background effects need WebGL2, and headless Firefox on a CI runner has none,
 // so it rightly offers none of them.
@@ -16,15 +22,13 @@ test.skip(
   "Background effects need WebGL2, which headless Firefox on CI does not have",
 );
 
-type Colour = [number, number, number];
-
 test.describe("background effects", () => {
   test("pre-join preview shows the chosen effect", async ({ page }) => {
     test.slow();
     await page.goto("/");
     await SpaHelpers.createCall(page, "Effect user", "Background effects");
     const preview = page.locator("video").first();
-    const camera = await averageColour(preview);
+    const camera = await cameraColour(preview);
 
     await page.getByRole("button", { name: "Camera", exact: true }).click();
     const tile = page
@@ -102,25 +106,847 @@ async function drawsPerSecond(page: Page): Promise<number> {
   });
 }
 
-/** The mean colour of a video's current frame or an image, drawn small. */
-async function averageColour(element: Locator): Promise<Colour> {
-  return element.evaluate(
-    async (source: HTMLVideoElement | HTMLImageElement) => {
-      if (source instanceof HTMLImageElement) await source.decode();
-      const canvas = document.createElement("canvas");
-      canvas.width = canvas.height = 32;
-      const context = canvas.getContext("2d")!;
-      context.drawImage(source, 0, 0, 32, 32);
-      const { data } = context.getImageData(0, 0, 32, 32);
-      const sum = [0, 0, 0];
-      for (let i = 0; i < data.length; i += 4)
-        for (let c = 0; c < 3; c++) sum[c] += data[i + c];
-      const pixels = data.length / 4;
-      return sum.map((s) => s / pixels) as Colour;
-    },
-  );
+test.describe("the camera menu's preview", () => {
+  test("shows the camera with the effect in force", async ({ page }) => {
+    test.setTimeout(120_000);
+    await page.goto("/");
+    await SpaHelpers.createCall(page, "Preview user", "Preview in the menu");
+    const camera = await cameraColour(page.locator("video").first());
+
+    await page.getByRole("button", { name: "Camera", exact: true }).click();
+    const preview = page.getByRole("menu").locator("video");
+    await expect(preview).toBeVisible();
+    await expect
+      .poll(async () => distance(await averageColour(preview), camera), {
+        timeout: 20_000,
+      })
+      .toBeLessThan(30);
+
+    const tile = page.getByRole("menuitemradio", { name: "Background 1" });
+    await tile.click();
+    const picture = await averageColour(tile.locator("img"));
+    await expect
+      .poll(async () => distance(await averageColour(preview), picture), {
+        timeout: 60_000,
+      })
+      .toBeLessThan(distance(camera, picture) / 2);
+  });
+
+  test("shows the call's own camera once joined", async ({ page }) => {
+    test.setTimeout(120_000);
+    await page.goto("/");
+    await SpaHelpers.createCall(
+      page,
+      "Call preview user",
+      "Preview in the call's menu",
+      true,
+    );
+    await expect(page.getByTestId("incall_videomute")).toBeEnabled({
+      timeout: 10_000,
+    });
+    const camera = await cameraColour(page.locator("video").first());
+
+    await page.getByRole("button", { name: "Camera", exact: true }).click();
+    const preview = page.getByRole("menu").locator("video");
+    await expect(preview).toBeVisible();
+    await expect
+      .poll(async () => distance(await averageColour(preview), camera), {
+        timeout: 20_000,
+      })
+      .toBeLessThan(30);
+
+    const tile = page.getByRole("menuitemradio", { name: "Background 1" });
+    await tile.click();
+    const picture = await averageColour(tile.locator("img"));
+    await expect
+      .poll(async () => distance(await averageColour(preview), picture), {
+        timeout: 60_000,
+      })
+      .toBeLessThan(distance(camera, picture) / 2);
+  });
+});
+
+test.describe("background effects section", () => {
+  test("section stays within the call area at every size", async ({ page }) => {
+    test.setTimeout(120_000);
+    await page.goto("/");
+    await SpaHelpers.createCall(page, "Sizes user", "Background effect sizes");
+
+    for (const size of [
+      { width: 1280, height: 800 },
+      { width: 800, height: 600 },
+      { width: 600, height: 420 },
+      { width: 480, height: 360 },
+      { width: 360, height: 640 },
+    ]) {
+      await page.setViewportSize(size);
+      await page.getByRole("button", { name: "Camera", exact: true }).click();
+      const menu = page.getByRole("menu");
+      await expect(menu).toBeVisible();
+
+      const box = (await menu.boundingBox())!;
+      const where = `at ${size.width}x${size.height}`;
+      expect(box.x, where).toBeGreaterThanOrEqual(0);
+      expect(box.y, where).toBeGreaterThanOrEqual(0);
+      expect(box.x + box.width, where).toBeLessThanOrEqual(size.width);
+      expect(box.y + box.height, where).toBeLessThanOrEqual(size.height);
+
+      const last = page
+        .getByRole("group", { name: "Background effects" })
+        .getByRole("menuitemradio")
+        .last();
+      await last.scrollIntoViewIfNeeded();
+      await expect(last, where).toBeInViewport({ ratio: 1 });
+      await last.click();
+      await expect(last, where).toHaveAttribute("aria-checked", "true");
+
+      // Back to no effect for the next size, and close.
+      await page
+        .getByRole("group", { name: "Background effects" })
+        .getByRole("menuitemradio", { name: "None" })
+        .click();
+      await page.keyboard.press("Escape");
+      await expect(menu).toBeHidden();
+    }
+  });
+});
+
+test.describe("a pipeline that fails to build", () => {
+  test("offers no effects for the session, and keeps the choice", async ({
+    page,
+  }) => {
+    test.setTimeout(120_000);
+    await page.goto("/");
+    await SpaHelpers.createCall(page, "Failing user", "Pipeline fails");
+    const preview = page.locator("video").first();
+    const camera = await cameraColour(preview);
+    await page.route("**/*.tflite*", async (route) => route.abort());
+
+    await page.getByRole("button", { name: "Camera", exact: true }).click();
+    const tile = page.getByRole("menuitemradio", { name: "Background 1" });
+    await tile.click();
+    await expect(
+      page.getByText("Background effects are not supported on this platform."),
+    ).toBeVisible({ timeout: 30_000 });
+    await expect(tile).toBeDisabled();
+    await page.keyboard.press("Escape");
+    // The camera and microphone carry on without it.
+    expect(distance(await cameraColour(preview), camera)).toBeLessThan(30);
+    await expect(page.getByTestId("incall_mute")).toHaveAttribute(
+      "aria-checked",
+      "true",
+    );
+
+    await page.unroute("**/*.tflite*");
+    await page.reload();
+    await expect(page.getByTestId("lobby_joinCall")).toBeVisible();
+    await page.getByRole("button", { name: "Camera", exact: true }).click();
+    await expect(tile).toHaveAttribute("aria-checked", "true");
+    const picture = await averageColour(tile.locator("img"));
+    await expect
+      .poll(async () => distance(await averageColour(preview), picture), {
+        timeout: 60_000,
+      })
+      .toBeLessThan(distance(camera, picture) / 2);
+  });
+});
+
+test.describe("the chosen effect", () => {
+  test("chosen effect survives leaving and rejoining", async ({ page }) => {
+    test.setTimeout(120_000);
+    await page.goto("/");
+    await SpaHelpers.createCall(page, "Returning user", "Effect remembered");
+    const { camera, picture } = await chooseAndWear(page, "Background 1");
+    await page.getByTestId("lobby_joinCall").click();
+    await page.getByTestId("incall_leave").click();
+    await expect(page.getByRole("heading")).toContainText(
+      "your call has ended",
+    );
+
+    await page.goto("/");
+    await page.getByTestId("home_callName").fill("Effect remembered again");
+    await page.getByTestId("home_go").click();
+    await expect(page.getByTestId("lobby_joinCall")).toBeVisible();
+    await page.getByRole("button", { name: "Camera", exact: true }).click();
+    const tile = page
+      .getByRole("group", { name: "Background effects" })
+      .getByRole("menuitemradio", { name: "Background 1" });
+    await expect(tile).toHaveAttribute("aria-checked", "true");
+    const preview = page.locator("video").first();
+    await expect
+      .poll(async () => distance(await averageColour(preview), picture), {
+        timeout: 60_000,
+      })
+      .toBeLessThan(distance(camera, picture) / 2);
+  });
+
+  test("second session still shows the existing error", async ({ page }) => {
+    test.setTimeout(120_000);
+    await page.goto("/");
+    await SpaHelpers.createCall(page, "Two tabs", "Effect in two tabs");
+    await chooseAndWear(page, "Background 1");
+
+    const second = await page.context().newPage();
+    await second.goto("/");
+    await expect(
+      page.getByRole("heading", { name: "Opened in another tab" }),
+    ).toBeVisible();
+  });
+});
+
+/** Chooses an effect in the lobby, and waits until the preview wears it. */
+async function chooseAndWear(
+  page: Page,
+  name: string,
+): Promise<{ camera: Colour; picture: Colour }> {
+  const preview = page.locator("video").first();
+  const camera = await cameraColour(preview);
+  await page.getByRole("button", { name: "Camera", exact: true }).click();
+  const tile = page.getByRole("menuitemradio", { name });
+  await tile.click();
+  const picture = await averageColour(tile.locator("img"));
+  await expect
+    .poll(async () => distance(await averageColour(preview), picture), {
+      timeout: 60_000,
+    })
+    .toBeLessThan(distance(camera, picture) / 2);
+  await page.keyboard.press("Escape");
+  return { camera, picture };
 }
 
-function distance(a: Colour, b: Colour): number {
-  return Math.hypot(a[0] - b[0], a[1] - b[1], a[2] - b[2]);
+test.describe("a background of one's own", () => {
+  test("adds an image from the device", async ({ page }) => {
+    test.setTimeout(120_000);
+    await page.goto("/");
+    await SpaHelpers.createCall(page, "Adding user", "Own background");
+    const preview = page.locator("video").first();
+    const camera = await cameraColour(preview);
+    const red = await redImage(page);
+
+    await addImage(page, red);
+    const mine = page
+      .getByRole("group", { name: "Background effects" })
+      .getByRole("menuitemradio", { name: "Background 3" });
+    await expect(mine).toBeVisible();
+    await expect(mine).toHaveAttribute("aria-checked", "false");
+
+    await mine.click();
+    await expect
+      .poll(async () => distance(await averageColour(preview), RED), {
+        timeout: 60_000,
+      })
+      .toBeLessThan(distance(camera, RED) / 2);
+  });
+
+  test("adding an image makes no upload", async ({ page }) => {
+    test.setTimeout(120_000);
+    await page.goto("/");
+    await SpaHelpers.createCall(page, "Private user", "Own background kept");
+    const preview = page.locator("video").first();
+    const camera = await cameraColour(preview);
+    const red = await redImage(page);
+    const sent: { request: string; body: Buffer | null }[] = [];
+    page.on("request", (request) =>
+      sent.push({
+        request: `${request.method()} ${request.url()}`,
+        body: request.postDataBuffer(),
+      }),
+    );
+
+    await addImage(page, red);
+    await page
+      .getByRole("group", { name: "Background effects" })
+      .getByRole("menuitemradio", { name: "Background 3" })
+      .click();
+    // Kept, chosen and in force: anything that would send it has had its turn.
+    await expect
+      .poll(async () => distance(await averageColour(preview), RED), {
+        timeout: 60_000,
+      })
+      .toBeLessThan(distance(camera, RED) / 2);
+    // The file as given, and the copy kept, which is encoded anew.
+    const samples = [red, await keptBytes(page)].map((bytes) =>
+      bytes.subarray(bytes.length - 64),
+    );
+    const carriesIt = sent.filter(
+      ({ request, body }) =>
+        request.includes("/_matrix/media/") ||
+        samples.some((sample) => body?.includes(sample)),
+    );
+    expect(carriesIt.map(({ request }) => request)).toEqual([]);
+  });
+
+  test("added image survives rejoining and is gone after storage is cleared", async ({
+    page,
+  }) => {
+    test.setTimeout(120_000);
+    await page.goto("/");
+    await SpaHelpers.createCall(page, "Keeping user", "Own background again");
+    const preview = page.locator("video").first();
+    const camera = await cameraColour(preview);
+    const red = await redImage(page);
+    await addImage(page, red);
+    const mine = page
+      .getByRole("group", { name: "Background effects" })
+      .getByRole("menuitemradio", { name: "Background 3" });
+    await mine.click();
+    await page.keyboard.press("Escape");
+
+    await page.reload();
+    await expect(page.getByTestId("lobby_joinCall")).toBeVisible();
+    await page.getByRole("button", { name: "Camera", exact: true }).click();
+    await expect(mine).toHaveAttribute("aria-checked", "true");
+    await page.keyboard.press("Escape");
+    await expect
+      .poll(async () => distance(await averageColour(preview), RED), {
+        timeout: 60_000,
+      })
+      .toBeLessThan(distance(camera, RED) / 2);
+
+    await page.evaluate(
+      async () =>
+        new Promise<void>((resolve, reject) => {
+          const request = indexedDB.deleteDatabase(
+            "element-call-background-images",
+          );
+          request.onsuccess = (): void => resolve();
+          request.onerror = (): void => reject(request.error);
+          request.onblocked = (): void => resolve();
+        }),
+    );
+    await page.reload();
+    await expect(page.getByTestId("lobby_joinCall")).toBeVisible();
+    await page.getByRole("button", { name: "Camera", exact: true }).click();
+    await expect(
+      page.getByRole("group", { name: "Background effects" }),
+    ).toBeVisible();
+    await expect(mine).toHaveCount(0);
+    await page.keyboard.press("Escape");
+
+    await addImage(page, red);
+    await expect(mine).toBeVisible();
+  });
+
+  test("a removed image stays removed", async ({ page }) => {
+    test.setTimeout(120_000);
+    await page.goto("/");
+    await SpaHelpers.createCall(
+      page,
+      "Removing user",
+      "Own background removed",
+    );
+    await addImage(page, await redImage(page));
+    const mine = page
+      .getByRole("group", { name: "Background effects" })
+      .getByRole("menuitemradio", { name: "Background 3" });
+    await expect(mine).toHaveAttribute("aria-keyshortcuts", "Delete");
+    await mine.focus();
+    await page.keyboard.press("Delete");
+    await expect(mine).toHaveCount(0);
+
+    await page.reload();
+    await expect(page.getByTestId("lobby_joinCall")).toBeVisible();
+    await page.getByRole("button", { name: "Camera", exact: true }).click();
+    await expect(
+      page.getByRole("group", { name: "Background effects" }),
+    ).toBeVisible();
+    await expect(mine).toHaveCount(0);
+    expect(await keptImages(page)).toEqual([]);
+  });
+});
+
+test.describe("what can be added", () => {
+  test("refuses an animated image", async ({ page }) => {
+    test.setTimeout(120_000);
+    await page.goto("/");
+    await SpaHelpers.createCall(page, "Refused user", "Animated refused");
+    await addImage(page, ANIMATED_GIF, {
+      name: "moving.gif",
+      type: "image/gif",
+    });
+
+    await expect(
+      page.getByText("Animated images cannot be used as a background"),
+    ).toBeVisible();
+    const section = page.getByRole("group", { name: "Background effects" });
+    await expect(
+      section.getByRole("menuitemradio", { name: "Background 3" }),
+    ).toHaveCount(0);
+    await expect(
+      section.getByRole("menuitemradio", { name: "None" }),
+    ).toHaveAttribute("aria-checked", "true");
+    expect(await keptImages(page)).toEqual([]);
+  });
+
+  test("reduces an oversized image", async ({ page }) => {
+    test.setTimeout(120_000);
+    await page.goto("/");
+    await SpaHelpers.createCall(page, "Large user", "Oversized reduced");
+    await addImage(page, await pngImage(page, { width: 4000, height: 3000 }));
+
+    await expect(
+      page
+        .getByRole("group", { name: "Background effects" })
+        .getByRole("menuitemradio", { name: "Background 3" }),
+    ).toBeVisible();
+    await expect(page.getByRole("alert")).toHaveCount(0);
+    const [kept] = await keptImages(page);
+    expect(kept).toMatchObject({ width: 1920, height: 1440 });
+  });
+
+  test("lays every image on an opaque ground", async ({ page }) => {
+    test.setTimeout(120_000);
+    await page.goto("/");
+    await SpaHelpers.createCall(page, "Logo user", "Transparent made opaque");
+    await addImage(
+      page,
+      await pngImage(page, { width: 320, height: 180, transparent: true }),
+    );
+
+    await expect(
+      page
+        .getByRole("group", { name: "Background effects" })
+        .getByRole("menuitemradio", { name: "Background 3" }),
+    ).toBeVisible();
+    const [kept] = await keptImages(page);
+    expect(kept.minAlpha).toBe(255);
+  });
+});
+
+/** Two frames of one pixel, red then blue. */
+const ANIMATED_GIF = Buffer.from(
+  "R0lGODlhAQABAPEAAP8AAAAA/wAAAAAAACH/C05FVFNDQVBFMi4wAwEAAAAh+QQACgAAACwAAAAAAQABAAACAkQBACH5BAAKAAAALAAAAAABAAEAAAICTAEAOw==",
+  "base64",
+);
+
+/** A red PNG of the given size; transparent leaves its right half empty. */
+async function pngImage(
+  page: Page,
+  size: { width: number; height: number; transparent?: boolean },
+): Promise<Buffer> {
+  const dataUrl = await page.evaluate(({ width, height, transparent }) => {
+    const canvas = document.createElement("canvas");
+    canvas.width = width;
+    canvas.height = height;
+    const context = canvas.getContext("2d")!;
+    context.fillStyle = "rgb(255, 0, 0)";
+    context.fillRect(0, 0, transparent ? width / 2 : width, height);
+    return canvas.toDataURL("image/png");
+  }, size);
+  return Buffer.from(dataUrl.split(",")[1], "base64");
+}
+
+/** The images the device keeps, as it keeps them. */
+async function keptImages(
+  page: Page,
+): Promise<{ width: number; height: number; minAlpha: number }[]> {
+  return page.evaluate(async () => {
+    const db = await new Promise<IDBDatabase>((resolve, reject) => {
+      const request = indexedDB.open("element-call-background-images");
+      request.onsuccess = (): void => resolve(request.result);
+      request.onerror = (): void => reject(request.error);
+    });
+    if (!db.objectStoreNames.contains("backgrounds")) return [];
+    const kept = await new Promise<{ image: Blob }[]>((resolve, reject) => {
+      const request = db
+        .transaction("backgrounds")
+        .objectStore("backgrounds")
+        .getAll();
+      request.onsuccess = (): void => resolve(request.result);
+      request.onerror = (): void => reject(request.error);
+    });
+    db.close();
+    return Promise.all(
+      kept.map(async ({ image }) => {
+        const bitmap = await createImageBitmap(image);
+        const canvas = new OffscreenCanvas(bitmap.width, bitmap.height);
+        const context = canvas.getContext("2d")!;
+        context.drawImage(bitmap, 0, 0);
+        const { data } = context.getImageData(
+          0,
+          0,
+          bitmap.width,
+          bitmap.height,
+        );
+        let minAlpha = 255;
+        for (let i = 3; i < data.length; i += 4)
+          minAlpha = Math.min(minAlpha, data[i]);
+        return { width: bitmap.width, height: bitmap.height, minAlpha };
+      }),
+    );
+  });
+}
+
+/** The bytes of the one image the device keeps. */
+async function keptBytes(page: Page): Promise<Buffer> {
+  const base64 = await page.evaluate(
+    async () =>
+      new Promise<string>((resolve, reject) => {
+        const open = indexedDB.open("element-call-background-images");
+        open.onerror = (): void => reject(open.error);
+        open.onsuccess = (): void => {
+          const all = open.result
+            .transaction("backgrounds")
+            .objectStore("backgrounds")
+            .getAll();
+          all.onerror = (): void => reject(all.error);
+          all.onsuccess = (): void => {
+            const reader = new FileReader();
+            reader.onload = (): void =>
+              resolve((reader.result as string).split(",")[1]);
+            reader.readAsDataURL((all.result[0] as { image: Blob }).image);
+          };
+        };
+      }),
+  );
+  return Buffer.from(base64, "base64");
+}
+
+const RED: Colour = [255, 0, 0];
+
+/** A solid red PNG, unlike the camera and the shipped pictures. */
+async function redImage(page: Page): Promise<Buffer> {
+  const dataUrl = await page.evaluate(() => {
+    const canvas = document.createElement("canvas");
+    canvas.width = 320;
+    canvas.height = 180;
+    const context = canvas.getContext("2d")!;
+    context.fillStyle = "rgb(255, 0, 0)";
+    context.fillRect(0, 0, canvas.width, canvas.height);
+    return canvas.toDataURL("image/png");
+  });
+  return Buffer.from(dataUrl.split(",")[1], "base64");
+}
+
+/** Adds an image from the camera menu's add tile, leaving the menu open. */
+async function addImage(
+  page: Page,
+  image: Buffer,
+  { name, type } = { name: "mine.png", type: "image/png" },
+): Promise<void> {
+  if (!(await page.getByRole("menu").isVisible()))
+    await page.getByRole("button", { name: "Camera", exact: true }).click();
+  const chooser = page.waitForEvent("filechooser");
+  await page.getByRole("menuitem", { name: "Add image" }).click();
+  await (await chooser).setFiles({ name, mimeType: type, buffer: image });
+}
+
+test.describe("joining with a background chosen", () => {
+  test("publishes no frame of the room", async ({ browser }) => {
+    // Two first builds of the pipeline, one of them held back.
+    test.setTimeout(180_000);
+    const hostContext = await browser.newContext();
+    const host = await hostContext.newPage();
+    await recordIncomingFrames(host);
+    await host.goto("/");
+    await SpaHelpers.createCall(host, "Host", "Join with a background", true);
+    await expect(host.getByTestId("incall_videomute")).toBeEnabled({
+      timeout: 10_000,
+    });
+    const inviteLink = await SpaHelpers.getCallInviteLink(host);
+    await host.keyboard.press("Escape");
+
+    const guestContext = await browser.newContext();
+    const guest = await guestContext.newPage();
+    await guest.goto(inviteLink);
+    await guest.getByTestId("joincall_displayName").fill("Guest");
+    await guest.getByTestId("joincall_joincall").click();
+    const preview = guest.locator("video").first();
+    await expect(preview).toBeVisible();
+    const camera = await cameraColour(preview);
+    await guest.getByRole("button", { name: "Camera", exact: true }).click();
+    const tile = guest.getByRole("menuitemradio", { name: "Background 1" });
+    await tile.click();
+    const picture = await averageColour(tile.locator("img"));
+    await expect
+      .poll(async () => distance(await averageColour(preview), picture), {
+        timeout: 60_000,
+      })
+      .toBeLessThan(distance(camera, picture) / 2);
+    // Were the pipeline built again for the call's track, it would take as
+    // long as on the slower route. Routing bypasses the cache, so it waits.
+    let heldBack = 0;
+    await guest.route("**/*.tflite*", async (route) => {
+      heldBack += 1;
+      await new Promise((resolve) => setTimeout(resolve, 15_000));
+      await route.continue();
+    });
+    await guest.keyboard.press("Escape");
+    await guest.getByTestId("lobby_joinCall").click();
+
+    const guestTile = host
+      .getByTestId("videoTile")
+      .filter({ has: host.getByTestId("name_tag").getByText("Guest") });
+    await expect(guestTile.locator("video")).toBeVisible({ timeout: 60_000 });
+    // Visible can come before the stream is attached.
+    let trackId: string | undefined;
+    await expect
+      .poll(async () => {
+        trackId = await guestTile
+          .locator("video")
+          .evaluate(
+            (video: HTMLVideoElement) =>
+              (video.srcObject as MediaStream | null)?.getVideoTracks()[0]?.id,
+          );
+        return trackId;
+      })
+      .toBeDefined();
+    await expectNoFrameOfTheRoom(host, trackId!, 0, camera, picture);
+    // The join adopts the lobby's pipeline, so the model is never fetched again.
+    expect(heldBack).toBe(0);
+
+    await hostContext.close();
+    await guestContext.close();
+  });
+});
+
+test.describe("the first build", () => {
+  test("survives the camera turned off and on while it runs", async ({
+    page,
+  }) => {
+    test.setTimeout(120_000);
+    const failures: string[] = [];
+    page.on("console", (m) => {
+      if (m.text().includes("Failed to attach video processor"))
+        failures.push(m.text());
+    });
+    await page.goto("/");
+    await SpaHelpers.createCall(page, "Toggling user", "Toggle while building");
+    const preview = page.locator("video").first();
+    const camera = await cameraColour(preview);
+
+    const held = await holdBackTheModel(page);
+    await page.getByRole("button", { name: "Camera", exact: true }).click();
+    const tile = page.getByRole("menuitemradio", { name: "Background 1" });
+    await tile.click();
+    const picture = await averageColour(tile.locator("img"));
+    await page.keyboard.press("Escape");
+    // New preview tracks, each attached while the first is still building.
+    for (let i = 0; i < 2; i++) {
+      await page.getByTestId("incall_videomute").click();
+      await page.getByTestId("incall_videomute").click();
+    }
+
+    await expect
+      .poll(async () => distance(await averageColour(preview), picture), {
+        timeout: 60_000,
+      })
+      .toBeLessThan(distance(camera, picture) / 2);
+    expect(failures).toEqual([]);
+    expect(held()).toBeGreaterThan(0);
+  });
+});
+
+test.describe("turning the camera on with a background chosen", () => {
+  test("publishes no frame of the room when the camera started off", async ({
+    browser,
+  }) => {
+    test.setTimeout(120_000);
+    const { host, guest, close } = await hostAndGuest(browser);
+    const camera = await cameraColour(guest.locator("video").first());
+    await guest.getByTestId("incall_videomute").click();
+    await guest.getByTestId("lobby_joinCall").click();
+
+    const picture = await chooseBackground(guest);
+    const held = await holdBackTheModel(guest);
+    await guest.getByTestId("incall_videomute").click();
+
+    const trackId = await incomingTrackId(host);
+    await expectNoFrameOfTheRoom(host, trackId, 0, camera, picture);
+    expect(held()).toBeGreaterThan(0);
+    await close();
+  });
+
+  test("publishes no frame of the room when the camera was turned off", async ({
+    browser,
+  }) => {
+    test.setTimeout(120_000);
+    const { host, guest, close } = await hostAndGuest(browser);
+    const camera = await cameraColour(guest.locator("video").first());
+    await guest.getByTestId("lobby_joinCall").click();
+    const trackId = await incomingTrackId(host);
+    await expect
+      .poll(async () => (await framesOf(host, trackId)).length, {
+        timeout: 20_000,
+      })
+      .toBeGreaterThan(0);
+    await guest.getByTestId("incall_videomute").click();
+
+    const picture = await chooseBackground(guest);
+    const held = await holdBackTheModel(guest);
+    const before = (await framesOf(host, trackId)).length;
+    await guest.getByTestId("incall_videomute").click();
+
+    await expectNoFrameOfTheRoom(host, trackId, before, camera, picture);
+    expect(held()).toBeGreaterThan(0);
+    await close();
+  });
+});
+
+/** A host in a call, recording what it receives, and a guest in its lobby. */
+async function hostAndGuest(browser: Browser): Promise<{
+  host: Page;
+  guest: Page;
+  close: () => Promise<void>;
+}> {
+  const hostContext = await browser.newContext();
+  const host = await hostContext.newPage();
+  await recordIncomingFrames(host);
+  await host.goto("/");
+  await SpaHelpers.createCall(host, "Host", "Camera with a background", true);
+  await expect(host.getByTestId("incall_videomute")).toBeEnabled({
+    timeout: 10_000,
+  });
+  const inviteLink = await SpaHelpers.getCallInviteLink(host);
+  await host.keyboard.press("Escape");
+
+  const guestContext = await browser.newContext();
+  const guest = await guestContext.newPage();
+  await guest.goto(inviteLink);
+  await guest.getByTestId("joincall_displayName").fill("Guest");
+  await guest.getByTestId("joincall_joincall").click();
+  await expect(guest.locator("video").first()).toBeVisible();
+  return {
+    host,
+    guest,
+    close: async (): Promise<void> => {
+      await hostContext.close();
+      await guestContext.close();
+    },
+  };
+}
+
+/** Chooses the first shipped picture in the call, and answers its colour. */
+async function chooseBackground(guest: Page): Promise<Colour> {
+  // The lobby has a camera button of its own, so wait for the call's.
+  await expect(guest.getByTestId("incall_leave")).toBeVisible({
+    timeout: 30_000,
+  });
+  await expect(guest.getByTestId("incall_videomute")).toBeEnabled({
+    timeout: 10_000,
+  });
+  await guest.getByRole("button", { name: "Camera", exact: true }).click();
+  const tile = guest.getByRole("menuitemradio", { name: "Background 1" });
+  await tile.click();
+  await expect(tile).toHaveAttribute("aria-checked", "true");
+  const picture = await averageColour(tile.locator("img"));
+  await guest.keyboard.press("Escape");
+  return picture;
+}
+
+/** Makes the pipeline's first build as slow as on the slower route. */
+/** Answers how often it held the model back, which a check should see. */
+async function holdBackTheModel(page: Page): Promise<() => number> {
+  let held = 0;
+  // Routing bypasses the cache, so it waits.
+  await page.route("**/*.tflite*", async (route) => {
+    held += 1;
+    await new Promise((resolve) => setTimeout(resolve, 5_000));
+    await route.continue();
+  });
+  return () => held;
+}
+
+/** The id of the guest's camera track, as the host receives it. */
+async function incomingTrackId(host: Page): Promise<string> {
+  const guestTile = host
+    .getByTestId("videoTile")
+    .filter({ has: host.getByTestId("name_tag").getByText("Guest") });
+  await expect(guestTile.locator("video")).toBeVisible({ timeout: 60_000 });
+  // Visible can come before the stream is attached.
+  let trackId: string | undefined;
+  await expect
+    .poll(async () => {
+      trackId = await guestTile
+        .locator("video")
+        .evaluate(
+          (video: HTMLVideoElement) =>
+            (video.srcObject as MediaStream | null)?.getVideoTracks()[0]?.id,
+        );
+      return trackId;
+    })
+    .toBeDefined();
+  return trackId!;
+}
+
+/** Waits for the picture to arrive, then finds no frame of the room since. */
+async function expectNoFrameOfTheRoom(
+  host: Page,
+  trackId: string,
+  since: number,
+  camera: Colour,
+  picture: Colour,
+): Promise<void> {
+  await expect
+    .poll(
+      async () => {
+        const frames = (await framesOf(host, trackId)).slice(since);
+        // A black frame, as a track starts, is nearer the picture than the
+        // camera, but shows neither.
+        return frames.some(
+          (f) =>
+            distance(f, picture) <
+            Math.min(distance(f, camera), distance(f, [0, 0, 0])),
+        );
+      },
+      { timeout: 60_000 },
+    )
+    .toBe(true);
+  const frames = (await framesOf(host, trackId)).slice(since);
+  expect(
+    frames.filter((f) => distance(f, camera) < distance(f, picture)),
+  ).toEqual([]);
+}
+
+/**
+ * Records the mean colour of every frame of every video track the page
+ * receives, from the moment it arrives: a tile may attach it later than its
+ * first frame.
+ */
+async function recordIncomingFrames(page: Page): Promise<void> {
+  await page.addInitScript(() => {
+    const frames: Record<string, [number, number, number][]> = {};
+    (window as unknown as { receivedFrames: typeof frames }).receivedFrames =
+      frames;
+    const record = (track: MediaStreamTrack): void => {
+      if (track.kind !== "video" || frames[track.id]) return;
+      const seen: [number, number, number][] = (frames[track.id] = []);
+      const video = document.createElement("video");
+      video.muted = true;
+      video.srcObject = new MediaStream([track]);
+      const canvas = document.createElement("canvas");
+      canvas.width = canvas.height = 16;
+      const context = canvas.getContext("2d", { willReadFrequently: true })!;
+      const step = (): void => {
+        context.drawImage(video, 0, 0, 16, 16);
+        const { data } = context.getImageData(0, 0, 16, 16);
+        const sum = [0, 0, 0];
+        for (let i = 0; i < data.length; i += 4)
+          for (let c = 0; c < 3; c++) sum[c] += data[i + c];
+        seen.push(sum.map((v) => v / (data.length / 4)) as Colour);
+        video.requestVideoFrameCallback(step);
+      };
+      video.requestVideoFrameCallback(step);
+      void video.play();
+    };
+    const Connection = window.RTCPeerConnection;
+    window.RTCPeerConnection = class extends Connection {
+      public constructor(...args: ConstructorParameters<typeof Connection>) {
+        super(...args);
+        this.addEventListener("track", (e) => record(e.track));
+      }
+    };
+  });
+}
+
+async function framesOf(page: Page, trackId: string): Promise<Colour[]> {
+  return page.evaluate(
+    (id) =>
+      (
+        window as unknown as {
+          receivedFrames: Record<string, [number, number, number][]>;
+        }
+      ).receivedFrames[id] ?? [],
+    trackId,
+  );
 }

playwright/component/background-effects.spec.ts

@@ -0,0 +1,85 @@
+/*
+Copyright 2026 Element Creations Ltd.
+
+SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
+Please see LICENSE in the repository root for full details.
+*/
+
+import { expect, type Locator, type Page, test } from "@playwright/test";
+
+import { createUserAndRoom, resizeContainer, startHarness } from "./harness.ts";
+import { averageColour, cameraColour, expectWearing } from "../utils/colour.ts";
+
+// Background effects need WebGL2, and headless Firefox on a CI runner has none,
+// so it rightly offers none of them.
+test.skip(
+  ({ browserName }) => browserName === "firefox",
+  "Background effects need WebGL2, which headless Firefox on CI does not have",
+);
+
+/**
+ * Background effects with Element Call as a component in a host page: the
+ * pipeline's model and WebAssembly have to load from the component's bundle,
+ * and the portalled menu has to be sized against the call, not the window.
+ * Driven from the lobby, which builds the same menu and pipeline.
+ */
+
+// Sign-in, crypto setup and sync happen twice before anything shows.
+test.describe.configure({ timeout: 180_000 });
+
+test("puts a picture on the call's preview", async ({ page }) => {
+  const { username, roomId } = await createUserAndRoom("effects");
+  const panes = await startHarness(page, username, roomId);
+  const pane = panes.first();
+  await resizeContainer(pane.getByTestId("call-container"), {
+    width: 900,
+    height: 480,
+  });
+  await expect(pane.getByTestId("lobby_joinCall")).toBeVisible({
+    timeout: 60_000,
+  });
+  const preview = pane.locator("video").first();
+  const camera = await cameraColour(preview);
+
+  const tile = await openEffect(page, pane, "Background 1");
+  const picture = await averageColour(tile.locator("img"));
+  await tile.click();
+  await expect(tile).toHaveAttribute("aria-checked", "true");
+  await expectWearing(preview, picture, camera);
+});
+
+test("keeps every effect reachable in a small container", async ({ page }) => {
+  const { username, roomId } = await createUserAndRoom("effectsreach");
+  const panes = await startHarness(page, username, roomId);
+  const pane = panes.first();
+  const container = pane.getByTestId("call-container");
+  await resizeContainer(container, { width: 400, height: 360 });
+  await expect(pane.getByTestId("lobby_joinCall")).toBeVisible({
+    timeout: 60_000,
+  });
+
+  const last = await openEffect(page, pane, "Background 2");
+  const list = page.locator("[role='menu'] div[role='none']").first();
+  expect((await list.boundingBox())!.height).toBeLessThanOrEqual(
+    (await container.boundingBox())!.height,
+  );
+  await last.scrollIntoViewIfNeeded();
+  await expect(last).toBeInViewport({ ratio: 1 });
+  await last.click();
+  await expect(last).toHaveAttribute("aria-checked", "true");
+});
+
+/** Opens a component's camera menu and returns one of its effects. */
+async function openEffect(
+  page: Page,
+  pane: Locator,
+  name: string,
+): Promise<Locator> {
+  await pane
+    .getByRole("button", { name: "Camera", exact: true })
+    .click({ timeout: 60_000 });
+  // Portalled out of the pane, so found on the page.
+  return page
+    .getByRole("group", { name: "Background effects" })
+    .getByRole("menuitemradio", { name });
+}

playwright/fixtures/widget-user.ts

@@ -29,47 +29,10 @@ export interface MyFixtures {
   addUser: (username: string, host: string) => Promise<UserBaseFixture>;
 }
 
