diff --git a/src/api/chat.ts b/src/api/chat.ts
index b068a0b..c3f5686 100644
--- a/src/api/chat.ts
+++ b/src/api/chat.ts
@@ -15,7 +15,11 @@ export interface ToolCallTrace {
 
 export interface ChatMessage {
   id: string;
-  role: 'user' | 'assistant';
+  role: 'user' | 'assistant' | 'agent' | 'system';
+  speaker?: {
+    id: string;
+    type: 'user' | 'agent';
+  };
   content: string;
   reasoning?: string | null;
   parentId?: string | null;
@@ -73,4 +77,3 @@ export const ChatAttachmentsAPI = {
     return api.post<{ files: ChatAttachment[] }>('/chat/attachments', fd).then((r) => r.data);
   }
 };
-
diff --git a/src/pages/chat/components/ChatBody.tsx b/src/pages/chat/components/ChatBody.tsx
index 2d6741a..2b79f24 100644
--- a/src/pages/chat/components/ChatBody.tsx
+++ b/src/pages/chat/components/ChatBody.tsx
@@ -60,7 +60,7 @@ export default function ChatBody(props: {
                 agentList={agentList}
                 currentAgentId={currentAgentId}
                 highlighted={highlightId === m.id}
-                branch={m.role === 'assistant' && m.parentId ? branches[m.parentId] : undefined}
+                branch={((m as any)?.speaker?.type ? (m as any).speaker.type === 'agent' : m.role === 'assistant') && m.parentId ? branches[m.parentId] : undefined}
                 busy={sending}
                 onRegenerate={onRegenerate}
                 onSwitchBranch={onSwitchBranch}
@@ -76,7 +76,9 @@ export default function ChatBody(props: {
                     const streamingAgent = agentList.find(a => a.id === streamingAgentId);
                     if (streamingAgent) {
                       return (
-                        <Avatar src={streamingAgent.avatar} size={36} style={{ flexShrink: 0, marginTop: 2 }} />
+                        <Avatar src={streamingAgent.avatar} size={36} style={{ flexShrink: 0, marginTop: 2, backgroundColor: '#52c41a' }}>
+                          {streamingAgent.name?.charAt(0)?.toUpperCase() || 'A'}
+                        </Avatar>
                       );
                     }
                     return null;
diff --git a/src/pages/chat/components/ChatOutline.tsx b/src/pages/chat/components/ChatOutline.tsx
index bcdc7d8..906cbde 100644
--- a/src/pages/chat/components/ChatOutline.tsx
+++ b/src/pages/chat/components/ChatOutline.tsx
@@ -14,7 +14,7 @@ function summarize(content: string) {
 
 export default function ChatOutline(props: { messages: ChatMessage[]; onJump: (id: string) => void; activeId?: string | null }) {
   const { messages, onJump, activeId } = props;
-  const items = messages.filter((m) => m.role === 'assistant');
+  const items = messages.filter((m) => ((m as any)?.speaker?.type ? (m as any).speaker.type === 'agent' : m.role === 'assistant'));
 
   if (items.length === 0) return null;
 
@@ -38,4 +38,3 @@ export default function ChatOutline(props: { messages: ChatMessage[]; onJump: (i
     </aside>
   );
 }
-
diff --git a/src/pages/chat/components/messages/MessageItem.tsx b/src/pages/chat/components/messages/MessageItem.tsx
index 00745fa..9906ce5 100644
--- a/src/pages/chat/components/messages/MessageItem.tsx
+++ b/src/pages/chat/components/messages/MessageItem.tsx
@@ -19,8 +19,12 @@ export default function MessageItem(props: {
 }) {
   const { message, agentList, currentAgentId, highlighted, branch, busy, onRegenerate, onSwitchBranch, onCopy } = props;
   
+  const speakerType = (message as any)?.speaker?.type as ('user' | 'agent' | undefined);
+  const isUser = speakerType ? speakerType === 'user' : message.role === 'user';
+  const bubbleRole = isUser ? 'user' : 'assistant';
+
   // 获取回答者 Agent 信息
-  const answerAgentId = message.agent_id || (message.role === 'assistant' ? currentAgentId : undefined);
+  const answerAgentId = message.agent_id || (!isUser ? currentAgentId : undefined);
   const answerAgent = answerAgentId ? agentList.find(a => a.id === answerAgentId) : undefined;
   const hasBranches = !!branch && branch.total > 1;
   const activeIdx = branch?.activeIndex ?? 0;
@@ -49,9 +53,8 @@ export default function MessageItem(props: {
         transition: 'background 0.4s, padding 0.4s'
       }}
     >
-      {message.role === 'assistant' ? (
+      {!isUser ? (
         <div style={{ display: 'flex', gap: 12, alignItems: 'flex-start' }}>
-          {/* AGENT: 头像在左侧，内容在右侧（靠左对齐） */}
           <Avatar 
             src={answerAgent?.avatar} 
             size={36} 
@@ -74,7 +77,7 @@ export default function MessageItem(props: {
                 {answerAgent?.name || 'AI'}
               </span>
             </div>
-            <div className={`bubble ${message.role}`}>
+            <div className={`bubble ${bubbleRole}`}>
               <Markdown>{message.content}</Markdown>
             </div>
             <div className="monica-msg-actions">
@@ -124,8 +127,7 @@ export default function MessageItem(props: {
         </div>
       ) : (
         <div style={{ display: 'flex', gap: 12, alignItems: 'flex-start', justifyContent: 'flex-end' }}>
-          {/* 用户: 头像在右侧，内容在左侧（靠右对齐） */}
-          <div style={{ maxWidth: '78%', display: 'flex', flexDirection: 'column', alignItems: 'flex-end' }}>
+          <div style={{ flex: 1, minWidth: 0, maxWidth: '78%', display: 'flex', flexDirection: 'column', alignItems: 'flex-end' }}>
             <div style={{
               display: 'flex',
               alignItems: 'center',
@@ -140,7 +142,7 @@ export default function MessageItem(props: {
                 我
               </span>
             </div>
-            <div className={`bubble ${message.role}`}>
+            <div className={`bubble ${bubbleRole}`}>
               {message.content.includes('![image](') ? (
                 <Markdown>{message.content}</Markdown>
               ) : (
diff --git a/src/styles.css b/src/styles.css
index a4c51f5..0fd6285 100644
--- a/src/styles.css
+++ b/src/styles.css
@@ -628,6 +628,7 @@ body {
 
 .bubble {
   max-width: 78%;
+  display: inline-block;
   padding: 14px 18px;
   border-radius: 14px;
   margin-bottom: 14px;
@@ -638,18 +639,18 @@ body {
 }
 
 .bubble.user {
-  background: var(--color-brand-soft);
-  color: var(--color-text);
+  background: #0a84ff;
+  color: #ffffff;
   margin-left: auto;
   border-bottom-right-radius: 5px;
 }
 
 .bubble.assistant {
-  background: #ffffff;
-  color: var(--color-text);
-  border: 1px solid var(--color-border);
+  background: #e9e9eb;
+  color: #111827;
+  border: 0;
   border-bottom-left-radius: 5px;
-  box-shadow: var(--shadow-xs);
+  box-shadow: none;
 }
 
 .bubble.assistant p {