Add Co-authored-by trailers to Merge's squash commit

internal/store/store.go

@@ -519,6 +519,30 @@ func (s *Store) closeTask(ctx context.Context, id string, status api.TaskStatus,
 	return s.GetTask(ctx, id)
 }
 
+func (s *Store) Participants(ctx context.Context, taskID string) ([]api.Participant, error) {
+	rows, err := s.db.QueryContext(ctx, `
+		SELECT u.login, u.display_name, u.git_name, u.git_email
+		FROM events e JOIN users u ON u.login = e.actor
+		WHERE e.task_id = ? AND e.kind = 'user.message'
+		GROUP BY u.login ORDER BY min(e.seq)
+	`, taskID)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	participants := []api.Participant{}
+	for rows.Next() {
+		p := api.Participant{}
+		err = rows.Scan(&p.Login, &p.DisplayName, &p.GitName, &p.GitEmail)
+		if err != nil {
+			return nil, err
+		}
+		participants = append(participants, p)
+	}
+	return participants, rows.Err()
+}
+
 func (s *Store) EventsAfter(ctx context.Context, after int64, limit int) ([]api.Event, error) {
 	rows, err := s.db.QueryContext(ctx, `
 		SELECT seq, kind, project_id, task_id, agent_session_id, actor, payload, created_at