-// Minimal config.json for the local element-web instance
-const CONFIG_JSON = {
-  default_server_config: {
-    "m.homeserver": {
-      base_url: "https://synapse.m.localhost",
-      server_name: "synapse.m.localhost",
-    },
-  },
-
-  element_call: {
-    participant_limit: 8,
-    brand: "Element Call",
-  },
-
-  // The default language is set here for test consistency
-  setting_defaults: {
-    language: "en-GB",
-    feature_group_calls: true,
-  },
-
-  // the location tests want a map style url.
-  map_style_url:
-    "https://api.maptiler.com/maps/streets/style.json?key=fU3vlMsMn4Jb6dnEIFsx",
-
-  features: {
-    // We don't want to go through the feature announcement during the e2e test
-    feature_release_announcement: false,
-    feature_element_call_video_rooms: true,
-    feature_video_rooms: true,
-    feature_group_calls: true,
-  },
-};
-
 export const widgetTest = test.extend<MyFixtures>({
   // allow per-test override: `widgetTest.use({ callType: "dm" })`
   callType: ["room", { option: true }],
-  asWidget: async ({ browser, context, callType }, pUse) => {
-    await context.route(`http://localhost:8081/config.json*`, async (route) => {
-      await route.fulfill({ json: CONFIG_JSON });
-    });
-
+  asWidget: async ({ browser, callType }, pUse) => {
     const brooksDisplayName = `brooks_${Date.now()}`;
     const whistlerDisplayName = `whistler_${Date.now()}`;
 
@@ -109,15 +72,7 @@ export const widgetTest = test.extend<MyFixtures>({
       await TestHelpers.dismissInviteUnknownUserModal(ewPage1);
 
       // Accept the invite
-      await TestHelpers.closeReleaseAnnouncement(
-        ewPage2,
-        "Introducing Sections",
-      );
-      await TestHelpers.expandAllSections(ewPage2);
-      await expect(
-        TestHelpers.roomListItem(ewPage2, "Welcome Room"),
-      ).toBeVisible();
-      await TestHelpers.roomListItem(ewPage2, "Welcome Room").click();
+      await TestHelpers.openRoomInvite(ewPage2, "Welcome Room");
       await ewPage2.getByRole("button", { name: "Accept" }).click();
       await expect(
         ewPage2
@@ -125,17 +80,7 @@ export const widgetTest = test.extend<MyFixtures>({
           .getByRole("heading", { name: "Welcome Room" }),
       ).toBeVisible();
     } else if (callType === "dm") {
-      await TestHelpers.closeReleaseAnnouncement(
-        ewPage1,
-        "Introducing Sections",
-      );
-
-      await ewPage1
-        .getByRole("navigation", { name: "Room list" })
-        .getByRole("button", { name: "New", exact: true })
-        .click();
-
-      await ewPage1.getByRole("menuitem", { name: "Start chat" }).click();
+      await TestHelpers.chooseFromRoomListNewMenu(ewPage1, "Start chat");
       await ewPage1.getByRole("textbox", { name: "Search" }).click();
       await ewPage1.getByRole("textbox", { name: "Search" }).fill(whistlerMxId);
       await ewPage1.getByRole("button", { name: "Go" }).click();
@@ -157,12 +102,7 @@ export const widgetTest = test.extend<MyFixtures>({
       ).toBeVisible();
 
       // Accept the DM invite from brooks
-      await TestHelpers.closeReleaseAnnouncement(
-        ewPage2,
-        "Introducing Sections",
-      );
-      await TestHelpers.expandAllSections(ewPage2);
-      await TestHelpers.roomListItem(ewPage2, brooksDisplayName).click();
+      await TestHelpers.openRoomInvite(ewPage2, brooksDisplayName);
       await ewPage2.getByRole("button", { name: "Start chatting" }).click();
     }
 
@@ -187,13 +127,14 @@ export const widgetTest = test.extend<MyFixtures>({
    * Provide a way to add additional users within a test.
    * The returned user will be registered on the default homeserver, the name will be made unique by appending a timestamp.
    */
-  addUser: async ({ browser }, use) => {
+  addUser: async ({ browser }, use, testInfo) => {
     await use(
       async (
         username: string,
         host: string = HOST1,
       ): Promise<UserBaseFixture> => {
-        const uniqueSuffix = Date.now();
+        // Tests in parallel workers can reach this in the same millisecond.
+        const uniqueSuffix = `${Date.now()}_${testInfo.parallelIndex}`;
         const { page, clientHandle, mxId } = await TestHelpers.registerUser(
           browser,
           `${username.toLowerCase()}_${uniqueSuffix}`,

playwright/sdk/data.spec.ts

@@ -11,25 +11,18 @@ import { startPair, tileOf } from "./harness";
 
 test.describe.configure({ timeout: 300_000 });
 
-test("a message sent on a data track reaches the peer, and only the peer", async ({
+test("a message sent beside the media reaches the peer, and only the peer", async ({
   browser,
 }) => {
   const { pages, users } = await startPair(browser, "sdkdata");
   const [sender, receiver] = pages;
   // Both are in the call before anything is sent, so the receiver knows the
-  // sender as a member
+  // sender as a member and does not drop the message
   for (const page of pages)
     await expect(page.getByTestId("member")).toHaveCount(2, {
       timeout: 60_000,
     });
-  // The receiver listens on the sender's track, published with the join
-  await expect(tileOf(receiver, users[0])).toHaveAttribute(
-    "data-chat",
-    "true",
-    {
-      timeout: 30_000,
-    },
-  );
+  await expect(tileOf(receiver, users[0])).toBeVisible();
 
   await sender.getByPlaceholder("message").fill("hello from the SDK");
   await sender.getByRole("button", { name: "Send" }).click();
@@ -41,9 +34,7 @@ test("a message sent on a data track reaches the peer, and only the peer", async
       timeout: 30_000,
     },
   );
-  await expect(message).toHaveAttribute("data-name", "chat");
-  // Decrypted with the sender's key, at the key index the stream carried
-  await expect(message).toHaveAttribute("data-encrypted", "true");
+  await expect(message).toHaveAttribute("data-topic", "chat");
   await expect(message).toHaveAttribute("data-user-id", users[0].userId);
   // Our own messages are not echoed back
   await expect(sender.getByTestId("message")).toHaveCount(0);

playwright/utils/colour.ts

@@ -0,0 +1,55 @@
+/*
+Copyright 2026 Element Creations Ltd.
+
+SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
+Please see LICENSE in the repository root for full details.
+*/
+
+import { expect, type Locator } from "@playwright/test";
+
+export type Colour = [number, number, number];
+
+/** The camera's colour, once the preview is showing it rather than nothing. */
+export async function cameraColour(preview: Locator): Promise<Colour> {
+  await expect
+    .poll(async () => Math.max(...(await averageColour(preview))))
+    .toBeGreaterThan(40);
+  return averageColour(preview);
+}
+
+/** The mean colour of a video's current frame or an image, drawn small. */
+export async function averageColour(element: Locator): Promise<Colour> {
+  return element.evaluate(
+    async (source: HTMLVideoElement | HTMLImageElement) => {
+      if (source instanceof HTMLImageElement) await source.decode();
+      const canvas = document.createElement("canvas");
+      canvas.width = canvas.height = 32;
+      const context = canvas.getContext("2d")!;
+      context.drawImage(source, 0, 0, 32, 32);
+      const { data } = context.getImageData(0, 0, 32, 32);
+      const sum = [0, 0, 0];
+      for (let i = 0; i < data.length; i += 4)
+        for (let c = 0; c < 3; c++) sum[c] += data[i + c];
+      const pixels = data.length / 4;
+      return sum.map((s) => s / pixels) as Colour;
+    },
+  );
+}
+
+export function distance(a: Colour, b: Colour): number {
+  return Math.hypot(a[0] - b[0], a[1] - b[1], a[2] - b[2]);
+}
+
+/** Waits until a preview shows a picture rather than the camera. */
+export async function expectWearing(
+  preview: Locator,
+  picture: Colour,
+  camera: Colour,
+): Promise<void> {
+  // Long enough for the first effect of a session to be built.
+  await expect
+    .poll(async () => distance(await averageColour(preview), picture), {
+      timeout: 60_000,
+    })
+    .toBeLessThan(distance(camera, picture) / 2);
+}

playwright/widget/background-effects.spec.ts

@@ -0,0 +1,43 @@
+/*
+Copyright 2026 Element Creations Ltd.
+
+SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
+Please see LICENSE in the repository root for full details.
+*/
+
+import { expect, test } from "@playwright/test";
+
+import { widgetTest } from "../fixtures/widget-user.ts";
+import { TestHelpers } from "./test-helpers.ts";
+import { averageColour, cameraColour, expectWearing } from "../utils/colour.ts";
+
+// Background effects need WebGL2, and headless Firefox on a CI runner has none,
+// so it rightly offers none of them.
+test.skip(
+  ({ browserName }) => browserName === "firefox",
+  "Background effects need WebGL2, which headless Firefox on CI does not have",
+);
+
+widgetTest(
+  "puts a picture on the preview inside Element Web",
+  async ({ asWidget }) => {
+    test.slow();
+    const { brooks } = asWidget;
+    await TestHelpers.startCallInCurrentRoom(brooks.page, false);
+    const frame = brooks.page
+      .locator('iframe[title="Element Call"]')
+      .contentFrame();
+    await expect(frame.getByTestId("lobby_joinCall")).toBeVisible();
+    const preview = frame.locator("video").first();
+    const camera = await cameraColour(preview);
+
+    await frame.getByRole("button", { name: "Camera", exact: true }).click();
+    const tile = frame
+      .getByRole("group", { name: "Background effects" })
+      .getByRole("menuitemradio", { name: "Background 1" });
+    const picture = await averageColour(tile.locator("img"));
+    await tile.click();
+    await expect(tile).toHaveAttribute("aria-checked", "true");
+    await expectWearing(preview, picture, camera);
+  },
+);

playwright/widget/embedded/build.setup.ts

@@ -0,0 +1,20 @@
+/*
+Copyright 2026 Element Creations Ltd.
+
+SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
+Please see LICENSE in the repository root for full details.
+*/
+
+import { test as setup } from "@playwright/test";
+import { execFileSync } from "node:child_process";
+import { mkdirSync } from "node:fs";
+
+const EMBEDDED_DIST = "embedded/web/dist";
+
+setup("build the embedded package", () => {
+  setup.setTimeout(10 * 60 * 1000);
+  mkdirSync(EMBEDDED_DIST, { recursive: true });
+  execFileSync("pnpm", ["build:embedded", "--outDir", EMBEDDED_DIST], {
+    stdio: "inherit",
+  });
+});

playwright/widget/embedded/config-json.spec.ts

@@ -0,0 +1,56 @@
+/*
+Copyright 2026 Element Creations Ltd.
+
+SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
+Please see LICENSE in the repository root for full details.
+*/
+
+import { expect, type Route } from "@playwright/test";
+
+import { widgetTest } from "../../fixtures/widget-user.ts";
+import { HOST2, TestHelpers } from "../test-helpers.ts";
+
+/** Where the other site's Element Web serves the embedded package from */
+const CONFIG_JSON = "**/widgets/element-call/config.json";
+
+const HOST_ANSWERS: Record<string, (route: Route) => Promise<void>> = {
+  "a 404": async (route) => route.fulfill({ status: 404 }),
+  "a failed fetch": async (route) => route.abort("failed"),
+  "an HTML page": async (route) =>
+    route.fulfill({
+      status: 200,
+      contentType: "text/html",
+      body: "<!doctype html><title>Element</title>",
+    }),
+};
+
+widgetTest.skip(
+  ({ browserName }) => browserName === "firefox",
+  "The widget suite does not run on Firefox, see the other specs here",
+);
+
+for (const [answer, respond] of Object.entries(HOST_ANSWERS)) {
+  widgetTest(
+    `reaches the lobby when config.json gets ${answer}`,
+    async ({ addUser }) => {
+      const { page } = await addUser("Brooks", HOST2);
+      await TestHelpers.createRoom("Config Room", page);
+
+      let answered = 0;
+      await page.route(CONFIG_JSON, async (route) => {
+        answered++;
+        await respond(route);
+      });
+
+      await TestHelpers.startCallInCurrentRoom(page);
+
+      await expect(
+        page
+          .locator('iframe[title="Element Call"]')
+          .contentFrame()
+          .getByTestId("lobby_joinCall"),
+      ).toBeVisible({ timeout: 15000 });
+      expect(answered).toBeGreaterThan(0);
+    },
+  );
+}

playwright/widget/test-helpers.ts

@@ -144,7 +144,11 @@ export class TestHelpers {
 
     await this.dismissStartupToasts(page);
 
-    await TestHelpers.setDevToolElementCallDevUrl(page);
+    // The other site's Element Web opens the embedded package it serves itself
+    // (see docker-compose-playwright.yml), not the dev server's app.
+    if (host !== HOST2) {
+      await TestHelpers.setDevToolElementCallDevUrl(page);
+    }
 
     const clientHandle = await page.evaluateHandle(() =>
       window.mxMatrixClientPeg.get(),
@@ -153,29 +157,40 @@ export class TestHelpers {
     return { page, clientHandle, mxId };
   }
 
-  // Dismisses any toasts that appear on startup, such as "Failed to load service worker" or "Back up your chats".
-  // Toast can be stacked, and only the top one can be dismiss, so just look at what is on top and
-  // dismiss (if part of expected toats)
+  // Dismisses the toasts a fresh device gets after sign-in.
+  //
+  // Toasts stack and only the top one can be dismissed, so look
+  // at what is on top each time.
   public static async dismissStartupToasts(page: Page): Promise<void> {
-    const expectedToasts = [
+    const expectedToasts: {
+      title: string;
+      button: string;
+      confirm?: string;
+    }[] = [
       { title: "Failed to load service worker", button: "OK" },
+      { title: "Verify this device", button: "Later" },
       { title: "Back up your chats", button: "Not now" },
-      { title: "Turn on key storage", button: "Dismiss" },
+      {
+        title: "Turn on key storage",
+        button: "Dismiss",
+        confirm: "Yes, dismiss",
+      },
+      { title: "Notifications", button: "Dismiss" },
       { title: "Element does not support this browser", button: "Dismiss" },
     ];
 
     const toast = page.locator(".mx_Toast_toast");
+    const toastTitle = toast.locator(".mx_Toast_title h2");
 
     // eslint-disable-next-line no-constant-condition
     while (true) {
       try {
         await toast.waitFor({ state: "visible", timeout: 700 });
-        const title = await toast.locator(".mx_Toast_title h2").textContent();
+        const title = await toastTitle.textContent();
+        if (!title) break;
 
         // Find the matching toast config
-        const toastConfig = expectedToasts.find((t) =>
-          title?.includes(t.title),
-        );
+        const toastConfig = expectedToasts.find((t) => title.includes(t.title));
 
         if (toastConfig) {
           // Bounded so that a renamed button leaves the toast in place and the
@@ -183,6 +198,16 @@ export class TestHelpers {
           await toast
             .getByRole("button", { name: toastConfig.button })
             .click({ timeout: 5000 });
+          if (toastConfig.confirm) {
+            const dialog = page.getByRole("dialog");
+            await dialog
+              .getByRole("button", { name: toastConfig.confirm })
+              .click({ timeout: 5000 });
+            await expect(dialog).toBeHidden({ timeout: 5000 });
+          }
+          // The same element shows the next toast a moment after the click, so
+          // reading it straight away acts on the dismissed one a second time
+          await expect(toastTitle).not.toHaveText(title, { timeout: 5000 });
         } else {
           // Unknown toast. We don't want to act on unknown toasts
           break;
@@ -194,20 +219,6 @@ export class TestHelpers {
     }
   }
 
-  public static async closeReleaseAnnouncement(
-    page: Page,
-    name: string,
-  ): Promise<void> {
-    try {
-      await page
-        .getByRole("dialog", { name })
-        .getByRole("button", { name: "OK" })
-        .click({ timeout: 2000 });
-    } catch {
-      // Announcement not shown; nothing to do
-    }
-  }
-
   public static async expandAllSections(page: Page): Promise<void> {
     try {
       await page
@@ -223,16 +234,7 @@ export class TestHelpers {
     page: Page,
     andInvite: string[] = [],
   ): Promise<void> {
-    await TestHelpers.closeReleaseAnnouncement(page, "Introducing Sections");
-
-    await page
-      .getByRole("navigation", { name: "Room list" })
-      .getByRole("button", { name: "New", exact: true })
-      .click();
-
-    await page.getByRole("menuitem", { name: "New Room" }).click({
-      timeout: 5000,
-    });
+    await TestHelpers.chooseFromRoomListNewMenu(page, "New Room");
     await page.getByRole("textbox", { name: "Name" }).fill(name);
     await page.getByRole("button", { name: "Create room" }).click();
     await expect(page.getByText("You created this room.")).toBeVisible({
@@ -259,6 +261,24 @@ export class TestHelpers {
     }
   }
 
+  /**
+   * Opens the room list's "New" menu and picks the given item.
+   *
+   * Driven by keyboard, as a toast arriving late sits over the button and
+   * swallows clicks.
+   */
+  public static async chooseFromRoomListNewMenu(
+    page: Page,
+    itemName: string,
+  ): Promise<void> {
+    await TestHelpers.dismissStartupToasts(page);
+    await page
+      .getByRole("navigation", { name: "Room list" })
+      .getByRole("button", { name: "New", exact: true })
+      .press("Enter");
+    await page.getByRole("menuitem", { name: itemName }).press("Enter");
+  }
+
   /**
    * Accepts a room invite using the room name.
    * Locatest the invite in the room list.
@@ -268,9 +288,7 @@ export class TestHelpers {
     roomName: string,
     page: Page,
   ): Promise<void> {
-    await TestHelpers.closeReleaseAnnouncement(page, "Introducing Sections");
-    await TestHelpers.expandAllSections(page);
-    await TestHelpers.roomListItem(page, roomName).click({ timeout: 10000 });
+    await TestHelpers.openRoomInvite(page, roomName);
     await page.getByRole("button", { name: "Accept" }).click({
       timeout: 5000,
     });
@@ -376,6 +394,28 @@ export class TestHelpers {
     return page.locator(`[aria-label^="Open room ${roomName}"]`);
   }
 
+  /**
+   * Opens a pending invite from the room list by its room name.
+   *
+   * Element Web collapses the Invites section every time it appears, so it is
+   * expanded here once the invite has arrived.
+   */
+  public static async openRoomInvite(
+    page: Page,
+    roomName: string,
+  ): Promise<void> {
+    const invitesSection = page.getByRole("button", {
+      name: "Toggle Invites section",
+    });
+    await expect(invitesSection).toBeVisible({ timeout: 10000 });
+    // Toasts sit over the top of the room list, where this header is.
+    await TestHelpers.dismissStartupToasts(page);
+    if ((await invitesSection.getAttribute("aria-expanded")) !== "true") {
+      await invitesSection.click();
+    }
+    await TestHelpers.roomListItem(page, roomName).click({ timeout: 10000 });
+  }
+
   /**
    * Switches to a room in the room list by its name.
    * @param page - The EW page

pnpm-lock.yaml

@@ -8,7 +8,7 @@ overrides:
   '@livekit/components-core>rxjs': ^7.8.1
   '@livekit/track-processors>@mediapipe/tasks-vision': ^0.10.18
   tar: ^7.5.11
-  minimatch: ^10.2.3
+  minimatch: ^11.0.0
   glob: ^10.5.0
   qs: ^6.15.2
   js-yaml: ^4.2.0
@@ -160,6 +160,9 @@ importers:
       eslint-plugin-storybook:
         specifier: ^10.3.6
         version: 10.6.2(eslint@8.57.1(supports-color@7.2.0))(supports-color@7.2.0)(typescript@5.9.3)
+      fake-indexeddb:
+        specifier: ^6.2.5
+        version: 6.2.5
       fetch-mock:
         specifier: 11.1.5
         version: 11.1.5(node-fetch@2.7.0)
@@ -188,8 +191,8 @@ importers:
         specifier: ^1.9.1
         version: 1.9.2
       matrix-js-sdk:
-        specifier: github:matrix-org/matrix-js-sdk#a9ef09fbf2f1644c8663d0aeaf6a921cd16e7b01
-        version: https://codeload.github.com/matrix-org/matrix-js-sdk/tar.gz/a9ef09fbf2f1644c8663d0aeaf6a921cd16e7b01
+        specifier: github:matrix-org/matrix-js-sdk#10e4faabbb49baca655492d523b58faa9eea04b9
+        version: https://codeload.github.com/matrix-org/matrix-js-sdk/tar.gz/10e4faabbb49baca655492d523b58faa9eea04b9
       matrix-widget-api:
         specifier: ^1.18.0
         version: 1.20.0
@@ -1142,6 +1145,9 @@ packages:
     resolution: {integrity: sha512-O8jcjabXaleOG9DQ0+ARXWZBTfnP4WNAqzuiJK7ll44AmxGKv/J2M4TPjxjY3znBCfvBXFzucm1twdyFybFqEA==}
     engines: {node: '>=12'}
 
+  '@isaacs/nonrecursive-glob-match@1.0.3':
+    resolution: {integrity: sha512-SI7kyKHq4XXDRozw+r9GlRZkia1ZkFrpLW98r2IC2Bpr8YkFGE3fvjzmxCG0x78A++69HmDNrDvSMYBZmHGpKA==}
+
   '@joshwooding/vite-plugin-react-docgen-typescript@0.7.0':
     resolution: {integrity: sha512-qvsTEwEFefhdirGOPnu9Wp6ChfIwy2dBCRuETU3uE+4cC+PFoxMSiiEhxk4lOluA34eARHA0OxqsEUYDqRMgeQ==}
     peerDependencies:
@@ -1189,8 +1195,8 @@ packages:
       '@types/dom-mediacapture-transform': ^0.1.9
       livekit-client: ^1.12.0 || ^2.1.0
 
-  '@matrix-org/matrix-sdk-crypto-wasm@18.9.0':
-    resolution: {integrity: sha512-NtLzNDTEfNASBjNCTGZHuk7N0jrQhS6Zx2CM857rCHZYYh/rpbKGQNrJ7azktm4S1P5Jy3WU3nwJTGohGw26qQ==}
+  '@matrix-org/matrix-sdk-crypto-wasm@18.9.2':
+    resolution: {integrity: sha512-GHeuSeb5Fj6Wg2+NE/WoLJJs9U3nOzttO+2sj7lOaS5gNBpGIksc48N/Q/kK/Z+Lxh7YMhopB7M8b6HyASXnGQ==}
     engines: {node: '>= 18'}
 
   '@mdx-js/react@3.1.1':
@@ -3527,8 +3533,8 @@ packages:
   boolbase@1.0.0:
     resolution: {integrity: sha512-JZOSA7Mo9sNGB8+UjSgzdLtokWAky1zbztM3WRLCbZ70/3cTANmQmOdR7y2g+J0e2WXywy1yS468tY+IruqEww==}
 
-  brace-expansion@5.0.9:
-    resolution: {integrity: sha512-ScQ4IuvIEF1TMlP7Zt+vjJ//9zlPb2SDcxWxM3bk8s6t6GGdJ7KO1dCcTidOPJKePW30LE/2cT7wCyPho9/Wxg==}
+  brace-expansion@5.0.12:
+    resolution: {integrity: sha512-YovQ3rzhaLMIrDjNDMkNS01tea93qhEhG5xy8f6+R0l+dw3Ki+5sCoIoI942iuLZTHWogWktgwVDhU09iNEimQ==}
     engines: {node: 20 || >=22}
 
   braces@3.0.3:
@@ -4048,6 +4054,10 @@ packages:
     resolution: {integrity: sha512-KfYbmpRm0VbLjEvVa9yGwCi9GI34xvi7A/HXYWQO65CSD2u3MczUJSuwXKFIxlGsgBQizV9q5J9NHj4VG0n+pA==}
     engines: {node: '>=12.0.0'}
 
+  fake-indexeddb@6.2.5:
+    resolution: {integrity: sha512-CGnyrvbhPlWYMngksqrSSUT1BAVP49dZocrHuK0SvtR0D5TMs5wP0o3j7jexDJW01KSadjBp1M/71o/KR3nD1w==}
+    engines: {node: '>=18'}
+
   fast-deep-equal@3.1.3:
     resolution: {integrity: sha512-f3qQ9oQy9j2AhBe/H9VC91wLmKBCCU/gDOnKNAYG5hswO7BLKj09Hc5HYNz9cGI++xlpDCIgDaitVs03ATR84Q==}
 
@@ -4724,9 +4734,9 @@ packages:
   matrix-events-sdk@0.0.1:
     resolution: {integrity: sha512-1QEOsXO+bhyCroIe2/A5OwaxHvBm7EsSQ46DEDn8RBIfQwN5HWBpFvyWWR4QY0KHPPnnJdI99wgRiAl7Ad5qaA==}
 
-  matrix-js-sdk@https://codeload.github.com/matrix-org/matrix-js-sdk/tar.gz/a9ef09fbf2f1644c8663d0aeaf6a921cd16e7b01:
-    resolution: {gitHosted: true, integrity: sha512-ZAhn/zB44MgrXqUzi9ffSFcmZY3+2nx7bEgfEJR7chYDFyT/XmlmfCJx7Ar4rOTAYZJRVnMxrEwiEHGDapUi0Q==, tarball: https://codeload.github.com/matrix-org/matrix-js-sdk/tar.gz/a9ef09fbf2f1644c8663d0aeaf6a921cd16e7b01}
-    version: 45.0.0
+  matrix-js-sdk@https://codeload.github.com/matrix-org/matrix-js-sdk/tar.gz/10e4faabbb49baca655492d523b58faa9eea04b9:
+    resolution: {gitHosted: true, integrity: sha512-7cbPN96wGt93B73jZieW2HBtTnasgKJ7wzTgiV0SjwkNyb50EK3vDa17LdSJpyOwEjFP5edyPRprk865HQJqww==, tarball: https://codeload.github.com/matrix-org/matrix-js-sdk/tar.gz/10e4faabbb49baca655492d523b58faa9eea04b9}
+    version: 45.1.0
     engines: {node: '>=22.0.0'}
 
   matrix-widget-api@1.20.0:
@@ -4761,9 +4771,9 @@ packages:
   minimalistic-crypto-utils@1.0.1:
     resolution: {integrity: sha512-JIYlbt6g8i5jKfJ3xz7rF0LXmv2TkDxBLUkiBeZ7bAx4GnnNMr8xFpGnOxn6GhTEHx3SjRrZEoU+j04prX1ktg==}
 
-  minimatch@10.2.6:
-    resolution: {integrity: sha512-vpLQEs+VLCr1nU0BXS07maYoFwlDAH0gngQuuttxIwutDFEMHq2blX+8vpgxDdK3J1PwjCJiep77OitTZ4Ll1A==}
-    engines: {node: 18 || 20 || >=22}
+  minimatch@11.0.4:
+    resolution: {integrity: sha512-/UJ1dEoVQTjPNDh6SGlUo+ueLMmoHTas4q+8yaAR/5t6nLAIiBDJtoYUh20IYleix7ehiQkgczb84PE3uzHkxg==}
+    engines: {node: 20 || >=22}
 
   minimist@1.2.8:
     resolution: {integrity: sha512-2yyAR8qBkN3YuheJanUpWC5U3bb5osDywNB8RzDVlDwDHbocAJveqqj1u8+SVD7jkWT4yvsHCpWqqWqAxb0zCA==}
@@ -4936,8 +4946,8 @@ packages:
     resolution: {integrity: sha512-LaNjtRWUBY++zB5nE/NwcaoMylSPk+S+ZHNB1TzdbMJMny6dynpAGt7X/tl/QYq3TIeE6nxHppbo2LGymrG5Pw==}
     engines: {node: '>=10'}
 
-  p-retry@8.0.1:
-    resolution: {integrity: sha512-NAigyu8hfvJe7MsS18mnc4is0MZtau3QMdBklaJKK23oBQb6occO3UPM3vHmTckW8KhfyjMZaUOqdTFEYliHgg==}
+  p-retry@9.0.0:
+    resolution: {integrity: sha512-HuEats8gYn/UUYa5uyveyQGv75mQmwdFtuMgnZlS12dj/7bdnJSO6keaTjgcZUhvkANTj5EO3lACUmV3xmgj0Q==}
     engines: {node: '>=22'}
 
   p-try@2.2.0:
@@ -5308,6 +5318,10 @@ packages:
   randomfill@1.0.4:
     resolution: {integrity: sha512-87lcbR8+MhcWcUiQ+9e+Rwx8MyR2P7qnt15ynUlbm3TU/fjbgz4GsvfSUDTemtCCtVCqb4ZcEFlyPNTh9bBTLw==}
 
+  re2js@2.9.1:
+    resolution: {integrity: sha512-JIT3bEEUZTOR2YS1walNEIfH4cF/cQeZcBUFq7ldqO6lR6g0X5CBq/S8rsa9omzZcsNf8qc36jCkWpKKtncrZg==}
+    engines: {node: '>=20.0.0'}
+
   react-docgen-typescript@2.4.0:
     resolution: {integrity: sha512-ZtAp5XTO5HRzQctjPU0ybY0RRCQO19X/8fxn3w7y2VVTUbGHDKULPTL4ky3vB05euSgG5NpALhEhDPvQ56wvXg==}
     peerDependencies:
@@ -6895,7 +6909,7 @@ snapshots:
       ignore: 5.3.2
       import-fresh: 3.3.1
       js-yaml: 4.3.1
-      minimatch: 10.2.6
+      minimatch: 11.0.4
       strip-json-comments: 3.1.1
     transitivePeerDependencies:
       - supports-color
@@ -6974,7 +6988,7 @@ snapshots:
     dependencies:
       '@humanwhocodes/object-schema': 2.0.3
       debug: 4.4.3(supports-color@7.2.0)
-      minimatch: 10.2.6
+      minimatch: 11.0.4
     transitivePeerDependencies:
       - supports-color
 
@@ -7110,6 +7124,8 @@ snapshots:
       wrap-ansi: 8.1.0
       wrap-ansi-cjs: wrap-ansi@7.0.0
 
+  '@isaacs/nonrecursive-glob-match@1.0.3': {}
+
   '@joshwooding/vite-plugin-react-docgen-typescript@0.7.0(typescript@5.9.3)(vite@8.2.4(@types/node@24.13.3)(esbuild@0.28.2)(jiti@2.7.0)(sass@1.103.1)(terser@5.46.1)(yaml@2.9.0))':
     dependencies:
       glob: 10.5.0
@@ -7162,7 +7178,7 @@ snapshots:
       '@types/dom-mediacapture-transform': 0.1.11
       livekit-client: 2.23.0(@types/dom-mediacapture-record@1.0.22)
 
-  '@matrix-org/matrix-sdk-crypto-wasm@18.9.0': {}
+  '@matrix-org/matrix-sdk-crypto-wasm@18.9.2': {}
 
   '@mdx-js/react@3.1.1(@types/react@19.2.18)(react@19.3.1)':
     dependencies:
@@ -8769,7 +8785,7 @@ snapshots:
       '@typescript-eslint/types': 8.69.0
       '@typescript-eslint/visitor-keys': 8.69.0
       debug: 4.4.3(supports-color@7.2.0)
-      minimatch: 10.2.6
+      minimatch: 11.0.4
       semver: 7.8.5
       tinyglobby: 0.2.17
       ts-api-utils: 2.5.0(typescript@5.9.3)
@@ -8784,7 +8800,7 @@ snapshots:
       '@typescript-eslint/types': 8.72.0
       '@typescript-eslint/visitor-keys': 8.72.0
       debug: 4.4.3(supports-color@7.2.0)
-      minimatch: 10.2.6
+      minimatch: 11.0.4
       semver: 7.8.5
       tinyglobby: 0.2.17
       ts-api-utils: 2.5.0(typescript@5.9.3)
@@ -9109,7 +9125,7 @@ snapshots:
 
   boolbase@1.0.0: {}
 
-  brace-expansion@5.0.9:
+  brace-expansion@5.0.12:
     dependencies:
       balanced-match: 4.0.4
 
