if we don't have our own member yet, fetch it from the server and store

src/matrix/net/HomeServerApi.js

@@ -189,6 +189,10 @@ export class HomeServerApi {
         return this._get(`/rooms/${encodeURIComponent(roomId)}/messages`, params, null, options);
     }
 
+    roomState(roomId, eventType, stateKey, options = null) {
+        return this._get(`/rooms/${encodeURIComponent(roomId)}/state/${encodeURIComponent(eventType)}/${encodeURIComponent(stateKey)}`, null, null, options);
+    }
+
     // params is at, membership and not_membership
     members(roomId, params, options = null) {
         return this._get(`/rooms/${encodeURIComponent(roomId)}/members`, params, null, options);

src/matrix/room/Room.js

@@ -425,8 +425,13 @@ export class Room extends EventEmitter {
 
     /** @public */
     sendEvent(eventType, content, attachments, log = null) {
-        this._platform.logger.wrapOrRun(log, "send", log => {
+        this._platform.logger.wrapOrRun(log, "send", async log => {
             log.set("id", this.id);
+            if (this._timeline) {
+                // ensure we have our own member loaded for the local echo
+                await this._timeline.ensureOwnMember(
+                    this._user, this._summary.data.membership, this._hsApi, log);
+            }
             return this._sendQueue.enqueueEvent(eventType, content, attachments, log);
         });
     }
@@ -678,7 +683,12 @@ export class Room extends EventEmitter {
             if (this._roomEncryption) {
                 this._timeline.enableEncryption(this._decryptEntries.bind(this, DecryptionSource.Timeline));
             }
-            await this._timeline.load(this._user, log);
+            if (this._sendQueue.pendingEvents.length !== 0) {
+                // ensure we have our own member loaded for the local echo
+                await this._timeline.ensureOwnMember(
+                    this._user, this._summary.data.membership, this._hsApi, log);
+            }
+            await this._timeline.load(log);
             return this._timeline;
         });
     }

src/matrix/room/members/RoomMember.js

@@ -23,6 +23,15 @@ export class RoomMember {
         this._data = data;
     }
 
+    static async fromFetch(roomId, userId, hsApi, log) {
+         const memberEvent = await hsApi.roomState(this._roomId, EVENT_TYPE, userId, {log}).response();
+         return RoomMember.fromMemberEvent(memberEvent);
+    }
+
+    static fromUserId(roomId, userId, membership) {
+        return new RoomMember({roomId, userId, membership});
+    }
+
     static fromMemberEvent(roomId, memberEvent) {
         const userId = memberEvent?.state_key;
         if (typeof userId !== "string") {

src/matrix/room/timeline/Timeline.js

@@ -45,14 +45,8 @@ export class Timeline {
     }
 
     /** @package */
-    async load(user, log) {
-        const txn = await this._storage.readTxn(this._timelineReader.readTxnStores.concat(this._storage.storeNames.roomMembers));
-        const memberData = await txn.roomMembers.get(this._roomId, user.id);
-        this._ownMember = new RoomMember(memberData);
-        // it should be fine to not update the local entries,
-        // as they should only populate once the view subscribes to it
-        // if they are populated already, the sender profile would be empty
-
+    async load(log) {
+        const txn = await this._storage.readTxn(this._timelineReader.readTxnStores);
         // 30 seems to be a good amount to fill the entire screen
         const readerRequest = this._disposables.track(this._timelineReader.readFromEnd(30, txn, log));
         try {
@@ -63,6 +57,41 @@ export class Timeline {
         }
     }
 
+    async ensureOwnMember(user, myMembership, hsApi, log) {
+        if (this._ownMember) {
+            return;
+        }
+        const txn = await this._storage.readTxn(this._storage.storeNames.roomMembers);
+        const memberData = await txn.roomMembers.get(this._roomId, user.id);
+        if (memberData) {
+            this._ownMember = new RoomMember(memberData);
+        } else {
+            await log.wrap("own member missing", async log => {
+                // important this *never* throws, not even when offline,
+                // as it would prevent enqueueing a message, or opening the timeline
+                try {
+                    this._ownMember = await RoomMember.fromFetch(this._roomId, user.id, hsApi, log);
+                    const writeTxn = await this._storage.readWriteTxn(this._storage.storeNames.roomMembers);
+                    // check we still don't have the member after the fetch (e.g. from sync)
+                    // just to make sure we don't overwrite it
+                    const memberData = await writeTxn.roomMembers.get(this._roomId, user.id);
+                    if(!memberData) {
+                        writeTxn.roomMembers.set(this._roomId, this._ownMember.serialize());
+                        await writeTxn.complete();
+                    } else {
+                        this._ownMember = new RoomMember(memberData);
+                    }
+                } catch (err) {
+                    log.error = err;
+                    if (!this._ownMember) {
+                        log.set("fallback", true);
+                        this._ownMember = RoomMember.fromUserId(this._roomId, user.id, myMembership);
+                    }
+                }
+            });
+        }
+    }
+
     updateOwnMember(member) {
         this._ownMember = member;
     }