feat(arena): improve cancellation handling and simplify to in-process mode

Co-authored-by: Qwen-Coder <qwen-coder@alibabacloud.com>

- Track user-initiated cancellation separately from failures

- Cancel round immediately when user denies a tool call

- Add message queue to handle input during streaming

- Add info messages during Arena operations (apply, stop, cleanup)

- Disable tmux/iTerm2 backends (only in-process mode supported)

- Polish UI: green tool count, updated warning prefix

This improves the Arena UX by providing clearer feedback and

properly handling user cancellations without treating them as failures.

packages/cli/src/ui/commands/arenaCommand.ts

@@ -249,10 +249,7 @@ function executeArenaCommand(
     } else if (event.type === 'info') {
       addAndRecordArenaMessage(MessageType.INFO, event.message);
     } else {
-      addAndRecordArenaMessage(
-        MessageType.WARNING,
-        `Arena warning: ${event.message}`,
-      );
+      addAndRecordArenaMessage(MessageType.WARNING, event.message);
     }
   };
 

packages/cli/src/ui/components/agent-view/AgentComposer.tsx

@@ -18,9 +18,10 @@
  */
 
 import { Box, Text, useStdin } from 'ink';
-import { useCallback, useEffect, useMemo } from 'react';
+import { useCallback, useEffect, useMemo, useState } from 'react';
 import {
   AgentStatus,
+  isTerminalStatus,
   ApprovalMode,
   APPROVAL_MODES,
 } from '@qwen-code/qwen-code-core';
@@ -38,6 +39,7 @@ import { useTextBuffer } from '../shared/text-buffer.js';
 import { calculatePromptWidths } from '../../utils/layoutUtils.js';
 import { BaseTextInput } from '../BaseTextInput.js';
 import { LoadingIndicator } from '../LoadingIndicator.js';
+import { QueuedMessageDisplay } from '../QueuedMessageDisplay.js';
 import { AgentFooter } from './AgentFooter.js';
 import { keyMatchers, Command } from '../../keyMatchers.js';
 import { theme } from '../../semantic-colors.js';
@@ -182,13 +184,35 @@ export const AgentComposer: React.FC<AgentComposerProps> = ({ agentId }) => {
     [buffer, agentTabBarFocused, setAgentTabBarFocused],
   );
 
+  // ── Message queue (accumulate while streaming, flush as one prompt on idle) ──
+
+  const [messageQueue, setMessageQueue] = useState<string[]>([]);
+
+  // When agent becomes idle (and not terminal), flush queued messages.
+  useEffect(() => {
+    if (
+      streamingState === StreamingState.Idle &&
+      messageQueue.length > 0 &&
+      status !== undefined &&
+      !isTerminalStatus(status)
+    ) {
+      const combined = messageQueue.join('\n');
+      setMessageQueue([]);
+      interactiveAgent?.enqueueMessage(combined);
+    }
+  }, [streamingState, messageQueue, interactiveAgent, status]);
+
   const handleSubmit = useCallback(
     (text: string) => {
       const trimmed = text.trim();
       if (!trimmed || !interactiveAgent) return;
-      interactiveAgent.enqueueMessage(trimmed);
+      if (streamingState === StreamingState.Idle) {
+        interactiveAgent.enqueueMessage(trimmed);
+      } else {
+        setMessageQueue((prev) => [...prev, trimmed]);
+      }
     },
-    [interactiveAgent],
+    [interactiveAgent, streamingState],
   );
 
   // ── Render ──
@@ -255,6 +279,8 @@ export const AgentComposer: React.FC<AgentComposerProps> = ({ agentId }) => {
           </Box>
         )}
 
+        <QueuedMessageDisplay messageQueue={messageQueue} />
+
         {/* Input prompt — always visible, like the main Composer */}
         <BaseTextInput
           buffer={buffer}

packages/cli/src/ui/components/arena/ArenaSelectDialog.tsx

@@ -74,6 +74,10 @@ export function ArenaSelectDialog({
         mgr.getAgentStates().find((item) => item.agentId === agentId);
       const label = agent?.model.modelId || agentId;
 
+      pushMessage({
+        messageType: 'info',
+        content: `Applying changes from ${label}…`,
+      });
       const result = await mgr.applyAgentResult(agentId);
       if (!result.success) {
         pushMessage({
@@ -111,6 +115,10 @@ export function ArenaSelectDialog({
     }
 
     try {
+      pushMessage({
+        messageType: 'info',
+        content: 'Discarding Arena results and cleaning up…',
+      });
       await config.cleanupArenaRuntime(true);
       pushMessage({
         messageType: 'info',

packages/cli/src/ui/components/arena/ArenaStatusDialog.tsx

@@ -264,7 +264,11 @@ export function ArenaStatusDialog({
                     <Text color={theme.status.error}>{failedToolCalls}</Text>
                   </Text>
                 ) : (
-                  <Text color={theme.text.primary}>
+                  <Text
+                    color={
+                      toolCalls > 0 ? theme.status.success : theme.text.primary
+                    }
+                  >
                     {pad(String(toolCalls), colTools - 1, 'right')}
                   </Text>
                 )}

packages/cli/src/ui/components/arena/ArenaStopDialog.tsx

@@ -80,9 +80,17 @@ export function ArenaStopDialog({
           sessionStatus === ArenaSessionStatus.RUNNING ||
           sessionStatus === ArenaSessionStatus.INITIALIZING
         ) {
+          pushMessage({
+            messageType: 'info',
+            content: 'Stopping Arena agents…',
+          });
           await mgr.cancel();
         }
         await mgr.waitForSettled();
+        pushMessage({
+          messageType: 'info',
+          content: 'Cleaning up Arena resources…',
+        });
 
         if (action === 'preserve') {
           await mgr.cleanupRuntime();

packages/cli/src/ui/components/messages/StatusMessages.tsx

@@ -75,7 +75,7 @@ export const SuccessMessage: React.FC<StatusTextProps> = ({ text }) => (
 export const WarningMessage: React.FC<StatusTextProps> = ({ text }) => (
   <StatusMessage
     text={text}
-    prefix="⚠"
+    prefix="△"
     prefixColor={theme.status.warning}
     textColor={theme.status.warning}
   />

packages/cli/src/ui/hooks/useAgentStreamingState.ts

@@ -124,7 +124,8 @@ export function useAgentStreamingState(
   }, [status, hasPendingApprovals]);
 
   const isInputActive =
-    streamingState === StreamingState.Idle &&
+    (streamingState === StreamingState.Idle ||
+      streamingState === StreamingState.Responding) &&
     status !== undefined &&
     !isTerminalStatus(status);