diff --git a/src/pages/Chat/ChatInput.tsx b/src/pages/Chat/ChatInput.tsx
index eddca86..c26d58b 100644
--- a/src/pages/Chat/ChatInput.tsx
+++ b/src/pages/Chat/ChatInput.tsx
@@ -19,6 +19,7 @@ export interface ChatAttachment {
 
 interface ChatInputProps {
   onSend: (text: string, attachments?: ChatAttachment[]) => void;
+  onStop?: () => void;
   disabled?: boolean;
   sending?: boolean;
 }
@@ -54,11 +55,12 @@ function fileToAttachment(file: File): Promise<ChatAttachment> {
   });
 }
 
-export function ChatInput({ onSend, disabled = false, sending = false }: ChatInputProps) {
+export function ChatInput({ onSend, onStop, disabled = false, sending = false }: ChatInputProps) {
   const [input, setInput] = useState('');
   const [attachments, setAttachments] = useState<ChatAttachment[]>([]);
   const textareaRef = useRef<HTMLTextAreaElement>(null);
   const fileInputRef = useRef<HTMLInputElement>(null);
+  const isComposingRef = useRef(false);
 
   // Auto-resize textarea
   useEffect(() => {
@@ -85,6 +87,7 @@ export function ChatInput({ onSend, disabled = false, sending = false }: ChatInp
   }, []);
 
   const canSend = (input.trim() || attachments.length > 0) && !disabled && !sending;
+  const canStop = sending && !disabled && !!onStop;
 
   const handleSend = useCallback(() => {
     if (!canSend) return;
@@ -96,9 +99,18 @@ export function ChatInput({ onSend, disabled = false, sending = false }: ChatInp
     }
   }, [input, attachments, canSend, onSend]);
 
+  const handleStop = useCallback(() => {
+    if (!canStop) return;
+    onStop?.();
+  }, [canStop, onStop]);
+
   const handleKeyDown = useCallback(
     (e: React.KeyboardEvent) => {
       if (e.key === 'Enter' && !e.shiftKey) {
+        const nativeEvent = e.nativeEvent as KeyboardEvent;
+        if (isComposingRef.current || nativeEvent.isComposing || nativeEvent.keyCode === 229) {
+          return;
+        }
         e.preventDefault();
         handleSend();
       }
@@ -221,6 +233,12 @@ export function ChatInput({ onSend, disabled = false, sending = false }: ChatInp
               value={input}
               onChange={(e) => setInput(e.target.value)}
               onKeyDown={handleKeyDown}
+              onCompositionStart={() => {
+                isComposingRef.current = true;
+              }}
+              onCompositionEnd={() => {
+                isComposingRef.current = false;
+              }}
               onPaste={handlePaste}
               placeholder={disabled ? 'Gateway not connected...' : 'Message (Enter to send, Shift+Enter for new line)'}
               disabled={disabled}
@@ -231,11 +249,12 @@ export function ChatInput({ onSend, disabled = false, sending = false }: ChatInp
 
           {/* Send Button */}
           <Button
-            onClick={handleSend}
-            disabled={!canSend}
+            onClick={sending ? handleStop : handleSend}
+            disabled={sending ? !canStop : !canSend}
             size="icon"
             className="shrink-0 h-[44px] w-[44px]"
             variant={sending ? 'destructive' : 'default'}
+            title={sending ? 'Stop' : 'Send'}
           >
             {sending ? (
               <Square className="h-4 w-4" />
diff --git a/src/pages/Chat/index.tsx b/src/pages/Chat/index.tsx
index 41bf5bb..4837b93 100644
--- a/src/pages/Chat/index.tsx
+++ b/src/pages/Chat/index.tsx
@@ -28,6 +28,7 @@ export function Chat() {
   const loadHistory = useChatStore((s) => s.loadHistory);
   const loadSessions = useChatStore((s) => s.loadSessions);
   const sendMessage = useChatStore((s) => s.sendMessage);
+  const abortRun = useChatStore((s) => s.abortRun);
   const clearError = useChatStore((s) => s.clearError);
 
