diff --git a/backend/api/server.py b/backend/api/server.py
index dd0daf8..e73142f 100644
--- a/backend/api/server.py
+++ b/backend/api/server.py
@@ -1901,7 +1901,14 @@ def create_app(state: AgentState) -> FastAPI:
                     break
                 yield json.dumps(item, ensure_ascii=False) + '\n'
 
-        return StreamingResponse(generate(), media_type='application/x-ndjson')
+        return StreamingResponse(
+            generate(),
+            media_type='application/x-ndjson',
+            headers={
+                'Cache-Control': 'no-cache, no-transform',
+                'X-Accel-Buffering': 'no',
+            },
+        )
 
     @app.post('/api/clear')
     async def clear_state(account_id: str | None = None) -> dict[str, Any]:
@@ -2117,12 +2124,17 @@ def _interrupted_session_message(status: str) -> str:
 
 def _runtime_event_stage(event: dict[str, object]) -> str:
     event_type = event.get('type')
+    if event_type == 'content_delta':
+        return ''
     if event_type == 'tool_start':
         stage_note = str(event.get('assistant_content') or '').strip()
         if stage_note.startswith(('进度：', '进度:')):
             return stage_note
         tool_name = str(event.get('tool_name') or '').strip()
         return f'调用工具 {tool_name}' if tool_name else '正在调用工具'
+    if event_type == 'tool_delta':
+        tool_name = str(event.get('tool_name') or '').strip()
+        return f'{tool_name} 输出中' if tool_name else '工具输出中'
     if event_type == 'tool_result':
         tool_name = str(event.get('tool_name') or '').strip()
         return f'工具完成 {tool_name}' if tool_name else '工具调用完成'
@@ -2149,7 +2161,9 @@ def _runtime_event_stage(event: dict[str, object]) -> str:
 _RUN_EVENT_TYPES = {
     'run_queued',
     'run_started',
+    'content_delta',
     'tool_start',
+    'tool_delta',
     'tool_result',
     'final_text_start',
     'final_text_end',
@@ -2175,8 +2189,10 @@ def _normalize_run_event(event: dict[str, object]) -> dict[str, Any] | None:
         'tool_name',
         'tool_call_id',
         'arguments',
+        'delta',
         'assistant_content',
         'message_id',
+        'stream',
         'ok',
         'metadata',
         'reason',
diff --git a/frontend/app/app/api/chat/route.ts b/frontend/app/app/api/chat/route.ts
index aa21d56..e71a5c3 100644
--- a/frontend/app/app/api/chat/route.ts
+++ b/frontend/app/app/api/chat/route.ts
@@ -56,6 +56,7 @@ type StreamState = {
 	phase: "waiting" | "queued" | "running" | "done";
 	runId?: string;
 	announcedToolCallKeys: Set<string>;
+	streamedToolCallIds: Set<string>;
 };
 
 type ChatRequestBody = {
@@ -112,6 +113,7 @@ export async function POST(req: Request) {
 				textStreamed: false,
 				phase: "waiting",
 				announcedToolCallKeys: new Set<string>(),
+				streamedToolCallIds: new Set<string>(),
 			};
 			writer.write({ type: "start" });
 			writer.write({ type: "start-step" });
@@ -142,7 +144,7 @@ export async function POST(req: Request) {
 					delta: `\n思考并执行完成，用时 ${formatDuration(elapsedMs)}。`,
 				});
 				writer.write({ type: "reasoning-end", id: "reasoning-1" });
-				writeToolTrace(writer, payload.transcript);
+				writeToolTrace(writer, payload.transcript, streamState);
 				if (!streamState.textStreamed) {
 					writer.write({ type: "text-start", id: "text-1" });
 					writer.write({ type: "text-delta", id: "text-1", delta: text });
@@ -183,7 +185,13 @@ export async function POST(req: Request) {
 		},
 	});
 
-	return createUIMessageStreamResponse({ stream });
+	return createUIMessageStreamResponse({
+		stream,
+		headers: {
+			"Cache-Control": "no-cache, no-transform",
+			"X-Accel-Buffering": "no",
+		},
+	});
 }
 
 function formatDuration(ms: number) {
@@ -199,6 +207,7 @@ function formatDuration(ms: number) {
 function writeToolTrace(
 	writer: UIMessageStreamWriter<UIMessage>,
 	transcript?: ClawTranscriptEntry[],
+	streamState?: StreamState,
 ) {
 	if (!transcript?.length) return;
 
