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

internal/server/server_test.go

@@ -314,7 +314,7 @@ func writeFile(t *testing.T, path, content string) {
 func TestEventStreamResume(t *testing.T) {
 	h := newHarness(t)
 
-	stream := h.openStream(nil)
+	stream := h.openStream("", nil)
 	p := h.createProject("demo")
 	first := stream.next()
 	if first.Kind != "project.created" || *first.ProjectId != p.Id {
@@ -326,7 +326,7 @@ func TestEventStreamResume(t *testing.T) {
 	h.do("POST", "/api/projects/"+p.Id+"/tasks", api.TaskCreate{Title: "while away"}, &task)
 	h.do("PUT", "/api/me", api.UserUpdate{GitName: "Alice", GitEmail: "alice@example.org"}, nil)
 
-	resumed := h.openStream(&first.Seq)
+	resumed := h.openStream("", &first.Seq)
 	missed := resumed.next()
 	if missed.Kind != "task.created" || *missed.TaskId != task.Id || missed.Seq != first.Seq+1 {
 		t.Fatalf("unexpected replayed event %+v", missed)
@@ -347,6 +347,33 @@ func TestEventStreamResume(t *testing.T) {
 	}
 }
 
+func TestTaskEventStream(t *testing.T) {
+	h := newHarness(t)
+	p := h.createProject("demo")
+
+	mine := api.Task{}
+	h.do("POST", "/api/projects/"+p.Id+"/tasks", api.TaskCreate{Title: "mine"}, &mine)
+	other := api.Task{}
+	h.do("POST", "/api/projects/"+p.Id+"/tasks", api.TaskCreate{Title: "other"}, &other)
+
+	stream := h.openStream("?task_id="+mine.Id, nil)
+	replayed := stream.next()
+	if replayed.Kind != "task.created" || *replayed.TaskId != mine.Id {
+		t.Fatalf("unexpected replayed event %+v", replayed)
+	}
+
+	h.do("POST", "/api/tasks/"+other.Id+"/discard", nil, nil)
+	h.do("POST", "/api/tasks/"+mine.Id+"/discard", nil, nil)
+	if live := stream.next(); live.Kind != "task.discarded" || *live.TaskId != mine.Id {
+		t.Fatalf("unexpected live event %+v", live)
+	}
+
+	code := h.do("GET", "/api/events?task_id=nope", nil, nil)
+	if code != http.StatusNotFound {
+		t.Fatalf("want 404 streaming an unknown task, got %d", code)
+	}
+}
+
 type stream struct {
 	t      *testing.T
 	cancel context.CancelFunc
@@ -354,11 +381,11 @@ type stream struct {
 	r      *bufio.Reader
 }
 
-func (h *harness) openStream(lastEventID *int64) *stream {
+func (h *harness) openStream(query string, lastEventID *int64) *stream {
 	h.t.Helper()
 
 	ctx, cancel := context.WithCancel(context.Background())
-	req, err := http.NewRequestWithContext(ctx, "GET", h.url+"/api/events", nil)
+	req, err := http.NewRequestWithContext(ctx, "GET", h.url+"/api/events"+query, nil)
 	if err != nil {
 		h.t.Fatalf("new request: %v", err)
 	}

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
 			}