@@ -9654,7 +9670,7 @@ snapshots:
       json-stable-stringify-without-jsonify: 1.0.1
       levn: 0.4.1
       lodash.merge: 4.6.2
-      minimatch: 10.2.6
+      minimatch: 11.0.4
       natural-compare: 1.4.0
       optionator: 0.9.4
       strip-ansi: 6.0.1
@@ -9712,6 +9728,8 @@ snapshots:
 
   expect-type@1.4.0: {}
 
+  fake-indexeddb@6.2.5: {}
+
   fast-deep-equal@3.1.3: {}
 
   fast-glob@3.3.3:
@@ -9772,7 +9790,7 @@ snapshots:
 
   filelist@1.0.6:
     dependencies:
-      minimatch: 10.2.6
+      minimatch: 11.0.4
 
   fill-range@7.1.1:
     dependencies:
@@ -9872,7 +9890,7 @@ snapshots:
     dependencies:
       foreground-child: 3.3.1
       jackspeak: 3.4.3
-      minimatch: 10.2.6
+      minimatch: 11.0.4
       minipass: 7.1.3
       package-json-from-dist: 1.0.1
       path-scurry: 1.11.1
@@ -9997,7 +10015,7 @@ snapshots:
       jiti: 2.7.0
       jsonc-parser: 3.3.1
       magic-string: 1.2.3
-      minimatch: 10.2.6
+      minimatch: 11.0.4
       ora: 9.4.1
       react: 19.2.8
       react-i18next: 17.0.13(i18next@26.4.1(typescript@5.9.3))(react-dom@19.2.8(react@19.2.8))(react@19.2.8)(typescript@5.9.3)
@@ -10395,17 +10413,18 @@ snapshots:
 
   matrix-events-sdk@0.0.1: {}
 
-  matrix-js-sdk@https://codeload.github.com/matrix-org/matrix-js-sdk/tar.gz/a9ef09fbf2f1644c8663d0aeaf6a921cd16e7b01:
+  matrix-js-sdk@https://codeload.github.com/matrix-org/matrix-js-sdk/tar.gz/10e4faabbb49baca655492d523b58faa9eea04b9:
     dependencies:
       '@babel/runtime': 8.0.8
-      '@matrix-org/matrix-sdk-crypto-wasm': 18.9.0
+      '@matrix-org/matrix-sdk-crypto-wasm': 18.9.2
       another-json: 0.2.0
       bs58: 6.0.0
       content-type: 3.1.1
       loglevel: 1.9.2
       matrix-events-sdk: 0.0.1
       matrix-widget-api: 1.20.0
-      p-retry: 8.0.1
+      p-retry: 9.0.0
+      re2js: 2.9.1
       sdp-transform: 3.0.0
       unhomoglyph: 1.0.6
 
@@ -10440,9 +10459,10 @@ snapshots:
 
   minimalistic-crypto-utils@1.0.1: {}
 
-  minimatch@10.2.6:
+  minimatch@11.0.4:
     dependencies:
-      brace-expansion: 5.0.9
+      '@isaacs/nonrecursive-glob-match': 1.0.3
+      brace-expansion: 5.0.12
 
   minimist@1.2.8: {}
 
@@ -10726,7 +10746,7 @@ snapshots:
     dependencies:
       p-limit: 3.1.0
 
-  p-retry@8.0.1:
+  p-retry@9.0.0:
     dependencies:
       is-network-error: 1.3.2
 
@@ -11150,6 +11170,8 @@ snapshots:
       randombytes: 2.1.0
       safe-buffer: 5.2.1
 
+  re2js@2.9.1: {}
+
   react-docgen-typescript@2.4.0(typescript@5.9.3):
     dependencies:
       typescript: 5.9.3

pnpm-workspace.yaml

@@ -27,7 +27,7 @@ overrides:
   # Security fixes:
   # - https://github.com/advisories/GHSA-7r86-cg39-jmmj
   # - https://github.com/advisories/GHSA-23c5-xmqv-rm74
-  "minimatch": "^10.2.3"
+  "minimatch": "^11.0.0"
   # Security fix: https://github.com/element-hq/element-call/security/dependabot/109
   "glob": "^10.5.0"
   # Security fixes:

sdk-target-based-on-call-view-model/main.ts

@@ -16,25 +16,11 @@ Please see LICENSE in the repository root for full details.
  */
 
 import { logger as rootLogger } from "matrix-js-sdk/lib/logger";
-import {
-  distinct,
-  distinctUntilChanged,
-  EMPTY,
-  filter,
-  map,
-  mergeMap,
-  type Observable,
-  of,
-  switchMap,
-  take,
-  takeUntil,
-} from "rxjs";
+import { EMPTY, filter, map, type Observable, of, switchMap, take } from "rxjs";
 import {
   type Behavior,
   createRTCSlot,
-  type DataTrack,
   E2eeType,
-  type LocalDataTrack,
   type LocalRTCMember,
   ObservableScope,
   type RemoteRTCMember,
@@ -59,7 +45,7 @@ import { getUrlParams } from "../src/UrlParams";
 import { observeElementSize$ } from "../src/utils/elementSize";
 import { initializeWidget } from "../src/widget";
 
-/** The name of our data track: the topic this bundle has always used, so that old and new builds talk. */
+/** The data channel topic this bundle has always used, so that old and new builds talk. */
 const TOPIC = "matrixRTC";
 
 export interface MatrixRTCSdk {
@@ -73,9 +59,9 @@ export interface MatrixRTCSdk {
   localMember$: Behavior<LocalRTCMember | null>;
   /** The other members of the slot, with the media the participation carries for them. */
   remoteMembers$: Behavior<RemoteRTCMember[]>;
-  /** What other members sent with `sendData`, on their data track. */
+  /** What other members sent with `sendData`. */
   data$: Observable<{ rtcBackendIdentity: string; data: string }>;
-  /** Sends on our data track, published with the first message. Rejects while not joined. */
+  /** Sends to every member on our transport. Rejects while not joined. */
   sendData: (data: unknown) => Promise<void>;
   sendRoomMessage: (message: string) => Promise<void>;
 }
@@ -114,9 +100,6 @@ export async function createMatrixRTCSdk(
     id,
   });
   let vm: CallViewModel | undefined;
-  let dataTrack: Promise<LocalDataTrack> | undefined;
-  const encoder = new TextEncoder();
-  const decoder = new TextDecoder();
   const failed =
     (what: string) =>
     (e: unknown): void =>
@@ -132,8 +115,6 @@ export async function createMatrixRTCSdk(
       ),
     );
 
-  const remoteMembers$ = over((p) => p.remoteMembers$, []);
-
   return {
     join: (): void => {
       if (slot.participation$.value !== null) return;
@@ -141,7 +122,6 @@ export async function createMatrixRTCSdk(
         widget.api
           .setAlwaysOnScreen(true)
           .catch(failed("Failed to make the widget sticky"));
-      dataTrack = undefined;
       const participation = slot.join({
         ...rtcParticipationOptions(urlParams),
         publish: initialPublishRequests(muteStates, mediaDevices, capture),
@@ -189,40 +169,20 @@ export async function createMatrixRTCSdk(
       false,
     ),
     localMember$: over((p) => p.localMember$, null),
-    remoteMembers$,
-    data$: remoteMembers$.pipe(
-      // Each member once, for as long as it stays: a data track is only
-      // subscribed while observed, so it is not dropped on every list change
-      mergeMap((members) => members),
-      distinct(),
-      mergeMap((member) =>
-        member.tracks$.pipe(
-          map((tracks) =>
-            tracks?.find(
-              (t): t is DataTrack => t.kind === "data" && t.name === TOPIC,
-            ),
-          ),
-          distinctUntilChanged(),
-          switchMap((track) => track?.data$ ?? EMPTY),
-          map((payload) => ({
-            rtcBackendIdentity: member.rtcBackendIdentity,
-            data: decoder.decode(payload),
-          })),
-          takeUntil(
-            remoteMembers$.pipe(filter((members) => !members.includes(member))),
-          ),
-        ),
-      ),
+    remoteMembers$: over((p) => p.remoteMembers$, []),
+    // Attested members only: the SDK has matched the sender
+    data$: slot.participation$.pipe(
+      switchMap((p) => p?.data$ ?? EMPTY),
+      filter(({ topic }) => topic === TOPIC),
+      map(({ member, text }) => ({
+        rtcBackendIdentity: member.rtcBackendIdentity,
+        data: text,
+      })),
     ),
     sendData: async (data): Promise<void> => {
       const participation = slot.participation$.value;
       if (participation === null) throw new Error("Not joined");
-      dataTrack ??= participation.publish({ source: "data", name: TOPIC });
-      const track = await dataTrack.catch((e: unknown) => {
-        dataTrack = undefined;
-        throw e;
-      });
-      await track.send(encoder.encode(JSON.stringify(data)));
+      await participation.sendData(TOPIC, JSON.stringify(data));
     },
     sendRoomMessage: async (message): Promise<void> => {
       await client.sendTextMessage(room.roomId, message);

sdk/SdkArchitecture.md

@@ -25,7 +25,7 @@ Call's `src/` to get there is listed in [`SdkMigration.md`](./SdkMigration.md).
 │                                                                              │
 │   public API, all Behaviors:                                                 │
 │     join() leave() state$                                                    │
-│     localMember$ remoteMembers$ memberCount$ publish(data)                   │
+│     localMember$ remoteMembers$ memberCount$ sendData() data$                │
 │     keyRotationSuppressed$ connectedTransports$                              │
 │                                                                              │
 │   per member    RTCMember   { id userId deviceId membership$ displayName$    │
@@ -48,7 +48,7 @@ Call's `src/` to get there is listed in [`SdkMigration.md`](./SdkMigration.md).
 │  │   (LocalMembership)       │ local.publish,  │ Publisher: local tracks,  │ │
 │  │ transport registry        │   setPublishing▶│   upstream paused until   │ │
 │  │   (TransportMetadata)     │ ◀─ connections$ │   joined                  │ │
-│  │                           │                 │ LivekitMemberMedia:       │ │
+│  │ data packet → member      │ ◀─ data$        │ LivekitMemberMedia:       │ │
 │  │                           │                 │   participant → tracks    │ │
 │  └───────────────────────────┘                 └───────────────────────────┘ │
 │                                                                              │
@@ -146,12 +146,12 @@ the sections below still describe `MatrixRTCClient` until that lands.
 | Word                        | Meaning here                                                                                                                                                                                                                                           | Elsewhere                                                                                                   |
 | --------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | ----------------------------------------------------------------------------------------------------------- |
 | slot                        | an `RTCSlot`: the namespace in a room that memberships join into, `application` plus `id`. It exists while the room does, with nobody in it too. Holds `members$`, its open or closed `status$`, and `join()`                                          | the js-sdk `MatrixRTCSession` is one per slot; the MSC4143 slot event                                       |
-| participation               | an `RTCParticipation`: the span between our `join()` of a slot and our `leave()`. Holds the connection and its `state$`, `localMember$`, `remoteMembers$`, and the connected transports. Made by `slot.join()`, never reused                           | "session" is not used here, because in the js-sdk it means the slot                                         |
+| participation               | an `RTCParticipation`: the span between our `join()` of a slot and our `leave()`. Holds the connection and its `state$`, `localMember$`, `remoteMembers$`, the connected transports and the data channel. Made by `slot.join()`, never reused          | "session" is not used here, because in the js-sdk it means the slot                                         |
 | member                      | an `RTCMember`: one membership in a slot with what the SDK derives from it, `rtcBackendIdentity`, `userId`, `deviceId`, `memberId`, `displayName$`, `avatarUrl$`, `transport$` and `applicationData$`. No media. What the slot hands out in `members$` | the js-sdk `CallMembership` behind it, which never leaves the SDK; Element Call's old "matrixLivekitMember" |
 | local member, remote member | `LocalRTCMember` and `RemoteRTCMember`: an `RTCMember` plus its `MemberMedia`, which only a participation can carry. The local one's tracks carry the controls. What the participation hands out in `localMember$` and `remoteMembers$`                | LiveKit `LocalParticipant` and `RemoteParticipant`, which never leave the SDK                               |
 | media                       | a `MemberMedia`: what a member sends once it has arrived on its transport, `tracks$`, null while waiting, and `encryptionError$` beside it. The media backend supplies exactly these two fields per member                                             | Element Call's `MediaViewModel` is a view of it                                                             |
-| track                       | a `Track`: one publication of a member. A `MediaTrack` is audio or video, with `source`, `kind`, `id` and the behaviors on it; a `DataTrack` is a named channel of bytes. The `Local…` variants add the controls over our own, and `send` for data     | LiveKit `TrackPublication` and `Track`, which never leave the SDK                                           |
-| publish request             | a `PublishRequest`: a source, where to capture it from and how to encode it. Given at the join in `publish`, or later to `publish` on the participation. A `DataPublishRequest` names a data track, and only goes to `publish`                         |                                                                                                             |
+| track                       | a `MediaTrack`: one publication of a member, audio or video, with `source`, `kind`, `id` and the behaviors on it. `LocalAudioMediaTrack` and `LocalVideoMediaTrack` add the controls over our own                                                      | LiveKit `TrackPublication` and `Track`, which never leave the SDK                                           |
+| publish request             | a `PublishRequest`: a source, where to capture it from and how to encode it. Given at the join in `publish`, or later to `publish` on the participation                                                                                                |                                                                                                             |
 | attach, detach              | handing a `<video>` or `<audio>` element to a track and taking it back. The SDK owns the stream and the observers on the element                                                                                                                       | LiveKit `Track.attach`                                                                                      |
 | transport                   | an `RTCTransport`: where media is exchanged, a LiveKit service url today. Carries the raw js-sdk `Transport` from the membership and, in `resolved$`, what the backend fetched to connect to it                                                        | MSC4143 "focus"                                                                                             |
 | media backend               | a `MediaBackend`: what carries the media, behind `sdk/src/media-backend/api.ts`. One per participation, chosen with `backend` in the join options; LiveKit under `sdk/src/media-backend/livekit/` is the one that exists                               | "SFU", a LiveKit room, a peer connection                                                                    |
@@ -340,6 +340,28 @@ export interface MatrixRTCClient {
    * the browser's choice, never calls it.
    */
   setAudioOutputDeviceId(deviceId: string): Promise<void>;
+
+  /**
+   * Sends a short text to every member on the local transport, over a
+   * reliable data channel beside the media. A packet holds about 15 KiB;
+   * anything larger belongs in a room event. Rejects while the local
+   * transport is not connected. Encrypted on the wire like the media, but
+   * not end to end with the media key.
+   */
+  sendData(topic: string, text: string): Promise<void>;
+  /**
+   * What remote members sent with `sendData`, on every transport the client
+   * is connected to. A message from an identity that is not a member is
+   * dropped, so a host only ever hears from attested members.
+   */
+  data$: Observable<DataMessage>;
+}
+
+/** One `sendData` call as it arrives at a remote member. */
+export interface DataMessage {
+  member: RemoteRTCMember;
+  topic: string;
+  text: string;
 }
 ```
 
@@ -430,15 +452,11 @@ export interface LocalRTCMember extends RTCMember {
    * user closing the picker. One publication per source: publishing a source
    * again unmutes it.
    */
-  publish(request: DataPublishRequest): Promise<LocalDataTrack>;
   publish(
     request: PublishRequest,
   ): Promise<LocalAudioMediaTrack | LocalVideoMediaTrack>;
-  /**
-   * Removes one of our tracks, as `publish` handed it out; a screen share
-   * takes its audio with it. The track's controls and `send` reject from then on.
-   */
-  unpublish(track: LocalTrack): Promise<void>;
+  /** Removes one of our tracks; a screen share takes its audio with it. */
+  unpublish(id: string): Promise<void>;
 }
 ```
 
@@ -539,6 +557,8 @@ export interface MediaBackend {
     membership$: Behavior<RTCMembership>,
   ): MemberMediaFields;
   readonly connections$: Behavior<BackendConnection[]>; // transport, state, resolved; diagnostics
+  sendData(topic: string, text: string): Promise<void>;
+  readonly data$: Observable<DataPacket>;
 }
 ```
 
@@ -548,7 +568,8 @@ LiveKit backend only, a last resort of another member's SFU that lets us
 publish (`findRemotePublishLivekitTransport`, wired in by `RTCParticipation` rather
 than by the backend interface, since it is an MSC4195 matter), the membership
 state machine in `LocalMembership.ts` and its combination with
-`local.connectionState$` into `state$`, the choice of delayed leave timings, and the transport registry, which keys on the raw
+`local.connectionState$` into `state$`, the choice of delayed leave timings,
+mapping a data packet's sender to a member, and the transport registry, which keys on the raw
 transport serialised with sorted keys and derives `connectedTransports$` and each
 `TransportMetadata.resolved$` from `connections$`.
 
@@ -592,43 +613,6 @@ the local transport, and keys its connections on the transport plus the server
 name where the transport has a `url`. A JWT service is reached directly, so
 members of several homeservers advertising the same one share a connection.
 
-### Data tracks on LiveKit
-
-A data track is a track like the media, in `tracks$`, so the backend carries it
-the way it carries the media: `local.publish` takes a `DataPublishRequest`, and
-`mediaFor` lists a remote member's data tracks after its media. Its sender is
-attested by construction: a track only exists on a member. The session never
-sees a key, a frame or a stream.
-
-Every data track is one LiveKit data track, whose publication announces it: a
-receiver sees the track before its first message, and sees it go. LiveKit's
-data tracks are lossy only, so the LiveKit name says how the payloads travel
-(`dataTrackName.ts`):
-
-| Request           | LiveKit name      | Payloads                                                        |
-| ----------------- | ----------------- | --------------------------------------------------------------- |
-| `reliable: false` | `lossy:<name>`    | frames on the data track: unordered, no retransmits             |
-| `reliable: true`  | `reliable:<name>` | one byte stream per `send` on topic `reliable:<name>`, in order |
-
-A track without a prefix, from a plain LiveKit publisher, is read as lossy. A
-room takes one byte stream handler per topic, so `ByteStreams.ts` shares it
-between every reliable track on that topic and filters by sender identity.
-
-Encryption is LiveKit's. The rooms are built with `encryption` rather than
-`e2ee`, which encrypts the data channel as well as the media with the same
-E2EE manager and our key provider. The sender encrypts with its current key
-and puts the key index and IV on the wire: in each frame's E2EE extension for a
-lossy track, in each packet's `EncryptedPacket` for a stream. The receiver
-decrypts with the sender's key at that index. A frame that does not decrypt is
-dropped. A stream cannot be checked: LiveKit 2.23 sends an encrypted packet
-without its encryption type, so every received stream reads as unencrypted,
-and a cleartext stream injected on the way would be accepted as the sender's.
-
-A local track is published on LiveKit once publishing is allowed, like the
-media, and again on every new connection to the local transport; `publish`
-resolves with that first publication. The object a host holds outlives the
-connections.
-
 ## Media: `tracks$` and `MediaTrack`
 
 Every member has media. Today, in Element Call, that media _is_ a `livekit-client`
@@ -723,52 +707,14 @@ export interface LocalVideoMediaTrack extends VideoMediaTrack, LocalMediaTrack {
   setProcessor(processor: VideoProcessor | undefined): Promise<void>;
 }
 
-/** A named channel of bytes a member publishes beside its media. */
-export interface DataPublishRequest {
-  source: "data";
-  /** Unique per member; what receivers find the track by. */
-  name: string;
-  /** Whether every message arrives, in order. Default true. */
-  reliable?: boolean;
-}
-
-/** One data track of a member; it exists only on a member, so its sender is attested. */
-export interface DataTrack {
-  source: "data";
-  kind: "data";
-  id: string;
-  name: string;
-  reliable: boolean;
-  /** Whether payloads are end-to-end encrypted with the media key. */
-  encrypted: boolean;
-  /** What the member sends from now on, subscribed while observed. */
-  data$: Observable<Uint8Array>;
-}
-
-/** Our own data track; its `data$` replays what we sent. */
-export interface LocalDataTrack extends DataTrack {
-  send(payload: Uint8Array): Promise<void>;
-}
-
-export type Track = AudioMediaTrack | VideoMediaTrack | DataTrack;
-export type LocalTrack =
-  LocalAudioMediaTrack | LocalVideoMediaTrack | LocalDataTrack;
-
 export type EncryptionError = "MissingKey" | "InvalidKey";
 
 /** The member's first track of a source; undefined while there is none, or no media yet. */
 export function trackBySource$<S extends MediaSource>(
   scope: ObservableScope,
-  tracks$: Behavior<readonly (MediaTrack | DataTrack)[] | null>,
+  tracks$: Behavior<MediaTrack[] | null>,
   source: S,
 ): Behavior<TrackOfSource<S> | undefined>;
-
-/** The member's data track of this name; undefined while there is none. */
-export function dataTrackByName$(
-  scope: ObservableScope,
-  tracks$: Behavior<readonly (MediaTrack | DataTrack)[] | null>,
-  name: string,
-): Behavior<DataTrack | undefined>;
 ```
 
 ### Rendering: `attach` and `detach`
@@ -876,11 +822,13 @@ public API only.
 - **Developer panel.** `resolved$` on each connected transport covers what the
   panel shows today. Anything beyond that (LiveKit room state, connection
   quality) needs an opaque `debug$` per transport.
-- **Data before a receiver listens.** Nothing is replayed: a message sent
-  before a receiver has subscribed to the track, which it does once it has
-  seen the track published, does not reach it. Old builds of the legacy
-  widget bundle, which sent bare packets, do not hear new builds or the other
-  way round.
+- **Data beside the media.** `sendData`/`data$` ride on LiveKit's reliable data
+  packets: topic-agnostic, matched to members by identity, received on every
+  connection but sent only on the local transport, so a member on another
+  transport does not hear us. They are transport-encrypted, not end to end:
+  LiveKit can encrypt data packets with the media key, but that is not wired
+  through the key provider yet. A host that needs either reach or end-to-end
+  encryption uses room events.
 - **Unencrypted rooms with per-participant keys.** Keys only reach devices the
   crypto tracks, which are the members of encrypted rooms. If the SDK is to work
   in an unencrypted room, tracking the members' devices becomes its job.

sdk/dev/main.ts

@@ -12,22 +12,12 @@ Please see LICENSE in the repository root for full details.
  */
 
 import { logger } from "matrix-js-sdk/lib/logger";
-import {
-  combineLatest,
-  EMPTY,
-  map,
-  type Observable,
-  of,
-  switchMap,
-} from "rxjs";
+import { combineLatest, type Observable, of, switchMap } from "rxjs";
 import {
   type AudioMediaTrack,
   createRTCSlot,
-  dataTrackByName$,
   E2eeType,
-  type LocalAudioMediaTrack,
   type LocalRTCMember,
-  type LocalVideoMediaTrack,
   MatrixRTCMode,
   ObservableScope,
   type RemoteRTCMember,
@@ -92,7 +82,7 @@ async function start(
         state.kind === "failed" ? `Error: ${state.error.message}` : state.kind;
     });
     showMembers(scope, rtcParticipation);
-    showMessages(rtcParticipation);
+    showMessages(scope, rtcParticipation);
 
     toggle(buttons.microphone, async (enabled) =>
       setPublished(rtcParticipation, "microphone", enabled),
@@ -130,11 +120,10 @@ async function setPublished(
   enabled: boolean,
 ): Promise<boolean> {
   const track = rtcParticipation.localMember$.value?.tracks$.value?.find(
-    (t): t is LocalAudioMediaTrack | LocalVideoMediaTrack =>
-      t.source === source,
+    (t) => t.source === source,
   );
   if (track && source === "screenShare") {
-    if (!enabled) await rtcParticipation.unpublish(track);
+    if (!enabled) await rtcParticipation.unpublish(source);
     return enabled;
   }
   if (track) return track.setEnabled(enabled);
@@ -156,63 +145,30 @@ function toggle(
   };
 }
 
-/**
- * Publishes our "chat" data track with the join, so that the others hear the
- * first message, and sends what the form holds on it. What arrives is listed
- * per member, in `memberTile`.
- */
-function showMessages(rtcParticipation: RTCParticipation): void {
-  const encoder = new TextEncoder();
-  const chat = rtcParticipation.publish({ source: "data", name: "chat" });
-  chat.catch((e: unknown) => {
-    status.textContent = `Error: ${e}`;
-  });
+/** Sends what the form holds on the "chat" topic, and lists what arrives. */
+function showMessages(
+  scope: ObservableScope,
+  rtcParticipation: RTCParticipation,
+): void {
   dataForm.hidden = false;
   dataForm.onsubmit = (event): void => {
     event.preventDefault();
     const text = new FormData(dataForm).get("text") as string;
-    chat
-      .then(async (track) => track.send(encoder.encode(text)))
-      .then(
-        () => dataForm.reset(),
-        (e: unknown) => {
-          status.textContent = `Error: ${e}`;
-        },
-      );
+    rtcParticipation.sendData("chat", text).then(
+      () => dataForm.reset(),
+      (e: unknown) => {
+        status.textContent = `Error: ${e}`;
+      },
+    );
   };
-}
-
-/**
- * Lists what a remote member sends on its "chat" data track, and marks its
- * tile while it has one.
- */
-function listMessages(
-  scope: ObservableScope,
-  member: RemoteRTCMember,
-  tile: HTMLElement,
-): void {
-  const decoder = new TextDecoder();
-  const chat$ = dataTrackByName$(scope, member.tracks$, "chat");
-  chat$.pipe(scope.bind()).subscribe((track) => {
-    tile.dataset.chat = String(track !== undefined);
-  });
-  chat$
-    .pipe(
-      switchMap(
-        (track) =>
-          track?.data$.pipe(
-            map((payload) => ({ payload, encrypted: track.encrypted })),
-          ) ?? EMPTY,
-      ),
-      scope.bind(),
-    )
-    .subscribe(({ payload, encrypted }) => {
+  rtcParticipation.data$
+    .pipe(scope.bind())
+    .subscribe(({ member, topic, text }) => {
       const line = messages.appendChild(document.createElement("li"));
       line.dataset.testid = "message";
-      line.dataset.name = "chat";
-      line.dataset.encrypted = String(encrypted);
+      line.dataset.topic = topic;
       line.dataset.userId = member.userId;
-      line.textContent = `${member.displayName$.value}: ${decoder.decode(payload)}`;
+      line.textContent = `${member.displayName$.value}: ${text}`;
     });
 }
 
@@ -262,14 +218,12 @@ function memberTile(
     tile.appendChild(document.createElement("video")),
   );
   // Our own microphone would only echo
-  if (!member.local) {
+  if (!member.local)
     render(
       scope,
       trackBySource$(scope, member.tracks$, "microphone"),
       tile.appendChild(document.createElement("audio")),
     );
-    listMessages(scope, member, tile);
-  }
   return tile;
 }
 

sdk/index.ts

@@ -55,11 +55,7 @@ export {
 export * from "./src/api";
 export * from "./src/media-api";
 export * from "./src/media-backend/api";
-export {
-  dataTrackByName$,
-  trackBySource$,
-  type TrackOfSource,
-} from "./src/utils/tracks";
+export { trackBySource$, type TrackOfSource } from "./src/utils/tracks";
 export { createRTCSlot } from "./src/RTCSlot";
 export {
   createLivekitBackend,

sdk/src/LocalMedia.test.ts

@@ -162,6 +162,7 @@ describe("createLocalMedia", () => {
     media.release("camera");
     expect(trackBehind(camera).stop).toHaveBeenCalled();
     expect(media.tracks$.value).toEqual([microphone]);
+    expect(media.requests.map((r) => r.source)).toEqual(["microphone"]);
 
     media.stop();
     expect(trackBehind(microphone).stop).toHaveBeenCalled();

sdk/src/LocalMedia.ts

@@ -107,6 +107,7 @@ export function createLocalMedia(
     if (source !== "microphone" && source !== "camera") return;
     capturedTracks.get(source)?.stop();
     capturedTracks.delete(source);
+    requests.delete(source);
     publishCapturedTracks();
   };
 

sdk/src/RTCParticipation.test.ts

@@ -14,10 +14,11 @@ import {
   type Transport,
   type UnstableLivekitTransport,
 } from "matrix-js-sdk/lib/matrixrtc";
-import { BehaviorSubject, EMPTY } from "rxjs";
+import { BehaviorSubject, EMPTY, Subject } from "rxjs";
 import { describe, expect, it, type Mock, vi } from "vitest";
 
 import {
+  type DataMessage,
   type ParticipationState,
   type RTCMember,
   type RTCParticipationOptions,
@@ -28,16 +29,13 @@ import { defaultSessionTimings, MatrixRTCMode } from "./config";
 import { E2eeType } from "./encryption";
 import { MatrixRTCError } from "./errors";
 import {
+  type DataPacket,
   type MediaBackend,
   type MediaBackendContext,
   MediaConnectionState,
   type MediaKey,
 } from "./media-backend/api";
-import {
-  type LocalDataTrack,
-  type LocalVideoMediaTrack,
-  type MemberMedia,
-} from "./media-api";
+import { type MemberMedia } from "./media-api";
 import { constant } from "./reactive/Behavior";
 import { ObservableScope } from "./reactive/ObservableScope";
 import { createRTCParticipation } from "./RTCParticipation";
@@ -105,6 +103,7 @@ interface FakeBackend {
   context: MediaBackendContext;
   prepared: PromiseWithResolvers<{ canDelegateDelayedLeave: boolean }>;
   connectionState$: BehaviorSubject<MediaConnectionState | Error>;
+  data$: Subject<DataPacket>;
   setPublishing: Mock<(publish: boolean) => void>;
   delegateDelayedLeave: Mock<(delayId: string) => Promise<void>>;
   mediaFor: Mock<(scope: ObservableScope, member: RTCMember) => MemberMedia>;
@@ -141,7 +140,7 @@ function setup(
     getDeviceId: () => deviceId,
     getDomain: () => "example.org",
     getSyncState: () => SyncState.Syncing,
-    _unstable_getRTCTransports: vi.fn().mockResolvedValue(homeserverTransports),
+    getRTCTransports: vi.fn().mockResolvedValue(homeserverTransports),
     _unstable_getLivekitToken: vi.fn().mockResolvedValue({ jwt: publisherJWT }),
   } as unknown as MatrixClient;
   const members$ = new BehaviorSubject<RTCMember[]>([]);
@@ -152,6 +151,7 @@ function setup(
     connectionState$: new BehaviorSubject<MediaConnectionState | Error>(
       MediaConnectionState.Initialized,
     ),
+    data$: new Subject<DataPacket>(),
     setPublishing: vi.fn(),
     delegateDelayedLeave: vi.fn(async () => Promise.resolve()),
     mediaFor: vi.fn(() => ({
@@ -179,6 +179,8 @@ function setup(
       mediaFor: fake.mediaFor,
       connections$: constant([]),
       setAudioOutputDeviceId: vi.fn(),
+      sendData: vi.fn(),
+      data$: fake.data$,
     };
     fake.context = context;
     fake.backend = backend;
@@ -412,30 +414,27 @@ describe("createRTCParticipation", () => {
     scope.end();
   });
 
-  it("hands publications to the backend, data tracks too", async () => {
-    const { participation, fake, scope } = setup();
-    const chat = { kind: "data", name: "chat" } as LocalDataTrack;
-    const screenShare = {
-      kind: "video",
-      source: "screenShare",
-    } as LocalVideoMediaTrack;
+  it("delivers data from a member with its member and drops the rest", () => {
+    const { participation, members$, fake, scope } = setup();
+    members$.next([
+      member({
+        userId: "@bob:example.org",
+        memberId: "bob-member",
+        backendIdentities: ["bob-hashed", "bob-member"],
+      }),
+    ]);
+    const messages: DataMessage[] = [];
+    participation.data$.subscribe((message) => messages.push(message));
 
-    await participation.publish({ source: "data", name: "chat" });
-    await participation.publish({ source: "camera" });
-    expect(fake.backend.local.publish).toHaveBeenNthCalledWith(1, {
-      source: "data",
-      name: "chat",
+    fake.data$.next({ senderId: "bob-hashed", topic: "chat", text: "hi" });
+    fake.data$.next({ senderId: "stranger", topic: "chat", text: "boo" });
+
+    expect(messages).toHaveLength(1);
+    expect(messages[0]).toMatchObject({
+      topic: "chat",
+      text: "hi",
+      member: { memberId: "bob-member" },
     });
-    expect(fake.backend.local.publish).toHaveBeenNthCalledWith(2, {
-      source: "camera",
-    });
-    await participation.unpublish(chat);
-    await participation.unpublish(screenShare);
-    expect(fake.backend.local.unpublish).toHaveBeenNthCalledWith(1, chat);
-    expect(fake.backend.local.unpublish).toHaveBeenNthCalledWith(
-      2,
-      screenShare,
-    );
     scope.end();
   });
 

sdk/src/RTCParticipation.ts

@@ -20,6 +20,7 @@ import { v4 as uuidv4 } from "uuid";
 import {
   combineLatest,
   distinctUntilChanged,
+  filter,
   from,
   fromEvent,
   map,
@@ -34,6 +35,7 @@ import { type ObservableScope } from "./reactive/ObservableScope";
 import { generateItems } from "./reactive/observable";
 import { mapScoped } from "./utils/mapScoped";
 import {
+  type DataMessage,
   type LocalRTCMember,
   type ParticipationState,
   type RemoteRTCMember,
@@ -43,14 +45,6 @@ import {
   type RTCSlot,
   type RTCSlotOptions,
 } from "./api";
-import {
-  type DataPublishRequest,
-  type LocalAudioMediaTrack,
-  type LocalDataTrack,
-  type LocalTrack,
-  type LocalVideoMediaTrack,
-  type PublishRequest,
-} from "./media-api";
 import {
   type MediaBackend,
   type MediaBackendContext,
@@ -190,6 +184,7 @@ export function createRTCParticipation(
           encryptMedia: encryptionSystem.kind !== E2eeType.NONE,
           matrixRTCMode,
           sendNotificationType: options.sendNotificationType,
+          callIntent: options.callIntent,
           applicationData: options.applicationData,
           timings,
           delayedLeave,
@@ -251,6 +246,22 @@ export function createRTCParticipation(
     ).pipe(map((member) => member ?? null)),
   );
 
