fix(room): resolve remaining defects from second review

- reaction.rs: query before insert to detect new vs duplicate reactions,
  only publish Redis event when a reaction was actually added
- room.rs: delete Redis seq key on room deletion to prevent seq
  collision on re-creation
- message.rs: use Redis-atomic next_room_message_seq_internal for
  concurrent safety; look up sender display name once for both
  mention notifications and response body; add warn log when
  should_ai_respond fails instead of silent unwrap_or(false)
- ws_universal.rs: re-check room access permission when re-subscribing
  dead streams after error to prevent revoked permissions being bypassed
- RoomChatPanel.tsx: truncate reply preview content to 80 chars
- RoomMessageList.tsx: remove redundant inline style on message row div

libs/api/room/ws_universal.rs

@@ -196,7 +196,7 @@ pub async fn ws_universal(
                     let _ = session.close(Some(actix_ws::CloseCode::Normal.into())).await;
                     break;
                 }
-                push_event = poll_push_streams(&mut push_streams, &manager, user_id) => {
+                push_event = poll_push_streams(&mut push_streams, &manager, &handler.service(), user_id) => {
                     match push_event {
                         Some(WsPushEvent::RoomMessage { room_id, event }) => {
                             let payload = serde_json::json!({
@@ -372,6 +372,7 @@ pub async fn ws_universal(
 async fn poll_push_streams(
     streams: &mut PushStreams,
     manager: &Arc<RoomConnectionManager>,
+    service: &Arc<AppService>,
     user_id: Uuid,
 ) -> Option<WsPushEvent> {
     loop {
@@ -412,16 +413,21 @@ async fn poll_push_streams(
             }
         }
 
-        // Re-subscribe dead rooms so we don't permanently lose events
+        // Re-subscribe dead rooms so we don't permanently lose events.
+        // Re-check access in case the user's permissions were revoked while the
+        // stream was dead.
         for room_id in dead_rooms {
             if streams.remove(&room_id).is_some() {
-                if let Ok(rx) = manager.subscribe(room_id, user_id).await {
-                    let stream_rx = manager.subscribe_room_stream(room_id).await;
-                    streams.insert(room_id, (
-                        BroadcastStream::new(rx),
-                        BroadcastStream::new(stream_rx),
-                    ));
+                if service.room.check_room_access(room_id, user_id).await.is_ok() {
+                    if let Ok(rx) = manager.subscribe(room_id, user_id).await {
+                        let stream_rx = manager.subscribe_room_stream(room_id).await;
+                        streams.insert(room_id, (
+                            BroadcastStream::new(rx),
+                            BroadcastStream::new(stream_rx),
+                        ));
+                    }
                 }
+                // If access check fails, silently skip re-subscribe (user was removed)
             }
         }
 

libs/room/src/helpers.rs

@@ -257,24 +257,6 @@ impl RoomService {
         }
     }
 
-    pub(crate) async fn next_room_message_seq<C>(
-        &self,
-        room_id: Uuid,
-        db: &C,
-    ) -> Result<i64, RoomError>
-    where
-        C: ConnectionTrait,
-    {
-        let max_seq: Option<Option<i64>> = room_message::Entity::find()
-            .filter(room_message::Column::Room.eq(room_id))
-            .select_only()
-            .column_as(room_message::Column::Seq.max(), "max_seq")
-            .into_tuple::<Option<i64>>()
-            .one(db)
-            .await?;
-        Ok(max_seq.flatten().unwrap_or(0) + 1)
-    }
-
     pub async fn utils_find_project_by_name(
         &self,
         name: String,

libs/room/src/message.rs

@@ -134,7 +134,7 @@ impl RoomService {
             }
         }
 
-        let seq = self.next_room_message_seq(room_id, &self.db).await?;
+        let seq = Self::next_room_message_seq_internal(room_id, &self.db, &self.cache).await?;
         let now = Utc::now();
         let id = Uuid::now_v7();
         let project_id = room_model.project;
@@ -207,6 +207,17 @@ impl RoomService {
         .await;
 
         let mentioned_users = self.resolve_mentions(&request.content).await;
+        // Look up sender display name once for all mention notifications
+        let sender_display_name = {
+            let user = user_model::Entity::find()
+                .filter(user_model::Column::Uid.eq(user_id))
+                .one(&self.db)
+                .await
+                .ok()
+                .flatten();
+            user.map(|u| u.display_name.unwrap_or_else(|| u.username))
+                .unwrap_or_else(|| user_id.to_string())
+        };
         for mentioned_user_id in mentioned_users {
             if mentioned_user_id == user_id {
                 continue;
@@ -215,7 +226,7 @@ impl RoomService {
                 .notification_create(super::NotificationCreateRequest {
                     notification_type: super::NotificationType::Mention,
                     user_id: mentioned_user_id,
-                    title: format!("{} 在 {} 中提到了你", user_id, room_model.room_name),
+                    title: format!("{} 在 {} 中提到了你", sender_display_name, room_model.room_name),
                     content: Some(content.clone()),
                     room_id: Some(room_id),
                     project_id,
@@ -228,7 +239,13 @@ impl RoomService {
                 .await;
         }
 
