diff --git a/locales/en/app.json b/locales/en/app.json
index c70a0a49..0b0ac7b4 100644
--- a/locales/en/app.json
+++ b/locales/en/app.json
@@ -116,7 +116,7 @@
     "matrix_rtc_transport_missing": "The server is not configured to work with {{brand}}. Please contact your server admin (Domain: {{domain}}, Error Code: {{ errorCode }}).",
     "membership_manager": "Membership Manager Error",
     "membership_manager_description": "The Membership Manager had to shut down. This is caused by many consequtive failed network requests.",
-    "no_matrix_2_authorization_service": "Your authorization service for you media server (SFU) is not on the newest version",
+    "no_matrix_2_authorization_service": "The authorization service for your media server (SFU) is out of date.",
     "open_elsewhere": "Opened in another tab",
     "open_elsewhere_description": "{{brand}} has been opened in another tab. If that doesn't sound right, try reloading the page.",
     "room_creation_restricted": "Failed to create call",
diff --git a/package.json b/package.json
index 47adc365..14193013 100644
--- a/package.json
+++ b/package.json
@@ -104,8 +104,8 @@
     "livekit-client": "^2.13.0",
     "lodash-es": "^4.17.21",
     "loglevel": "^1.9.1",
-    "matrix-js-sdk": "matrix-org/matrix-js-sdk#4a75d2c92f1ac7476a6d398057b91c65054f1b80",
-    "matrix-widget-api": "^1.14.0",
+    "matrix-js-sdk": "matrix-org/matrix-js-sdk#develop",
+    "matrix-widget-api": "^1.16.1",
     "node-stdlib-browser": "^1.3.1",
     "normalize.css": "^8.0.1",
     "observable-hooks": "^4.2.3",
diff --git a/sdk/main.ts b/sdk/main.ts
index c371587f..a273ed8a 100644
--- a/sdk/main.ts
+++ b/sdk/main.ts
@@ -57,7 +57,7 @@ import {
   tryMakeSticky,
   widget,
 } from "./helper";
-import { ElementWidgetActions } from "../src/widget";
+import { ElementWidgetActions, initializeWidget } from "../src/widget";
 import { type Connection } from "../src/state/CallViewModel/remoteMembers/Connection";
 
 interface MatrixRTCSdk {
@@ -88,7 +88,7 @@ export async function createMatrixRTCSdk(
   application: string = "m.call",
   id: string = "",
 ): Promise<MatrixRTCSdk> {
-  logger.info("Hello");
+  initializeWidget();
   const client = await widget.client;
   logger.info("client created");
   const scope = new ObservableScope();
diff --git a/src/button/ReactionToggleButton.test.tsx b/src/button/ReactionToggleButton.test.tsx
index f6b7a2ea..c6010562 100644
--- a/src/button/ReactionToggleButton.test.tsx
+++ b/src/button/ReactionToggleButton.test.tsx
@@ -18,7 +18,8 @@ import { getBasicCallViewModelEnvironment } from "../utils/test-viewmodel";
 import { alice, local, localRtcMember } from "../utils/test-fixtures";
 import { type MockRTCSession } from "../utils/test";
 import { ReactionsSenderProvider } from "../reactions/useReactionsSender";
-
+import { initializeWidget } from "../widget";
+initializeWidget();
 vi.mock("livekit-client/e2ee-worker?worker");
 
 const localIdent = `${localRtcMember.userId}:${localRtcMember.deviceId}`;
diff --git a/src/initializer.tsx b/src/initializer.tsx
index 419b1291..2bd6f577 100644
--- a/src/initializer.tsx
+++ b/src/initializer.tsx
@@ -28,6 +28,7 @@ import { getUrlParams } from "./UrlParams";
 import { Config } from "./config/Config";
 import { platform } from "./Platform";
 import { isFailure } from "./utils/fetch";
+import { initializeWidget } from "./widget";
 