+  // A packet from an identity that is not a member is dropped, so a host only
+  // ever hears from attested members
+  const data$ = backend.data$.pipe(
+    map(({ senderId, topic, text }): DataMessage | null => {
+      const member = remoteMembers$.value.find((m) =>
+        m.backendIdentities.includes(senderId),
+      );
+      if (member === undefined) {
+        logger.warn(`Dropping data from ${senderId}: not a member`);
+        return null;
+      }
+      return { member, topic, text };
+    }),
+    filter((message) => message !== null),
+  );
+
   // Nothing leaves this device while it may already have been dropped from
   // the session: the member would show as away while still being heard
   localMembership.state$
@@ -275,19 +286,6 @@ export function createRTCParticipation(
     ),
   );
 
-  function publish(request: DataPublishRequest): Promise<LocalDataTrack>;
-  function publish(
-    request: PublishRequest,
-  ): Promise<LocalAudioMediaTrack | LocalVideoMediaTrack>;
-  async function publish(
-    request: DataPublishRequest | PublishRequest,
-  ): Promise<LocalTrack> {
-    // Narrowed for the overloads; both go to the backend alike
-    return request.source === "data"
-      ? backend.local.publish(request)
-      : backend.local.publish(request);
-  }
-
   const leave = (): void => {
     if (state$.value.kind === "left") return;
     localMembership.leave();
@@ -302,12 +300,14 @@ export function createRTCParticipation(
       state$,
       localMember$,
       remoteMembers$,
-      publish,
-      unpublish: async (track) => backend.local.unpublish(track),
+      publish: async (request) => backend.local.publish(request),
+      unpublish: async (source) => backend.local.unpublish(source),
       keyRotationSuppressed$: createKeyRotationSuppressed$(scope, jsSdkSession),
       connectedTransports$: transports.connected$,
       setAudioOutputDeviceId: async (deviceId) =>
         backend.setAudioOutputDeviceId(deviceId),
+      sendData: async (topic, text) => backend.sendData(topic, text),
+      data$,
     },
   };
 }

sdk/src/api.ts

@@ -12,18 +12,19 @@ Please see LICENSE in the repository root for full details.
  */
 
 import {
+  type RTCCallIntent,
   type RTCNotificationType,
   type Transport,
 } from "matrix-js-sdk/lib/matrixrtc";
+import { type Observable } from "rxjs";
+
 import { type Behavior } from "./reactive/Behavior";
 import {
-  type DataPublishRequest,
   type LocalAudioMediaTrack,
-  type LocalDataTrack,
   type LocalMedia,
   type LocalMemberMedia,
-  type LocalTrack,
   type LocalVideoMediaTrack,
+  type MediaSource,
   type MemberMedia,
   type PublishRequest,
 } from "./media-api";
@@ -103,11 +104,14 @@ export interface RTCParticipationOptions {
    * to a notification (ringing, timeouts, declines) is the application's job.
    */
   sendNotificationType?: RTCNotificationType;
+  /**
+   * The kind of call the local member intends to take part in: `"m.audio"`
+   * or `"m.video"`. Carried by the membership as a field of its own.
+   */
+  callIntent?: RTCCallIntent;
   /**
    * Whatever the application wants to say about itself in the membership,
-   * under namespaced keys. Opaque to the SDK, apart from `m.call.intent`
-   * (`"audio"` or `"video"`), which the membership format carries as a
-   * field of its own.
+   * under namespaced keys. Opaque to the SDK.
    */
   applicationData?: Record<string, unknown>;
   /** Timings the host has configured; the defaults otherwise. */
@@ -176,19 +180,15 @@ export interface RTCParticipation {
   remoteMembers$: Behavior<RemoteRTCMember[]>;
 
   /**
-   * Publishes a source, or a data track, and resolves with its track, which
-   * also shows up in `localMember$.tracks$`. Works from the moment `join()`
-   * returns: before the transport is connected.
+   * Publishes a source and resolves with its track, which also shows up in
+   * `localMember$.tracks$`. Works from the moment `join()` returns: before the
+   * transport is connected.
    */
-  publish(request: DataPublishRequest): Promise<LocalDataTrack>;
   publish(
     request: PublishRequest,
   ): Promise<LocalAudioMediaTrack | LocalVideoMediaTrack>;
-  /**
-   * Removes one of our publications; a screen share takes its audio with it.
-   * The track's object is finished: its controls and `send` reject from then on.
-   */
-  unpublish(track: LocalTrack): Promise<void>;
+  /** Removes one of our publications; a screen share takes its audio with it. */
+  unpublish(source: MediaSource): Promise<void>;
 
   /**
    * Whether the slot has grown large enough that MatrixRTC has stopped
@@ -205,6 +205,28 @@ export interface RTCParticipation {
    * the browser's choice, never calls it.
    */
   setAudioOutputDeviceId(deviceId: string): Promise<void>;
+
+  /**
+   * Sends a short text to every member on the local transport, over a
+   * reliable data channel beside the media. A packet holds about 15 KiB;
+   * anything larger belongs in a room event. Rejects while the local
+   * transport is not connected. Encrypted on the wire like the media, but
+   * not end to end with the media key.
+   */
+  sendData(topic: string, text: string): Promise<void>;
+  /**
+   * What remote members sent with `sendData`, on every transport the
+   * participation is connected to. A message from an identity that is not a
+   * member is dropped, so a host only ever hears from attested members.
+   */
+  data$: Observable<DataMessage>;
+}
+
+/** One `sendData` call as it arrives at a remote member. */
+export interface DataMessage {
+  member: RemoteRTCMember;
+  topic: string;
+  text: string;
 }
 
 // ---------------------------------------------------------------------------
@@ -269,7 +291,7 @@ export interface RTCMember {
   memberId: string;
   /** Which transport this member is on; undefined when the membership has none. */
   transport$: Behavior<TransportMetadata | undefined>;
-  /** What the member's application says about itself, e.g. `m.call.intent`. */
+  /** What the member's application says about itself, e.g. `intent`. */
   applicationData$: Behavior<Record<string, unknown>>;
 
   displayName$: Behavior<string>;

sdk/src/matrixrtc/LocalTransport.test.ts

@@ -31,7 +31,7 @@ function client(
 ): Parameters<typeof discoverLocalTransport>[0] {
   return {
     getDomain: () => "example.org",
-    _unstable_getRTCTransports: vi.fn().mockResolvedValue(advertised),
+    getRTCTransports: vi.fn().mockResolvedValue(advertised),
   };
 }
 
@@ -54,7 +54,7 @@ describe("discoverLocalTransport", () => {
         logger,
       ),
     ).resolves.toBe(hostTransport);
-    expect(c._unstable_getRTCTransports).not.toHaveBeenCalled();
+    expect(c.getRTCTransports).not.toHaveBeenCalled();
   });
 
   it("prefers the homeserver's transport over the host's fallback", async () => {

sdk/src/matrixrtc/LocalTransport.ts

@@ -22,7 +22,7 @@ import { TransportAutoDiscovery } from "./TransportAutoDiscovery";
  * @throws {MatrixRTCTransportMissingError} where none of these exists.
  */
 export async function discoverLocalTransport(
-  client: Pick<MatrixClient, "getDomain" | "_unstable_getRTCTransports">,
+  client: Pick<MatrixClient, "getDomain" | "getRTCTransports">,
   transportTypes: readonly string[],
   {
     transport: override,

sdk/src/matrixrtc/TransportAutoDiscovery.test.ts

@@ -36,11 +36,7 @@ const configTransport: Transport = {
 
 function makeClient(): MockedObject<DiscoveryClient> {
   return {
-    getDomain: vi.fn().mockReturnValue("example.org"),
-    baseUrl: "https://matrix.example.org",
-    _unstable_getRTCTransports: vi.fn().mockResolvedValue([]),
-    getOpenIdToken: vi.fn(),
-    getDeviceId: vi.fn(),
+    getRTCTransports: vi.fn().mockResolvedValue([]),
   } as unknown as MockedObject<DiscoveryClient>;
 }
 
@@ -57,7 +53,7 @@ describe("TransportAutoDiscovery", () => {
     "prefers backend transport other app config $transports",
     async ({ transports }) => {
       const client = makeClient();
-      client._unstable_getRTCTransports.mockResolvedValue(transports);
+      client.getRTCTransports.mockResolvedValue(transports);
 
       const discovery = new TransportAutoDiscovery({
         client,
@@ -71,7 +67,7 @@ describe("TransportAutoDiscovery", () => {
       expect(discoveredTransport).toStrictEqual(backendTransport);
       expect(discoveredTransport).not.toStrictEqual(configTransport);
 
-      expect(client._unstable_getRTCTransports).toHaveBeenCalledTimes(1);
+      expect(client.getRTCTransports).toHaveBeenCalledTimes(1);
     },
   );
 
@@ -81,10 +77,7 @@ describe("TransportAutoDiscovery", () => {
       url: "wss://sfu.example.org",
     };
     const client = makeClient();
-    client._unstable_getRTCTransports.mockResolvedValue([
-      backendTransport,
-      mLivekit,
-    ]);
+    client.getRTCTransports.mockResolvedValue([backendTransport, mLivekit]);
 
     const discovery = new TransportAutoDiscovery({
       client,
@@ -100,7 +93,7 @@ describe("TransportAutoDiscovery", () => {
 
   it("Retries limit_exceeded backend transport", async () => {
     const client = makeClient();
-    client._unstable_getRTCTransports
+    client.getRTCTransports
       .mockRejectedValueOnce(
         new MatrixError(
           {
@@ -124,7 +117,7 @@ describe("TransportAutoDiscovery", () => {
       backendTransport,
     );
 
-    expect(client._unstable_getRTCTransports).toHaveBeenCalledTimes(2);
+    expect(client.getRTCTransports).toHaveBeenCalledTimes(2);
   });
 
   const INVALID_TEST_CASES: Array<{ transports: Transport[] }> = [
@@ -135,7 +128,7 @@ describe("TransportAutoDiscovery", () => {
     "falls back to config when backend has no (valid) livekit transports $transports",
     async ({ transports }) => {
       const client = makeClient();
-      client._unstable_getRTCTransports.mockResolvedValue(transports);
+      client.getRTCTransports.mockResolvedValue(transports);
 
       const discovery = new TransportAutoDiscovery({
         client,
@@ -152,7 +145,7 @@ describe("TransportAutoDiscovery", () => {
 
   it("returns null when backend and config are all unavailable", async () => {
     const client = makeClient();
-    client._unstable_getRTCTransports.mockResolvedValue([]);
+    client.getRTCTransports.mockResolvedValue([]);
 
     const discovery = new TransportAutoDiscovery({
       client,

sdk/src/matrixrtc/TransportAutoDiscovery.ts

@@ -10,10 +10,7 @@ import { type Logger } from "matrix-js-sdk/lib/logger";
 
 import { doNetworkOperationWithRetry } from "../utils/network";
 
-type TransportDiscoveryClient = Pick<
-  MatrixClient,
-  "getDomain" | "_unstable_getRTCTransports"
->;
+type TransportDiscoveryClient = Pick<MatrixClient, "getRTCTransports">;
 
 export interface TransportAutoDiscoveryProps {
   client: TransportDiscoveryClient;
@@ -74,7 +71,7 @@ export class TransportAutoDiscovery {
     this.logger.info("First try to use getRTCTransports end point ...");
     try {
       const transportList = await doNetworkOperationWithRetry(async () =>
-        client._unstable_getRTCTransports(),
+        client.getRTCTransports(),
       );
       for (const type of this.transportTypes) {
         const first = transportList.find(

sdk/src/matrixrtc/joinJsSdkSession.test.ts

@@ -60,7 +60,7 @@ describe("joinJsSdkSession", () => {
     expect(s.join).toHaveBeenCalledWith(ownMemberMock, [transportWithAlias], {
       notificationType: "ring",
       callIntent: undefined,
-      applicationData: {},
+      applicationData: undefined,
       manageMediaKeys: true,
       delayedLeaveEventRestartMs: 300_000,
       delayedLeaveEventDelayMs: 3_600_000,
@@ -95,13 +95,14 @@ describe("joinJsSdkSession", () => {
     );
   });
 
-  it("lifts the call intent out of the application data and sends sticky events in Matrix 2.0 mode", () => {
+  it("passes the call intent and application data through and sends sticky events in Matrix 2.0 mode", () => {
     const s = session();
 
     joinJsSdkSession("!room:example.org", s, ownMemberMock, transport, {
       encryptMedia: true,
       matrixRTCMode: MatrixRTCMode.Matrix_2_0,
-      applicationData: { "m.call.intent": "audio", custom: 1 },
+      callIntent: "m.audio",
+      applicationData: { custom: 1 },
       timings: defaultSessionTimings,
       delayedLeave: defaultSessionTimings.delayedLeave,
     });
@@ -110,7 +111,7 @@ describe("joinJsSdkSession", () => {
       ownMemberMock,
       [transportWithAlias],
       expect.objectContaining({
-        callIntent: "audio",
+        callIntent: "m.audio",
         applicationData: { custom: 1 },
         unstableSendStickyEvents: true,
       }),
@@ -124,7 +125,8 @@ describe("joinJsSdkSession", () => {
     joinJsSdkSession("!room:example.org", s, ownMemberMock, transport, {
       encryptMedia: true,
       matrixRTCMode: MatrixRTCMode.Matrix_2_0,
-      applicationData: { "m.call.intent": "audio", custom: 1 },
+      callIntent: "m.audio",
+      applicationData: { custom: 1 },
       timings: defaultSessionTimings,
       delayedLeave: defaultSessionTimings.delayedLeave,
     });
@@ -133,7 +135,7 @@ describe("joinJsSdkSession", () => {
       ownMemberMock,
       [transport],
       expect.objectContaining({
-        callIntent: "audio",
+        callIntent: "m.audio",
         applicationData: { custom: 1 },
         unstableSendStickyEvents: true,
       }),

sdk/src/matrixrtc/joinJsSdkSession.ts

@@ -23,6 +23,7 @@ interface Options {
   encryptMedia: boolean;
   matrixRTCMode: MatrixRTCMode;
   sendNotificationType?: RTCNotificationType;
+  callIntent?: RTCCallIntent;
   applicationData?: Record<string, unknown>;
   timings: SessionTimings;
   /** The delayed leave timings to use: delegated to the SFU or not. */
@@ -43,15 +44,12 @@ export function joinJsSdkSession(
     encryptMedia,
     matrixRTCMode,
     sendNotificationType,
+    callIntent,
     applicationData,
     timings,
     delayedLeave,
   }: Options,
 ): void {
-  // The membership format carries the intent as a field of its own
-  const { "m.call.intent": intent, ...rest } = applicationData ?? {};
-  const callIntent =
-    typeof intent === "string" ? (intent as RTCCallIntent) : undefined;
   // Give up on the network as soon as either the sync has been down for the
   // grace period or the delayed leave has probably been sent, whichever is
   // sooner
@@ -78,7 +76,7 @@ export function joinJsSdkSession(
     {
       notificationType: sendNotificationType,
       callIntent,
-      applicationData: rest,
+      applicationData,
       manageMediaKeys: encryptMedia,
       delayedLeaveEventRestartMs: delayedLeave.restart_ms,
       delayedLeaveEventDelayMs: delayedLeave.delay_ms,

sdk/src/media-api.ts

@@ -69,21 +69,6 @@ export type PublishRequest =
       capture?: VideoCaptureSettings;
     };
 
-/** A named channel of bytes a member publishes beside its media. */
-export interface DataPublishRequest {
-  source: "data";
-  /**
-   * What receivers find the track by, with `dataTrackByName$`. Unique per
-   * member: publishing a name that is published already rejects.
-   */
-  name: string;
-  /**
-   * Whether every message arrives, in order. Default true. Lossy delivery is
-   * for high-rate state where only the newest value matters, such as cursors.
-   */
-  reliable?: boolean;
-}
-
 export type MediaSource =
   | "microphone"
   | "camera"
@@ -97,7 +82,7 @@ export type MediaStreamStats =
   | RTCOutboundRtpStreamStats
   | undefined;
 
-/** One published audio or video track of a member. */
+/** One published track of a member. */
 export interface MediaTrack {
   source: MediaSource;
   kind: "audio" | "video";
@@ -178,48 +163,6 @@ export interface LocalVideoMediaTrack extends VideoMediaTrack, LocalMediaTrack {
   setProcessor(processor: VideoProcessor | undefined): Promise<void>;
 }
 
-/**
- * One data track of a member. It exists only on a member of the slot, so
- * whatever arrives on it comes from an attested member.
- */
-export interface DataTrack {
-  source: "data";
-  kind: "data";
-  /** Stable for the life of the track. */
-  id: string;
-  /** As the publisher named it in its `DataPublishRequest`. */
-  name: string;
-  reliable: boolean;
-  /** Whether payloads are end-to-end encrypted with the media key. */
-  encrypted: boolean;
-  /**
-   * What the member sends from now on. The track is subscribed while this is
-   * observed and not at all otherwise; nothing sent earlier is replayed.
-   */
-  data$: Observable<Uint8Array>;
-}
-
-/**
- * Our own data track. Its `data$` replays what we sent: each payload once
- * `send` has handed it to the transport, so a host renders its own messages
- * from the same stream as a remote member's.
- */
-export interface LocalDataTrack extends DataTrack {
-  /**
-   * Sends to every member subscribed to this track. Rejects while the local
-   * transport is not connected, and where the payload is larger than the
-   * backend carries.
-   */
-  send(payload: Uint8Array): Promise<void>;
-}
-
-/** Any track of a member: its media and its data. */
-export type Track = AudioMediaTrack | VideoMediaTrack | DataTrack;
-export type LocalTrack =
-  | LocalAudioMediaTrack
-  | LocalVideoMediaTrack
-  | LocalDataTrack;
-
 export type EncryptionError = "MissingKey" | "InvalidKey";
 
 /**
@@ -229,19 +172,18 @@ export type EncryptionError = "MissingKey" | "InvalidKey";
  */
 export interface MemberMedia {
   /**
-   * The member's tracks, media and data, in publication order, once it has
-   * shown up on its transport; null until then ("waiting for media"). An
-   * entry stays the same object for as long as the same publication is
-   * behind it. Which track is which is in its `source`: `trackBySource$`
-   * picks a media track out, `dataTrackByName$` a data track.
+   * The member's tracks, in publication order, once it has shown up on its
+   * transport; null until then ("waiting for media"). An entry stays the same
+   * object for as long as the same publication is behind it. Which track is
+   * which is in its `source`; `trackBySource$` picks one out.
    */
-  tracks$: Behavior<Track[] | null>;
+  tracks$: Behavior<(AudioMediaTrack | VideoMediaTrack)[] | null>;
   /** Emits when the SFU reports a key problem for this member. */
   encryptionError$: Observable<EncryptionError>;
 }
 
 export interface LocalMemberMedia extends MemberMedia {
-  tracks$: Behavior<LocalTrack[] | null>;
+  tracks$: Behavior<(LocalAudioMediaTrack | LocalVideoMediaTrack)[] | null>;
 }
 
 /**

sdk/src/media-backend/api.ts

@@ -19,13 +19,11 @@ import { type Observable } from "rxjs";
 
 import { type ResolvedTransport, type RTCMember } from "../api";
 import {
-  type DataPublishRequest,
   type LocalAudioMediaTrack,
-  type LocalDataTrack,
   type LocalMedia,
   type LocalMemberMedia,
-  type LocalTrack,
   type LocalVideoMediaTrack,
+  type MediaSource,
   type MemberMedia,
   type PublishRequest,
 } from "../media-api";
@@ -108,6 +106,13 @@ export interface BackendConnection {
   resolved: ResolvedTransport | undefined;
 }
 
+export interface DataPacket {
+  /** The backend identity of the sender. */
+  senderId: string;
+  topic: string;
+  text: string;
+}
+
 export interface MediaBackend {
   /**
    * The membership transport types this backend serves, ordered decreasingly
@@ -153,6 +158,14 @@ export interface MediaBackend {
    * exists keeps the device it was created with.
    */
   setAudioOutputDeviceId(deviceId: string): Promise<void>;
+
+  /**
+   * A text channel beside the media: sent on the local transport, received on every one.
+   * This could well be just another track kind. Not needed for element call. just for the sdk target.
+   * Keeping it on the top level for visibility. Should be tackled in a future refactor.
+   */
+  sendData(topic: string, text: string): Promise<void>;
+  readonly data$: Observable<DataPacket>;
 }
 
 /** `tracks$` is null until the connection carries a local participant. */
@@ -174,17 +187,14 @@ export interface LocalMediaBackend extends LocalMemberMedia {
   readonly publishError$: Behavior<Error | null>;
 
   /**
-   * Publishes a source, or a data track, and resolves with its track once it
-   * is in `tracks$`. Remembered across connections, so a request before the
+   * Publishes a source and resolves with its track once it is in `tracks$`.
+   * Remembered across connections, so a request before the
    * transport is up is applied once it is, and republished after a
-   * reconnection. Rejects where the device could not be used. A data track
-   * is end-to-end encrypted by the backend wherever the media is; the session
-   * never sees how.
+   * reconnection. Rejects where the device could not be used.
    */
-  publish(request: DataPublishRequest): Promise<LocalDataTrack>;
   publish(
     request: PublishRequest,
   ): Promise<LocalAudioMediaTrack | LocalVideoMediaTrack>;
   /** Removes one of our publications; a screen share takes its audio with it. */
-  unpublish(track: LocalTrack): Promise<void>;
+  unpublish(source: MediaSource): Promise<void>;
 }

sdk/src/media-backend/livekit/ByteStreams.test.ts

@@ -1,85 +0,0 @@
-/*
-Copyright 2026 Element Creations Ltd.
-
-SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
-Please see LICENSE in the repository root for full details.
-*/
-
-import {
-  type ByteStreamHandler,
-  type ByteStreamReader,
-  type Room as LivekitRoom,
-} from "livekit-client";
-import { describe, expect, it, vi } from "vitest";
-
-import { byteStreams$, type ReceivedBytes } from "./ByteStreams";
-import { flushPromises } from "../../utils/test";
-
-function fakeRoom(): {
-  room: LivekitRoom;
-  handlers: Map<string, ByteStreamHandler>;
-} {
-  const handlers = new Map<string, ByteStreamHandler>();
-  const room = {
-    registerByteStreamHandler: vi.fn(
-      (topic: string, handler: ByteStreamHandler) => {
-        if (handlers.has(topic)) throw new Error("already registered");
-        handlers.set(topic, handler);
-      },
-    ),
-    unregisterByteStreamHandler: vi.fn((topic: string) =>
-      handlers.delete(topic),
-    ),
-  } as unknown as LivekitRoom;
-  return { room, handlers };
-}
-
-function reader(chunks: number[][]): {
-  reader: ByteStreamReader;
-  finish: () => void;
-} {
-  const done = Promise.withResolvers<Uint8Array[]>();
-  return {
-    reader: {
-      readAll: async () => done.promise,
-    } as unknown as ByteStreamReader,
-    finish: (): void => done.resolve(chunks.map((c) => new Uint8Array(c))),
-  };
-}
-
-describe("byteStreams$", () => {
-  it("shares one handler per topic, released with the last observer", () => {
-    const { room, handlers } = fakeRoom();
-    const first = byteStreams$(room, "reliable:chat").subscribe();
-    const second = byteStreams$(room, "reliable:chat").subscribe();
-    expect(room.registerByteStreamHandler).toHaveBeenCalledTimes(1);
-    first.unsubscribe();
-    expect(handlers.has("reliable:chat")).toBe(true);
-    second.unsubscribe();
-    expect(handlers.has("reliable:chat")).toBe(false);
-  });
-
-  it("joins the chunks and keeps the order the streams started in", async () => {
-    const { room, handlers } = fakeRoom();
-    const received: ReceivedBytes[] = [];
-    const subscription = byteStreams$(room, "reliable:chat").subscribe((r) =>
-      received.push(r),
-    );
-    const handler = handlers.get("reliable:chat")!;
-    const one = reader([[1, 2], [3]]);
-    const two = reader([[4]]);
-    handler(one.reader, { identity: "alice" });
-    handler(two.reader, { identity: "bob" });
-    two.finish();
-    await flushPromises();
-    expect(received).toEqual([]);
-    one.finish();
-    await flushPromises();
-
-    expect(received).toEqual([
-      { identity: "alice", payload: new Uint8Array([1, 2, 3]) },
-      { identity: "bob", payload: new Uint8Array([4]) },
-    ]);
-    subscription.unsubscribe();
-  });
-});

sdk/src/media-backend/livekit/ByteStreams.ts

@@ -1,82 +0,0 @@
-/*
-Copyright 2026 Element Creations Ltd.
-
-SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
-Please see LICENSE in the repository root for full details.
-*/
-
-import { logger as rootLogger } from "matrix-js-sdk/lib/logger";
-import {
-  type ByteStreamReader,
-  type Room as LivekitRoom,
-} from "livekit-client";
-import { catchError, concatMap, EMPTY, from, Observable, share } from "rxjs";
-
-/** One byte stream, read to its end. */
-export interface ReceivedBytes {
-  /** The participant identity of the sender. */
-  identity: string;
-  payload: Uint8Array;
-}
-
-const byTopicByRoom = new WeakMap<
-  LivekitRoom,
-  Map<string, Observable<ReceivedBytes>>
->();
-
-/**
- * The byte streams a room receives on a topic, in the order they started. A
- * room takes one handler per topic, so every observer of a topic shares it:
- * it is registered with the first subscription and released with the last.
- */
-export function byteStreams$(
-  room: LivekitRoom,
-  topic: string,
-): Observable<ReceivedBytes> {
-  let byTopic = byTopicByRoom.get(room);
-  if (byTopic === undefined) {
-    byTopic = new Map();
-    byTopicByRoom.set(room, byTopic);
-  }
-  let streams$ = byTopic.get(topic);
-  if (streams$ === undefined) {
-    streams$ = new Observable<{ reader: ByteStreamReader; identity: string }>(
-      (subscriber) => {
-        room.registerByteStreamHandler(topic, (reader, { identity }) =>
-          subscriber.next({ reader, identity }),
-        );
-        return (): void => room.unregisterByteStreamHandler(topic);
-      },
-    ).pipe(
-      concatMap(({ reader, identity }) =>
-        from(readStream(reader, identity)).pipe(
-          catchError((e: unknown) => {
-            rootLogger
-              .getChild("[ByteStreams]")
-              .warn(`Dropping a stream on ${topic} from ${identity}`, e);
-            return EMPTY;
-          }),
-        ),
-      ),
-      share(),
-    );
-    byTopic.set(topic, streams$);
-  }
-  return streams$;
-}
-
-async function readStream(
-  reader: ByteStreamReader,
-  identity: string,
-): Promise<ReceivedBytes> {
-  const chunks = await reader.readAll();
-  const payload = new Uint8Array(
-    chunks.reduce((length, chunk) => length + chunk.length, 0),
-  );
-  let offset = 0;
-  for (const chunk of chunks) {
-    payload.set(chunk, offset);
-    offset += chunk.length;
-  }
-  return { identity, payload };
-}

sdk/src/media-backend/livekit/ConnectionFactory.test.ts

@@ -77,7 +77,6 @@ describe("LivekitConnectionFactory", () => {
       resolution: expect.objectContaining({ height: 720 }),
     });
     expect(options.audioOutput).toEqual({ deviceId: undefined });
-    expect(options.encryption).toBeUndefined();
     expect(options.e2ee).toBeUndefined();
   });
 

sdk/src/media-backend/livekit/ConnectionFactory.ts

@@ -19,7 +19,6 @@ import { type CallMembershipIdentityParts } from "matrix-js-sdk/lib/matrixrtc/En
 import { BehaviorSubject, combineLatest, map } from "rxjs";
 
 import { type ResolvedTransport } from "../../api";
-import { watchRemoteDataTracks } from "./RemoteDataTracks";
 import { type MediaQuality } from "../../config";
 import { type PublishRequest } from "../../media-api";
 import { type Behavior } from "../../reactive/Behavior";
@@ -129,14 +128,12 @@ export class LivekitConnectionFactory implements ConnectionFactory {
         client: this.client,
         scope,
         livekitRoomFactory: () =>
-          watchRemoteDataTracks(
-            new LivekitRoom(
-              roomOptions(
-                this.publish,
-                this.audioOutputDeviceId$.value,
-                this.keyProvider,
-                this.mediaQuality,
-              ),
+          new LivekitRoom(
+            roomOptions(
+              this.publish,
+              this.audioOutputDeviceId$.value,
+              this.keyProvider,
+              this.mediaQuality,
             ),
           ),
         ownMembershipIdentity,
@@ -172,10 +169,8 @@ function roomOptions(
     },
     audioOutput: { deviceId: audioOutputDeviceId },
     // Every room needs a worker of its own: one gets confused by streams from
-    // several rooms. `encryption` rather than `e2ee`, so that LiveKit encrypts
-    // the data channel too, which carries the reliable data tracks; media is
-    // encrypted the same either way
-    encryption: keyProvider && { keyProvider, worker: new E2EEWorker() },
+    // several rooms
+    e2ee: keyProvider && { keyProvider, worker: new E2EEWorker() },
   };
 }
 

sdk/src/media-backend/livekit/DataChannel.test.ts

@@ -0,0 +1,143 @@
+/*
+Copyright 2026 Element Creations Ltd.
+
+SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
+Please see LICENSE in the repository root for full details.
+*/
+
+import { EventEmitter } from "events";
+import {
+  ConnectionState as LivekitConnectionState,
+  type RemoteParticipant,
+  RoomEvent,
+} from "livekit-client";
+import { BehaviorSubject } from "rxjs";
+import { describe, expect, it, vi } from "vitest";
+
+import { Epoch } from "../../reactive/ObservableScope";
+import { constant } from "../../reactive/Behavior";
+import { type DataPacket } from "../api";
+import { type Connection, type ConnectionState } from "./Connection";
+import { ConnectionMap } from "./ConnectionMap";
+import { createDataChannel$ } from "./DataChannel";
+import { testScope } from "../../utils/test";
+import { exampleTransport } from "./test";
+
+const encode = (text: string): Uint8Array => new TextEncoder().encode(text);
+
+const connected: ConnectionState = {
+  state: "authenticated",
+  livekitState: LivekitConnectionState.Connected,
+};
+
+function fakeConnection(
+  url: string,
+  state: ConnectionState = connected,
+): {
+  connection: Connection;
+  room: EventEmitter;
+  publishData: ReturnType<typeof vi.fn>;
+} {
+  const room = new EventEmitter();
+  const publishData = vi.fn(async () => Promise.resolve());
+  const connection = {
+    transport: { ...exampleTransport, livekit_service_url: url },
+    serverName: "example.org",
+    state$: constant(state),
+    livekitRoom: Object.assign(room, { localParticipant: { publishData } }),
+  } as unknown as Connection;
+  return { connection, room, publishData };
+}
+
+function setup(connections: Connection[]): {
+  received: DataPacket[];
+  connections$: BehaviorSubject<Epoch<ConnectionMap>>;
+  sendData: (topic: string, text: string) => Promise<void>;
+} {
+  const data = new ConnectionMap();
+  for (const connection of connections) data.add(connection, []);
+  const connections$ = new BehaviorSubject(new Epoch(data));
+  const { data$, sendData } = createDataChannel$({
+    scope: testScope(),
+    connectionMap$: connections$,
+    connection$: constant(connections[0] ?? null),
+  });
+  const received: DataPacket[] = [];
+  data$.subscribe((message) => received.push(message));
+  return { received, connections$, sendData };
+}
+
+describe("data$", () => {
+  it("delivers a packet with its sender, topic and text", () => {
+    const { connection, room } = fakeConnection("https://sfu");
+    const { received } = setup([connection]);
+
+    room.emit(
+      RoomEvent.DataReceived,
+      encode("hello"),
+      { identity: "alice" } as RemoteParticipant,
+      undefined,
+      "chat",
+    );
+
+    expect(received).toEqual([
+      { senderId: "alice", topic: "chat", text: "hello" },
+    ]);
+  });
+
+  it("drops packets from the server", () => {
+    const { connection, room } = fakeConnection("https://sfu");
+    const { received } = setup([connection]);
+
+    room.emit(RoomEvent.DataReceived, encode("server"), undefined);
+
+    expect(received).toEqual([]);
+  });
+
+  it("listens on every connection, including ones added later", () => {
+    const first = fakeConnection("https://sfu-1");
+    const second = fakeConnection("https://sfu-2");
+    const { received, connections$ } = setup([first.connection]);
+
+    const data = new ConnectionMap();
+    data.add(first.connection, []);
+    data.add(second.connection, []);
+    connections$.next(new Epoch(data, 1));
+
+    first.room.emit(RoomEvent.DataReceived, encode("one"), {
+      identity: "alice",
+    } as RemoteParticipant);
+    second.room.emit(RoomEvent.DataReceived, encode("two"), {
+      identity: "bob",
+    } as RemoteParticipant);
+
+    expect(received.map((m) => [m.senderId, m.text])).toEqual([
+      ["alice", "one"],
+      ["bob", "two"],
+    ]);
+  });
+});
+
+describe("sendData", () => {
+  it("publishes the text as a reliable packet on the local connection", async () => {
+    const { connection, publishData } = fakeConnection("https://sfu");
+    const { sendData } = setup([connection]);
+
+    await sendData("chat", "hello");
+
+    expect(publishData).toHaveBeenCalledWith(encode("hello"), {
+      reliable: true,
+      topic: "chat",
+    });
+  });
+
+  it("rejects while the local transport is not connected", async () => {
+    const { connection, publishData } = fakeConnection("https://sfu", {
+      state: "initialized",
+    });
+    const { sendData } = setup([connection]);
+
+    await expect(sendData("chat", "hello")).rejects.toThrow("not connected");
+    expect(publishData).not.toHaveBeenCalled();
+  });
+});

sdk/src/media-backend/livekit/DataChannel.ts

@@ -0,0 +1,119 @@
+/*
+Copyright 2026 Element Creations Ltd.
+
+SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
+Please see LICENSE in the repository root for full details.
+*/
+
+import {
+  ConnectionState as LivekitConnectionState,
+  type RemoteParticipant,
+  type Room as LivekitRoom,
+  RoomEvent,
+} from "livekit-client";
+import {
+  distinctUntilChanged,
+  filter,
+  fromEvent,
+  map,
+  merge,
+  type Observable,
+  share,
+  switchMap,
+} from "rxjs";
+
+import { type Behavior } from "../../reactive/Behavior";
+import {
+  type Epoch,
+  type ObservableScope,
+} from "../../reactive/ObservableScope";
+import { type DataPacket } from "../api";
+import { type Connection } from "./Connection";
+import { type ConnectionMap } from "./ConnectionMap";
+
+interface Props {
+  scope: ObservableScope;
+  connectionMap$: Behavior<Epoch<ConnectionMap>>;
+  /** The local member's connection, which carries what we send. */
+  connection$: Behavior<Connection | null>;
+}
+
+export interface DataChannel {
+  data$: Observable<DataPacket>;
+  sendData: (topic: string, text: string) => Promise<void>;
+}
+
+/**
+ * A text channel beside the media: LiveKit's reliable data packets, received
+ * on every connection the client holds and sent on the local member's. The
+ * sender is reported by its identity; the packet's own claim of who sent it
+ * never reaches the host.
+ */
+export function createDataChannel$({
+  scope,
+  connectionMap$,
+  connection$,
+}: Props): DataChannel {
+  const decoder = new TextDecoder();
+  const encoder = new TextEncoder();
+
+  const rooms$ = connectionMap$.pipe(
+    map(({ value }) => value.getConnections().map((c) => c.livekitRoom)),
+    distinctUntilChanged(
+      (a, b) => a.length === b.length && a.every((room, i) => room === b[i]),
+    ),
+  );
+
+  const data$ = rooms$.pipe(
+    switchMap((rooms) => merge(...rooms.map(receivedOn))),
+    map(({ payload, participant, topic }): DataPacket | null =>
+      // Only the server sends without a participant; a host has no use for it
+      participant === undefined
+        ? null
+        : {
+            senderId: participant.identity,
+            topic: topic ?? "",
+            text: decoder.decode(payload),
+          },
+    ),
+    filter((packet) => packet !== null),
+    scope.bind(),
+    share(),
+  );
+
+  const sendData = async (topic: string, text: string): Promise<void> => {
+    const connection = connection$.value;
+    const state = connection?.state$.value;
+    if (
+      connection === null ||
+      state?.state !== "authenticated" ||
+      state.livekitState !== LivekitConnectionState.Connected
+    )
+      throw new Error("Cannot send data: the local transport is not connected");
+    await connection.livekitRoom.localParticipant.publishData(
+      encoder.encode(text),
+      { reliable: true, topic },
+    );
+  };
+
+  return { data$, sendData };
+}
+
+interface Received {
+  payload: Uint8Array;
+  participant: RemoteParticipant | undefined;
+  topic: string | undefined;
+}
+
+function receivedOn(room: LivekitRoom): Observable<Received> {
+  return fromEvent(
+    room,
+    RoomEvent.DataReceived,
+    (
+      payload: Uint8Array,
+      participant?: RemoteParticipant,
+      _kind?: unknown,
+      topic?: string,
+    ): Received => ({ payload, participant, topic }),
+  );
+}

sdk/src/media-backend/livekit/LivekitBackend.ts

@@ -58,6 +58,7 @@ import {
   ResolvedConnection,
 } from "./ConnectionFactory";
 import { toMediaConnectionState } from "./connectionState";
+import { createDataChannel$ } from "./DataChannel";
 import { createKeyProvider } from "./KeyProvider";
 import {
   createLivekitMemberMedia,
@@ -262,12 +263,7 @@ export function createLivekitBackend(
           `${member.rtcBackendIdentity}: LiveKit participant missing on ${transportString}`,
         );
     });
-    return createLivekitMemberMedia(
-      memberScope,
-      source$,
-      encryptionSystem,
-      logger,
-    );
+    return createLivekitMemberMedia(memberScope, source$, encryptionSystem);
   };
 
   const connections$ = scope.behavior<BackendConnection[]>(
@@ -280,6 +276,12 @@ export function createLivekitBackend(
     ),
   );
 
