Directed acyclic graph (DAG)-based Byzantine Fault-Tolerant (BFT) protocols achieve high throughput by decoupling dissemination from agreement and allowing many vertices to be committed concurrently. This same concurrency, however, weakens ordering evidence at the execution boundary: once units are committed in a shared DAG frontier, their final linearization is driven by traversal or deterministic tie-breaking rather than verifiable structural precedence. Prior fair-ordering designs address ambiguity by collecting or reconstructing transaction-level ordering evidence within the consensus workflow. While effective, this couples ordering with agreement and places ordering logic on the critical path. This paper presents Multi-Round Visibility (MRV), a post-consensus structural ordering layer for DAG-based BFT that reinterprets the committed DAG as an ordering evidence substrate. Committed vertices inherently carry authenticated creator, round, and ancestry metadata, enabling replicas to derive multi-round structural visibility without extra consensus-path messages. MRV accumulates this visibility within a bounded evidence horizon, compares concurrently committed atomic units of fairness (AUFs) after they coexist in the DAG, and derives precedence constraints from Byzantine-robust visibility advantages. When the DAG lacks such constraints, MRV exposes and resolves the remaining ambiguity through deterministic graph completion rather than hiding it inside traversal rules. We implement MRV on a Narwhal/Tusk-based prototype. Evaluation across 5-50 replicas under various fault settings shows MRV preserves the high-throughput regime of the DAG-BFT stack, proving it provides post-consensus structural ordering without burdening the consensus-critical path.

翻译：有向无环图（DAG）的拜占庭容错（BFT）协议通过将传播与共识解耦并允许多个顶点并发提交，实现了高吞吐量。然而，这种并发性在执行边界削弱了排序证据：一旦顶点在共享DAG前沿被提交，其最终线性化结果由遍历算法或确定性断结决定，而非基于可验证的结构化优先级。现有公平排序设计通过在共识流程内收集或重构交易级排序证据来消除歧义。然而这种方法虽然有效，却将排序与协议强耦合，并使排序逻辑处于关键路径上。本文提出多轮可见性（MRV），一种面向基于DAG的BFT协议的后共识结构化排序层，将已提交DAG重新解释为排序证据基质。已提交顶点天然携带经过认证的创建者、轮次和祖先元数据，使副本能够在无需额外共识路径消息的情况下推导多轮结构化可见性。MRV在有限证据范围内累积这种可见性，对并发提交的公平性原子单元（AUF）在DAG共存后进行比较，并从拜占庭鲁棒的可见性优势推导优先级约束。当DAG缺乏此类约束时，MRV通过确定性图补全而非隐藏于遍历规则来暴露并解决剩余歧义。我们在基于Narwhal/Tusk原型上实现MRV。在5-50个副本、不同故障设置下的评估表明，MRV保留了DAG-BFT堆栈的高吞吐量特性，证明其能在不增加共识关键路径负担的前提下提供后共识结构化排序。