   const messagesEndRef = useRef<HTMLDivElement>(null);
@@ -145,6 +146,7 @@ export function Chat() {
       {/* Input Area */}
       <ChatInput
         onSend={sendMessage}
+        onStop={abortRun}
         disabled={!isGatewayRunning}
         sending={sending}
       />
diff --git a/src/stores/chat.ts b/src/stores/chat.ts
index 9d54595..a5fef1f 100644
--- a/src/stores/chat.ts
+++ b/src/stores/chat.ts
@@ -63,12 +63,41 @@ interface ChatState {
   newSession: () => void;
   loadHistory: () => Promise<void>;
   sendMessage: (text: string, attachments?: { type: string; mimeType: string; fileName: string; content: string }[]) => Promise<void>;
+  abortRun: () => Promise<void>;
   handleChatEvent: (event: Record<string, unknown>) => void;
   toggleThinking: () => void;
   refresh: () => Promise<void>;
   clearError: () => void;
 }
 
+function isToolOnlyMessage(message: RawMessage | undefined): boolean {
+  if (!message) return false;
+  if (message.role === 'toolresult') return true;
+
+  const content = message.content;
+  if (!Array.isArray(content)) return false;
+
+  let hasTool = false;
+  let hasText = false;
+  let hasNonToolContent = false;
+
+  for (const block of content as ContentBlock[]) {
+    if (block.type === 'tool_use' || block.type === 'tool_result') {
+      hasTool = true;
+      continue;
+    }
+    if (block.type === 'text' && block.text && block.text.trim()) {
+      hasText = true;
+      continue;
+    }
+    if (block.type === 'image' || block.type === 'thinking') {
+      hasNonToolContent = true;
+    }
+  }
+
+  return hasTool && !hasText && !hasNonToolContent;
+}
+
 // ── Store ────────────────────────────────────────────────────────
 
 export const useChatStore = create<ChatState>((set, get) => ({
@@ -260,6 +289,23 @@ export const useChatStore = create<ChatState>((set, get) => ({
     }
   },
 
+  // ── Abort active run ──
+
+  abortRun: async () => {
+    const { currentSessionKey } = get();
+    set({ sending: false, streamingText: '', streamingMessage: null });
+
+    try {
+      await window.electron.ipcRenderer.invoke(
+        'gateway:rpc',
+        'chat.abort',
+        { sessionKey: currentSessionKey },
+      );
+    } catch (err) {
+      set({ error: String(err) });
+    }
+  },
+
   // ── Handle incoming chat events from Gateway ──
 
   handleChatEvent: (event: Record<string, unknown>) => {
@@ -282,20 +328,32 @@ export const useChatStore = create<ChatState>((set, get) => ({
         // Message complete - add to history and clear streaming
         const finalMsg = event.message as RawMessage | undefined;
         if (finalMsg) {
-          const msgId = finalMsg.id || `run-${runId}`;
+          const toolOnly = isToolOnlyMessage(finalMsg);
+          const msgId = finalMsg.id || (toolOnly ? `run-${runId}-tool-${Date.now()}` : `run-${runId}`);
           set((s) => {
             // Check if message already exists (prevent duplicates)
             const alreadyExists = s.messages.some(m => m.id === msgId);
             if (alreadyExists) {
               // Just clear streaming state, don't add duplicate
-              return {
+              return toolOnly ? {
+                streamingText: '',
+                streamingMessage: null,
+              } : {
                 streamingText: '',
                 streamingMessage: null,
                 sending: false,
                 activeRunId: null,
               };
             }
-            return {
+            return toolOnly ? {
+              messages: [...s.messages, {
+                ...finalMsg,
+                role: finalMsg.role || 'assistant',
+                id: msgId,
+              }],
+              streamingText: '',
+              streamingMessage: null,
+            } : {
               messages: [...s.messages, {
                 ...finalMsg,
                 role: finalMsg.role || 'assistant',