+  const { data$, sendData } = createDataChannel$({
+    scope,
+    connectionMap$,
+    connection$: localMedia_.connection$,
+  });
+
   return {
     transportTypes: ["m.livekit", "livekit"],
     prepareLocalTransport,
@@ -288,6 +290,8 @@ export function createLivekitBackend(
     mediaFor,
     connections$,
     setAudioOutputDeviceId: localMedia_.setAudioOutputDeviceId,
+    sendData,
+    data$,
   };
 }
 

sdk/src/media-backend/livekit/LivekitDataTrack.test.ts

@@ -1,124 +0,0 @@
-/*
-Copyright 2026 Element Creations Ltd.
-
-SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
-Please see LICENSE in the repository root for full details.
-*/
-
-import { logger } from "matrix-js-sdk/lib/logger";
-import {
-  type ByteStreamHandler,
-  type ByteStreamReader,
-  type DataTrackFrame,
-  type RemoteDataTrack,
-  type Room as LivekitRoom,
-} from "livekit-client";
-import { describe, expect, it, vi } from "vitest";
-
-import { createLivekitDataTrack } from "./LivekitDataTrack";
-import { flushPromises } from "../../utils/test";
-
-function remoteTrack(
-  name: string,
-  usesE2ee = true,
-): {
-  track: RemoteDataTrack;
-  frames: ReadableStreamDefaultController<DataTrackFrame>[];
-  cancel: ReturnType<typeof vi.fn>;
-} {
-  const frames: ReadableStreamDefaultController<DataTrackFrame>[] = [];
-  const cancel = vi.fn();
-  const track = {
-    info: { sid: "DT_1", name, usesE2ee },
-    publisherIdentity: "alice",
-    subscribe: vi.fn(
-      () =>
-        new ReadableStream<DataTrackFrame>({
-          start: (controller): void => {
-            frames.push(controller);
-          },
-          cancel,
-        }),
-    ),
-  } as unknown as RemoteDataTrack;
-  return { track, frames, cancel };
-}
-
-function roomWithStreams(): {
-  room: LivekitRoom;
-  send: (identity: string, bytes: number[]) => void;
-} {
-  const handlers = new Map<string, ByteStreamHandler>();
-  return {
-    room: {
-      registerByteStreamHandler: (topic: string, h: ByteStreamHandler) =>
-        handlers.set(topic, h),
-      unregisterByteStreamHandler: (topic: string) => handlers.delete(topic),
-    } as unknown as LivekitRoom,
-    send: (identity, bytes): void =>
-      handlers.get("reliable:chat")!(
-        {
-          readAll: async () => Promise.resolve([new Uint8Array(bytes)]),
-        } as unknown as ByteStreamReader,
-        { identity },
-      ),
-  };
-}
-
-describe("a remote data track", () => {
-  it("names itself without the LiveKit prefix", () => {
-    const { track } = remoteTrack("reliable:chat", false);
-    expect(
-      createLivekitDataTrack(roomWithStreams().room, track, logger),
-    ).toMatchObject({
-      source: "data",
-      kind: "data",
-      id: "DT_1",
-      name: "chat",
-      reliable: true,
-      encrypted: false,
-    });
-  });
-
-  it("subscribes a lossy track while observed, once for all observers", async () => {
-    const { track, frames, cancel } = remoteTrack("lossy:cursors");
-    const dataTrack = createLivekitDataTrack(
-      roomWithStreams().room,
-      track,
-      logger,
-    );
-    expect(track.subscribe).not.toHaveBeenCalled();
-
-    const received: Uint8Array[] = [];
-    const first = dataTrack.data$.subscribe((p) => received.push(p));
-    const second = dataTrack.data$.subscribe();
-    expect(track.subscribe).toHaveBeenCalledTimes(1);
-    frames[0].enqueue({ payload: new Uint8Array([7]) });
-    await flushPromises();
-    expect(received).toEqual([new Uint8Array([7])]);
-
-    first.unsubscribe();
-    expect(cancel).not.toHaveBeenCalled();
-    second.unsubscribe();
-    expect(cancel).toHaveBeenCalled();
-  });
-
-  it("takes a reliable track's streams from its publisher only", async () => {
-    const { room, send } = roomWithStreams();
-    const dataTrack = createLivekitDataTrack(
-      room,
-      remoteTrack("reliable:chat").track,
-      logger,
-    );
-    const received: Uint8Array[] = [];
-    const subscription = dataTrack.data$.subscribe((p) => received.push(p));
-
-    send("bob", [1]);
-    send("alice", [2]);
-    await flushPromises();
-
-    // Bob's is not this track's
-    expect(received).toEqual([new Uint8Array([2])]);
-    subscription.unsubscribe();
-  });
-});

sdk/src/media-backend/livekit/LivekitDataTrack.ts

@@ -1,74 +0,0 @@
-/*
-Copyright 2026 Element Creations Ltd.
-
-SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
-Please see LICENSE in the repository root for full details.
-*/
-
-import { type Logger } from "matrix-js-sdk/lib/logger";
-import { type RemoteDataTrack, type Room as LivekitRoom } from "livekit-client";
-import { filter, map, Observable, share } from "rxjs";
-
-import { type DataTrack } from "../../media-api";
-import { byteStreams$ } from "./ByteStreams";
-import { fromLivekitDataTrackName } from "./dataTrackName";
-
-/**
- * A remote member's data track. Decryption is LiveKit's: its E2EE manager
- * reads the key index and IV off each frame or stream and decrypts with the
- * sender's key, so nothing here sees a key. A frame of an encrypted track that
- * does not decrypt is dropped by LiveKit. A stream is not checked: LiveKit
- * 2.23 sends an encrypted packet without its encryption type, so a received
- * stream reads as unencrypted either way, and a cleartext one would pass.
- */
-export function createLivekitDataTrack(
-  room: LivekitRoom,
-  track: RemoteDataTrack,
-  logger: Logger,
-): DataTrack {
-  const { name, reliable } = fromLivekitDataTrackName(track.info.name);
-  const encrypted = track.info.usesE2ee;
-  const data$ = reliable
-    ? byteStreams$(room, track.info.name).pipe(
-        filter(({ identity }) => identity === track.publisherIdentity),
-        map(({ payload }) => payload),
-      )
-    : framesOf(track, logger);
-  return {
-    source: "data",
-    kind: "data",
-    id: track.info.sid,
-    name,
-    reliable,
-    encrypted,
-    data$,
-  };
-}
-
-/** The track's frames, subscribed at the SFU while observed. */
-function framesOf(
-  track: RemoteDataTrack,
-  logger: Logger,
-): Observable<Uint8Array> {
-  return new Observable<Uint8Array>((subscriber) => {
-    const reader = track.subscribe().getReader();
-    let cancelled = false;
-    void (async (): Promise<void> => {
-      try {
-        for (;;) {
-          const { done, value } = await reader.read();
-          if (done) break;
-          subscriber.next(value.payload);
-        }
-      } catch (e) {
-        // A failed subscription ends the stream; a host's pipeline survives it
-        if (!cancelled) logger.warn(`Data track ${track.info.name} ended`, e);
-      }
-      subscriber.complete();
-    })();
-    return (): void => {
-      cancelled = true;
-      reader.cancel().catch(() => {});
-    };
-  }).pipe(share());
-}

sdk/src/media-backend/livekit/LivekitMediaTrack.test.ts

@@ -225,6 +225,51 @@ describe("createLivekitMediaTrack", () => {
     );
   });
 
+  // LiveKit's media stream track is the processed one while a processor runs,
+  // and that one names no device; the camera behind it does
+  it.each([
+    { deviceId: "cam-1", switches: false },
+    { deviceId: "cam-2", switches: true },
+  ])(
+    "leaves a processed camera alone unless its device changes: $deviceId",
+    async ({ deviceId, switches }) => {
+      vi.stubGlobal("MediaStreamTrack", class {});
+      onTestFinished(() => {
+        vi.unstubAllGlobals();
+      });
+      const camera = Object.assign(Object.create(LocalVideoTrack.prototype), {
+        source: Track.Source.Camera,
+        _mediaStreamTrack: {
+          readyState: "live",
+          label: "",
+          getSettings: () => ({ deviceId: "cam-1" }),
+        },
+        // What LiveKit shows as the track, with no device of its own
+        processor: {
+          processedTrack: { label: "", getSettings: () => ({}) },
+        },
+      }) as LocalVideoTrack;
+      const switchActiveDevice = vi.fn().mockResolvedValue(true);
+      const { participant, publication, room } = fakes({
+        track: camera as unknown as FakeTrack,
+      });
+      const track = createLocalLivekitMediaTrack(
+        scope,
+        Object.assign(participant, {
+          isLocal: true,
+        }) as unknown as LocalParticipant,
+        publication as unknown as TrackPublication,
+        Object.assign(room, { switchActiveDevice }),
+        vi.fn(),
+      );
+
+      await track.setDevice(deviceId);
+      expect(switchActiveDevice.mock.calls).toEqual(
+        switches ? [["videoinput", deviceId, false]] : [],
+      );
+    },
+  );
+
   // LiveKit stops a camera that is turned off; the processor is built when it
   // is turned on again
   it.each([

sdk/src/media-backend/livekit/LivekitMediaTrack.ts

@@ -199,11 +199,13 @@ export function createLocalLivekitMediaTrack(
         throw new MatrixRTCError(`A ${base.source} track has no device`);
       // LiveKit decides whether to restart by the constraints it keeps, which
       // a browser that does not echo the device id back (Firefox) leaves
-      // without one; a track already on the device is left alone here
+      // without one; a track already on the device is left alone here. Asked
+      // of the camera track itself: with a processor on, LiveKit's media
+      // stream track is the processed one, which names no device
       const current = publication.track;
       if (
         current instanceof LocalTrack &&
-        current.mediaStreamTrack.getSettings().deviceId === deviceId
+        (await current.getDeviceId(false)) === deviceId
       )
         return;
       await room.switchActiveDevice(

sdk/src/media-backend/livekit/LivekitMemberMedia.test.ts

@@ -6,12 +6,9 @@ Please see LICENSE in the repository root for full details.
 */
 
 import { EventEmitter } from "events";
-import { logger } from "matrix-js-sdk/lib/logger";
 import {
   ParticipantEvent,
-  type RemoteDataTrack,
   type RemoteParticipant,
-  RoomEvent,
   type Room as LivekitRoom,
   Track,
   type TrackPublication,
@@ -30,7 +27,6 @@ describe("createLivekitMemberMedia", () => {
       testScope(),
       constant({ participants: [participant], room }),
       { kind: E2eeType.NONE },
-      logger,
     );
     expect(media.tracks$.value).toEqual([]);
 
@@ -58,7 +54,6 @@ describe("createLivekitMemberMedia", () => {
       testScope(),
       constant({ participants: [participant], room }),
       { kind: E2eeType.NONE },
-      logger,
     );
     emitter.emit(
       ParticipantEvent.TrackPublished,
@@ -90,44 +85,6 @@ function publish(
   return publication;
 }
 
-describe("a member's data tracks", () => {
-  it("follow the room's data track events, after the media", () => {
-    const { participant, publications, room, emitter } = fakes();
-    const media = createLivekitMemberMedia(
-      testScope(),
-      constant({ participants: [participant], room }),
-      { kind: E2eeType.NONE },
-      logger,
-    );
-    const camera = publish(publications, "TR_1", Track.Source.Camera);
-    emitter.emit(ParticipantEvent.TrackPublished, camera);
-
-    const chat = {
-      info: { sid: "DT_1", name: "reliable:chat", usesE2ee: true },
-      publisherIdentity: participant.identity,
-    } as unknown as RemoteDataTrack;
-    (room as unknown as EventEmitter).emit(RoomEvent.DataTrackPublished, chat);
-    const [video, data] = media.tracks$.value!;
-    expect(video.source).toBe("camera");
-    expect(data).toMatchObject({
-      kind: "data",
-      name: "chat",
-      reliable: true,
-      encrypted: true,
-    });
-
-    // An unrelated media event keeps the same object
-    emitter.emit(ParticipantEvent.TrackMuted, camera);
-    expect(media.tracks$.value![1]).toBe(data);
-
-    (room as unknown as EventEmitter).emit(
-      RoomEvent.DataTrackUnpublished,
-      "DT_1",
-    );
-    expect(media.tracks$.value).toEqual([video]);
-  });
-});
-
 function fakes(): {
   participant: RemoteParticipant;
   publications: Map<string, TrackPublication>;

sdk/src/media-backend/livekit/LivekitMemberMedia.ts

@@ -9,7 +9,6 @@ import {
   observeParticipantMedia,
   roomEventSelector,
 } from "@livekit/components-core";
-import { type Logger } from "matrix-js-sdk/lib/logger";
 import {
   type LocalParticipant,
   type Participant,
@@ -32,14 +31,11 @@ import { generateItems } from "../../reactive/observable";
 import { E2eeType, type EncryptionSystem } from "../../encryption";
 import { type Behavior } from "../../reactive/Behavior";
 import {
-  type DataTrack,
   type EncryptionError,
   type LocalMemberMedia,
   type MediaSource,
   type MemberMedia,
 } from "../../media-api";
-import { createLivekitDataTrack } from "./LivekitDataTrack";
-import { remoteDataTracks$ } from "./RemoteDataTracks";
 import {
   createLivekitMediaTrack,
   createLocalLivekitMediaTrack,
@@ -74,21 +70,13 @@ export function createLivekitMemberMedia(
   scope: ObservableScope,
   source$: Behavior<ParticipantSource>,
   encryptionSystem: EncryptionSystem,
-  logger: Logger,
 ): MemberMedia {
-  const media$ = memberTracks$(
-    scope,
-    source$,
-    (trackScope, participant, publication, room) =>
-      createLivekitMediaTrack(trackScope, participant, publication, room),
-  );
-  const data$ = memberDataTracks$(scope, source$, logger);
   return {
-    // The data tracks after the media, both null while there is no participant
-    tracks$: scope.behavior(
-      combineLatest([media$, data$], (media, data) =>
-        media === null ? null : [...media, ...data],
-      ),
+    tracks$: memberTracks$(
+      scope,
+      source$,
+      (trackScope, participant, publication, room) =>
+        createLivekitMediaTrack(trackScope, participant, publication, room),
     ),
     encryptionError$: encryptionErrors$(source$, encryptionSystem),
   };
@@ -157,40 +145,6 @@ function memberTracks$<P extends Participant, T>(
   );
 }
 
-/**
- * One data track per LiveKit data track of the member's participants, each
- * living as long as it is published.
- */
-function memberDataTracks$(
-  scope: ObservableScope,
-  source$: Behavior<ParticipantSource>,
-  logger: Logger,
-): Behavior<DataTrack[]> {
-  return scope.behavior(
-    source$.pipe(
-      switchMap((source) => {
-        if (source === null) return of([]);
-        const { participants, room } = source;
-        const identities = new Set(participants.map((p) => p.identity));
-        return remoteDataTracks$(room).pipe(
-          map((tracks) =>
-            tracks.filter((t) => identities.has(t.publisherIdentity)),
-          ),
-          generateItems(
-            `${[...identities].join(",")} dataTracks$`,
-            function* (tracks) {
-              for (const track of tracks)
-                yield { keys: [track.info.sid], data: track };
-            },
-            (_trackScope, track$) =>
-              createLivekitDataTrack(room, track$.value, logger),
-          ),
-        );
-      }),
-    ),
-  );
-}
-
 function encryptionErrors$(
   source$: Behavior<ParticipantSource>,
   encryptionSystem: EncryptionSystem,

sdk/src/media-backend/livekit/LocalDataTracks.ts

@@ -1,195 +0,0 @@
-/*
-Copyright 2026 Element Creations Ltd.
-
-SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
-Please see LICENSE in the repository root for full details.
-*/
-
-import {
-  ConnectionState as LivekitConnectionState,
-  type LocalDataTrack as LivekitLocalDataTrack,
-  type LocalParticipant,
-} from "livekit-client";
-import { type Logger } from "matrix-js-sdk/lib/logger";
-import {
-  BehaviorSubject,
-  combineLatest,
-  distinctUntilChanged,
-  first,
-  map,
-  type Observable,
-  of,
-  startWith,
-  Subject,
-  switchMap,
-} from "rxjs";
-
-import { type DataPublishRequest, type LocalDataTrack } from "../../media-api";
-import { type Behavior } from "../../reactive/Behavior";
-import { ObservableScope } from "../../reactive/ObservableScope";
-import { type Connection } from "./Connection";
-import { toLivekitDataTrackName } from "./dataTrackName";
-
-interface Props {
-  scope: ObservableScope;
-  /** The connection the local member publishes on. */
-  connection$: Behavior<Connection | null>;
-  /** Whether anything may leave this device: joined and the homeserver reachable. */
-  publishing$: Observable<boolean>;
-  /** Whether the rooms carry a key provider, so LiveKit encrypts what we send. */
-  encrypted: boolean;
-  logger: Logger;
-}
-
-export interface LocalDataTracks {
-  tracks$: Behavior<LocalDataTrack[]>;
-  /**
-   * Resolves once the track is published on LiveKit, which waits for the
-   * join. Rejects where a track of that name is published already, or where
-   * LiveKit refuses it.
-   */
-  publish(request: DataPublishRequest): Promise<LocalDataTrack>;
-  unpublish(track: LocalDataTrack): void;
-}
-
-interface Published {
-  track: LivekitLocalDataTrack;
-  participant: LocalParticipant;
-}
-
-interface Entry {
-  track: LocalDataTrack;
-  finish: () => void;
-}
-
-/**
- * The local member's data tracks. Each is one LiveKit data track, published
- * on every connection to the local transport while publishing is allowed, so
- * a track requested before the join goes out once we are joined. The object a
- * host holds outlives the connections. Encryption is LiveKit's: its E2EE
- * manager encrypts with our current key and writes the key index and IV into
- * each frame, or each stream for a reliable track.
- */
-export function createLocalDataTracks({
-  scope,
-  connection$,
-  publishing$,
-  encrypted,
-  logger,
-}: Props): LocalDataTracks {
-  const entries = new Map<string, Entry>();
-  const tracks$ = new BehaviorSubject<LocalDataTrack[]>([]);
-  const update = (): void =>
-    tracks$.next([...entries.values()].map(({ track }) => track));
-  scope.onEnd(() => {
-    for (const entry of entries.values()) entry.finish();
-  });
-
-  // Where to publish: the local connection once it has connected, while
-  // publishing is allowed
-  const target$ = scope.behavior(
-    combineLatest([connection$, publishing$]).pipe(
-      switchMap(([connection, publishing]) =>
-        connection === null || !publishing
-          ? of(null)
-          : connection.state$.pipe(
-              first(
-                (s) =>
-                  s.state === "authenticated" &&
-                  s.livekitState === LivekitConnectionState.Connected,
-              ),
-              map(() => connection),
-              startWith(null),
-            ),
-      ),
-      distinctUntilChanged(),
-    ),
-  );
-
-  const publish = async ({
-    name,
-    reliable = true,
-  }: DataPublishRequest): Promise<LocalDataTrack> => {
-    if (entries.has(name))
-      throw new Error(`A data track named ${name} is published already`);
-    const firstPublished = Promise.withResolvers<void>();
-    const livekitName = toLivekitDataTrackName(name, reliable);
-    const trackScope = new ObservableScope();
-    const published$ = new BehaviorSubject<Published | null>(null);
-    const sent$ = new Subject<Uint8Array>();
-    let finished = false;
-
-    trackScope.reconcile(target$, async (connection) => {
-      if (connection === null) return;
-      const participant = connection.livekitRoom.localParticipant;
-      let track: LivekitLocalDataTrack;
-      try {
-        track = await participant.publishDataTrack({ name: livekitName });
-      } catch (e) {
-        logger.error(`Failed to publish the data track ${name}`, e);
-        firstPublished.reject(e);
-        return;
-      }
-      published$.next({ track, participant });
-      firstPublished.resolve();
-      return async (): Promise<void> => {
-        published$.next(null);
-        await track.unpublish().catch((e: unknown) => {
-          logger.warn(`Failed to unpublish the data track ${name}`, e);
-        });
-      };
-    });
-
-    const track: LocalDataTrack = {
-      source: "data",
-      kind: "data",
-      id: `data:${name}`,
-      name,
-      reliable,
-      encrypted,
-      data$: sent$.asObservable(),
-      send: async (payload): Promise<void> => {
-        if (finished) throw new Error(`The data track ${name} is unpublished`);
-        const published = published$.value;
-        if (published === null)
-          throw new Error(
-            `Cannot send on ${name}: not published on the transport yet`,
-          );
-        if (reliable)
-          await published.participant.sendBytes(payload, {
-            topic: livekitName,
-          });
-        else
-          await published.track.tryPush({ payload: new Uint8Array(payload) });
-        sent$.next(payload);
-      },
-    };
-
-    entries.set(name, {
-      track,
-      finish: (): void => {
-        finished = true;
-        trackScope.end();
-        sent$.complete();
-      },
-    });
-    update();
-    try {
-      await firstPublished.promise;
-    } catch (e) {
-      unpublish(track);
-      throw e;
-    }
-    return track;
-  };
-
-  const unpublish = (track: LocalDataTrack): void => {
-    const entry = entries.get(track.name);
-    if (entry?.track !== track) return;
-    entries.delete(track.name);
-    entry.finish();
-    update();
-  };
-
-  return { tracks$: scope.behavior(tracks$), publish, unpublish };
-}

sdk/src/media-backend/livekit/LocalMedia.test.ts

@@ -7,7 +7,6 @@ Please see LICENSE in the repository root for full details.
 
 import {
   ConnectionState as LivekitConnectionState,
-  type LocalDataTrack as LivekitLocalDataTrack,
   type LocalParticipant,
   type LocalTrack,
   type LocalTrackPublication,
@@ -29,10 +28,6 @@ import { type Connection, type ConnectionState } from "./Connection";
 import { ConnectionMap } from "./ConnectionMap";
 import { createLivekitLocalMedia } from "./LocalMedia";
 import { exampleTransport } from "./test";
-import {
-  type LocalAudioMediaTrack,
-  type LocalDataTrack,
-} from "../../media-api";
 
 const localTransport: TransportLocator = {
   transport: exampleTransport,
@@ -275,8 +270,9 @@ describe("createLivekitLocalMedia", () => {
     media.setPublishing(true);
     await flushPromises();
 
-    const microphone = media.tracks$.value![0] as LocalAudioMediaTrack;
-    await expect(microphone.setEnabled(false)).resolves.toBe(false);
+    await expect(media.tracks$.value![0].setEnabled(false)).resolves.toBe(
+      false,
+    );
     expect(first.participant.setMicrophoneEnabled).toHaveBeenLastCalledWith(
       false,
     );
@@ -297,16 +293,10 @@ describe("createLivekitLocalMedia", () => {
     await flushPromises();
     await media.publish({ source: "screenShare" });
 
-    await media.unpublish({
-      kind: "audio",
-      source: "screenShareAudio",
-    } as LocalAudioMediaTrack);
+    await media.unpublish("screenShareAudio");
     expect(participant.setScreenShareEnabled).toHaveBeenLastCalledWith(false);
 
-    await media.unpublish({
-      kind: "audio",
-      source: "microphone",
-    } as LocalAudioMediaTrack);
+    await media.unpublish("microphone");
     expect(participant.unpublishTrack).toHaveBeenCalledOnce();
     expect(media.tracks$.value).toEqual([]);
   });
@@ -395,116 +385,6 @@ function fakeLocalTrack(source: Track.Source): LocalTrack {
   return t as unknown as LocalTrack;
 }
 
-describe("local data tracks", () => {
-  function joined(): ReturnType<typeof setup> & FakeConnection {
-    const fixture = setup();
-    const fake = fakeConnection();
-    fixture.connectionMap$.next(mapOf(fake.connection));
-    fixture.localTransport$.next(localTransport);
-    return { ...fixture, ...fake };
-  }
-
-  it("publishes on LiveKit only once publishing is allowed, and again on a new connection", async () => {
-    const { media, participant, connectionMap$ } = joined();
-    let published = false;
-    const publishing = media
-      .publish({ source: "data", name: "chat" })
-      .then((track) => {
-        published = true;
-        return track;
-      });
-    await flushPromises();
-    expect(participant.publishDataTrack).not.toHaveBeenCalled();
-    expect(published).toBe(false);
-    // Listed from the request on, like a media publication
-    const listed = media.tracks$.value!.find((t) => t.kind === "data");
-    expect(listed).toMatchObject({ name: "chat", reliable: true });
-
-    media.setPublishing(true);
-    const chat = await publishing;
-    expect(chat).toBe(listed);
-    expect(participant.publishDataTrack).toHaveBeenCalledWith({
-      name: "reliable:chat",
-    });
-
-    const next = fakeConnection();
-    connectionMap$.next(mapOf(next.connection));
-    await flushPromises();
-    expect(next.participant.publishDataTrack).toHaveBeenCalledWith({
-      name: "reliable:chat",
-    });
-    // The host's object outlives the connection
-    expect(media.tracks$.value).toContain(chat);
-  });
-
-  it("sends reliable data as a byte stream and lossy data as frames, replaying what was sent", async () => {
-    const { media, participant } = joined();
-    media.setPublishing(true);
-    const chat = await media.publish({ source: "data", name: "chat" });
-    const cursors = await media.publish({
-      source: "data",
-      name: "cursors",
-      reliable: false,
-    });
-    await flushPromises();
-    const sent: Uint8Array[] = [];
-    chat.data$.subscribe((p) => sent.push(p));
-
-    await chat.send(new Uint8Array([1]));
-    expect(participant.sendBytes).toHaveBeenCalledWith(new Uint8Array([1]), {
-      topic: "reliable:chat",
-    });
-    expect(sent).toEqual([new Uint8Array([1])]);
-
-    await cursors.send(new Uint8Array([2]));
-    const livekitCursors = await vi.mocked(participant.publishDataTrack).mock
-      .results[1].value;
-    expect(livekitCursors.tryPush).toHaveBeenCalledWith({
-      payload: new Uint8Array([2]),
-    });
-  });
-
-  it("rejects a second track of the same name, or one LiveKit refuses", async () => {
-    const { media, participant } = joined();
-    media.setPublishing(true);
-    await media.publish({ source: "data", name: "chat" });
-    await expect(
-      media.publish({ source: "data", name: "chat", reliable: false }),
-    ).rejects.toThrow("published already");
-
-    vi.mocked(participant.publishDataTrack).mockRejectedValueOnce(
-      new Error("DuplicateName"),
-    );
-    await expect(
-      media.publish({ source: "data", name: "cursors" }),
-    ).rejects.toThrow("DuplicateName");
-    expect(
-      media.tracks$.value!.filter((t) => t.kind === "data").map((t) => t.name),
-    ).toEqual(["chat"]);
-  });
-
-  it("finishes a track on unpublish", async () => {
-    const { media, participant } = joined();
-    media.setPublishing(true);
-    const chat: LocalDataTrack = await media.publish({
-      source: "data",
-      name: "chat",
-    });
-    await flushPromises();
-    let completed = false;
-    chat.data$.subscribe({ complete: () => (completed = true) });
-
-    await media.unpublish(chat);
-    await flushPromises();
-    const livekitChat = await vi.mocked(participant.publishDataTrack).mock
-      .results[0].value;
-    expect(livekitChat.unpublish).toHaveBeenCalled();
-    expect(completed).toBe(true);
-    expect(media.tracks$.value).not.toContain(chat);
-    await expect(chat.send(new Uint8Array([1]))).rejects.toThrow("unpublished");
-  });
-});
-
 /**
  * The slice of a local participant the publisher and the local tracks use:
  * enabling a source publishes a fake track at once, muting an existing one
@@ -562,14 +442,6 @@ function fakeLocalParticipant(): LocalParticipant {
 
   const participant = {
     ...emitter,
-    publishDataTrack: vi.fn(async ({ name }: { name: string }) =>
-      Promise.resolve({
-        name,
-        tryPush: vi.fn(async () => Promise.resolve()),
-        unpublish: vi.fn(async () => Promise.resolve()),
-      } as unknown as LivekitLocalDataTrack),
-    ),
-    sendBytes: vi.fn(async () => Promise.resolve({})),
     identity: "@alice:example.org:DEVICE",
     isLocal: true,
     isSpeaking: false,

sdk/src/media-backend/livekit/LocalMedia.ts

@@ -26,16 +26,13 @@ import {
 } from "rxjs";
 
 import {
-  type DataPublishRequest,
   type LocalAudioMediaTrack,
-  type LocalDataTrack,
   type LocalMedia,
-  type LocalTrack,
   type LocalVideoMediaTrack,
   type MediaSource,
   type PublishRequest,
 } from "../../media-api";
-import { E2eeType, type EncryptionSystem } from "../../encryption";
+import { type EncryptionSystem } from "../../encryption";
 import { FailToStartLivekitConnection, toMatrixRTCError } from "../../errors";
 import { type Behavior } from "../../reactive/Behavior";
 import {
@@ -53,7 +50,6 @@ import {
 } from "./LivekitMemberMedia";
 import { livekitSources } from "./LivekitMediaTrack";
 import { type DesiredMedia, Publisher } from "./Publisher";
-import { createLocalDataTracks } from "./LocalDataTracks";
 import { toMediaConnectionState } from "./connectionState";
 
 interface Props {
@@ -71,7 +67,7 @@ interface Props {
 }
 
 export interface LivekitLocalMedia extends LocalMediaBackend {
-  /** The connection the local member publishes on. */
+  /** The connection the local member publishes on; the data channel sends on it. */
   connection$: Behavior<Connection | null>;
   setAudioOutputDeviceId(deviceId: string): Promise<void>;
 }
@@ -175,42 +171,14 @@ export function createLivekitLocalMedia({
     return result;
   };
 
