diff --git a/lib/channel/http/out_event.rs b/lib/channel/http/out_event.rs
index 4b9bdcf..05fee98 100644
--- a/lib/channel/http/out_event.rs
+++ b/lib/channel/http/out_event.rs
@@ -118,6 +118,9 @@ pub enum WsOutEvent {
         room: RoomInfo,
         data: thread::ThreadArchivedService,
     },
+    ThreadList {
+        data: thread::ThreadListService,
+    },
     CategoryCreated {
         workspace: WorkspaceInfo,
         data: category::CategoryCreatedService,
diff --git a/lib/channel/http/types.rs b/lib/channel/http/types.rs
index aa6b56b..cf63640 100644
--- a/lib/channel/http/types.rs
+++ b/lib/channel/http/types.rs
@@ -36,6 +36,7 @@ pub enum WsInMessage {
         room: Uuid,
         seq: i64,
         limit: Option<u64>,
+        thread: Option<Uuid>,
     },
     MessageCreate {
         room: Uuid,
@@ -120,6 +121,9 @@ pub enum WsInMessage {
         room: Uuid,
         parent: i64,
     },
+    ThreadList {
+        room: Uuid,
+    },
     ThreadResolve {
         thread_id: Uuid,
     },
@@ -298,6 +302,7 @@ impl WsInMessage {
             ReactionAdd,
             ReactionRemove,
             ThreadCreate,
+            ThreadList,
             PinAdd,
             PinRemove,
             DraftSave,
diff --git a/lib/channel/http/ws.rs b/lib/channel/http/ws.rs
index f4d3373..3fc92d9 100644
--- a/lib/channel/http/ws.rs
+++ b/lib/channel/http/ws.rs
@@ -55,7 +55,7 @@ async fn handle_inbound(bus: &ChannelBus, socket: &Socket, data: EventPayload) {
         let pong = WsOutEvent::Pong {
             protocol_version: super::types::WS_PROTOCOL_VERSION,
         };
-        send_event(socket, &pong).await.ok();
+        send_event(socket, &pong).await;
         return;
     }
     if !check_rate_limit(bus, user_id).await {
@@ -85,7 +85,7 @@ async fn handle_inbound(bus: &ChannelBus, socket: &Socket, data: EventPayload) {
                     request_id: rid,
                     data: serde_json::to_value(&event).unwrap_or_default(),
                 };
-                send_event(socket, &resp).await.ok();
+                send_event(socket, &resp).await;
             }
             Ok(None) => {
                 let rid = request_id.unwrap_or(Uuid::nil());
@@ -93,7 +93,7 @@ async fn handle_inbound(bus: &ChannelBus, socket: &Socket, data: EventPayload) {
                     request_id: rid,
                     data: serde_json::json!({"ok": true}),
                 };
-                send_event(socket, &ack).await.ok();
+                send_event(socket, &ack).await;
             }
             Err(e) => {
                 tracing::warn!(user_id = %user_id, error = %e, "WS message processing failed");
@@ -103,20 +103,31 @@ async fn handle_inbound(bus: &ChannelBus, socket: &Socket, data: EventPayload) {
                     data: serde_json::to_value(&e.to_ws_error())
                         .unwrap_or_default(),
                 };
-                send_event(socket, &err_resp).await.ok();
+                send_event(socket, &err_resp).await;
             }
         },
         Err(e) => {
             tracing::warn!(error = %e, "WS transport parse error");
-            send_error(
-                socket,
-                WsError {
-                    code: 400,
-                    error: "parse_error".to_string(),
-                    message: e.to_string(),
-                },
-            )
-            .await;
+            if let Some(rid) = request_id {
+                let err_resp = WsOutEvent::Response {
+                    request_id: rid,
+                    data: serde_json::to_value(&WsError {
+                        code: 400,
+                        error: "parse_error".to_string(),
+                        message: e.to_string(),
+                    }).unwrap_or_default(),
+                };
+                send_event(socket, &err_resp).await;
+            } else {
+                send_error(
+                    socket,
+                    WsError {
+                        code: 400,
+                        error: "parse_error".to_string(),
+                        message: e.to_string(),
+                    },
+                ).await;
+            }
         }
     }
 }
@@ -129,25 +140,22 @@ async fn check_rate_limit(bus: &ChannelBus, user_id: Uuid) -> bool {
         .unwrap_or(true)
 }
 
-async fn send_event(socket: &Socket, event: &WsOutEvent) -> ChannelResult<()> {
-    let json = serde_json::to_string(event)?;
-    socket
-        .emit(CHANNEL_EVENT, &json)
-        .await
-        .map_err(|e| {
-            tracing::warn!(error = %e, "WS send failed");
-            ChannelError::SocketIo(e)
-        })
+async fn send_event(socket: &Socket, event: &WsOutEvent) {
+    // Serialize to Value (not String) to avoid double JSON encoding
+    let value = serde_json::to_value(event).unwrap_or_default();
+    if let Err(e) = socket.emit(CHANNEL_EVENT, value).await {
+        tracing::warn!(error = %e, "WS response send failed");
+    }
 }
 
 async fn send_error(socket: &Socket, error: WsError) {
-    let json = serde_json::json!({
+    let value = serde_json::json!({
         "type": "error",
         "code": error.code,
         "error": error.error,
         "message": error.message,
     });
-    if let Err(e) = socket.emit(CHANNEL_EVENT, json.to_string()).await {
+    if let Err(e) = socket.emit(CHANNEL_EVENT, value).await {
         tracing::warn!(error = %e, "WS error send failed");
     }
 }