 // This generates a map of locale names to their URL (based on import.meta.url), which looks like this:
 // {
@@ -115,6 +116,8 @@ export class Initializer {
   }
 
   public static async initBeforeReact(): Promise<void> {
+    initializeWidget();
+
     const polyfills: Promise<unknown>[] = [];
     if (shouldPolyfillSegmenter()) {
       polyfills.push(import("@formatjs/intl-segmenter/polyfill-force"));
diff --git a/src/livekit/MatrixAudioRenderer.test.tsx b/src/livekit/MatrixAudioRenderer.test.tsx
index 049add97..c6122b4b 100644
--- a/src/livekit/MatrixAudioRenderer.test.tsx
+++ b/src/livekit/MatrixAudioRenderer.test.tsx
@@ -28,7 +28,8 @@ import {
   mockRemoteParticipant,
   mockTrack,
 } from "../utils/test";
-
+import { initializeWidget } from "../widget";
+initializeWidget();
 export const TestAudioContextConstructor = vi.fn(() => testAudioContext);
 
 const MediaDevicesProvider = MediaDevicesContext.MediaDevicesContext.Provider;
diff --git a/src/room/CallEventAudioRenderer.test.tsx b/src/room/CallEventAudioRenderer.test.tsx
index 733346eb..5d3eff5e 100644
--- a/src/room/CallEventAudioRenderer.test.tsx
+++ b/src/room/CallEventAudioRenderer.test.tsx
@@ -39,7 +39,8 @@ import {
   localRtcMember,
 } from "../utils/test-fixtures";
 import { MAX_PARTICIPANT_COUNT_FOR_SOUND } from "../state/CallViewModel/CallViewModel";
-
+import { initializeWidget } from "../widget";
+initializeWidget();
 vitest.mock("livekit-client/e2ee-worker?worker");
 vitest.mock("../useAudioContext");
 vitest.mock("../soundUtils");
diff --git a/src/room/InCallView.test.tsx b/src/room/InCallView.test.tsx
index eaf35fe1..43a689e0 100644
--- a/src/room/InCallView.test.tsx
+++ b/src/room/InCallView.test.tsx
@@ -43,7 +43,8 @@ import { useRoomEncryptionSystem } from "../e2ee/sharedKeyManagement";
 import { LivekitRoomAudioRenderer } from "../livekit/MatrixAudioRenderer";
 import { MediaDevicesContext } from "../MediaDevicesContext";
 import { HeaderStyle } from "../UrlParams";
-
+import { initializeWidget } from "../widget";
+initializeWidget();
 vi.hoisted(
   () =>
     (global.ImageData = class MockImageData {
diff --git a/src/room/ReactionAudioRenderer.test.tsx b/src/room/ReactionAudioRenderer.test.tsx
index 988d43a6..0f847572 100644
--- a/src/room/ReactionAudioRenderer.test.tsx
+++ b/src/room/ReactionAudioRenderer.test.tsx
@@ -37,6 +37,8 @@ import {
   local,
   localRtcMember,
 } from "../utils/test-fixtures";
+import { initializeWidget } from "../widget";
+initializeWidget();
 
 function TestComponent({ vm }: { vm: CallViewModel }): ReactNode {
   return (
diff --git a/src/room/ReactionsOverlay.test.tsx b/src/room/ReactionsOverlay.test.tsx
index 3ca82b1e..727fbb58 100644
--- a/src/room/ReactionsOverlay.test.tsx
+++ b/src/room/ReactionsOverlay.test.tsx
@@ -19,6 +19,8 @@ import {
   bobRtcMember,
 } from "../utils/test-fixtures";
 import { getBasicCallViewModelEnvironment } from "../utils/test-viewmodel";
+import { initializeWidget } from "../widget";
+initializeWidget();
 
 vi.mock("livekit-client/e2ee-worker?worker");
 
diff --git a/src/state/CallViewModel/CallViewModel.test.ts b/src/state/CallViewModel/CallViewModel.test.ts
index 376d8986..c355c627 100644
--- a/src/state/CallViewModel/CallViewModel.test.ts
+++ b/src/state/CallViewModel/CallViewModel.test.ts
@@ -62,6 +62,9 @@ import { getValue } from "../../utils/observable.ts";
 import { type Behavior, constant } from "../Behavior.ts";
 import { withCallViewModel as withCallViewModelInMode } from "./CallViewModelTestUtils.ts";
 import { MatrixRTCMode } from "../../settings/settings.ts";
+import { initializeWidget } from "../../widget.ts";
+
+initializeWidget();
 
