fix duplicate messages when history fetch races firehose

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/state/messages/convo/agent.ts

@@ -881,6 +881,15 @@ export class Convo {
             ChatBskyConvoDefs.isLogCreateMessage(ev) &&
             ChatBskyConvoDefs.isMessageView(ev.message)
           ) {
+            /*
+             * If this message is already in past messages, the initial
+             * history fetch raced this log event and already returned it.
+             * Update in place rather than inserting a duplicate into new
+             * messages.
+             */
+            if (this.pastMessages.has(ev.message.id)) {
+              this.pastMessages.set(ev.message.id, ev.message)
+            } else {
               /**
                * If this message is already in new messages, it was added by our
                * sending logic, and is based on client-ordering. When we receive
@@ -892,6 +901,7 @@ export class Convo {
                 this.newMessages.delete(ev.message.id)
               }
               this.newMessages.set(ev.message.id, ev.message)
+            }
             needsCommit = true
           } else if (
             ChatBskyConvoDefs.isLogDeleteMessage(ev) &&
@@ -928,7 +938,12 @@ export class Convo {
           } else {
             const systemView = toSystemMessageView(ev)
             if (systemView) {
+              // same as above: avoid duplicating if history fetch won the race
+              if (this.pastMessages.has(systemView.id)) {
+                this.pastMessages.set(systemView.id, systemView)
+              } else {
                 this.newMessages.set(systemView.id, systemView)
+              }
               needsCommit = true
             }
           }