From 9e7f2a44eab320905cd71ec99b544a0018a87ef9 Mon Sep 17 00:00:00 2001
From: wuyang6 <wuyang6@xiaomi.com>
Date: Thu, 14 May 2026 22:11:44 +0800
Subject: [PATCH] Hide pre-tool content from chat stream

---
 frontend/app/app/api/chat/route.ts | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/frontend/app/app/api/chat/route.ts b/frontend/app/app/api/chat/route.ts
index 4537610..927743b 100644
--- a/frontend/app/app/api/chat/route.ts
+++ b/frontend/app/app/api/chat/route.ts
@@ -563,7 +563,11 @@ function writeRuntimeEvent(
 		);
 	}
 	if (event.type === "content_delta" && event.delta) {
-		writeTextDelta(writer, event.delta, streamState);
+		// content_delta 是模型本轮原始 assistant 消息流。若本轮随后调用工具，
+		// 这段文本会作为 tool_start.assistant_content 进入右侧活动阶段说明；
+		// 若本轮不调用工具，后端也会用 final_text_delta 输出最终回复。
+		// 因此这里不要直接写到对话正文，避免“工具调用前说明”占一条回复。
+		return;
 	}
 	if (event.type === "tool_call_delta") {
 		const key =