diff --git a/crates/df-tunnel/src/tunnel.rs b/crates/df-tunnel/src/tunnel.rs
index 52fd30b..2111adf 100644
--- a/crates/df-tunnel/src/tunnel.rs
+++ b/crates/df-tunnel/src/tunnel.rs
@@ -81,6 +81,13 @@ pub trait TunnelClient: Send + Sync {
     ///
     /// 非阻塞入队,实际 socket 写入异步完成。连接断开时返回 NotConnected。
     async fn send_event(&self, event: TunnelEvent) -> Result<()>;
+
+    /// 发送原始事件(桌面端 → 云后端 → 小程序),payload 为 AiChatEvent 序列化 JSON Value
+    ///
+    /// Phase3 阶段2(D2 全 19 变体透传):EventBus subscriber 把 AiChatEvent Value 经此方法
+    /// 透传(不经 TunnelEvent 强类型子集)。与 [`send_event`](TunnelClient::send_event) 伴行,
+    /// 后者保留作高频子集快捷方式(D5 强类型保留)。非阻塞入队,连接断开返 NotConnected。
+    async fn send_raw_event(&self, payload: serde_json::Value) -> Result<()>;
 }
 
 /// 握手探测窗口(relay 校验通过后静默进入收发循环,无 ack 帧;
@@ -105,8 +112,11 @@ struct ConnState {
 
 /// 收发循环出站帧(SendLoop 内部消费)
 enum OutFrame {
-    /// 业务事件(序列化后写 socket)
-    Event(TunnelEvent),
+    /// 业务事件(已序列化 JSON 字符串,run_loop 直接写 socket)
+    ///
+    /// send_event(TunnelEvent) 与 send_raw_event(Value) 各自预序列化为 String 入队,
+    /// 统一经此变体写 socket(DRY:序列化在调用侧,run_loop 只负责写)。
+    Event(String),
     /// 优雅关闭
     Close,
 }
@@ -260,13 +270,29 @@ impl TunnelClient for WsTunnelClient {
     }
 
     async fn send_event(&self, event: TunnelEvent) -> Result<()> {
+        // 序列化提前(OutFrame::Event 持 String),失败返 Serde 错给调用方
+        let json = serde_json::to_string(&event)?;
         let conn = self.conn.lock().await;
         let Some(state) = conn.as_ref() else {
             return Err(TunnelError::NotConnected);
         };
         state
             .tx
-            .send(OutFrame::Event(event))
+            .send(OutFrame::Event(json))
+            .map_err(|_| TunnelError::NotConnected)?;
+        Ok(())
+    }
+
+    async fn send_raw_event(&self, payload: serde_json::Value) -> Result<()> {
+        // AiChatEvent Value 序列化为 JSON 字符串入队(与 send_event 共用 OutFrame::Event(String))
+        let json = serde_json::to_string(&payload)?;
+        let conn = self.conn.lock().await;
+        let Some(state) = conn.as_ref() else {
+            return Err(TunnelError::NotConnected);
+        };
+        state
+            .tx
+            .send(OutFrame::Event(json))
             .map_err(|_| TunnelError::NotConnected)?;
         Ok(())
     }
@@ -358,14 +384,8 @@ async fn run_loop(
             // 出站队列
             maybe_out = rx.recv() => {
                 match maybe_out {
-                    Some(OutFrame::Event(ev)) => {
-                        let json = match serde_json::to_string(&ev) {
-                            Ok(j) => j,
-                            Err(e) => {
-                                tracing::warn!(error = %e, "事件序列化失败,跳过");
-                                continue;
-                            }
-                        };
+                    // OutFrame::Event 持已序列化 JSON 字符串(send_event/send_raw_event 预序列化)
+                    Some(OutFrame::Event(json)) => {
                         if let Err(e) = sink.send(WsMessage::Text(json)).await {
                             tracing::warn!(error = %e, "socket 写入失败,收发循环退出");
                             break;