Fetch server capabilities during client initialisation (#2093)

src/client.ts

@@ -411,14 +411,19 @@ export interface IRoomVersionsCapability {
     "org.matrix.msc3244.room_capabilities"?: Record<string, IRoomCapability>; // MSC3244
 }
 
-export interface IChangePasswordCapability {
+export interface ICapability {
     enabled: boolean;
 }
 
+export interface IChangePasswordCapability extends ICapability {}
+
+export interface IThreadsCapability extends ICapability {}
+
 interface ICapabilities {
     [key: string]: any;
     "m.change_password"?: IChangePasswordCapability;
     "m.room_versions"?: IRoomVersionsCapability;
+    "io.element.thread"?: IThreadsCapability;
 }
 
 /* eslint-disable camelcase */
@@ -996,7 +1001,7 @@ export class MatrixClient extends EventEmitter {
      * state change events.
      * @param {Object=} opts Options to apply when syncing.
      */
-    public async startClient(opts: IStartClientOpts) {
+    public async startClient(opts: IStartClientOpts): Promise<void> {
         if (this.clientRunning) {
             // client is already running.
             return;
@@ -1036,6 +1041,8 @@ export class MatrixClient extends EventEmitter {
             this.syncApi.stop();
         }
 
+        await this.getCapabilities(true);
+
         // shallow-copy the opts dict before modifying and storing it
         this.clientOpts = Object.assign({}, opts) as IStoredClientOpts;
         this.clientOpts.crypto = this.crypto;