fix: handle user.updated in threads

src/thread.ts

@@ -661,6 +661,18 @@ export class Thread extends WithSubscriptions {
     this.messagePaginator.reflectQuotedMessageUpdate(formatMessage(message));
   };
 
+  public handleUserUpdated = (event: PipelineEvent) => {
+    const { user } = event;
+    if (!user) return;
+    this.messagePaginator.reflectUserUpdate(user);
+
+    // the parent message might not yet be loaded in channel.messagePaginator
+    const parent = this.client.messageStore.get(this.id);
+    if (parent?.user?.id === user.id && parent.user !== user) {
+      this.client.messageStore.upsert({ ...parent, user });
+    }
+  };
+
   // Applies a user ban or deletion to this thread's replies.
   public handleUserMessagesDeleted = (event: PipelineEvent) => {
     if (!event.user) return;

src/thread_manager.ts

@@ -338,14 +338,17 @@ export class ThreadManager extends WithSubscriptions {
             ),
           ),
       ),
-      // A banned or deleted user's replies can be in any thread, so these two are the exception.
+      // A user's replies can be in any thread, so the user events are the exception.
       ...(['user.messages.deleted', 'user.deleted'] as const).map((eventType) =>
         this.client.on(eventType, (event) =>
           this.threadStore
             .values()
             .forEach((thread) => thread.handleUserMessagesDeleted(event)),
         ),
       ),
+      this.client.on('user.updated', (event) =>
+        this.threadStore.values().forEach((thread) => thread.handleUserUpdated(event)),
+      ),
     ].map(({ unsubscribe }) => unsubscribe);
 
     return () => unsubscribeFunctions.forEach((unsubscribe) => unsubscribe());

test/unit/threads.test.ts

@@ -2375,6 +2375,67 @@ describe('Threads 2.0', () => {
           });
         });
 
+        it('replaces an updated user in the thread paginator\'s replies on "user.updated"', () => {
+          const thread = createTestThread();
+          subscribeThread(thread);
+          const authorId = 'renamed-user';
+          const replyId = uuidv4();
+          thread.messagePaginator.ingestPage({
+            page: [
+              formatMessage(
+                generateMsg({
+                  id: replyId,
+                  parent_id: thread.id,
+                  user: { id: authorId, name: 'Old name' },
+                }) as MessageResponse,
+              ),
+            ],
+            isHead: true,
+            isTail: true,
+            setActive: true,
+          });
+
+          client.dispatchEvent({
+            type: 'user.updated',
+            user: { id: authorId, name: 'New name' },
+            created_at: nowNs(),
+          });
+
+          expect(thread.messagePaginator.getItem(replyId)?.user?.name).to.equal(
+            'New name',
+          );
+          expect(
+            thread.messagePaginator.items?.find((reply) => reply.id === replyId)?.user
+              ?.name,
+          ).to.equal('New name');
+
+          thread.unregisterSubscriptions();
+        });
+
+        it('replaces an updated user in the parent message on "user.updated" when no channel paginator holds it', () => {
+          const authorId = 'renamed-parent-author';
+          const thread = createTestThread({
+            parentMessageOverrides: { user: { id: authorId, name: 'Old name' } },
+          });
+          subscribeThread(thread);
+          expect(channel.messagePaginator.getItem(thread.id)).to.be.undefined;
+          expect(thread.state.getLatestValue().parentMessage.user?.name).to.equal(
+            'Old name',
+          );
+
+          client.dispatchEvent({
+            type: 'user.updated',
+            user: { id: authorId, name: 'New name' },
+            created_at: nowNs(),
+          });
+
+          expect(thread.state.getLatestValue().parentMessage.user?.name).to.equal(
+            'New name',
+          );
+
+          thread.unregisterSubscriptions();
+        });
+
         it('applies "reaction.new" to a reply the thread paginator already holds', () => {
           const thread = createTestThread();
           subscribeThread(thread);