diff --git a/ui/colony/src/App.tsx b/ui/colony/src/App.tsx
index 882ee61..3042d73 100644
--- a/ui/colony/src/App.tsx
+++ b/ui/colony/src/App.tsx
@@ -12,35 +12,52 @@ export default function App() {
   const [messages, setMessages] = useState<Message[]>([]);
   const [replyTo, setReplyTo] = useState<string | null>(null);
   const scrollRef = useRef<HTMLDivElement>(null);
+  const prevMsgCountRef = useRef(0);
+  const activeChannelRef = useRef(activeChannelId);
+
+  // Keep ref in sync
+  activeChannelRef.current = activeChannelId;
 
   const loadChannels = useCallback(async () => {
     const chs = await getChannels();
     setChannels(chs);
-    if (!activeChannelId && chs.length > 0) {
-      setActiveChannelId(chs[0].id);
-    }
-  }, [activeChannelId]);
+    // Auto-select first channel only if none selected
+    setActiveChannelId((prev) => (prev ? prev : chs[0]?.id ?? null));
+  }, []);
 
   const loadMessages = useCallback(async () => {
-    if (!activeChannelId) return;
-    const msgs = await getMessages(activeChannelId);
-    setMessages(msgs);
-  }, [activeChannelId]);
+    const channelId = activeChannelRef.current;
+    if (!channelId) return;
+    try {
+      const msgs = await getMessages(channelId);
+      // Only update if we're still on the same channel (prevent race)
+      if (activeChannelRef.current === channelId) {
+        setMessages(msgs);
+      }
+    } catch {
+      // Silently ignore fetch errors during polling
+    }
+  }, []);
 
+  // Initial channel load
   useEffect(() => {
     loadChannels();
   }, [loadChannels]);
 
+  // Load messages on channel switch
   useEffect(() => {
-    loadMessages();
+    setMessages([]); // Clear immediately on switch
     setReplyTo(null);
-  }, [loadMessages]);
+    prevMsgCountRef.current = 0;
+    loadMessages();
+  }, [activeChannelId, loadMessages]);
 
-  // Auto-scroll on new messages
+  // Auto-scroll only when NEW messages arrive (not on every poll)
   useEffect(() => {
-    if (scrollRef.current) {
+    if (messages.length > prevMsgCountRef.current && scrollRef.current) {
       scrollRef.current.scrollTop = scrollRef.current.scrollHeight;
     }
+    prevMsgCountRef.current = messages.length;
   }, [messages]);
 
   // Poll until WebSocket (S5)
@@ -51,13 +68,14 @@ export default function App() {
 
   const messagesById = new Map(messages.map((m) => [m.id, m]));
   const activeChannel = channels.find((c) => c.id === activeChannelId);
+  const _currentUser = getCurrentUsername();
 
   return (
     <div className="flex h-full">
       <ChannelSidebar
         channels={channels}
         activeId={activeChannelId}
-        onSelect={(id) => setActiveChannelId(id)}
+        onSelect={setActiveChannelId}
         onChannelCreated={loadChannels}
       />
 
@@ -105,9 +123,10 @@ export default function App() {
           ))}
         </div>
 
-        {/* Compose */}
+        {/* Compose — key forces reset on channel switch */}
         {activeChannelId && (
           <ComposeBox
+            key={activeChannelId}
             channelId={activeChannelId}
             replyTo={replyTo}
             onClearReply={() => setReplyTo(null)}
diff --git a/ui/colony/src/components/ChannelSidebar.tsx b/ui/colony/src/components/ChannelSidebar.tsx
index 2d60768..6dfc28d 100644
--- a/ui/colony/src/components/ChannelSidebar.tsx
+++ b/ui/colony/src/components/ChannelSidebar.tsx
@@ -21,10 +21,13 @@ export function ChannelSidebar({
   async function handleCreate() {
     if (!newName.trim()) return;
     setCreating(true);
-    await createChannel({ name: newName.trim(), description: "" });
-    setNewName("");
-    setCreating(false);
-    onChannelCreated();
+    try {
+      await createChannel({ name: newName.trim(), description: "" });
+      setNewName("");
+      onChannelCreated();
+    } finally {
+      setCreating(false);
+    }
   }
 
   return (
diff --git a/ui/colony/src/components/ComposeBox.tsx b/ui/colony/src/components/ComposeBox.tsx
index 199ec9e..bd19bd8 100644
--- a/ui/colony/src/components/ComposeBox.tsx
+++ b/ui/colony/src/components/ComposeBox.tsx
@@ -30,16 +30,19 @@ export function ComposeBox({
   async function handleSend() {
     if (!content.trim() || sending) return;
     setSending(true);
-    await postMessage(channelId, {
-      content: content.trim(),
-      type: msgType,
-      reply_to: replyTo ?? undefined,
-    });
-    setContent("");
-    setMsgType("text");
-    onClearReply();
-    onMessageSent();
-    setSending(false);
+    try {
+      await postMessage(channelId, {
+        content: content.trim(),
+        type: msgType,
+        reply_to: replyTo ?? undefined,
+      });
+      setContent("");
+      setMsgType("text");
+      onClearReply();
+      onMessageSent();
+    } finally {
+      setSending(false);
+    }
   }
 
   return (