 vi.mock("rxjs", async (importOriginal) => ({
   ...(await importOriginal()),
diff --git a/src/state/CallViewModel/localMember/LocalMember.test.ts b/src/state/CallViewModel/localMember/LocalMember.test.ts
index 1f2ad758..b383c295 100644
--- a/src/state/CallViewModel/localMember/LocalMember.test.ts
+++ b/src/state/CallViewModel/localMember/LocalMember.test.ts
@@ -40,6 +40,9 @@ import { ConnectionManagerData } from "../remoteMembers/ConnectionManager";
 import { ConnectionState, type Connection } from "../remoteMembers/Connection";
 import { type Publisher } from "./Publisher";
 import { type LocalTransportWithSFUConfig } from "./LocalTransport";
+import { initializeWidget } from "../../../widget";
+
+initializeWidget();
 
 const MATRIX_RTC_MODE = MatrixRTCMode.Legacy;
 const getUrlParams = vi.hoisted(() => vi.fn(() => ({})));
diff --git a/src/state/MuteStates.test.ts b/src/state/MuteStates.test.ts
index d62074c3..b7a75545 100644
--- a/src/state/MuteStates.test.ts
+++ b/src/state/MuteStates.test.ts
@@ -20,6 +20,8 @@ import {
 import { constant } from "./Behavior";
 import { ObservableScope } from "./ObservableScope";
 import { flushPromises, mockMediaDevices } from "../utils/test";
+import { initializeWidget } from "../widget";
+initializeWidget();
 
 const getUrlParams = vi.hoisted(() => vi.fn(() => ({})));
 vi.mock("../UrlParams", () => ({ getUrlParams }));
diff --git a/src/widget.test.ts b/src/widget.test.ts
new file mode 100644
index 00000000..f85c56bc
--- /dev/null
+++ b/src/widget.test.ts
@@ -0,0 +1,127 @@
+/*
+Copyright 2026 New Vector Ltd.
+
+SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
+Please see LICENSE in the repository root for full details.
+*/
+
+import { beforeAll, describe, expect, vi, it } from "vitest";
+import { createRoomWidgetClient, EventType } from "matrix-js-sdk";
+
+import { getUrlParams } from "./UrlParams";
+import { initializeWidget, widget } from "./widget";
+import { Config } from "./config/Config";
+import { ElementCallReactionEventType } from "./reactions";
+
+vi.mock("matrix-js-sdk", { spy: true });
+const createRoomWidgetClientSpy = vi.mocked(createRoomWidgetClient);
+
+vi.mock("./config/Config", () => ({
+  Config: {
+    init: vi.fn().mockImplementation(async () => Promise.resolve()),
+  },
+}));
+const configInitSpy = vi.mocked(Config.init);
+
+vi.mock("./UrlParams", () => ({
+  getUrlParams: vi.fn(() => ({
+    widgetId: "id",
+    parentUrl: "http://parentUrl",
+    roomId: "room",
+    userId: "myYser",
+    deviceId: "AAAAA",
+    baseUrl: "http://baseUrl",
+    e2eEnabled: true,
+  })),
+}));
+
+initializeWidget();
+describe("widget", () => {
+  beforeAll(() => {});
+
+  it("should create an embedded client with the correct params", () => {
+    expect(getUrlParams()).toStrictEqual({
+      widgetId: "id",
+      parentUrl: "http://parentUrl",
+      roomId: "room",
+      userId: "myYser",
+      deviceId: "AAAAA",
+      baseUrl: "http://baseUrl",
+      e2eEnabled: true,
+    });
+    expect(widget).toBeDefined();
+    expect(configInitSpy).toHaveBeenCalled();
+    const sendEvent = [
+      EventType.CallNotify, // Sent as a deprecated fallback
+      EventType.RTCNotification,
+    ];
+    const sendRecvEvent = [
+      "org.matrix.rageshake_request",
+      EventType.CallEncryptionKeysPrefix,
+      EventType.Reaction,
+      EventType.RoomRedaction,
+      ElementCallReactionEventType,
+      EventType.RTCDecline,
+      EventType.RTCMembership,
+    ];
+
+    const sendState = [
+      "myYser", // Legacy call membership events
+      `_myYser_AAAAA_m.call`, // Session membership events
+      `myYser_AAAAA_m.call`, // The above with no leading underscore, for room versions whose auth rules allow it
+    ].map((stateKey) => ({
+      eventType: EventType.GroupCallMemberPrefix,
+      stateKey,
+    }));
+    const receiveState = [
+      { eventType: EventType.RoomCreate },
+      { eventType: EventType.RoomName },
+      { eventType: EventType.RoomMember },
+      { eventType: EventType.RoomEncryption },
+      { eventType: EventType.GroupCallMemberPrefix },
+    ];
+
+    const sendRecvToDevice = [
+      EventType.CallInvite,
+      EventType.CallCandidates,
+      EventType.CallAnswer,
+      EventType.CallHangup,
+      EventType.CallReject,
+      EventType.CallSelectAnswer,
+      EventType.CallNegotiate,
+      EventType.CallSDPStreamMetadataChanged,
+      EventType.CallSDPStreamMetadataChangedPrefix,
+      EventType.CallReplaces,
+      EventType.CallEncryptionKeysPrefix,
+    ];
+
+    expect(createRoomWidgetClientSpy.mock.calls[0][1]).toStrictEqual({
+      sendEvent: [...sendEvent, ...sendRecvEvent],
+      receiveEvent: sendRecvEvent,
+      sendState,
+      receiveState,
+      sendToDevice: sendRecvToDevice,
+      receiveToDevice: sendRecvToDevice,
+      turnServers: false,
+      sendDelayedEvents: true,
+      updateDelayedEvents: true,
+      sendSticky: true,
+      receiveSticky: true,
+    });
+
+    expect(createRoomWidgetClientSpy.mock.calls[0][2]).toStrictEqual("room");
+    expect(createRoomWidgetClientSpy.mock.calls[0][3]).toStrictEqual({
+      baseUrl: "http://baseUrl",
+      userId: "myYser",
+      deviceId: "AAAAA",
+      timelineSupport: true,
+      useE2eForGroupCall: true,
+      fallbackICEServerAllowed: undefined,
+      store: expect.any(Object),
+      cryptoStore: expect.any(Object),
+      idBaseUrl: undefined,
+      scheduler: expect.any(Object),
+    });
+    expect(createRoomWidgetClientSpy.mock.calls[0][4]).toStrictEqual(false);
+  });
+});
diff --git a/src/widget.ts b/src/widget.ts
index 7b8201ed..16dbf514 100644
--- a/src/widget.ts
+++ b/src/widget.ts
@@ -6,14 +6,17 @@ Please see LICENSE in the repository root for full details.
 */
 