-        let should_respond = self.should_ai_respond(room_id).await.unwrap_or(false);
+        let should_respond = match self.should_ai_respond(room_id).await {
+            Ok(v) => v,
+            Err(e) => {
+                slog::warn!(self.log, "should_ai_respond failed for room {}: {}", room_id, e);
+                false
+            }
+        };
         let is_text_message = request
             .content_type
             .as_ref()
@@ -243,23 +260,13 @@ impl RoomService {
             }
         }
 
-        let display_name = {
-            let user = user_model::Entity::find()
-                .filter(user_model::Column::Uid.eq(user_id))
-                .one(&self.db)
-                .await
-                .ok()
-                .flatten();
-            user.map(|u| u.display_name.unwrap_or_else(|| u.username))
-        };
-
         Ok(super::RoomMessageResponse {
             id,
             seq,
             room: room_id,
             sender_type: "member".to_string(),
             sender_id: Some(user_id),
-            display_name,
+            display_name: Some(sender_display_name),
             thread: thread_id,
             in_reply_to,
             content: request.content,

libs/room/src/reaction.rs

@@ -54,20 +54,29 @@ impl RoomService {
             created_at: Set(now),
         };
 
-        let result = room_message_reaction::Entity::insert(reaction)
-            .on_conflict(
-                OnConflict::columns([
-                    room_message_reaction::Column::Message,
-                    room_message_reaction::Column::User,
-                    room_message_reaction::Column::Emoji,
-                ])
-                .do_nothing()
-                .to_owned(),
-            )
-            .exec(&self.db)
-            .await;
+        // Check if reaction already exists before inserting
+        let existing = room_message_reaction::Entity::find()
+            .filter(room_message_reaction::Column::Message.eq(message_id))
+            .filter(room_message_reaction::Column::User.eq(user_id))
+            .filter(room_message_reaction::Column::Emoji.eq(&emoji))
+            .one(&self.db)
+            .await?;
 
-        if result.is_ok() {
+        if existing.is_none() {
+            room_message_reaction::Entity::insert(reaction)
+                .on_conflict(
+                    OnConflict::columns([
+                        room_message_reaction::Column::Message,
+                        room_message_reaction::Column::User,
+                        room_message_reaction::Column::Emoji,
+                    ])
+                    .do_nothing()
+                    .to_owned(),
+                )
+                .exec(&self.db)
+                .await?;
+
+            // Only publish if we actually inserted a new reaction
             let reactions = self
                 .get_message_reactions(message_id, Some(user_id))
                 .await?;

libs/room/src/room.rs

@@ -273,6 +273,19 @@ impl RoomService {
 
         self.room_manager.shutdown_room(room_id).await;
 
+        // Clean up Redis seq key so re-creating the room starts fresh
+        let seq_key = format!("room:seq:{}", room_id);
+        if let Ok(mut conn) = self.cache.conn().await {
+            let _: Option<String> = redis::cmd("DEL")
+                .arg(&seq_key)
+                .query_async(&mut conn)
+                .await
+                .inspect_err(|e| {
+                    slog::warn!(self.log, "room_delete: failed to DEL seq key {}: {}", seq_key, e);
+                })
+                .ok();
+        }
+
         let event = ProjectRoomEvent {
             event_type: super::RoomEventType::RoomDeleted.as_str().into(),
             project_id,

libs/room/src/service.rs

@@ -1112,7 +1112,7 @@ impl RoomService {
         Vec::new()
     }
 
-    async fn next_room_message_seq_internal(
+    pub(crate) async fn next_room_message_seq_internal(
         room_id: Uuid,
         db: &AppDatabase,
         cache: &AppCache,

src/components/room/RoomChatPanel.tsx

@@ -131,7 +131,7 @@ const ChatInputArea = memo(function ChatInputArea({
       {replyingTo && (
         <div className="mb-2 flex items-center gap-2 rounded-md bg-muted/50 px-3 py-2 text-xs">
           <span className="font-medium text-foreground">Replying to {replyingTo.display_name}</span>
-          <span className="truncate text-muted-foreground">{replyingTo.content}</span>
+          <span className="truncate text-muted-foreground" title={replyingTo.content}>{replyingTo.content.length > 80 ? replyingTo.content.slice(0, 80) + '…' : replyingTo.content}</span>
           <button onClick={onCancelReply} className="ml-auto text-muted-foreground hover:text-foreground">
             <X className="h-3 w-3" />
           </button>

src/components/room/RoomMessageList.tsx

@@ -345,12 +345,8 @@ export const RoomMessageList = memo(function RoomMessageList({
             return (
               <div
                 key={row.key}
-                className="absolute left-0 w-full"
+                className="absolute left-0 top-0 w-full"
                 style={{
-                  position: 'absolute',
-                  top: 0,
-                  left: 0,
-                  width: '100%',
                   transform: `translateY(${virtualRow.start}px)`,
                 }}
               >