@@ -216,6 +225,7 @@ function writeToolTrace(
 			const toolCallId = call.id;
 			const toolName = call.function?.name ?? call.name;
 			if (!toolCallId || !toolName) continue;
+			if (streamState?.streamedToolCallIds.has(toolCallId)) continue;
 
 			writer.write({
 				type: "tool-input-available",
@@ -539,6 +549,7 @@ function writeRuntimeEvent(
 		}
 	}
 	if (event.type === "tool_start" && event.tool_call_id && event.tool_name) {
+		streamState?.streamedToolCallIds.add(event.tool_call_id);
 		writer.write({
 			type: "tool-input-available",
 			toolCallId: event.tool_call_id,
diff --git a/frontend/app/components/assistant-ui/activity-panel.tsx b/frontend/app/components/assistant-ui/activity-panel.tsx
index 1271ede..bd3d25e 100644
--- a/frontend/app/components/assistant-ui/activity-panel.tsx
+++ b/frontend/app/components/assistant-ui/activity-panel.tsx
@@ -979,6 +979,10 @@ function summarizeLiveRunEvents(
 		if (event.type === "run_started") {
 			lines.push("后端已开始执行本轮任务。");
 		}
+		if (event.type === "content_delta" && event.delta) {
+			const note = event.delta.trim();
+			if (note && !isNoisyLiveDelta(note)) lines.push(note);
+		}
 		if (event.type === "tool_start") {
 			const stageNote =
 				typeof event.assistant_content === "string"
@@ -994,6 +998,9 @@ function summarizeLiveRunEvents(
 				event.tool_name ? `工具完成 ${event.tool_name}` : "工具调用完成",
 			);
 		}
+		if (event.type === "tool_delta") {
+			lines.push(event.tool_name ? `${event.tool_name} 输出中` : "工具输出中");
+		}
 		if (event.type === "final_text_start") {
 			lines.push("正在整理回复");
 		}
@@ -1011,6 +1018,10 @@ function summarizeLiveRunEvents(
 	return lines.slice(-40);
 }
 
+function isNoisyLiveDelta(value: string) {
+	return value === "。" || value === "，" || value === "," || value.length <= 1;
+}
+
 function collectActivityItems(messages: readonly MessageState[]) {
 	const items: ActivityItem[] = [];
 
diff --git a/frontend/app/components/assistant-ui/thread-list.tsx b/frontend/app/components/assistant-ui/thread-list.tsx
index 68f79c6..bb8d5e9 100644
--- a/frontend/app/components/assistant-ui/thread-list.tsx
+++ b/frontend/app/components/assistant-ui/thread-list.tsx
@@ -86,6 +86,7 @@ type ClawRunEvent = {
 	tool_call_id?: string;
 	arguments?: unknown;
 	assistant_content?: string;
+	delta?: string;
 	ok?: boolean;
 	metadata?: {
 		output_preview?: unknown;
@@ -430,7 +431,12 @@ export function toReplayRepository(
 				? shouldShowAssistantText
 					? [...toolParts, { type: "text", text: content }]
 					: toolParts
-				: [{ type: "text", text: content }]
+				: message.role === "assistant" && elapsedMs !== undefined
+					? [
+							{ type: "reasoning", text: "思考并执行完成。", elapsedMs },
+							{ type: "text", text: content },
+						]
+					: [{ type: "text", text: content }]
 		) as UIMessage["parts"];
 		const replayParts = withReplayElapsedMs(parts, elapsedMs);
 		const uiMessage: UIMessage = {
@@ -599,6 +605,10 @@ function summarizeRunEvents(runStatus: ClawActiveRunStatus) {
 		if (event.type === "run_started") {
 			lines.push("后端已开始执行本轮任务。");
 		}
+		if (event.type === "content_delta" && event.delta) {
+			const note = event.delta.trim();
+			if (note && !isNoisyLiveDelta(note)) lines.push(note);
+		}
 		if (event.type === "tool_start") {
 			const stageNote =
 				typeof event.assistant_content === "string"
@@ -614,6 +624,9 @@ function summarizeRunEvents(runStatus: ClawActiveRunStatus) {
 				event.tool_name ? `工具完成 ${event.tool_name}` : "工具调用完成",
 			);
 		}
+		if (event.type === "tool_delta") {
+			lines.push(event.tool_name ? `${event.tool_name} 输出中` : "工具输出中");
+		}
 		if (event.type === "final_text_start") {
 			lines.push("正在整理回复");
 		}
@@ -627,6 +640,10 @@ function summarizeRunEvents(runStatus: ClawActiveRunStatus) {
 	return lines.slice(-40);
 }
 
+function isNoisyLiveDelta(value: string) {
+	return value === "。" || value === "，" || value === "," || value.length <= 1;
+}
+
 function buildRunToolParts(events: readonly ClawRunEvent[]) {
 	const resultById = new Map<string, ClawRunEvent>();
 	for (const event of events) {