-  const { tracks$: mediaTracks$, encryptionError$ } =
-    createLocalLivekitMemberMedia(
-      scope,
-      participantAndRoom$(scope, participant$, connection$),
-      encryptionSystem,
-      setEnabled,
-    );
-  const dataTracks = createLocalDataTracks({
+  const { tracks$, encryptionError$ } = createLocalLivekitMemberMedia(
     scope,
-    connection$,
-    publishing$,
-    encrypted: encryptionSystem.kind !== E2eeType.NONE,
-    logger,
-  });
-  // The data tracks after the media, both null while there is no participant
-  const tracks$ = scope.behavior<LocalTrack[] | null>(
-    combineLatest([mediaTracks$, dataTracks.tracks$], (media, data) =>
-      media === null ? null : [...media, ...data],
-    ),
+    participantAndRoom$(scope, participant$, connection$),
+    encryptionSystem,
+    setEnabled,
   );
 
-  function publish(request: DataPublishRequest): Promise<LocalDataTrack>;
-  function publish(
-    request: PublishRequest,
-  ): Promise<LocalAudioMediaTrack | LocalVideoMediaTrack>;
-  async function publish(
-    request: DataPublishRequest | PublishRequest,
-  ): Promise<LocalTrack> {
-    if (request.source === "data")
-      return dataTracks.publish(request).catch((e: unknown) => {
-        throw toMatrixRTCError(e);
-      });
-    return publishMedia(request);
-  }
-
-  const publishMedia = async (
+  const publish = async (
     request: PublishRequest,
   ): Promise<LocalAudioMediaTrack | LocalVideoMediaTrack> => {
     desired.set(request.source, { request, enabled: true });
@@ -227,9 +195,8 @@ export function createLivekitLocalMedia({
     }
   };
 
-  const unpublish = async (track: LocalTrack): Promise<void> => {
-    if (track.kind === "data") return dataTracks.unpublish(track);
-    const published = publishedSource(track.source);
+  const unpublish = async (source: MediaSource): Promise<void> => {
+    const published = publishedSource(source);
     if (published === undefined) return;
     desired.delete(published);
     await publisher$.value?.unpublish(published);
@@ -292,16 +259,11 @@ function publication$(
 }
 
 function trackWithId$(
-  tracks$: Behavior<LocalTrack[] | null>,
+  tracks$: Behavior<(LocalAudioMediaTrack | LocalVideoMediaTrack)[] | null>,
   id: string,
 ): Observable<LocalAudioMediaTrack | LocalVideoMediaTrack> {
   return tracks$.pipe(
-    map((tracks) =>
-      tracks?.find(
-        (track): track is LocalAudioMediaTrack | LocalVideoMediaTrack =>
-          track.kind !== "data" && track.id === id,
-      ),
-    ),
+    map((tracks) => tracks?.find((track) => track.id === id)),
     filter((track) => track !== undefined),
   );
 }

sdk/src/media-backend/livekit/Publisher.ts

@@ -72,11 +72,9 @@ export class Publisher {
     private readonly media?: LocalMedia,
   ) {
     this.room = room;
-    room
-      .setE2EEEnabled(room.options.encryption !== undefined)
-      ?.catch((e: Error) => {
-        this.logger.error("Failed to enable E2EE on the room", e);
-      });
+    room.setE2EEEnabled(room.options.e2ee !== undefined)?.catch((e: Error) => {
+      this.logger.error("Failed to enable E2EE on the room", e);
+    });
     this.onLocalTrackPublished = this.onLocalTrackPublished.bind(this);
     room.localParticipant.on(
       ParticipantEvent.LocalTrackPublished,

sdk/src/media-backend/livekit/RemoteDataTracks.test.ts

@@ -1,39 +0,0 @@
-/*
-Copyright 2026 Element Creations Ltd.
-
-SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
-Please see LICENSE in the repository root for full details.
-*/
-
-import { EventEmitter } from "events";
-import {
-  type RemoteDataTrack,
-  type Room as LivekitRoom,
-  RoomEvent,
-} from "livekit-client";
-import { describe, expect, it } from "vitest";
-
-import { remoteDataTracks$, watchRemoteDataTracks } from "./RemoteDataTracks";
-
-const track = (sid: string): RemoteDataTrack =>
-  ({ info: { sid }, publisherIdentity: "alice" }) as RemoteDataTrack;
-
-describe("remoteDataTracks$", () => {
-  it("keeps what the room announced before anyone observed it", () => {
-    const emitter = new EventEmitter();
-    const room = watchRemoteDataTracks(emitter as unknown as LivekitRoom);
-    // As in a join response: announced before any member asks
-    emitter.emit(RoomEvent.DataTrackPublished, track("DT_1"));
-    emitter.emit(RoomEvent.DataTrackPublished, track("DT_2"));
-    emitter.emit(RoomEvent.DataTrackUnpublished, "DT_1");
-
-    const seen: string[][] = [];
-    remoteDataTracks$(room).subscribe((tracks) =>
-      seen.push(tracks.map((t) => t.info.sid)),
-    );
-    expect(seen).toEqual([["DT_2"]]);
-
-    emitter.emit(RoomEvent.Disconnected);
-    expect(seen.at(-1)).toEqual([]);
-  });
-});

sdk/src/media-backend/livekit/RemoteDataTracks.ts

@@ -1,60 +0,0 @@
-/*
-Copyright 2026 Element Creations Ltd.
-
-SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
-Please see LICENSE in the repository root for full details.
-*/
-
-import {
-  type RemoteDataTrack,
-  type Room as LivekitRoom,
-  RoomEvent,
-} from "livekit-client";
-import { BehaviorSubject, type Observable } from "rxjs";
-
-const tracksByRoom = new WeakMap<
-  LivekitRoom,
-  BehaviorSubject<readonly RemoteDataTrack[]>
->();
-
-/**
- * Starts keeping the room's remote data tracks, from its own events. Called
- * as the room is created: LiveKit announces the tracks in the join response
- * before the participants that publish them exist, so a participant's
- * `dataTracks` misses them, and it adds a track to that map only after
- * announcing it.
- */
-export function watchRemoteDataTracks(room: LivekitRoom): LivekitRoom {
-  remoteDataTracksOf(room);
-  return room;
-}
-
-/** Every remote data track the room knows of, as LiveKit announced them. */
-export function remoteDataTracks$(
-  room: LivekitRoom,
-): Observable<readonly RemoteDataTrack[]> {
-  return remoteDataTracksOf(room);
-}
-
-function remoteDataTracksOf(
-  room: LivekitRoom,
-): BehaviorSubject<readonly RemoteDataTrack[]> {
-  let tracks$ = tracksByRoom.get(room);
-  if (tracks$ === undefined) {
-    const subject$ = new BehaviorSubject<readonly RemoteDataTrack[]>([]);
-    room.on(RoomEvent.DataTrackPublished, (track: RemoteDataTrack) =>
-      subject$.next([
-        ...subject$.value.filter((t) => t.info.sid !== track.info.sid),
-        track,
-      ]),
-    );
-    room.on(RoomEvent.DataTrackUnpublished, (sid: string) =>
-      subject$.next(subject$.value.filter((t) => t.info.sid !== sid)),
-    );
-    // A new session announces its tracks again
-    room.on(RoomEvent.Disconnected, () => subject$.next([]));
-    tracksByRoom.set(room, subject$);
-    tracks$ = subject$;
-  }
-  return tracks$;
-}

sdk/src/media-backend/livekit/dataTrackName.test.ts

@@ -1,28 +0,0 @@
-/*
-Copyright 2026 Element Creations Ltd.
-
-SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
-Please see LICENSE in the repository root for full details.
-*/
-
-import { describe, expect, it } from "vitest";
-
-import {
-  fromLivekitDataTrackName,
-  toLivekitDataTrackName,
-} from "./dataTrackName";
-
-describe("data track names on LiveKit", () => {
-  it.each([true, false])("round-trips reliable=%s", (reliable) => {
-    expect(
-      fromLivekitDataTrackName(toLivekitDataTrackName("chat:room", reliable)),
-    ).toEqual({ name: "chat:room", reliable });
-  });
-
-  it("reads a name without a prefix as lossy", () => {
-    expect(fromLivekitDataTrackName("telemetry")).toEqual({
-      name: "telemetry",
-      reliable: false,
-    });
-  });
-});

sdk/src/media-backend/livekit/dataTrackName.ts

@@ -1,36 +0,0 @@
-/*
-Copyright 2026 Element Creations Ltd.
-
-SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
-Please see LICENSE in the repository root for full details.
-*/
-
-/**
- * How a data track is named on LiveKit. Every data track of a member is one
- * LiveKit data track, which announces it; the prefix says how its payloads
- * travel. A lossy track pushes them as frames on the data track itself. A
- * reliable one sends each as a byte stream on a topic of the same name,
- * because LiveKit's data tracks are lossy only.
- */
-
-const lossyPrefix = "lossy:";
-const reliablePrefix = "reliable:";
-
-export function toLivekitDataTrackName(
-  name: string,
-  reliable: boolean,
-): string {
-  return (reliable ? reliablePrefix : lossyPrefix) + name;
-}
-
-/** A track without a prefix, from a plain LiveKit publisher, is lossy under its own name. */
-export function fromLivekitDataTrackName(livekitName: string): {
-  name: string;
-  reliable: boolean;
-} {
-  if (livekitName.startsWith(reliablePrefix))
-    return { name: livekitName.slice(reliablePrefix.length), reliable: true };
-  if (livekitName.startsWith(lossyPrefix))
-    return { name: livekitName.slice(lossyPrefix.length), reliable: false };
-  return { name: livekitName, reliable: false };
-}

sdk/src/utils/tracks.test.ts

@@ -8,9 +8,9 @@ Please see LICENSE in the repository root for full details.
 import { BehaviorSubject } from "rxjs";
 import { describe, expect, it } from "vitest";
 
-import { type DataTrack, type MediaTrack } from "../media-api";
+import { type MediaTrack } from "../media-api";
 import { testScope } from "./test";
-import { dataTrackByName$, trackBySource$ } from "./tracks";
+import { trackBySource$ } from "./tracks";
 
 const camera = { source: "camera", kind: "video", id: "1" } as MediaTrack;
 const microphone = {
@@ -39,40 +39,3 @@ describe("trackBySource$", () => {
     expect(emissions).toEqual([camera]);
   });
 });
-
-const chat = {
-  source: "data",
-  kind: "data",
-  id: "3",
-  name: "chat",
-} as DataTrack;
-const cursors = {
-  source: "data",
-  kind: "data",
-  id: "4",
-  name: "cursors",
-} as DataTrack;
-
-describe("dataTrackByName$", () => {
-  it("picks the data track of a name and follows the list", () => {
-    const tracks$ = new BehaviorSubject<(MediaTrack | DataTrack)[] | null>(
-      null,
-    );
-    const chat$ = dataTrackByName$(testScope(), tracks$, "chat");
-    expect(chat$.value).toBeUndefined();
-    tracks$.next([camera, cursors, chat]);
-    expect(chat$.value).toBe(chat);
-    tracks$.next([camera, cursors]);
-    expect(chat$.value).toBeUndefined();
-  });
-
-  it("does not emit when the list changes elsewhere", () => {
-    const tracks$ = new BehaviorSubject<(MediaTrack | DataTrack)[]>([chat]);
-    const chat$ = dataTrackByName$(testScope(), tracks$, "chat");
-    const emissions: unknown[] = [];
-    chat$.subscribe((t) => emissions.push(t));
-    tracks$.next([chat, camera]);
-    tracks$.next([microphone, chat, cursors]);
-    expect(emissions).toEqual([chat]);
-  });
-});

sdk/src/utils/tracks.ts

@@ -11,7 +11,6 @@ import { type Behavior } from "../reactive/Behavior";
 import { type ObservableScope } from "../reactive/ObservableScope";
 import {
   type AudioMediaTrack,
-  type DataTrack,
   type MediaSource,
   type MediaTrack,
   type VideoMediaTrack,
@@ -28,7 +27,7 @@ export type TrackOfSource<S extends MediaSource> = S extends
 /** The member's first track of a source; undefined while there is none, or no media yet. */
 export function trackBySource$<S extends MediaSource>(
   scope: ObservableScope,
-  tracks$: Behavior<readonly (MediaTrack | DataTrack)[] | null>,
+  tracks$: Behavior<MediaTrack[] | null>,
   source: S,
 ): Behavior<TrackOfSource<S> | undefined> {
   return scope.behavior(
@@ -43,21 +42,3 @@ export function trackBySource$<S extends MediaSource>(
     ),
   );
 }
-
-/** The member's data track of this name; undefined while there is none, or no media yet. */
-export function dataTrackByName$(
-  scope: ObservableScope,
-  tracks$: Behavior<readonly (MediaTrack | DataTrack)[] | null>,
-  name: string,
-): Behavior<DataTrack | undefined> {
-  return scope.behavior(
-    tracks$.pipe(
-      map((tracks) =>
-        tracks?.find(
-          (t): t is DataTrack => t.kind === "data" && t.name === name,
-        ),
-      ),
-      distinctUntilChanged(),
-    ),
-  );
-}

src/App.tsx

@@ -30,7 +30,7 @@ import { HomePage } from "./home/HomePage";
 import { LoginPage } from "./auth/LoginPage";
 import { RegisterPage } from "./auth/RegisterPage";
 import { RoomPage } from "./room/RoomPage";
-import { ClientProvider } from "./ClientContext";
+import { type ClientLoader, ClientProvider } from "./ClientContext";
 import { ErrorPage, LoadingPage } from "./FullScreenView";
 import { Initializer } from "./initializer";
 import { type WidgetHelpers } from "./widget";
@@ -57,6 +57,16 @@ import { LeaveToHomeProvider } from "./LeaveToHomeContext";
 
 const SentryRoute = Sentry.withSentryReactRouterV7Routing(Route);
 
+// Element Call's own session, for when no host supplies a client.
+// - Passed in here, not imported by ClientProvider: this module is only in the
+//   app builds, so the client setup and the store worker behind it stay out of
+//   the component package (see the `loadClient` prop).
+// - Imported on demand, as it was before, so that a widget, which gets its
+//   client from the host, never downloads it.
+// - Module-level, so that the provider's effect sees one stable loader.
+const loadStandaloneClient: ClientLoader = async (...args) =>
+  (await import("./utils/spa")).initSPA(...args);
+
 interface SimpleProviderProps {
   children: JSX.Element;
 }
@@ -146,7 +156,7 @@ export const App: FC<Props> = ({ vm, widget }) => {
 
   const content =
     loaded && clientReady ? (
-      <ClientProvider client={widgetClient}>
+      <ClientProvider client={widgetClient} loadClient={loadStandaloneClient}>
         <MediaDevicesContext value={vm.mediaDevices}>
           <BackgroundEffectsProvider effects={vm.backgroundEffects}>
             <Sentry.ErrorBoundary

src/ClientContext.test.tsx

@@ -11,7 +11,11 @@ import { BrowserRouter } from "react-router-dom";
 import { type MatrixClient } from "matrix-js-sdk";
 import { type FC } from "react";
 
-import { ClientProvider, useClientState } from "./ClientContext";
+import {
+  type ClientLoader,
+  ClientProvider,
+  useClientState,
+} from "./ClientContext";
 
 const mockClient = (userId = "@alice:example.org"): MatrixClient =>
   ({
@@ -95,13 +99,13 @@ test("follows the client when the host swaps it", () => {
 
 test("finds a client of its own when the host supplies none", async () => {
   const client = mockClient();
-  vi.doMock("./utils/spa", () => ({
-    initSPA: vi.fn().mockResolvedValue({ client, passwordlessUser: true }),
-  }));
+  const loadClient = vi
+    .fn<ClientLoader>()
+    .mockResolvedValue({ client, passwordlessUser: true });
 
   const { container } = render(
     <BrowserRouter>
-      <ClientProvider>
+      <ClientProvider loadClient={loadClient}>
         <ShowClientState />
       </ClientProvider>
     </BrowserRouter>,
@@ -110,6 +114,21 @@ test("finds a client of its own when the host supplies none", async () => {
   // Nothing to show until a session has been restored or created
   expect(container.textContent).toBe("loading");
   await waitFor(() => expect(container.textContent).toBe("@alice:example.org"));
+  // Given the session store to restore from and to clear on a stale session
+  expect(loadClient).toHaveBeenCalledWith(
+    expect.any(Function),
+    expect.any(Function),
+  );
+});
 
-  vi.doUnmock("./utils/spa");
+test("has no one signed in when given neither a client nor a way to load one", async () => {
+  const { container } = render(
+    <BrowserRouter>
+      <ClientProvider>
+        <ShowClientState />
+      </ClientProvider>
+    </BrowserRouter>,
+  );
+
+  await waitFor(() => expect(container.textContent).toBe("unauthenticated"));
 });

src/ClientContext.tsx

@@ -143,9 +143,34 @@ interface Props {
    * own.
    */
   client?: MatrixClient;
+  /**
+   * How Element Call finds a client when none is supplied: the standalone app
+   * restores or creates a session of its own. Stable, as a hook dependency.
+   * Left out along with the client, no one is signed in.
+   *
+   * A prop, rather than this module importing `utils/spa` itself, because:
+   * - This module is in the component build, and so is everything it imports,
+   *   dynamically or not: a dynamic import becomes a chunk in the package,
+   *   not a module left out of it.
+   * - Behind `utils/spa` sits `utils/initClient` and the client store worker,
+   *   which the bundler emits as soon as it loads the import (see there).
+   * - `App.tsx`, which the component never imports, is where the standalone
+   *   app passes the loader in; the component passes nothing, having the
+   *   host's client.
+   */
+  loadClient?: ClientLoader;
 }
 
-export const ClientProvider: FC<Props> = ({ children, client }) => {
+/**
+ * Restores or creates a session of Element Call's own, kept where the given
+ * functions keep it. Resolves to null when no one is signed in.
+ */
+export type ClientLoader = (
+  loadSession: () => Session | undefined,
+  clearSession: () => void,
+) => Promise<InitResult | null>;
+
+export const ClientProvider: FC<Props> = ({ children, client, loadClient }) => {
   const leaveToHome = useLeaveToHome();
   const hostBridge = useHostBridge();
 
@@ -179,9 +204,13 @@ export const ClientProvider: FC<Props> = ({ children, client }) => {
     // React does in strict mode), we need to make sure not to doubly initialize
     // the client.
     if (initializing.current) return;
+    if (loadClient === undefined) {
+      setInitClientState(null);
+      return;
+    }
     initializing.current = true;
 
-    loadClient()
+    loadClient(loadSession, clearSession)
       .then((initResult) => {
         setInitClientState(initResult);
         if (PosthogAnalytics.instance.isEnabled())
@@ -189,7 +218,7 @@ export const ClientProvider: FC<Props> = ({ children, client }) => {
       })
       .catch((err) => logger.error(err))
       .finally(() => (initializing.current = false));
-  }, [client]);
+  }, [client, loadClient]);
 
   const changePassword = useCallback(
     async (password: string) => {
@@ -360,15 +389,6 @@ export type InitResult = {
   passwordlessUser: boolean;
 };
 
-/**
- * Restores or creates a session of Element Call's own. Only reached when no
- * client was supplied for it to use.
- */
-async function loadClient(): Promise<InitResult | null> {
-  const { initSPA } = await import("./utils/spa");
-  return initSPA(loadSession, clearSession);
-}
-
 export interface Session {
   user_id: string;
   device_id: string;

src/UrlConfiguration.ts

@@ -18,6 +18,8 @@ Please see LICENSE in the repository root for full details.
  */
 
 import {
+  RTC_CALL_INTENT_AUDIO,
+  RTC_CALL_INTENT_VIDEO,
   type RTCCallIntent,
   type RTCNotificationType,
 } from "matrix-js-sdk/lib/matrixrtc";
@@ -179,40 +181,40 @@ export function configurationForIntent(intent: UserIntent): UrlConfiguration {
   switch (intent) {
     case UserIntent.StartNewCall:
       preset.skipLobby = false;
-      preset.callIntent = "video";
+      preset.callIntent = RTC_CALL_INTENT_VIDEO;
       break;
     case UserIntent.JoinExistingCall:
       // On desktop this will be overridden based on which button was used to join the call
       preset.skipLobby = false;
-      preset.callIntent = "video";
+      preset.callIntent = RTC_CALL_INTENT_VIDEO;
       break;
     case UserIntent.StartNewCallVoice:
       preset.skipLobby = false;
-      preset.callIntent = "audio";
+      preset.callIntent = RTC_CALL_INTENT_AUDIO;
       break;
     case UserIntent.JoinExistingCallVoice:
       // On desktop this will be overridden based on which button was used to join the call
       preset.skipLobby = false;
-      preset.callIntent = "audio";
+      preset.callIntent = RTC_CALL_INTENT_AUDIO;
       break;
     case UserIntent.StartNewCallDMVoice:
-      preset.callIntent = "audio";
+      preset.callIntent = RTC_CALL_INTENT_AUDIO;
     // Fall through
     case UserIntent.StartNewCallDM:
       preset.skipLobby = true;
       preset.sendNotificationType = "ring";
       preset.autoLeaveWhenOthersLeft = true;
       preset.waitForCallPickup = true;
-      preset.callIntent = preset.callIntent ?? "video";
+      preset.callIntent = preset.callIntent ?? RTC_CALL_INTENT_VIDEO;
       break;
     case UserIntent.JoinExistingCallDMVoice:
-      preset.callIntent = "audio";
+      preset.callIntent = RTC_CALL_INTENT_AUDIO;
     // Fall through
     case UserIntent.JoinExistingCallDM:
       // On desktop this will be overridden based on which button was used to join the call
       preset.skipLobby = true;
       preset.autoLeaveWhenOthersLeft = true;
-      preset.callIntent = preset.callIntent ?? "video";
+      preset.callIntent = preset.callIntent ?? RTC_CALL_INTENT_VIDEO;
       break;
     // Non widget usecase defaults
     default:

src/UrlParams.test.ts

@@ -21,6 +21,10 @@ import {
   UserIntent,
 } from "../src/UrlParams";
 import { mockConfig } from "./utils/test";
+import {
+  RTC_CALL_INTENT_AUDIO,
+  RTC_CALL_INTENT_VIDEO,
+} from "matrix-js-sdk/lib/matrixrtc";
 
 const ROOM_NAME = "roomNameHere";
 const ROOM_ID = "!d45f138fsd";
@@ -275,7 +279,7 @@ describe("UrlParams", () => {
       ).toMatchObject({
         ...startNewCallDefaults("desktop"),
         skipLobby: false,
-        callIntent: "video",
+        callIntent: RTC_CALL_INTENT_VIDEO,
       });
     });
 
@@ -322,7 +326,7 @@ describe("UrlParams", () => {
       ).toMatchObject({
         ...startNewCallDefaults("desktop"),
         skipLobby: false,
-        callIntent: "audio",
+        callIntent: RTC_CALL_INTENT_AUDIO,
       });
     });
 
@@ -333,7 +337,7 @@ describe("UrlParams", () => {
         ),
       ).toMatchObject({
         ...joinExistingCallDefaults("desktop"),
-        callIntent: "audio",
+        callIntent: RTC_CALL_INTENT_AUDIO,
       });
     });
 
@@ -348,7 +352,7 @@ describe("UrlParams", () => {
         sendNotificationType: "ring",
         autoLeaveWhenOthersLeft: true,
         waitForCallPickup: true,
-        callIntent: "audio",
+        callIntent: RTC_CALL_INTENT_AUDIO,
       });
     });
 
@@ -363,7 +367,7 @@ describe("UrlParams", () => {
         skipLobby: true,
         autoLeaveWhenOthersLeft: true,
         waitForCallPickup: false,
-        callIntent: "video",
+        callIntent: RTC_CALL_INTENT_VIDEO,
       });
     });
 
@@ -377,7 +381,7 @@ describe("UrlParams", () => {
         skipLobby: true,
         autoLeaveWhenOthersLeft: true,
         waitForCallPickup: false,
-        callIntent: "audio",
+        callIntent: RTC_CALL_INTENT_AUDIO,
       });
     });
   });

src/auth/useInteractiveLogin.ts

@@ -13,7 +13,7 @@ import {
   type MatrixClient,
 } from "matrix-js-sdk";
 
-import { initClient } from "../utils/matrix";
+import { initClient } from "../utils/initClient";
 import { type Session } from "../ClientContext";
 /**
  * This provides the login method to login using user credentials.

src/auth/useInteractiveRegistration.ts

@@ -14,7 +14,7 @@ import {
 } from "matrix-js-sdk";
 import { logger } from "matrix-js-sdk/lib/logger";
 
-import { initClient } from "../utils/matrix";
+import { initClient } from "../utils/initClient";
 import { type Session } from "../ClientContext";
 import { Config } from "../config/Config";
 import { useUrlParams } from "../UrlParams";

src/components/BackgroundEffectGrid.module.css

@@ -90,3 +90,42 @@ Please see LICENSE in the repository root for full details.
   text-align: center;
   overflow-wrap: anywhere;
 }
+
+.removable {
+  position: relative;
+  display: flex;
+  min-inline-size: 0;
+}
+
+.removable > .tile {
+  flex: 1;
+}
+
+/* Clear of the target for choosing the tile. */
+.remove {
+  position: absolute;
+  inset-block-start: 0;
+  inset-inline-end: 0;
+  translate: 20% -20%;
+  display: none;
+  align-items: center;
+  justify-content: center;
+  inline-size: 28px;
+  block-size: 28px;
+  border-radius: 50%;
+  background: var(--cpd-color-bg-canvas-default);
+  color: var(--cpd-color-icon-critical-primary);
+  box-shadow: 0 1.2px 2.4px 0 rgb(0 0 0 / 15%);
+  cursor: pointer;
+}
+
+.remove:hover {
+  background: var(--cpd-color-bg-critical-subtle-hovered);
+  box-shadow: 0 0 0 var(--cpd-border-width-1)
+    var(--cpd-color-border-critical-subtle);
+}
+
+.removable:hover .remove,
+.removable:focus-within .remove {
+  display: flex;
+}

src/components/BackgroundEffectGrid.tsx

@@ -5,14 +5,16 @@ SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
 Please see LICENSE in the repository root for full details.
 */
 
-import { type FC, type ReactElement } from "react";
+import { type FC, type KeyboardEvent, type ReactElement } from "react";
 import { useTranslation } from "react-i18next";
 import { VisuallyHidden } from "@radix-ui/react-visually-hidden";
-import { InlineSpinner, MenuItem } from "@vector-im/compound-web";
+import { InlineSpinner, MenuItem, Tooltip } from "@vector-im/compound-web";
 import {
   BlockIcon,
   BlurIcon,
   CheckCircleSolidIcon,
+  CloseIcon,
+  PlusIcon,
 } from "@vector-im/compound-design-tokens/assets/web/icons";
 
 import styles from "./BackgroundEffectGrid.module.css";
@@ -27,6 +29,8 @@ export interface BackgroundEffectGridItem {
   kind: "none" | "blur" | "image";
   /** For kind "image". */
   imageUrl?: string;
+  /** Whether it is the user's to remove. */
+  removable?: boolean;
 }
 
 interface Props {
@@ -38,6 +42,12 @@ interface Props {
   settling?: boolean;
   /** Id of the text saying what the user should know before choosing. */
   describedBy?: string;
+  /** Offers to add a background of one's own. Omit to leave that tile out. */
+  onAdd?: () => void;
+  addLabel?: string;
+  /** Removes a removable one, never the one in force. Omit to offer none. */
+  onRemove?: (id: string) => void;
+  removeLabel?: string;
 }
 
 /**
@@ -51,6 +61,10 @@ export const BackgroundEffectGrid: FC<Props> = ({
   onSelect,
   settling = false,
   describedBy,
+  onAdd,
+  addLabel,
+  onRemove,
+  removeLabel,
 }) => {
   const { t } = useTranslation();
   const choose = (id: string): void => {
@@ -66,7 +80,30 @@ export const BackgroundEffectGrid: FC<Props> = ({
           : t("background_effects.numbered", { n: ++pictures });
     const checked = effect.id === selected;
     const disabled = onSelect === undefined && effect.kind !== "none";
-    return (
+    const remove =
+      effect.removable && !checked && onRemove !== undefined
+        ? (): void => onRemove(effect.id)
+        : undefined;
+    const removeProps =
+      remove === undefined
+        ? {}
+        : {
+            "aria-keyshortcuts": "Delete",
+            onKeyDown: (e: KeyboardEvent): void => {
+              if (e.key !== "Delete" && e.key !== "Backspace") return;
+              e.preventDefault();
+              remove();
+            },
+          };
+    const content = (
+      <TileContent
+        effect={effect}
+        label={label}
+        checked={checked}
+        settling={checked && settling}
+      />
+    );
+    const tile = (
       <MenuItem
         key={effect.id}
         role="menuitemradio"
@@ -88,21 +125,57 @@ export const BackgroundEffectGrid: FC<Props> = ({
                 choose(effect.id);
               }
         }
+        {...removeProps}
       >
-        <TileContent
-          effect={effect}
-          label={label}
-          checked={checked}
-          settling={checked && settling}
-        />
+        {content}
       </MenuItem>
     );
+    if (remove === undefined) return tile;
+    // Beside the item, not in it: inside, the item takes the press first and
+    // the tile is chosen instead.
+    return (
+      <div key={effect.id} className={styles.removable}>
+        {tile}
+        <Tooltip label={removeLabel ?? ""}>
+          {/* Not a control of its own, so the menu keeps one keyboard model:
+              the keyboard reaches the same action through Delete. */}
+          <span aria-hidden className={styles.remove} onClick={remove}>
+            <CloseIcon width={20} height={20} />
+          </span>
+        </Tooltip>
+      </div>
+    );
   });
 
+  // A command rather than a choice, so an item beside the radios.
+  const addContent = (
+    <>
+      <span aria-hidden className={styles.swatch}>
+        <PlusIcon width={24} height={24} />
+      </span>
+      <VisuallyHidden>{addLabel}</VisuallyHidden>
+    </>
+  );
+  const addTile =
+    onAdd === undefined ? null : (
+      <MenuItem
+        label={null}
+        hideChevron
+        className={styles.tile}
+        onSelect={(e) => {
+          e.preventDefault();
+          onAdd();
+        }}
+      >
+        {addContent}
+      </MenuItem>
+    );
+
   return (
     // A group of its own, as the section's can't carry the description.
     <div role="group" aria-describedby={describedBy} className={styles.grid}>
       {tiles}
+      {addTile}
     </div>
   );
 };

src/components/CallFooter.stories.tsx

@@ -127,16 +127,21 @@ export const Default: Story = {
     selectBackgroundEffect: fn(),
     backgroundEffect: "blur",
     backgroundEffects: [
-      { id: "none", kind: "none" },
-      { id: "blur", kind: "blur" },
+      { id: "none", kind: "none", removable: false },
+      { id: "blur", kind: "blur", removable: false },
       ...shippedBackgrounds.map((background) => ({
         id: `image:${background.id}`,
         kind: "image" as const,
         imageUrl: background.imagePath,
+        removable: false,
       })),
     ],
     backgroundEffectNotice: undefined,
     backgroundEffectSettling: false,
+    backgroundImageRefusal: undefined,
+    addBackgroundImage: fn(),
+    removeBackgroundEffect: fn(),
+    cameraTrack: null,
     hangup: fn(),
     buttonSize: "lg",
     showFooter: true,

src/components/CallFooter.tsx

@@ -33,6 +33,13 @@ import { useBehavior } from "../useBehavior";
 import { type LayoutSwitchViewModel } from "../state/LayoutSwitchViewModel";
 import { LayoutSwitch } from "../room/LayoutSwitch";
 import { type BackgroundEffectGridItem } from "./BackgroundEffectGrid";
+import { SelfPreview } from "./SelfPreview";
+import { type UnusableReason } from "../tracks/backgroundImages";
+import { type LocalVideoMediaTrack } from "@element-hq/matrixrtc-sdk";
+
+export interface BackgroundImageRefusal {
+  reason: UnusableReason | "not-kept";
+}
 
 export interface AudioOutputSwitcher {
   targetOutput: string;
@@ -60,6 +67,10 @@ export interface FooterActions {
   toggleVideo: (() => void) | undefined;
   /** Undefined where background effects can't be chosen. */
   selectBackgroundEffect: ((id: string) => void) | undefined;
+  /** Undefined where no background can be added. */
+  addBackgroundImage: ((file: File) => void) | undefined;
+  /** Removes an added background by its option id; never the one in force. */
+  removeBackgroundEffect: ((id: string) => void) | undefined;
   toggleScreenSharing: (() => void) | undefined;
   /** Also controls if the settings button is visible */
   openSettings: (() => void) | undefined;
@@ -81,6 +92,10 @@ export interface FooterState {
   backgroundEffectNotice: "unavailable" | "slow" | undefined;
   /** Whether the first effect chosen is still being prepared. */
   backgroundEffectSettling: boolean;
+  /** Why the last file offered couldn't be kept, if it couldn't. */
+  backgroundImageRefusal: BackgroundImageRefusal | undefined;
+  /** The camera to preview, with the effect in force; null while it is off. */
+  cameraTrack: LocalVideoMediaTrack | null;
   showFooter: boolean;
 