 import { logger } from "matrix-js-sdk/lib/logger";
-import { EventType, createRoomWidgetClient } from "matrix-js-sdk";
+import {
+  EventType,
+  createRoomWidgetClient,
+  type MatrixClient,
+} from "matrix-js-sdk";
 import {
   WidgetApi,
   MatrixCapabilities,
   WidgetApiToWidgetAction,
 } from "matrix-widget-api";
 
-import type { MatrixClient } from "matrix-js-sdk";
 import type { IWidgetApiRequest } from "matrix-widget-api";
 import { LazyEventEmitter } from "./LazyEventEmitter";
 import { getUrlParams } from "./UrlParams";
@@ -55,15 +58,29 @@ export interface WidgetHelpers {
 
 /**
  * A point of access to the widget API, if the app is running as a widget. This
- * is declared and initialized on the top level because the widget messaging
+ * is initialized with `initializeWidget`. This should happen at the top level because the widget messaging
  * needs to be set up ASAP on load to ensure it doesn't miss any requests.
  */
-export const widget = ((): WidgetHelpers | null => {
-  try {
-    const { widgetId, parentUrl } = getUrlParams();
+export let widget: WidgetHelpers | null;
+
+/**
+ * Should be called as soon as possible on app start. (In the initilizer before react)
+ */
+// this needs to be a seperate call and cannot be done on import to allow us to spy on methods in here before
+// execution.
+export const initializeWidget = (): void => {
+  try {
+    const {
+      widgetId,
+      parentUrl,
+      roomId,
+      userId,
+      deviceId,
+      baseUrl,
+      e2eEnabled,
+      allowIceFallback,
+    } = getUrlParams();
 
-    const { roomId, userId, deviceId, baseUrl, e2eEnabled, allowIceFallback } =
-      getUrlParams();
     if (!roomId) throw new Error("Room ID must be supplied");
     if (!userId) throw new Error("User ID must be supplied");
     if (!deviceId) throw new Error("Device ID must be supplied");
@@ -106,6 +123,7 @@ export const widget = ((): WidgetHelpers | null => {
         EventType.RoomRedaction,
         ElementCallReactionEventType,
         EventType.RTCDecline,
+        EventType.RTCMembership,
       ];
 
       const sendState = [
@@ -150,6 +168,8 @@ export const widget = ((): WidgetHelpers | null => {
           turnServers: false,
           sendDelayedEvents: true,
           updateDelayedEvents: true,
+          sendSticky: true,
+          receiveSticky: true,
         },
         roomId,
         {
@@ -172,14 +192,14 @@ export const widget = ((): WidgetHelpers | null => {
         return client;
       };
 
