Stream each task's transcript over its own SSE; keep session note order

internal/server/sse.go

@@ -19,6 +19,21 @@ func (s *Server) StreamEvents(w http.ResponseWriter, r *http.Request, params api
 	if params.LastEventID != nil {
 		last = *params.LastEventID
 	}
+	taskID := ""
+	if params.TaskId != nil {
+		taskID = *params.TaskId
+		_, err := s.store.GetTask(r.Context(), taskID)
+		if err != nil {
+			writeStoreError(w, err)
+			return
+		}
+	}
+	backfill := func(after int64) ([]api.Event, error) {
+		if taskID == "" {
+			return s.store.EventsAfter(r.Context(), after, backfillPage)
+		}
+		return s.store.TaskEvents(r.Context(), taskID, after, backfillPage)
+	}
 
 	rc := http.NewResponseController(w)
 	w.Header().Set("Content-Type", "text/event-stream")
@@ -29,7 +44,7 @@ func (s *Server) StreamEvents(w http.ResponseWriter, r *http.Request, params api
 	defer s.hub.unsubscribe(live)
 
 	for {
-		events, err := s.store.EventsAfter(r.Context(), last, backfillPage)
+		events, err := backfill(last)
 		if err != nil {
 			return
 		}
@@ -60,6 +75,9 @@ func (s *Server) StreamEvents(w http.ResponseWriter, r *http.Request, params api
 			if ev.Seq != 0 && ev.Seq <= last {
 				continue
 			}
+			if taskID != "" && (ev.TaskId == nil || *ev.TaskId != taskID) {
+				continue
+			}
 			if !writeEvent(w, ev) {
 				return
 			}