- model.rs: 13 个 FlowGraph 测试(build/outgoing/incoming/start-end 边界) - error.rs: 7 个 WorkflowError → AppError 转换测试 - parser.rs: 11 个新增验证边界测试(空图/多起点/幽灵边/网关约束) - expression.rs: 13 个新增求值测试(float/bool/string/复合表达式/空白容错) - executor.rs: 3 个 is_join_gateway 纯函数测试