-      return { api, lazyActions, client: clientPromise() };
+      widget = { api, lazyActions, client: clientPromise() };
     } else {
       if (import.meta.env.MODE !== "test")
         logger.info("No widget API available");
-      return null;
+      widget = null;
     }
   } catch (e) {
     logger.warn("Continuing without the widget API", e);
-    return null;
+    widget = null;
   }
-})();
+};
diff --git a/yarn.lock b/yarn.lock
index 55e6a99b..8edc3d07 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -8364,8 +8364,8 @@ __metadata:
     livekit-client: "npm:^2.13.0"
     lodash-es: "npm:^4.17.21"
     loglevel: "npm:^1.9.1"
-    matrix-js-sdk: "matrix-org/matrix-js-sdk#4a75d2c92f1ac7476a6d398057b91c65054f1b80"
-    matrix-widget-api: "npm:^1.14.0"
+    matrix-js-sdk: "matrix-org/matrix-js-sdk#develop"
+    matrix-widget-api: "npm:^1.16.1"
     node-stdlib-browser: "npm:^1.3.1"
     normalize.css: "npm:^8.0.1"
     observable-hooks: "npm:^4.2.3"
@@ -11452,9 +11452,9 @@ __metadata:
   languageName: node
   linkType: hard
 
-"matrix-js-sdk@matrix-org/matrix-js-sdk#4a75d2c92f1ac7476a6d398057b91c65054f1b80":
+"matrix-js-sdk@matrix-org/matrix-js-sdk#develop":
   version: 40.0.0
-  resolution: "matrix-js-sdk@https://github.com/matrix-org/matrix-js-sdk.git#commit=4a75d2c92f1ac7476a6d398057b91c65054f1b80"
+  resolution: "matrix-js-sdk@https://github.com/matrix-org/matrix-js-sdk.git#commit=dbb2ae5c0752c28639502e93f26cb3003d0d0595"
   dependencies:
     "@babel/runtime": "npm:^7.12.5"
     "@matrix-org/matrix-sdk-crypto-wasm": "npm:^17.0.0"
@@ -11464,23 +11464,23 @@ __metadata:
     jwt-decode: "npm:^4.0.0"
     loglevel: "npm:^1.9.2"
     matrix-events-sdk: "npm:0.0.1"
-    matrix-widget-api: "npm:^1.14.0"
+    matrix-widget-api: "npm:^1.16.1"
     oidc-client-ts: "npm:^3.0.1"
     p-retry: "npm:7"
     sdp-transform: "npm:^3.0.0"
     unhomoglyph: "npm:^1.0.6"
     uuid: "npm:13"
-  checksum: 10c0/4b0d970fcdd6a43a369c08ce224a7d52d30706020b30af6896e07f2335df4616c068147ae76fca46506a1c6dedadfd633d96a4c9f43ce751e2b411d2c80211d3
+  checksum: 10c0/9f97cec346e0dcce8599bc3afa1608f5166408260937f8311fa9af95b8fd2ff6d86422124fcb721fc830a3ec269389067334c344b4f512b64299561484135326
   languageName: node
   linkType: hard
 
-"matrix-widget-api@npm:^1.14.0":
-  version: 1.15.0
-  resolution: "matrix-widget-api@npm:1.15.0"
+"matrix-widget-api@npm:^1.16.1":
+  version: 1.16.1
+  resolution: "matrix-widget-api@npm:1.16.1"
   dependencies:
     "@types/events": "npm:^3.0.0"
     events: "npm:^3.2.0"
-  checksum: 10c0/1c08b5284cd98aed312d95594335e1391d937dfad70ef862a1f90fdbaaa27709e1c44dcda37f8045e4814779d8d5816d240aee396d52cfd9b37fbf243a6baf6a
+  checksum: 10c0/d88180f514104b84d3018055fc955138d65195465480a51e9afe5dbf2f3175b54e3483b4c4f1feab2dd27440f403051d9c8b293bd0532c09b136c6b23606e1ee
   languageName: node
   linkType: hard