fix: resolve chat message duplication and empty thinking blocks

- Refactor useApp.ts to pass through original data without accumulation
  - ChatView is now the single source of truth for chunk accumulation
  - Add empty content check in ThoughtBlockView to skip rendering whitespace-only thoughts

  Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/renderer/src/components/ChatView.tsx

@@ -377,6 +377,9 @@ function TextContentBlock({ content }: { content: string }) {
 
 // Thought block view - expanded, collapsible
 function ThoughtBlockView({ text }: { text: string }) {
+  // Skip rendering if content is empty or only whitespace
+  if (!text || !text.trim()) return null
+
   const [isExpanded, setIsExpanded] = useState(false)
   const isLong = text.length > 200
 

src/renderer/src/hooks/useApp.ts

@@ -1,7 +1,7 @@
 /**
  * Main application state hook
  */
-import { useState, useEffect, useCallback, useRef } from 'react'
+import { useState, useEffect, useCallback } from 'react'
 import type {
   MulticaSession,
   StoredSessionUpdate,
@@ -56,9 +56,6 @@ export function useApp(): AppState & AppActions {
     ? runningSessionsStatus.processingSessionIds.includes(currentSession.id)
     : false
 
-  // Track streaming text for current message
-  const streamingTextRef = useRef<string>('')
-
   // Load sessions on mount
   useEffect(() => {
     loadSessions()
@@ -71,71 +68,24 @@ export function useApp(): AppState & AppActions {
   // Subscribe to agent events
   useEffect(() => {
     const unsubMessage = window.electronAPI.onAgentMessage((message) => {
-      // Log all incoming ACP messages for debugging
-      console.log('[ACP Message]', JSON.stringify(message, null, 2))
-
       // Only process messages for the current session
       // message.sessionId is ACP Agent Session ID, compare with currentAgentSessionId
       if (!currentAgentSessionId || message.sessionId !== currentAgentSessionId) {
-        console.log('[ACP] Ignoring message for different session:', message.sessionId, 'current:', currentAgentSessionId)
         return
       }
 
-      const update = message.update
-      const updateType = update?.sessionUpdate
-      console.log('[ACP Update Type]', updateType)
-
-      // Handle streaming text accumulation for agent messages
-      if (updateType === 'agent_message_chunk' && update.content?.type === 'text') {
-        streamingTextRef.current += update.content.text
-      }
-
-      // Add the update to session updates for real-time display
+      // Pass through original update without any accumulation
+      // ChatView is responsible for accumulating chunks into complete messages
       setSessionUpdates((prev) => {
-        const now = new Date().toISOString()
-
-        // For agent_message_chunk, we want to show accumulated text
-        if (updateType === 'agent_message_chunk') {
-          const streamingUpdate: StoredSessionUpdate = {
-            timestamp: now,
-            update: {
-              sessionId: message.sessionId,
-              update: {
-                sessionUpdate: 'agent_message_chunk',
-                content: { type: 'text', text: streamingTextRef.current },
-              },
-            },
-          }
-
-          // Replace last streaming update if it was also agent_message_chunk
-          const lastIdx = prev.length - 1
-          if (lastIdx >= 0) {
-            const last = prev[lastIdx]
-            if (
-              last.update.update &&
-              'sessionUpdate' in last.update.update &&
-              last.update.update.sessionUpdate === 'agent_message_chunk'
-            ) {
-              return [...prev.slice(0, lastIdx), streamingUpdate]
-            }
-          }
-          return [...prev, streamingUpdate]
-        }
-
-        // For all other update types, add them directly
         const newUpdate = {
-          timestamp: now,
+          timestamp: new Date().toISOString(),
           update: {
             sessionId: message.sessionId,
-            update: update,
+            update: message.update,
           },
         } as StoredSessionUpdate
         return [...prev, newUpdate]
       })
-
-      if (message.done) {
-        streamingTextRef.current = ''
-      }
     })
 
     const unsubStatus = window.electronAPI.onAgentStatus((status) => {
@@ -238,7 +188,6 @@ export function useApp(): AppState & AppActions {
 
     try {
       setError(null)
-      streamingTextRef.current = ''
 
       // Add user message to updates (use a custom marker for UI display)
       // 'user_message' is a custom type not in ACP SDK, used for UI purposes only