   /* This is needed for WindowMode = "flat" */
@@ -168,6 +183,24 @@ export const CallFooter: FC<FooterProps> = ({
   const selectBackgroundEffect = useBehavior(vm.selectBackgroundEffect$);
   const backgroundEffectNotice = useBehavior(vm.backgroundEffectNotice$);
   const backgroundEffectSettling = useBehavior(vm.backgroundEffectSettling$);
+  const addBackgroundImage = useBehavior(vm.addBackgroundImage$);
+  const removeBackgroundEffect = useBehavior(vm.removeBackgroundEffect$);
+  const cameraTrack = useBehavior(vm.cameraTrack$);
+  const refusal = useBehavior(vm.backgroundImageRefusal$);
+  const refusalMessage = useMemo(() => {
+    switch (refusal?.reason) {
+      case undefined:
+        return undefined;
+      case "not-an-image":
+        return { text: t("error.background_not_an_image") };
+      case "animated":
+        return { text: t("error.background_animated") };
+      case "undecodable":
+        return { text: t("error.background_undecodable") };
+      case "not-kept":
+        return { text: t("error.background_not_kept") };
+    }
+  }, [refusal, t]);
   const backgroundEffects = useBehavior(vm.backgroundEffects$);
   const buttonSize = useBehavior(vm.buttonSize$);
   const showLogo = useBehavior(vm.showLogo$);
@@ -234,6 +267,10 @@ export const CallFooter: FC<FooterProps> = ({
         selectedBackgroundEffect={backgroundEffect}
         onSelectBackgroundEffect={selectBackgroundEffect}
         backgroundEffectSettling={backgroundEffectSettling}
+        onAddBackgroundImage={addBackgroundImage}
+        onRemoveBackgroundEffect={removeBackgroundEffect}
+        selfPreview={<SelfPreview track={cameraTrack} />}
+        backgroundImageRefusal={refusalMessage}
         backgroundEffectNotice={
           backgroundEffectNotice === "unavailable"
             ? t("background_effects.unavailable")

src/components/CallFooterViewModel.test.ts

@@ -7,9 +7,17 @@ Please see LICENSE in the repository root for full details.
 
 import { afterEach, describe, expect, it, vi } from "vitest";
 import { BehaviorSubject } from "rxjs";
+import { type LocalVideoMediaTrack } from "@element-hq/matrixrtc-sdk";
 
-import { testScope, mockMuteStates, mockMediaDevices } from "../utils/test";
-import { constant } from "../state/Behavior";
+import {
+  flushPromises,
+  testScope,
+  mockMuteStates,
+  mockMediaDevices,
+  mockVideoTrack,
+} from "../utils/test";
+import { type Behavior, constant } from "../state/Behavior";
+import { type BackgroundEffectsState } from "../state/BackgroundEffects";
 import type { CallViewModel } from "../state/CallViewModel/CallViewModel";
 import type { Layout } from "../state/layout-types";
 import type { SpotlightTileViewModel } from "../state/TileViewModel";
@@ -21,6 +29,13 @@ import {
 import { HeaderStyle } from "../UrlParams";
 import { backgroundEffect as backgroundEffectSetting } from "../settings/settings";
 import { shippedBackgrounds } from "../tracks/backgroundEffectCatalog";
+import type * as BackgroundImages from "../tracks/backgroundImages";
+import {
+  type AddedBackground,
+  addedBackgrounds,
+  maxAddedBackgrounds,
+  UnusableImage,
+} from "../tracks/backgroundImages";
 
 const platformMock = vi.hoisted(() => vi.fn(() => "desktop"));
 vi.mock("../Platform", () => ({
@@ -37,6 +52,22 @@ vi.mock("@livekit/track-processors", () => ({
   supportsModernBackgroundProcessors: (): boolean => modernRouteMock(),
 }));
 
+const store = vi.hoisted(() => ({
+  add: vi.fn<(file: Blob) => Promise<string>>(),
+  remove: vi.fn<(id: string) => Promise<void>>(),
+}));
+vi.mock("../tracks/backgroundImages", async (original) => {
+  const { BehaviorSubject } = await import("rxjs");
+  return {
+    ...(await original<typeof BackgroundImages>()),
+    addedBackgrounds: {
+      added$: new BehaviorSubject<AddedBackground[] | undefined>([]),
+      add: store.add,
+      remove: store.remove,
+    },
+  };
+});
+
 const outputSelectionMock = vi.hoisted(() => vi.fn(() => true));
 vi.mock("livekit-client", () => ({
   supportsAudioOutputSelection: (): boolean => outputSelectionMock(),
@@ -50,6 +81,7 @@ vi.mock("livekit-client", () => ({
 function buildMinimalCallViewModel(layout: Layout): CallViewModel {
   return {
     layout$: constant(layout),
+    camera$: constant(undefined),
     edgeToEdge$: constant(false),
     showHeader$: constant(false),
     hangup: (): void => {},
@@ -81,6 +113,16 @@ const pipLayout: Layout = {
   spotlight: {} as SpotlightTileViewModel,
 };
 
+const noPipeline = constant<BackgroundEffectsState>({
+  supported: false,
+  processor: undefined,
+});
+
+/** The provider's verdict, which the SDK's check stands for here. */
+function pipelineAsTheSdkSays(): Behavior<BackgroundEffectsState> {
+  return constant({ supported: sdkSupportMock(), processor: undefined });
+}
+
 const twoMicsAndOneCamMediaDevices = mockMediaDevices({
   audioInput: {
     available$: constant(
@@ -112,7 +154,7 @@ describe("createCallFooterViewModel", () => {
         buildMinimalCallViewModel(gridLayout),
         mockMuteStates(),
         twoMicsAndOneCamMediaDevices,
-        constant(false),
+        noPipeline,
         /* reactionIdentifier */ undefined,
         { showControls: true, header: HeaderStyle.Standard },
       );
@@ -155,7 +197,7 @@ describe("createCallFooterViewModel", () => {
             select: vi.fn(),
           },
         }),
-        constant(false),
+        noPipeline,
         /* reactionIdentifier */ undefined,
         { showControls: true, header: HeaderStyle.Standard },
       );
@@ -174,7 +216,7 @@ describe("createCallFooterViewModel", () => {
         buildMinimalCallViewModel(layout),
         mockMuteStates(),
         twoMicsAndOneCamMediaDevices,
-        constant(false),
+        noPipeline,
         /* reactionIdentifier */ undefined,
         { showControls: true, header: HeaderStyle.Standard },
       );
@@ -197,7 +239,7 @@ describe("createCallFooterViewModel", () => {
         buildMinimalCallViewModel(gridLayout),
         mockMuteStates(),
         twoMicsAndOneCamMediaDevices,
-        constant(false),
+        noPipeline,
         /* reactionIdentifier */ undefined,
         { showControls: true, header: HeaderStyle.Standard },
       );
@@ -243,7 +285,8 @@ describe("createCallFooterViewModel", () => {
         testScope(),
         mockMuteStates(),
         twoMicsAndOneCamMediaDevices,
-        constant(false),
+        pipelineAsTheSdkSays(),
+        /* camera$ */ constant(null),
         /* openSettings */ undefined,
         /* hangup */ undefined,
         /* showLogo */ false,
@@ -263,6 +306,7 @@ describe("createCallFooterViewModel", () => {
     it("offers nothing where the browser itself cannot run them", () => {
       sdkSupportMock.mockReturnValue(false);
       expect(lobbyOn("desktop").selectBackgroundEffect$.value).toBeUndefined();
+      expect(lobbyOn("desktop").addBackgroundImage$.value).toBeUndefined();
     });
 
     it("puts no effect in force where the browser cannot run them", () => {
@@ -293,17 +337,29 @@ describe("createCallFooterViewModel", () => {
       expect(lobbyOn("desktop").backgroundEffectNotice$.value).toBeUndefined();
     });
 
-    it("offers every effect in order", () => {
+    it("offers every effect in order, the added ones removable", () => {
       sdkSupportMock.mockReturnValue(true);
+      const added$ = addedBackgrounds.added$ as BehaviorSubject<
+        AddedBackground[] | undefined
+      >;
+      added$.next([{ id: "mine", url: "blob:mine" }]);
       expect(lobbyOn("desktop").backgroundEffects$.value).toEqual([
-        { id: "none", kind: "none" },
-        { id: "blur", kind: "blur" },
+        { id: "none", kind: "none", removable: false },
+        { id: "blur", kind: "blur", removable: false },
         ...shippedBackgrounds.map((background) => ({
           id: `image:${background.id}`,
           kind: "image",
           imageUrl: background.imagePath,
+          removable: false,
         })),
+        {
+          id: "added:mine",
+          kind: "image",
+          imageUrl: "blob:mine",
+          removable: true,
+        },
       ]);
+      added$.next([]);
     });
 
     it("says they are unavailable where they cannot be chosen", () => {
@@ -315,21 +371,146 @@ describe("createCallFooterViewModel", () => {
 
     it("passes on the wait for the first effect", () => {
       platformMock.mockReturnValue("desktop");
-      const settling$ = new BehaviorSubject(true);
+      const pipeline$ = new BehaviorSubject<BackgroundEffectsState>({
+        supported: true,
+        processor: undefined,
+        wait: "settling",
+      });
       const vm = createLobbyFooterViewModel(
         testScope(),
         mockMuteStates(),
         twoMicsAndOneCamMediaDevices,
-        settling$,
+        pipeline$,
+        /* camera$ */ constant(null),
         /* openSettings */ undefined,
         /* hangup */ undefined,
         /* showLogo */ false,
       );
       expect(vm.backgroundEffectSettling$.value).toBe(true);
-      settling$.next(false);
+      pipeline$.next({ ...pipeline$.value, wait: undefined });
       expect(vm.backgroundEffectSettling$.value).toBe(false);
     });
 
+    it("offers nothing once the pipeline fails to build, keeping the choice", () => {
+      platformMock.mockReturnValue("desktop");
+      backgroundEffectSetting.setValue("blur");
+      const pipeline$ = new BehaviorSubject<BackgroundEffectsState>({
+        supported: true,
+        processor: undefined,
+      });
+      const vm = createLobbyFooterViewModel(
+        testScope(),
+        mockMuteStates(),
+        twoMicsAndOneCamMediaDevices,
+        pipeline$,
+        /* camera$ */ constant(null),
+        /* openSettings */ undefined,
+        /* hangup */ undefined,
+        /* showLogo */ false,
+      );
+      expect(vm.backgroundEffect$.value).toBe("blur");
+
+      pipeline$.next({ supported: false, processor: undefined });
+      expect(vm.selectBackgroundEffect$.value).toBeUndefined();
+      expect(vm.addBackgroundImage$.value).toBeUndefined();
+      expect(vm.backgroundEffect$.value).toBe("none");
+      expect(backgroundEffectSetting.getValue()).toBe("blur");
+    });
+
+    it("adding is unavailable at the limit", () => {
+      sdkSupportMock.mockReturnValue(true);
+      const added$ = addedBackgrounds.added$ as BehaviorSubject<
+        AddedBackground[] | undefined
+      >;
+      const vm = lobbyOn("desktop");
+      expect(vm.addBackgroundImage$.value).toBeDefined();
+      added$.next(
+        Array.from({ length: maxAddedBackgrounds }, (_, i) => ({
+          id: `${i}`,
+          url: `blob:${i}`,
+        })),
+      );
+      expect(vm.addBackgroundImage$.value).toBeUndefined();
+      added$.next(added$.value!.slice(1));
+      expect(vm.addBackgroundImage$.value).toBeDefined();
+      added$.next([]);
+    });
+
+    it("says why each refused file was refused", async () => {
+      sdkSupportMock.mockReturnValue(true);
+      const vm = lobbyOn("desktop");
+      store.add.mockRejectedValue(new UnusableImage("animated"));
+      vm.addBackgroundImage$.value!(new File(["x"], "a.gif"));
+      await flushPromises();
+      const first = vm.backgroundImageRefusal$.value;
+      expect(first).toEqual({ reason: "animated" });
+
+      // The same again is a refusal of its own, so it is shown again.
+      vm.addBackgroundImage$.value!(new File(["x"], "a.gif"));
+      await flushPromises();
+      expect(vm.backgroundImageRefusal$.value).toEqual({ reason: "animated" });
+      expect(vm.backgroundImageRefusal$.value).not.toBe(first);
+
+      store.add.mockRejectedValue(new Error("quota"));
+      vm.addBackgroundImage$.value!(new File(["x"], "b.png"));
+      await flushPromises();
+      expect(vm.backgroundImageRefusal$.value).toEqual({ reason: "not-kept" });
+
+      store.add.mockResolvedValue("kept");
+      vm.addBackgroundImage$.value!(new File(["x"], "c.png"));
+      await flushPromises();
+      expect(vm.backgroundImageRefusal$.value).toBeUndefined();
+    });
+
+    it("never removes the background in force", () => {
+      sdkSupportMock.mockReturnValue(true);
+      store.remove.mockResolvedValue();
+      const vm = lobbyOn("desktop");
+      backgroundEffectSetting.setValue("added:worn");
+      vm.removeBackgroundEffect$.value!("added:worn");
+      expect(store.remove).not.toHaveBeenCalled();
+      vm.removeBackgroundEffect$.value!("added:spare");
+      expect(store.remove).toHaveBeenCalledWith("spare");
+    });
+
+    it("previews the lobby's camera while there is one", () => {
+      const track = mockVideoTrack({});
+      const camera$ = new BehaviorSubject<LocalVideoMediaTrack | null>(track);
+      const vm = createLobbyFooterViewModel(
+        testScope(),
+        mockMuteStates(),
+        twoMicsAndOneCamMediaDevices,
+        noPipeline,
+        camera$,
+        /* openSettings */ undefined,
+        /* hangup */ undefined,
+        /* showLogo */ false,
+      );
+      expect(vm.cameraTrack$.value).toBe(track);
+      // The lobby releases the camera when it is turned off
+      camera$.next(null);
+      expect(vm.cameraTrack$.value).toBeNull();
+    });
+
+    it("previews the call's camera only while it is not muted", () => {
+      const muted$ = new BehaviorSubject(false);
+      const track = mockVideoTrack({ muted$ });
+      const vm = createCallFooterViewModel(
+        testScope(),
+        { ...buildMinimalCallViewModel(gridLayout), camera$: constant(track) },
+        mockMuteStates(),
+        twoMicsAndOneCamMediaDevices,
+        noPipeline,
+        /* reactionIdentifier */ undefined,
+        { showControls: true, header: HeaderStyle.Standard },
+      );
+      expect(vm.cameraTrack$.value).toBe(track);
+      muted$.next(true);
+      expect(vm.cameraTrack$.value).toBeNull();
+      muted$.next(false);
+      expect(vm.cameraTrack$.value).toBe(track);
+    });
+
     it("availability is the same before and during a call", () => {
       for (const supported of [true, false]) {
         sdkSupportMock.mockReturnValue(supported);
@@ -339,7 +520,7 @@ describe("createCallFooterViewModel", () => {
           buildMinimalCallViewModel(gridLayout),
           mockMuteStates(),
           twoMicsAndOneCamMediaDevices,
-          constant(false),
+          pipelineAsTheSdkSays(),
           /* reactionIdentifier */ undefined,
           { showControls: true, header: HeaderStyle.Standard },
         );

src/components/CallFooterViewModel.tsx

@@ -6,25 +6,33 @@ Please see LICENSE in the repository root for full details.
 */
 
 import {
+  BehaviorSubject,
   combineLatest,
   distinctUntilChanged,
   map,
   type Observable,
+  of,
   switchMap,
 } from "rxjs";
 import { supportsAudioOutputSelection } from "livekit-client";
-import {
-  supportsBackgroundProcessors,
-  supportsModernBackgroundProcessors,
-} from "@livekit/track-processors";
+import { type LocalVideoMediaTrack } from "@element-hq/matrixrtc-sdk";
+import { supportsModernBackgroundProcessors } from "@livekit/track-processors";
+import { logger } from "matrix-js-sdk/lib/logger";
 
 import {
   parseEffect,
   serializeEffect,
   shippedBackgrounds,
 } from "../tracks/backgroundEffectCatalog";
+import {
+  type AddedBackground,
+  addedBackgrounds,
+  maxAddedBackgrounds,
+  UnusableImage,
+} from "../tracks/backgroundImages";
 
 import { type CallViewModel } from "../state/CallViewModel/CallViewModel";
+import { type BackgroundEffectsState } from "../state/BackgroundEffects";
 import { type MenuOptions } from "./MediaMuteAndSwitchButton";
 import { type MediaDevices } from "../state/MediaDevices";
 import {
@@ -37,7 +45,7 @@ import { type MuteStates } from "../state/MuteStates";
 import { createStaticViewModel, type ViewModel } from "../state/ViewModel";
 import { HeaderStyle } from "../UrlParams";
 import { platform } from "../Platform";
-import { type FooterSnapshot } from "./CallFooter";
+import { type BackgroundImageRefusal, type FooterSnapshot } from "./CallFooter";
 import { type BackgroundEffectGridItem } from "./BackgroundEffectGrid";
 
 /**
@@ -79,7 +87,9 @@ function buildDeviceBehaviors(
   mediaDevices: MediaDevices,
   /** return empty arrays for  audioOptions and videoOptions*/
   disableSwitcher$: Behavior<boolean>,
-  backgroundEffectSettling$: Observable<boolean>,
+  backgroundEffectsState$: Observable<BackgroundEffectsState>,
+  /** The camera as the pipeline has it, for the menu's preview. */
+  camera$: Observable<LocalVideoMediaTrack | null | undefined>,
 ): Pick<
   ViewModel<FooterSnapshot>,
   | "audioOptions$"
@@ -96,6 +106,10 @@ function buildDeviceBehaviors(
   | "backgroundEffects$"
   | "backgroundEffectNotice$"
   | "backgroundEffectSettling$"
+  | "addBackgroundImage$"
+  | "backgroundImageRefusal$"
+  | "removeBackgroundEffect$"
+  | "cameraTrack$"
 > {
   const options$ = (
     available$: Behavior<Map<string, MenuOptions["label"]>>,
@@ -112,10 +126,18 @@ function buildDeviceBehaviors(
       ),
     );
 
-  const supported = supportsBackgroundProcessors();
+  // Also false once the pipeline has failed to build this session.
+  const supported$ = backgroundEffectsState$.pipe(
+    map(({ supported }) => supported === true),
+    distinctUntilChanged(),
+  );
   const slow = !supportsModernBackgroundProcessors();
-  const offered$ = disableSwitcher$.pipe(
-    map((switcherDisabled) => !switcherDisabled && supported),
+  const offered$ = combineLatest([disableSwitcher$, supported$]).pipe(
+    map(([switcherDisabled, supported]) => !switcherDisabled && supported),
+  );
+  // A new object for each refusal, so the same one twice is shown twice.
+  const refusal$ = new BehaviorSubject<BackgroundImageRefusal | undefined>(
+    undefined,
   );
   return {
     audioOptions$: scope.behavior(options$(mediaDevices.audioInput.available$)),
@@ -142,8 +164,10 @@ function buildDeviceBehaviors(
     ),
     selectVideoButtonOption$: constant(mediaDevices.videoInput.select),
     backgroundEffect$: scope.behavior(
-      backgroundEffectSetting.value$.pipe(
-        map((raw) => (supported ? serializeEffect(parseEffect(raw)) : "none")),
+      combineLatest([backgroundEffectSetting.value$, supported$]).pipe(
+        map(([raw, supported]) =>
+          supported ? serializeEffect(parseEffect(raw)) : "none",
+        ),
       ),
     ),
     selectBackgroundEffect$: scope.behavior(
@@ -158,7 +182,11 @@ function buildDeviceBehaviors(
         ),
       ),
     ),
-    backgroundEffects$: constant(backgroundEffectChoices()),
+    backgroundEffects$: scope.behavior(
+      addedBackgrounds.added$.pipe(
+        map((added) => backgroundEffectChoices(added ?? [])),
+      ),
+    ),
     backgroundEffectNotice$: scope.behavior(
       offered$.pipe(
         map((offered) =>
@@ -167,9 +195,61 @@ function buildDeviceBehaviors(
       ),
     ),
     backgroundEffectSettling$: scope.behavior(
-      backgroundEffectSettling$.pipe(distinctUntilChanged()),
+      backgroundEffectsState$.pipe(
+        map(({ wait }) => wait !== undefined),
+        distinctUntilChanged(),
+      ),
       false,
     ),
+    // Kept and offered, not put on: that waits for the user to choose it.
+    addBackgroundImage$: scope.behavior(
+      combineLatest([offered$, addedBackgrounds.added$]).pipe(
+        map(([offered, added]) =>
+          offered && (added?.length ?? 0) < maxAddedBackgrounds
+            ? (file: File): void => {
+                refusal$.next(undefined);
+                addedBackgrounds.add(file).catch((e) => {
+                  logger.warn("Could not keep that background", e);
+                  refusal$.next({
+                    reason: e instanceof UnusableImage ? e.reason : "not-kept",
+                  });
+                });
+              }
+            : undefined,
+        ),
+      ),
+    ),
+    backgroundImageRefusal$: refusal$,
+    // None while muted: the call mutes its track rather than releasing it.
+    cameraTrack$: scope.behavior(
+      camera$.pipe(
+        switchMap((camera) =>
+          camera
+            ? camera.muted$.pipe(map((muted) => (muted ? null : camera)))
+            : of(null),
+        ),
+      ),
+      null,
+    ),
+    // Never the one in force: taking it away would leave nothing chosen.
+    removeBackgroundEffect$: scope.behavior(
+      offered$.pipe(
+        map((offered) =>
+          offered
+            ? (optionId: string): void => {
+                const effect = parseEffect(optionId);
+                if (effect.kind !== "added") return;
+                if (backgroundEffectSetting.getValue() === optionId) return;
+                addedBackgrounds
+                  .remove(effect.id)
+                  .catch((e) =>
+                    logger.warn("Could not remove that background", e),
+                  );
+              }
+            : undefined,
+        ),
+      ),
+    ),
   };
 }
 
@@ -180,8 +260,8 @@ function buildDeviceBehaviors(
  * @param callModel - The root CallViewModel; provides layout, grid mode, reactions, etc.
  * @param muteStates - Audio and video mute state + toggles.
  * @param mediaDevices - Available and selected input devices.
- * @param backgroundEffectSettling$ - Whether the first effect chosen is still
- *   being prepared.
+ * @param backgroundEffectsState$ - The background pipeline's state: whether
+ *   effects run here, and the wait for the first.
  * @param reactionIdentifier - The local user's reaction identifier string, or
  *   undefined when reactions are not supported (hides the reaction button).
  * @param options - `showControls`: whether the call controls should be shown.
@@ -192,7 +272,7 @@ export function createCallFooterViewModel(
   callModel: CallViewModel,
   muteStates: MuteStates,
   mediaDevices: MediaDevices,
-  backgroundEffectSettling$: Observable<boolean>,
+  backgroundEffectsState$: Observable<BackgroundEffectsState>,
   reactionIdentifier: string | undefined,
   options: { showControls: boolean; header: HeaderStyle },
 ): ViewModel<FooterSnapshot> {
@@ -211,7 +291,8 @@ export function createCallFooterViewModel(
       scope,
       mediaDevices,
       disableDeviceSwitcher$,
-      backgroundEffectSettling$,
+      backgroundEffectsState$,
+      callModel.camera$,
     ),
     // candidat to move into the FooterViewModel
     showFooter$: callModel.showFooter$,
@@ -274,8 +355,9 @@ export function createCallFooterViewModel(
  * @param scope - ObservableScope that bounds the lifetime of derived behaviors.
  * @param muteStates - Audio and video mute state + toggles.
  * @param mediaDevices - Available and selected input devices.
- * @param backgroundEffectSettling$ - Whether the first effect chosen is still
- *   being prepared.
+ * @param backgroundEffectsState$ - The background pipeline's state: whether
+ *   effects run here, and the wait for the first.
+ * @param camera$ - The lobby's camera, for the camera menu's preview.
  * @param openSettings - Callback to open the settings modal, or undefined.
  * @param hangup - Callback to leave/cancel, or undefined (hides the button).
  * @param showLogo - Whether to show the Element Call logo.
@@ -284,7 +366,8 @@ export function createLobbyFooterViewModel(
   scope: ObservableScope,
   muteStates: MuteStates,
   mediaDevices: MediaDevices,
-  backgroundEffectSettling$: Observable<boolean>,
+  backgroundEffectsState$: Observable<BackgroundEffectsState>,
+  camera$: Behavior<LocalVideoMediaTrack | null>,
   openSettings: (() => void) | undefined,
   hangup: (() => void) | undefined,
   showLogo: boolean,
@@ -332,19 +415,29 @@ export function createLobbyFooterViewModel(
       scope,
       mediaDevices,
       constant(false),
-      backgroundEffectSettling$,
+      backgroundEffectsState$,
+      camera$,
     ),
   };
 }
 
-function backgroundEffectChoices(): BackgroundEffectGridItem[] {
+function backgroundEffectChoices(
+  added: AddedBackground[],
+): BackgroundEffectGridItem[] {
   return [
-    { id: serializeEffect({ kind: "none" }), kind: "none" },
-    { id: serializeEffect({ kind: "blur" }), kind: "blur" },
+    { id: serializeEffect({ kind: "none" }), kind: "none", removable: false },
+    { id: serializeEffect({ kind: "blur" }), kind: "blur", removable: false },
     ...shippedBackgrounds.map((background) => ({
       id: serializeEffect({ kind: "shipped", id: background.id }),
       kind: "image" as const,
       imageUrl: background.imagePath,
+      removable: false,
+    })),
+    ...added.map((background) => ({
+      id: serializeEffect({ kind: "added", id: background.id }),
+      kind: "image" as const,
+      imageUrl: background.url,
+      removable: true,
     })),
   ];
 }

src/components/MediaMuteAndSwitchButton.module.css

@@ -93,3 +93,39 @@ Please see LICENSE in the repository root for full details.
   flex-shrink: 0;
   color: var(--cpd-color-icon-secondary);
 }
+
+.refusal {
+  margin: var(--cpd-space-2x) var(--cpd-space-4x) 0;
+}
+
+.selfPreview {
+  position: relative;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  flex-shrink: 0;
+  aspect-ratio: 16 / 9;
+  margin-block-end: var(--cpd-space-2x);
+  overflow: clip;
+  border-start-start-radius: var(--cpd-space-3x);
+  border-start-end-radius: var(--cpd-space-3x);
+  background: var(--cpd-color-bg-subtle-secondary);
+  color: var(--cpd-color-icon-secondary);
+}
+
+.selfPreview > video {
+  position: absolute;
+  inset: 0;
+  inline-size: 100%;
+  block-size: 100%;
+  object-fit: cover;
+  /* Rounded itself too: a video can be drawn on a layer of its own, which the
+     frame's rounded clip doesn't always reach. */
+  border-radius: inherit;
+}
+
+/* Up to the menu's frame, over the padding at its top. */
+.selfPreviewPinned,
+.deviceListLeadsWithPreview {
+  margin-block-start: calc(-1 * var(--cpd-space-5x));
+}

src/components/MediaMuteAndSwitchButton.stories.tsx

@@ -12,6 +12,7 @@ import type { Meta, StoryObj } from "@storybook/react-vite";
 import { MediaMuteAndSwitchButton } from "./MediaMuteAndSwitchButton";
 import styles from "./MediaMuteAndSwitchButton.module.css";
 import { type BackgroundEffectGridItem } from "./BackgroundEffectGrid";
+import { SelfPreview } from "./SelfPreview";
 import { shippedBackgrounds } from "../tracks/backgroundEffectCatalog";
 import meterStyles from "./MicrophoneLevelMeter.module.css";
 import { MediaDevicesContext } from "../MediaDevicesContext";
@@ -60,6 +61,50 @@ const WithAMicrophone: FC<{ children: ReactNode }> = ({ children }) => {
   return <>{children}</>;
 };
 
+/** A camera for the preview: a figure against a room, drawn to a stream. */
+const FakeCamera: FC = () => {
+  const [stream, setStream] = useState<MediaStream>();
+  useEffect(() => {
+    const canvas = document.createElement("canvas");
+    canvas.width = 640;
+    canvas.height = 360;
+    const context = canvas.getContext("2d")!;
+    const draw = (): void => {
+      context.fillStyle = "#6b7f8e";
+      context.fillRect(0, 0, 640, 360);
+      context.fillStyle = "#c9a27e";
+      context.beginPath();
+      context.arc(320, 150, 62, 0, 2 * Math.PI);
+      context.fill();
+      context.fillStyle = "#34495e";
+      context.beginPath();
+      context.ellipse(320, 380, 150, 140, 0, Math.PI, 2 * Math.PI);
+      context.fill();
+    };
+    draw();
+    // Redrawn, so the stream keeps delivering frames.
+    const timer = setInterval(draw, 200);
+    const captured = canvas.captureStream(10);
+    setStream(captured);
+    return (): void => {
+      clearInterval(timer);
+      captured.getTracks().forEach((track) => track.stop());
+    };
+  }, []);
+  return (
+    <video
+      data-testid="preview-camera"
+      autoPlay
+      muted
+      playsInline
+      ref={(video): void => {
+        if (video && stream && video.srcObject !== stream)
+          video.srcObject = stream;
+      }}
+    />
+  );
+};
+
 /** Supplies a call-sized root. Without one the list is bounded by the whole Storybook frame. */
 const WithACallArea: FC<{ children: ReactNode; blockSize?: number }> = ({
   children,
@@ -171,8 +216,8 @@ export const VideoMute: Story = {
       { label: { type: "name", name: "Camera 1" }, id: "1" },
       { label: { type: "name", name: "Camera 2" }, id: "2" },
     ],
-
     selectedOption: "1",
+    selfPreview: <SelfPreview track={null} />,
   },
 };
 
@@ -198,6 +243,9 @@ export const VideoUnmute: Story = {
     backgroundEffects: effects,
     selectedBackgroundEffect: "none",
     onSelectBackgroundEffect: fn(),
+    onAddBackgroundImage: fn(),
+    // As the footer always gives the camera menu one.
+    selfPreview: <FakeCamera />,
   },
 };
 
@@ -241,6 +289,11 @@ export const BackgroundEffects: Story = {
         true,
       );
 
