Retry failed sends with their send_id until the server confirms them

internal/store/store.go

@@ -1356,6 +1356,16 @@ func (s *Store) SessionStarted(ctx context.Context, sessionID string) (bool, err
 	return started, err
 }
 
+func (s *Store) UnusedSession(ctx context.Context, taskID, member string) (string, bool, error) {
+	id := ""
+	err := s.db.QueryRowContext(ctx, `SELECT id FROM agent_sessions WHERE task_id = ? AND member = ? AND role = ? AND state = ? AND started = 0 AND pending = 0 LIMIT 1`,
+		taskID, member, string(api.Implementer), string(api.AgentSessionStateIdle)).Scan(&id)
+	if errors.Is(err, sql.ErrNoRows) {
+		return "", false, nil
+	}
+	return id, err == nil, err
+}
+
 func (s *Store) SessionPending(ctx context.Context, sessionID string) (bool, error) {
 	pending := false
 	err := s.db.QueryRowContext(ctx, `SELECT pending FROM agent_sessions WHERE id = ?`, sessionID).Scan(&pending)