Handle SDKContextClass client initialisation internally (#34146)

* Handle SDKContextClass `client` initialisation internally

Rather than via MatrixChat - this is predominantly for Lifecycle tests as they don't use a MatrixChat and it doesn't make much sense for this component to own this state.

* Fix tests

apps/web/src/Lifecycle.ts

@@ -81,6 +81,7 @@ import {
 import { TokenRefresher } from "./utils/oidc/TokenRefresher";
 import { checkBrowserSupport } from "./SupportedBrowser";
 import { type URLParams } from "./vector/url_utils.ts";
+import { type OnLoggedInPayload } from "./dispatcher/payloads/OnLoggedInPayload.ts";
 
 const HOMESERVER_URL_KEY = "mx_hs_url";
 const ID_SERVER_URL_KEY = "mx_is_url";
@@ -906,9 +907,9 @@ async function doSetLoggedIn(
     }
     checkSessionLock();
 
-    // We are now logged in, so fire this. We have yet to start the client but the
-    // client_started dispatch is for that.
-    dis.fire(Action.OnLoggedIn);
+    // We are now logged in, so fire this. We have yet to start the client but the client_started dispatch is for that.
+    // Dispatch this synchronously so SDKContextClass can set the client for other modules to consume.
+    dis.dispatch<OnLoggedInPayload>({ action: Action.OnLoggedIn, client }, true);
 
     const clientPegOpts: MatrixClientPegAssignOpts = {};
     if (credentials.pickleKey) {

apps/web/src/components/structures/MatrixChat.tsx

@@ -1521,7 +1521,6 @@ export default class MatrixChat extends React.PureComponent<IProps, IState> {
      * Handle an {@link Action.OnLoggedIn} action (i.e, we now have a client with working credentials).
      */
     private onLoggedIn(): void {
-        this.stores.client = MatrixClientPeg.safeGet();
         StorageManager.tryPersistStorage();
 
         // If we're loading the app for the first time, we can now transition to a splash screen while we wait for the

apps/web/src/contexts/SDKContextClass.ts

@@ -26,6 +26,9 @@ import { OidcClientStore } from "../stores/oidc/OidcClientStore";
 import WidgetStore from "../stores/WidgetStore";
 import ResizeNotifier from "../utils/ResizeNotifier";
 import { MultiRoomViewStore } from "../stores/MultiRoomViewStore";
+import { type ActionPayload, isAction } from "../dispatcher/payloads.ts";
+import { Action } from "../dispatcher/actions.ts";
+import { type OnLoggedInPayload } from "../dispatcher/payloads/OnLoggedInPayload.ts";
 
 /**
  * A class which (mostly) lazily initialises stores as and when they are requested, ensuring they remain
@@ -43,11 +46,13 @@ export class SDKContextClass {
      */
     public static readonly instance = new SDKContextClass();
 
-    // Optional as we don't have a client on initial load if unregistered. This should be set
-    // when the MatrixClient is first acquired in the dispatcher event Action.OnLoggedIn.
+    // Optional as we don't have a client on initial load if unregistered.
     // It is only safe to set this once, as updating this value will NOT notify components using
     // this Context.
-    public client?: MatrixClient;
+    protected _client?: MatrixClient;
+    public get client(): MatrixClient | undefined {
+        return this._client;
+    }
 
     // All protected fields to make it easier to derive test stores
     protected _WidgetPermissionStore?: WidgetPermissionStore;
@@ -67,6 +72,16 @@ export class SDKContextClass {
     protected _ResizeNotifier?: ResizeNotifier;
     protected _MultiRoomViewStore?: MultiRoomViewStore;
 
+    public constructor() {
+        defaultDispatcher.register(this.onDispatch);
+    }
+
+    private onDispatch = (payload: ActionPayload): void => {
+        if (isAction<OnLoggedInPayload>(payload, Action.OnLoggedIn)) {
+            this._client = payload.client;
+        }
+    };
+
     /**
      * Automatically construct stores which need to be created eagerly so they can register with
      * the dispatcher.
@@ -193,5 +208,6 @@ export class SDKContextClass {
     public onLoggedOut(): void {
         this._UserProfilesStore = undefined;
         this._OidcClientStore = undefined;
+        this._client = undefined;
     }
 }

apps/web/src/dispatcher/actions.ts

@@ -335,7 +335,7 @@ export enum Action {
      * access token from local storage). Note that this does not necessarily mean that a login action has happened,
      * just that authentication creds have been set up.
      *
-     * No additional payload information required.
+     * Use with a OnLoggedInPayload.
      */
     OnLoggedIn = "on_logged_in",
 

apps/web/src/dispatcher/payloads.ts

@@ -16,6 +16,15 @@ export interface ActionPayload {
     action: DispatcherAction;
 }
 
+/**
+ * Type guard to check if a payload is of a specific action type.
+ * @param payload - the incoming payload to check
+ * @param action - the action to return true for
+ */
+export function isAction<P extends ActionPayload>(payload: ActionPayload, action: P["action"]): payload is P {
+    return payload.action === action;
+}
+
 /**
  * The function the dispatcher calls when ready for an AsyncActionPayload. The
  * single argument is used to start a dispatch. First the dispatcher calls the

apps/web/src/dispatcher/payloads/OnLoggedInPayload.ts

@@ -0,0 +1,17 @@
+/*
+Copyright 2026 Element Creations Ltd.
+
+SPDX-License-Identifier: AGPL-3.0-only OR GPL-3.0-only OR LicenseRef-Element-Commercial
+Please see LICENSE files in the repository root for full details.
+*/
+
+import { type MatrixClient } from "matrix-js-sdk/src/matrix";
+
+import { type ActionPayload } from "../payloads";
+import { type Action } from "../actions";
+
+export interface OnLoggedInPayload extends ActionPayload {
+    action: Action.OnLoggedIn;
+
+    client: MatrixClient;
+}