+    const add = within(section).getByRole("menuitem", { name: "Add image" });
+    await expect(
+      tiles[3].compareDocumentPosition(add) & Node.DOCUMENT_POSITION_FOLLOWING,
+    ).toBeTruthy();
+
     await userEvent.click(menu.getByRole("menuitemradio", { name: "Blur" }));
     await expect(args.onSelectBackgroundEffect).toHaveBeenCalledWith("blur");
     await expect(menu.getByRole("menu")).toBeVisible();
@@ -338,6 +391,270 @@ export const BackgroundEffectsSettling: Story = {
       checked: false,
     }))
       await expect(other).toHaveAttribute("aria-busy", "false");
+    await expect(menu.queryByTestId("preview-camera")).toBeNull();
+    const frames = document.body.querySelectorAll(`.${styles.selfPreview} svg`);
+    await expect(frames).toHaveLength(1);
+  },
+};
+
+/** A file that can't be used: said where it was chosen, and nothing changes. */
+export const BackgroundImageRefused: Story = {
+  args: {
+    ...VideoUnmute.args,
+    selectedBackgroundEffect: "blur",
+    backgroundEffectNotice:
+      "Background effects run slowly on this platform, which may cause your video to stutter.",
+    backgroundImageRefusal: { text: "That file is not a supported image" },
+  },
+  decorators: [
+    (Story): JSX.Element => (
+      <WithACallArea blockSize={300}>
+        <Story />
+      </WithACallArea>
+    ),
+  ],
+  play: async ({ canvasElement }) => {
+    const canvas = within(canvasElement);
+    await userEvent.click(canvas.getByRole("button", { name: "Camera" }));
+    const menu = within(document.body);
+    const message = await menu.findByText("That file is not a supported image");
+    const list = document.body.querySelector<HTMLElement>(
+      `.${styles.deviceList}`,
+    )!;
+    await expect(list.scrollHeight).toBeGreaterThan(list.clientHeight);
+    const scrollport = list.getBoundingClientRect();
+    const shown = message.getBoundingClientRect();
+    await expect(shown.bottom).toBeLessThanOrEqual(scrollport.bottom + 1);
+    await expect(shown.top).toBeGreaterThanOrEqual(scrollport.top - 1);
+    await expect(menu.queryByText(/run slowly/)).toBeNull();
+    await expect(
+      menu.getByRole("menuitemradio", { name: "Blur" }),
+    ).toHaveAttribute("aria-checked", "true");
+  },
+};
+
+/** A flat picture, for backgrounds of one's own. */
+function swatch(colour: string): string {
+  return `data:image/svg+xml,${encodeURIComponent(
+    `<svg xmlns="http://www.w3.org/2000/svg" width="16" height="9"><rect width="16" height="9" fill="${colour}"/></svg>`,
+  )}`;
+}
+
+/** One's own backgrounds are removable, never the one in force. */
+export const AddedBackgroundsCanBeRemoved: Story = {
+  args: {
+    ...VideoUnmute.args,
+    backgroundEffects: [
+      ...effects,
+      {
+        id: "added:one",
+        kind: "image",
+        imageUrl: swatch("#c2410c"),
+        removable: true,
+      },
+      {
+        id: "added:two",
+        kind: "image",
+        imageUrl: swatch("#1d4ed8"),
+        removable: true,
+      },
+    ],
+    selectedBackgroundEffect: "added:one",
+    onRemoveBackgroundEffect: fn(),
+  },
+  play: async ({ args, canvasElement }) => {
+    const canvas = within(canvasElement);
+    await userEvent.click(canvas.getByRole("button", { name: "Camera" }));
+    const body = within(document.body);
+
+    const inForce = await body.findByRole("menuitemradio", {
+      name: "Background 3",
+    });
+    await expect(inForce).not.toHaveAttribute("aria-keyshortcuts");
+
+    const other = body.getByRole("menuitemradio", { name: "Background 4" });
+    await expect(other).toHaveAttribute("aria-keyshortcuts", "Delete");
+    other.focus();
+    await userEvent.keyboard("{Delete}");
+    await expect(args.onRemoveBackgroundEffect).toHaveBeenCalledWith(
+      "added:two",
+    );
+
+    const wrapper = other.parentElement!;
+    await userEvent.hover(wrapper);
+    const cross = wrapper.querySelector<HTMLElement>(
+      "[aria-hidden]:last-child",
+    )!;
+    const probe = document.createElement("span");
+    probe.style.color = "var(--cpd-color-icon-critical-primary)";
+    cross.append(probe);
+    const critical = getComputedStyle(probe).color;
+    probe.remove();
+    await expect(getComputedStyle(cross).color).toBe(critical);
+    const tile = other.getBoundingClientRect();
+    const box = cross.getBoundingClientRect();
+    await expect(box.right).toBeGreaterThan(tile.right);
+    await expect(box.top).toBeLessThan(tile.top);
+
+    await userEvent.hover(cross);
+    await waitFor(async () =>
+      expect(
+        [...document.body.querySelectorAll("div")].some(
+          (d) => d.textContent === "Remove" && d.offsetParent !== null,
+        ),
+      ).toBe(true),
+    );
+  },
+};
+
+/** Removing by pointer while the selection really changes. */
+export const RemovingWithLiveSelection: Story = {
+  args: AddedBackgroundsCanBeRemoved.args,
+  render: function WithLiveSelection(args): JSX.Element {
+    const [selected, setSelected] = useState("none");
+    const [offered, setOffered] = useState(args.backgroundEffects ?? []);
+    return (
+      <MediaMuteAndSwitchButton
+        {...args}
+        backgroundEffects={offered}
+        selectedBackgroundEffect={selected}
+        onSelectBackgroundEffect={setSelected}
+        onRemoveBackgroundEffect={(id): void =>
+          setOffered((current) => current.filter((o) => o.id !== id))
+        }
+      />
+    );
+  },
+  play: async ({ canvasElement }) => {
+    const canvas = within(canvasElement);
+    await userEvent.click(canvas.getByRole("button", { name: "Camera" }));
+    const body = within(document.body);
+
+    const tile = await body.findByRole("menuitemradio", {
+      name: "Background 4",
+    });
+    await userEvent.hover(tile);
+    const cross = tile.parentElement!.querySelector<HTMLElement>(
+      "[aria-hidden]:last-child",
+    )!;
+    await expect(cross).toBeVisible();
+    await userEvent.click(cross);
+
+    await waitFor(async () =>
+      expect(
+        body.queryByRole("menuitemradio", { name: "Background 4" }),
+      ).toBeNull(),
+    );
+    await expect(
+      body.getByRole("menuitemradio", { name: "None" }),
+    ).toHaveAttribute("aria-checked", "true");
+  },
+};
+
+/** Where the call leaves room, the camera holds the top while the options scroll. */
+export const BackgroundEffectsWithPreview: Story = {
+  args: {
+    ...VideoUnmute.args,
+    // Enough that the list fills its share, so the preview's cost counts.
+    options: Array.from({ length: 8 }, (_, i) => ({
+      label: { type: "name" as const, name: `Camera ${i + 1}` },
+      id: `${i + 1}`,
+    })),
+  },
+  decorators: [
+    (Story): JSX.Element => (
+      <WithACallArea blockSize={640}>
+        <Story />
+      </WithACallArea>
+    ),
+  ],
+  play: async ({ canvasElement }) => {
+    const canvas = within(canvasElement);
+    await userEvent.click(canvas.getByRole("button", { name: "Camera" }));
+    const picture = await within(document.body).findByTestId("preview-camera");
+    const preview = picture.parentElement!;
+    const list = document.body.querySelector<HTMLElement>(
+      `.${styles.deviceList}`,
+    )!;
+    const frame = document.body
+      .querySelector("[role='menu']")!
+      .getBoundingClientRect();
+
+    const box = preview.getBoundingClientRect();
+    await expect(list.contains(preview)).toBe(false);
+    await expect(box.top - frame.top).toBeLessThanOrEqual(2);
+    await expect(frame.width - box.width).toBeLessThanOrEqual(2);
+    await expect(box.width / box.height).toBeCloseTo(16 / 9, 1);
+    await expect(box.bottom).toBeLessThanOrEqual(
+      list.getBoundingClientRect().top,
+    );
+
+    const listShare = Math.round(640 * 0.6);
+    // The list runs on through the menu's padding at its foot, which isn't
+    // part of its share.
+    const listEnd =
+      list.getBoundingClientRect().bottom -
+      Number.parseFloat(getComputedStyle(list).paddingBlockEnd);
+    await expect(listEnd - box.top).toBeLessThanOrEqual(listShare + 1);
+
+    await expect(list.scrollHeight).toBeGreaterThan(list.clientHeight);
+    list.scrollTop = list.scrollHeight;
+    await expect(preview.getBoundingClientRect().top).toBe(box.top);
+  },
+};
+
+/** With the camera off the preview says so, and effects can still be chosen. */
+export const BackgroundEffectsPreviewWithTheCameraOff: Story = {
+  args: {
+    ...VideoUnmute.args,
+    enabled: false,
+    selfPreview: <SelfPreview track={null} />,
+  },
+  play: async ({ args, canvasElement }) => {
+    const canvas = within(canvasElement);
+    await userEvent.click(canvas.getByRole("button", { name: "Camera" }));
+    const menu = within(document.body);
+    await menu.findByRole("group", { name: "Background effects" });
+    const preview = document.body.querySelector(`.${styles.selfPreview}`)!;
+    await expect(preview.querySelector("video")).toBeNull();
+    await expect(preview.querySelector("svg")).not.toBeNull();
+
+    await userEvent.click(menu.getByRole("menuitemradio", { name: "Blur" }));
+    await expect(args.onSelectBackgroundEffect).toHaveBeenCalledWith("blur");
+  },
+};
+
+/** In a call too short to hold it, the camera leads the options and scrolls away. */
+export const BackgroundEffectsPreviewScrollsWithTheList: Story = {
+  args: VideoUnmute.args,
+  decorators: [
+    (Story): JSX.Element => (
+      <WithACallArea blockSize={300}>
+        <Story />
+      </WithACallArea>
+    ),
+  ],
+  play: async ({ canvasElement }) => {
+    const canvas = within(canvasElement);
+    await userEvent.click(canvas.getByRole("button", { name: "Camera" }));
+    const picture = await within(document.body).findByTestId("preview-camera");
+    const preview = picture.parentElement!;
+    const list = document.body.querySelector<HTMLElement>(
+      `.${styles.deviceList}`,
+    )!;
+    await expect(list.contains(preview)).toBe(true);
+    const cameras = within(document.body).getByRole("group", {
+      name: "Camera",
+    });
+    await expect(
+      preview.compareDocumentPosition(cameras) &
+        Node.DOCUMENT_POSITION_FOLLOWING,
+    ).toBeTruthy();
+
+    list.scrollTop = list.scrollHeight;
+    await expect(preview.getBoundingClientRect().bottom).toBeLessThan(
+      list.getBoundingClientRect().top,
+    );
   },
 };
 

src/components/MediaMuteAndSwitchButton.test.tsx

@@ -5,7 +5,7 @@ SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
 Please see LICENSE in the repository root for full details.
 */
 
-import { afterEach, describe, expect, test, vi } from "vitest";
+import { afterEach, describe, expect, onTestFinished, test, vi } from "vitest";
 import { axe } from "vitest-axe";
 import {
   act,
@@ -367,6 +367,120 @@ describe("MediaMuteAndSwitchButton", () => {
     expect(onSelectBackgroundEffect).not.toHaveBeenCalled();
   });
 
+  test("added images are chosen like shipped ones", async () => {
+    const user = userEvent.setup();
+    const onSelectBackgroundEffect = vi.fn();
+    const { getByRole } = renderComponent(
+      <MediaMuteAndSwitchButton
+        iconsAndLabels="video"
+        enabled={true}
+        options={[{ label: { type: "name", name: "Camera 1" }, id: "cam1" }]}
+        selectedOption="cam1"
+        backgroundEffects={[
+          ...effects,
+          {
+            id: "added:mine",
+            kind: "image",
+            imageUrl: "",
+          },
+        ]}
+        selectedBackgroundEffect="none"
+        onSelectBackgroundEffect={onSelectBackgroundEffect}
+      />,
+    );
+
+    await user.click(getByRole("button", { name: "Camera" }));
+    const section = screen.getByRole("group", { name: "Background effects" });
+    await user.click(
+      within(section).getByRole("menuitemradio", { name: "Background 3" }),
+    );
+    expect(onSelectBackgroundEffect).toHaveBeenCalledWith("added:mine");
+  });
+
+  test("adds the file chosen from the add tile, and stays open", async () => {
+    const user = userEvent.setup();
+    const onAddBackgroundImage = vi.fn();
+    const pick = vi
+      .spyOn(HTMLInputElement.prototype, "click")
+      .mockImplementation(() => {});
+    try {
+      const { getByRole, container } = renderComponent(
+        <MediaMuteAndSwitchButton
+          iconsAndLabels="video"
+          enabled={true}
+          options={[{ label: { type: "name", name: "Camera 1" }, id: "cam1" }]}
+          selectedOption="cam1"
+          backgroundEffects={effects}
+          selectedBackgroundEffect="none"
+          onSelectBackgroundEffect={vi.fn()}
+          onAddBackgroundImage={onAddBackgroundImage}
+        />,
+      );
+
+      await user.click(getByRole("button", { name: "Camera" }));
+      await user.click(screen.getByRole("menuitem", { name: "Add image" }));
+      expect(pick).toHaveBeenCalled();
+      // The picker takes the focus, which would otherwise close the menu.
+      await user.keyboard("{Escape}");
+      expect(screen.getByRole("menu")).toBeInTheDocument();
+
+      const file = new File(["x"], "mine.png", { type: "image/png" });
+      // What the picker hands back; the open menu blocks pointer events.
+      fireEvent.change(
+        container.querySelector<HTMLInputElement>("input[type=file]")!,
+        { target: { files: [file] } },
+      );
+      expect(onAddBackgroundImage).toHaveBeenCalledWith(file);
+      screen.getByRole("menuitemradio", { name: "None", checked: true });
+    } finally {
+      pick.mockRestore();
+    }
+  });
+
+  test("a refusal can be dismissed and does not outlive the menu", async () => {
+    const user = userEvent.setup();
+    // jsdom lays nothing out, so has nothing to scroll.
+    const scroll = Element.prototype.scrollIntoView;
+    Element.prototype.scrollIntoView = vi.fn();
+    onTestFinished(() => {
+      Element.prototype.scrollIntoView = scroll;
+    });
+    const menu = (refusal?: { text: string }): JSX.Element =>
+      withProviders(
+        <MediaMuteAndSwitchButton
+          iconsAndLabels="video"
+          enabled={true}
+          options={[{ label: { type: "name", name: "Camera 1" }, id: "cam1" }]}
+          selectedOption="cam1"
+          backgroundEffects={effects}
+          selectedBackgroundEffect="blur"
+          onSelectBackgroundEffect={vi.fn()}
+          onAddBackgroundImage={vi.fn()}
+          backgroundImageRefusal={refusal}
+        />,
+      );
+    const { rerender, getByRole } = render(menu());
+    await user.click(getByRole("button", { name: "Camera" }));
+
+    rerender(menu({ text: "That file is not a supported image" }));
+    expect(
+      screen.getByText("That file is not a supported image"),
+    ).toBeVisible();
+    screen.getByRole("menuitemradio", { name: "Blur", checked: true });
+    await user.click(screen.getByRole("button", { name: "Close" }));
+    expect(screen.queryByText("That file is not a supported image")).toBeNull();
+
+    // The next refusal is shown, even if it says the same.
+    rerender(menu({ text: "That file is not a supported image" }));
+    expect(
+      screen.getByText("That file is not a supported image"),
+    ).toBeVisible();
+
+    await user.keyboard("{Escape}");
+    await user.click(getByRole("button", { name: "Camera" }));
+    expect(screen.queryByText("That file is not a supported image")).toBeNull();
+  });
+
   test("offers the background effects in a phone's drawer", async () => {
     const userAgent = vi
       .spyOn(navigator, "userAgent", "get")

src/components/MediaMuteAndSwitchButton.tsx

@@ -8,14 +8,18 @@ Please see LICENSE in the repository root for full details.
 import {
   useCallback,
   useId,
+  useRef,
   useState,
   type CSSProperties,
   type FC,
   useEffect,
   type ReactElement,
+  type ReactNode,
 } from "react";
 import {
+  Alert,
   Button,
+  InlineSpinner,
   Menu,
   MenuItem,
   MenuScrollArea,
@@ -79,6 +83,14 @@ export interface MediaMuteAndSwitchButtonProps {
   backgroundEffectNotice?: string;
   /** Whether the first effect chosen is still being prepared. */
   backgroundEffectSettling?: boolean;
+  /** Called with the file chosen from the add tile. Omit to leave it out. */
+  onAddBackgroundImage?: (file: File) => void;
+  /** Removes a removable effect, never the one in force. */
+  onRemoveBackgroundEffect?: (id: string) => void;
+  /** Why the last file offered couldn't be used; a new object each time. */
+  backgroundImageRefusal?: { text: string };
+  /** The user's own camera, shown at the top of the camera menu. */
+  selfPreview?: ReactNode;
   /**
    * For any toggle and option this method will be called.
    * So toggles need to be implemented by listening here and setting the right toggle item to `enabled`
@@ -95,9 +107,16 @@ const LIST_SHARE_OF_CALL = 0.6;
 /** Smallest device list height in px, so a short call still shows more than one device. */
 const MIN_LIST_HEIGHT = 160;
 
+/** The menu's width as its stylesheet sets it, to place the preview before
+    the menu is drawn. */
+const MENU_WIDTH = 296;
+
 /** Space kept between the menu and the call area's sides. */
 const MENU_MARGIN = 16;
 
+/** Below the preview, as its stylesheet draws it. */
+const PREVIEW_GAP = 12;
+
 export const MediaMuteAndSwitchButton: FC<MediaMuteAndSwitchButtonProps> = ({
   enabled,
   busy,
@@ -113,6 +132,10 @@ export const MediaMuteAndSwitchButton: FC<MediaMuteAndSwitchButtonProps> = ({
   onSelectBackgroundEffect,
   backgroundEffectNotice,
   backgroundEffectSettling,
+  onAddBackgroundImage,
+  onRemoveBackgroundEffect,
+  backgroundImageRefusal,
+  selfPreview,
   onSelect,
 }) => {
   // Requested but not yet selected. Keyed by kind too, since Chrome uses
@@ -122,11 +145,42 @@ export const MediaMuteAndSwitchButton: FC<MediaMuteAndSwitchButtonProps> = ({
     id: string;
   } | null>(null);
   const [menuOpen, setMenuOpen] = useState(false);
-  const onOpenChange = useCallback((open: boolean): void => {
-    setMenuOpen(open);
-    // Drop a request that never arrived.
-    if (!open) setPlannedSelection(null);
+  // The file picker takes the focus, which the menu reads as a click
+  // elsewhere; it is held open until the picker is done.
+  const choosingFile = useRef(false);
+  const fileInput = useRef<HTMLInputElement | null>(null);
+  // A refusal is about the attempt that caused it: shown until dismissed or
+  // until the menu closes, and again for the next one.
+  const [seenRefusal, setSeenRefusal] = useState<object>();
+  const refusal =
+    backgroundImageRefusal !== seenRefusal ? backgroundImageRefusal : undefined;
+  const onOpenChange = useCallback(
+    (open: boolean): void => {
+      if (!open && choosingFile.current) return;
+      setMenuOpen(open);
+      // Drop a request that never arrived.
+      if (!open) setPlannedSelection(null);
+      if (!open) setSeenRefusal(backgroundImageRefusal);
+    },
+    [backgroundImageRefusal],
+  );
+  // Scrolled to as it appears, as the list may be scrolled away from it.
+  const scrollIntoView = useCallback((element: HTMLElement | null): void => {
+    element?.scrollIntoView({ block: "nearest" });
   }, []);
+  const watchFileInput = useCallback(
+    (input: HTMLInputElement | null): (() => void) | undefined => {
+      fileInput.current = input;
+      if (input === null) return;
+      // Dismissing the picker fires cancel, which React doesn't type.
+      const done = (): void => {
+        choosingFile.current = false;
+      };
+      input.addEventListener("cancel", done);
+      return (): void => input.removeEventListener("cancel", done);
+    },
+    [],
+  );
   const isBusy = busy ?? false;
   const { t } = useTranslation();
   const devices = useMediaDevices();
@@ -160,21 +214,53 @@ export const MediaMuteAndSwitchButton: FC<MediaMuteAndSwitchButtonProps> = ({
 
   // Measured on the call area: CSS can't size the portalled menu against it.
   const rootElement = useRootElement();
-  const [listMaxHeight, setListMaxHeight] = useState<number>();
+  const [listShare, setListShare] = useState<number>();
+  const [previewBlock, setPreviewBlock] = useState(0);
   useEffect(() => {
     if (!menuOpen) return;
     // Followed, since a host can resize the call while the menu is open.
     const subscription = observeElementSize$(rootElement)
       .pipe(
-        map(({ height }) =>
-          Math.max(MIN_LIST_HEIGHT, Math.round(height * LIST_SHARE_OF_CALL)),
+        map(({ width, height }) => ({
+          height: Math.round(height * LIST_SHARE_OF_CALL),
+          width: Math.min(MENU_WIDTH, Math.round(width - 2 * MENU_MARGIN)),
+        })),
+        distinctUntilChanged(
+          (a, b) => a.height === b.height && a.width === b.width,
         ),
-        distinctUntilChanged(),
       )
-      .subscribe(setListMaxHeight);
+      .subscribe(({ height, width }) => {
+        setListShare(height);
+        setPreviewBlock(Math.round((width * 9) / 16) + PREVIEW_GAP);
+      });
     return (): void => subscription.unsubscribe();
   }, [menuOpen, rootElement]);
 
+  // Paid for out of the list's share, so a preview makes the menu no taller.
+  const hasPreview =
+    iconsAndLabels === "video" &&
+    selfPreview !== undefined &&
+    listShare !== undefined;
+  const previewPinned =
+    hasPreview && listShare - previewBlock >= MIN_LIST_HEIGHT;
+  const listMaxHeight =
+    listShare === undefined
+      ? undefined
+      : Math.max(
+          MIN_LIST_HEIGHT,
+          listShare - (previewPinned ? previewBlock : 0),
+        );
+  const preview = hasPreview && (
+    <div
+      aria-hidden
+      className={classNames(styles.selfPreview, {
+        [styles.selfPreviewPinned]: previewPinned,
+      })}
+    >
+      {backgroundEffectSettling ? <InlineSpinner size={32} /> : selfPreview}
+    </div>
+  );
+
   useEffect(() => {
     if (menuOpen) devices.requestDeviceNames(); // No-op after the first call
   }, [menuOpen, devices]);
@@ -326,6 +412,21 @@ export const MediaMuteAndSwitchButton: FC<MediaMuteAndSwitchButtonProps> = ({
     >
       {/* The mute button lives inside */}
       {button}
+      {onAddBackgroundImage !== undefined && (
+        <input
+          ref={watchFileInput}
+          type="file"
+          accept="image/*"
+          hidden
+          onChange={(e) => {
+            const file = e.target.files?.[0];
+            // Cleared, so the same file can be chosen twice in a row.
+            e.target.value = "";
+            choosingFile.current = false;
+            if (file) onAddBackgroundImage(file);
+          }}
+        />
+      )}
       <Menu
         className={styles.menu}
         // Named for screen readers only: each section has its own heading.
@@ -350,9 +451,12 @@ export const MediaMuteAndSwitchButton: FC<MediaMuteAndSwitchButtonProps> = ({
           />
         }
       >
+        {previewPinned && preview}
         <MenuScrollArea
           ref={trackFocusSource}
-          className={styles.deviceList}
+          className={classNames(styles.deviceList, {
+            [styles.deviceListLeadsWithPreview]: hasPreview && !previewPinned,
+          })}
           data-testid="device-list"
           style={
             {
@@ -361,6 +465,7 @@ export const MediaMuteAndSwitchButton: FC<MediaMuteAndSwitchButtonProps> = ({
             } as CSSProperties
           }
         >
+          {hasPreview && !previewPinned && preview}
           {audioMeter && speakerOptions && (
             <MenuScrollSection title={t("settings.devices.speaker")}>
               {deviceItems(
@@ -394,14 +499,39 @@ export const MediaMuteAndSwitchButton: FC<MediaMuteAndSwitchButtonProps> = ({
                 describedBy={
                   backgroundEffectNotice === undefined ? undefined : noticeId
                 }
+                onAdd={
+                  onAddBackgroundImage === undefined
+                    ? undefined
+                    : (): void => {
+                        choosingFile.current = true;
+                        fileInput.current?.click();
+                      }
+                }
+                addLabel={t("action.add_background_image")}
+                onRemove={onRemoveBackgroundEffect}
+                removeLabel={t("action.remove")}
               />
               {/* In the list, so the menu grows no taller for it. */}
-              {backgroundEffectNotice !== undefined && (
-                <div id={noticeId} role="none" className={styles.notice}>
-                  <InfoIcon width={20} height={20} />
-                  <span>{backgroundEffectNotice}</span>
+              {refusal !== undefined && (
+                <div
+                  ref={scrollIntoView}
+                  role="none"
+                  className={styles.refusal}
+                >
+                  <Alert
+                    type="critical"
+                    title={refusal.text}
+                    onClose={(): void => setSeenRefusal(refusal)}
+                  />
                 </div>
               )}
+              {refusal === undefined &&
+                backgroundEffectNotice !== undefined && (
+                  <div id={noticeId} role="none" className={styles.notice}>
+                    <InfoIcon width={20} height={20} />
+                    <span>{backgroundEffectNotice}</span>
+                  </div>
+                )}
             </MenuScrollSection>
           )}
         </MenuScrollArea>

src/components/SelfPreview.module.css

@@ -0,0 +1,10 @@
+/*
+Copyright 2026 Element Creations Ltd.
+
+SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
+Please see LICENSE in the repository root for full details.
+*/
+
+.mirrored {
+  transform: scaleX(-1);
+}

src/components/SelfPreview.test.tsx

@@ -0,0 +1,47 @@
+/*
+Copyright 2026 Element Creations Ltd.
+
+SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
+Please see LICENSE in the repository root for full details.
+*/
+
+import { act, render } from "@testing-library/react";
+import { describe, expect, it } from "vitest";
+import { BehaviorSubject } from "rxjs";
+
+import { SelfPreview } from "./SelfPreview";
+import styles from "./SelfPreview.module.css";
+import { mockVideoTrack } from "../utils/test";
+
+describe("SelfPreview", () => {
+  it("detaches only its own element from a camera shown twice", () => {
+    const track = mockVideoTrack({});
+    const first = render(<SelfPreview track={track} />);
+    const second = render(<SelfPreview track={track} />);
+    const [a, b] = [first, second].map((r) =>
+      r.container.querySelector("video"),
+    );
+    expect(track.attach).toHaveBeenCalledWith(a);
+    expect(track.attach).toHaveBeenCalledWith(b);
+
+    first.unmount();
+    expect(track.detach).toHaveBeenCalledExactlyOnceWith(a);
+  });
+
+  it("mirrors the camera while it faces the user, and only then", () => {
+    const facingMode$ = new BehaviorSubject<"user" | "environment">("user");
+    const { container } = render(
+      <SelfPreview track={mockVideoTrack({ facingMode$ })} />,
+    );
+    const video = (): HTMLVideoElement => container.querySelector("video")!;
+    expect(video().classList.contains(styles.mirrored)).toBe(true);
+    act(() => facingMode$.next("environment"));
+    expect(video().classList.contains(styles.mirrored)).toBe(false);
+  });
+
+  it("says the camera is off while there is none", () => {
+    const { container } = render(<SelfPreview track={null} />);
+    expect(container.querySelector("video")).toBeNull();
+    expect(container.querySelector("svg")).not.toBeNull();
+  });
+});

src/components/SelfPreview.tsx

@@ -0,0 +1,48 @@
+/*
+Copyright 2026 Element Creations Ltd.
+
+SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
+Please see LICENSE in the repository root for full details.
+*/
+
+import { type FC, useEffect, useRef } from "react";
+import { constant, type LocalVideoMediaTrack } from "@element-hq/matrixrtc-sdk";
+import { VideoCallOffIcon } from "@vector-im/compound-design-tokens/assets/web/icons";
+
+import styles from "./SelfPreview.module.css";
+import { useBehavior } from "../useBehavior";
+
+const noFacingMode = constant(undefined);
+
+interface Props {
+  /** The camera as the pipeline has it, or none while the camera is off. */
+  track: LocalVideoMediaTrack | null;
+}
+
+/**
+ * The user's own camera with the effect in force: the pipeline's own track,
+ * shown a second time rather than captured again.
+ */
+export const SelfPreview: FC<Props> = ({ track }) => {
+  const videoRef = useRef<HTMLVideoElement | null>(null);
+  useEffect(() => {
+    const element = videoRef.current;
+    if (!track || !element) return;
+    track.attach(element);
+    // This element only: the pre-join preview may be showing the same camera
+    return (): void => {
+      track.detach(element);
+    };
+  }, [track]);
+  const facingMode = useBehavior(track?.facingMode$ ?? noFacingMode);
+
+  if (!track) return <VideoCallOffIcon width={32} height={32} />;
+  return (
+    <video
+      ref={videoRef}
+      muted
+      playsInline
+      className={facingMode === "user" ? styles.mirrored : undefined}
+    />
+  );
+};

src/config/Config.test.ts

@@ -95,6 +95,35 @@ describe("Config.initWith", () => {
     expect(Config.get().ssla).toBe("https://example.invalid/ssla");
   });
 
+  it("falls back to the defaults when fetching config.json rejects", async () => {
+    // A rejected promise is what a webview gives for a missing local file.
+    vi.spyOn(globalThis, "fetch").mockRejectedValue(
+      new TypeError("Load failed"),
+    );
+    vi.spyOn(logger, "info").mockImplementation(() => {});
+    Reflect.set(Config, "internalInstance", undefined);
+
+    await expect(Config.init()).resolves.toBeUndefined();
+
+    expect(Config.get().media_quality).toEqual(DEFAULT_CONFIG.media_quality);
+  });
+
+  it("falls back to the defaults when config.json is not JSON", async () => {
+    vi.spyOn(globalThis, "fetch").mockResolvedValue(
+      new Response("<!doctype html><title>Element</title>", {
+        status: 200,
+        headers: { "content-type": "text/html" },
+      }),
+    );
+    const warnSpy = vi.spyOn(logger, "warn").mockImplementation(() => {});
+    Reflect.set(Config, "internalInstance", undefined);
+
+    await expect(Config.init()).resolves.toBeUndefined();
+
+    expect(Config.get().media_quality).toEqual(DEFAULT_CONFIG.media_quality);
+    expect(warnSpy).toHaveBeenCalledTimes(1);
+  });
+
   it("replaces a config initialized earlier", () => {
     Config.initWith({ ssla: "https://first.invalid/ssla" });
     Config.initWith({ ssla: "https://second.invalid/ssla" });

src/config/Config.ts

@@ -140,14 +140,26 @@ export function validateConfig(config: ConfigOptions): ConfigOptions {
 }
 
 async function downloadConfig(fetchTarget: string): Promise<ConfigOptions> {
-  const response = await fetch(fetchTarget);
-
-  if (isFailure(response)) {
-    // Lack of a config isn't an error, we should just use the defaults.
-    // Also treat a blank config as no config, assuming the status code is 0, because we don't get 404s from file:
-    // URIs so this is the only way we can not fail if the file doesn't exist when loading from a file:// URI.
-    return DEFAULT_CONFIG;
+  let response: Response;
+  try {
+    response = await fetch(fetchTarget);
+  } catch (e) {
+    // The embedded package ships no config.json, and some webviews (Element X
+    // iOS) reject the fetch of a missing local file rather than answering 404.
+    logger.info(`No config at ${fetchTarget}, using defaults`, e);
+    // resolveConfig merges in the defaults.
+    return {};
   }
 
-  return response.json();
+  if (isFailure(response)) {
+    // resolveConfig merges in the defaults.
+    return {};
+  }
+
+  try {
+    return await response.json();
+  } catch (e) {
+    logger.warn(`Config at ${fetchTarget} is not JSON, using defaults`, e);
+    return {};
+  }
 }

src/reactions/index.ts

@@ -7,30 +7,30 @@ Please see LICENSE in the repository root for full details.
 
 import { type RelationType } from "matrix-js-sdk";
 
-import catSoundOgg from "../sound/reactions/cat.ogg?url";
-import catSoundMp3 from "../sound/reactions/cat.mp3?url";
-import clapSoundOgg from "../sound/reactions/clap.ogg?url";
-import clapSoundMp3 from "../sound/reactions/clap.mp3?url";
-import cricketsSoundOgg from "../sound/reactions/crickets.ogg?url";
-import cricketsSoundMp3 from "../sound/reactions/crickets.mp3?url";
-import dogSoundOgg from "../sound/reactions/dog.ogg?url";
-import dogSoundMp3 from "../sound/reactions/dog.mp3?url";
-import genericSoundOgg from "../sound/reactions/generic.ogg?url";
-import genericSoundMp3 from "../sound/reactions/generic.mp3?url";
-import lightbulbSoundOgg from "../sound/reactions/lightbulb.ogg?url";
-import lightbulbSoundMp3 from "../sound/reactions/lightbulb.mp3?url";
-import partySoundOgg from "../sound/reactions/party.ogg?url";
-import partySoundMp3 from "../sound/reactions/party.mp3?url";
-import deerSoundOgg from "../sound/reactions/deer.ogg?url";
-import deerSoundMp3 from "../sound/reactions/deer.mp3?url";
-import rockSoundOgg from "../sound/reactions/rock.ogg?url";
-import rockSoundMp3 from "../sound/reactions/rock.mp3?url";
-import waveSoundOgg from "../sound/reactions/wave.ogg?url";
-import waveSoundMp3 from "../sound/reactions/wave.mp3?url";
-import baduntssSoundOgg from "../sound/reactions/baduntss.ogg?url";
-import baduntssSoundMp3 from "../sound/reactions/baduntss.mp3?url";
-import bellSoundOgg from "../sound/reactions/bell.ogg?url";
-import bellSoundMp3 from "../sound/reactions/bell.mp3?url";
+import catSoundOgg from "../sound/reactions/cat.ogg?url&no-inline";
+import catSoundMp3 from "../sound/reactions/cat.mp3?url&no-inline";
+import clapSoundOgg from "../sound/reactions/clap.ogg?url&no-inline";
+import clapSoundMp3 from "../sound/reactions/clap.mp3?url&no-inline";
+import cricketsSoundOgg from "../sound/reactions/crickets.ogg?url&no-inline";
+import cricketsSoundMp3 from "../sound/reactions/crickets.mp3?url&no-inline";
+import dogSoundOgg from "../sound/reactions/dog.ogg?url&no-inline";
+import dogSoundMp3 from "../sound/reactions/dog.mp3?url&no-inline";
+import genericSoundOgg from "../sound/reactions/generic.ogg?url&no-inline";
+import genericSoundMp3 from "../sound/reactions/generic.mp3?url&no-inline";
+import lightbulbSoundOgg from "../sound/reactions/lightbulb.ogg?url&no-inline";
+import lightbulbSoundMp3 from "../sound/reactions/lightbulb.mp3?url&no-inline";
+import partySoundOgg from "../sound/reactions/party.ogg?url&no-inline";
+import partySoundMp3 from "../sound/reactions/party.mp3?url&no-inline";
+import deerSoundOgg from "../sound/reactions/deer.ogg?url&no-inline";
+import deerSoundMp3 from "../sound/reactions/deer.mp3?url&no-inline";
+import rockSoundOgg from "../sound/reactions/rock.ogg?url&no-inline";
+import rockSoundMp3 from "../sound/reactions/rock.mp3?url&no-inline";
+import waveSoundOgg from "../sound/reactions/wave.ogg?url&no-inline";
+import waveSoundMp3 from "../sound/reactions/wave.mp3?url&no-inline";
+import baduntssSoundOgg from "../sound/reactions/baduntss.ogg?url&no-inline";
+import baduntssSoundMp3 from "../sound/reactions/baduntss.mp3?url&no-inline";
+import bellSoundOgg from "../sound/reactions/bell.ogg?url&no-inline";
+import bellSoundMp3 from "../sound/reactions/bell.mp3?url&no-inline";
 
 export const ElementCallReactionEventType = "io.element.call.reaction";
 

src/room/CallEventAudioRenderer.tsx

@@ -8,18 +8,18 @@ Please see LICENSE in the repository root for full details.
 import { type ReactNode, useEffect } from "react";
 
 import { type CallViewModel } from "../state/CallViewModel/CallViewModel";
-import joinCallSoundMp3 from "../sound/join_call.mp3";
-import joinCallSoundOgg from "../sound/join_call.ogg";
-import leftCallSoundMp3 from "../sound/left_call.mp3";
-import leftCallSoundOgg from "../sound/left_call.ogg";
-import handSoundOgg from "../sound/raise_hand.ogg";
-import handSoundMp3 from "../sound/raise_hand.mp3";
-import screenShareStartedOgg from "../sound/screen_share_started.ogg";
-import screenShareStartedMp3 from "../sound/screen_share_started.mp3";
-import declineMp3 from "../sound/call_declined.mp3?url";
-import declineOgg from "../sound/call_declined.ogg?url";
-import timeoutMp3 from "../sound/call_timeout.mp3?url";
-import timeoutOgg from "../sound/call_timeout.ogg?url";
+import joinCallSoundMp3 from "../sound/join_call.mp3?url&no-inline";
+import joinCallSoundOgg from "../sound/join_call.ogg?url&no-inline";
+import leftCallSoundMp3 from "../sound/left_call.mp3?url&no-inline";
+import leftCallSoundOgg from "../sound/left_call.ogg?url&no-inline";
+import handSoundOgg from "../sound/raise_hand.ogg?url&no-inline";
+import handSoundMp3 from "../sound/raise_hand.mp3?url&no-inline";
+import screenShareStartedOgg from "../sound/screen_share_started.ogg?url&no-inline";
+import screenShareStartedMp3 from "../sound/screen_share_started.mp3?url&no-inline";
+import declineMp3 from "../sound/call_declined.mp3?url&no-inline";
+import declineOgg from "../sound/call_declined.ogg?url&no-inline";
+import timeoutMp3 from "../sound/call_timeout.mp3?url&no-inline";
+import timeoutOgg from "../sound/call_timeout.ogg?url&no-inline";
 import { useAudioContext } from "../useAudioContext";
 import { prefetchSounds } from "../soundUtils";
 import { useLatest } from "../useLatest";