diff --git a/src/pages/Chat/ChatMessage.tsx b/src/pages/Chat/ChatMessage.tsx
index 8de44b0e2..416bcd6b6 100644
--- a/src/pages/Chat/ChatMessage.tsx
+++ b/src/pages/Chat/ChatMessage.tsx
@@ -346,9 +346,9 @@ function MessageBubble({
       )}
     >
       {isUser ? (
-        <p className="whitespace-pre-wrap break-words text-sm">{text}</p>
+        <p className="whitespace-pre-wrap break-words break-all text-sm">{text}</p>
       ) : (
-        <div className="prose prose-sm dark:prose-invert max-w-none">
+        <div className="prose prose-sm dark:prose-invert max-w-none break-words break-all">
           <ReactMarkdown
             remarkPlugins={[remarkGfm]}
             components={{
@@ -357,7 +357,7 @@ function MessageBubble({
                 const isInline = !match && !className;
                 if (isInline) {
                   return (
-                    <code className="bg-background/50 px-1.5 py-0.5 rounded text-sm font-mono" {...props}>
+                    <code className="bg-background/50 px-1.5 py-0.5 rounded text-sm font-mono break-words break-all" {...props}>
                       {children}
                     </code>
                   );
@@ -372,7 +372,7 @@ function MessageBubble({
               },
               a({ href, children }) {
                 return (
-                  <a href={href} target="_blank" rel="noopener noreferrer" className="text-primary hover:underline">
+                  <a href={href} target="_blank" rel="noopener noreferrer" className="text-primary hover:underline break-words break-all">
                     {children}
                   </a>
                 );
diff --git a/src/pages/Chat/index.tsx b/src/pages/Chat/index.tsx
index 4a2c65d2a..cfc2e99fc 100644
--- a/src/pages/Chat/index.tsx
+++ b/src/pages/Chat/index.tsx
@@ -35,6 +35,8 @@ export function Chat() {
   const abortRun = useChatStore((s) => s.abortRun);
   const clearError = useChatStore((s) => s.clearError);
 
+  const cleanupEmptySession = useChatStore((s) => s.cleanupEmptySession);
+
   const messagesEndRef = useRef<HTMLDivElement>(null);
   const [streamingTimestamp, setStreamingTimestamp] = useState<number>(0);
 
@@ -54,8 +56,11 @@ export function Chat() {
     })();
     return () => {
       cancelled = true;
+      // If the user navigates away without sending any messages, remove the
+      // empty session so it doesn't linger as a ghost entry in the sidebar.
+      cleanupEmptySession();
     };
-  }, [isGatewayRunning, loadHistory, loadSessions]);
+  }, [isGatewayRunning, loadHistory, loadSessions, cleanupEmptySession]);
 
   // Auto-scroll on new messages, streaming, or activity changes
   useEffect(() => {
diff --git a/src/stores/chat.ts b/src/stores/chat.ts
index 62ebf1e62..54c14cac5 100644
--- a/src/stores/chat.ts
+++ b/src/stores/chat.ts
@@ -99,6 +99,7 @@ interface ChatState {
   switchSession: (key: string) => void;
   newSession: () => void;
   deleteSession: (key: string) => Promise<void>;
+  cleanupEmptySession: () => void;
   loadHistory: (quiet?: boolean) => Promise<void>;
   sendMessage: (text: string, attachments?: Array<{ fileName: string; mimeType: string; fileSize: number; stagedPath: string; preview: string | null }>) => Promise<void>;
   abortRun: () => Promise<void>;
@@ -973,8 +974,11 @@ export const useChatStore = create<ChatState>((set, get) => ({
           }
         }
         if (!dedupedSessions.find((s) => s.key === nextSessionKey) && dedupedSessions.length > 0) {
-          // Current session not found at all — switch to the first available session
-          nextSessionKey = dedupedSessions[0].key;
+          // Current session not found in the backend list
+          const isNewEmptySession = get().messages.length === 0;
+          if (!isNewEmptySession) {
+            nextSessionKey = dedupedSessions[0].key;
+          }
         }
 
         const sessionsWithCurrent = !dedupedSessions.find((s) => s.key === nextSessionKey) && nextSessionKey
@@ -1153,6 +1157,27 @@ export const useChatStore = create<ChatState>((set, get) => ({
     }));
   },
 
+  // ── Cleanup empty session on navigate away ──
+
+  cleanupEmptySession: () => {
+    const { currentSessionKey, messages } = get();
+    // Only remove non-main sessions that were never used (no messages sent).
+    // This mirrors the "leavingEmpty" logic in switchSession so that creating
+    // a new session and immediately navigating away doesn't leave a ghost entry
+    // in the sidebar.
+    const isEmptyNonMain = !currentSessionKey.endsWith(':main') && messages.length === 0;
+    if (!isEmptyNonMain) return;
+    set((s) => ({
+      sessions: s.sessions.filter((sess) => sess.key !== currentSessionKey),
+      sessionLabels: Object.fromEntries(
+        Object.entries(s.sessionLabels).filter(([k]) => k !== currentSessionKey),
+      ),
+      sessionLastActivity: Object.fromEntries(
+        Object.entries(s.sessionLastActivity).filter(([k]) => k !== currentSessionKey),
+      ),
+    }));
+  },
+
   // ── Load chat history ──
 
   loadHistory: async (quiet = false) => {