发表机构
University College London (UCL); Mysten Labs（伦敦大学学院; Mysten Labs）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
Steelhead是一种双模式共识机制，在共享DAG上交错部分同步与异步提交规则，通过动态调整周期和公共硬币保持活性，经模拟验证性能优异。
AI 中文摘要
双模式共识协议在网络部分同步时速度快，在异步条件下仍保持活性。我们提出Steelhead，一种双模式机制，在一个DAG上组合部分同步和异步提交规则：每第k轮由异步规则决定，其领导者由公共硬币在投票后揭示，其余所有轮次由部分同步规则决定。每个间隔，验证者在每个候选周期下重放已提交的DAG，采用预期消息延迟最少的那个，并在输出停滞时回退到k=1；仅应用于硬币轮的异步规则保持协议活性。Steelhead不发送超出DAG区块的任何消息，甚至不用于协商周期，并且仅在需要隐藏领导者的轮次上开启硬币。它适用于共享委员会的一对DAG提交规则；我们在n>=3f+1时用Mysticeti和Mahi-Mahi实例化，在n>=5f+1时用BlueBottle的两个变体实例化。我们证明其安全性和活性，并在Lean 4中提供机械化证明。在模拟中，Steelhead在健康网络中匹配部分同步协议，在网络条件使部分同步协议停滞时接近异步协议，并在两个方向快速适应。
英文摘要
Dual-mode consensus protocols are fast when the network is partially synchronous and remain live under asynchrony. We introduce Steelhead, a dual-mode mechanism that composes a partially synchronous and an asynchronous commit rule over one DAG: every k-th round is decided by the asynchronous rule, whose leader a common coin reveals after the votes, and all other rounds by the partially synchronous rule. Every interval, validators replay the committed DAG under each candidate period, adopt the one with the fewest expected message delays, and fall back to k = 1 when the output stalls; the asynchronous rule applied to the coin rounds alone keeps the protocol live. Steelhead sends no message beyond the DAG's blocks, not even to agree on the period, and opens a coin only on the rounds that need a hidden leader. It is generic over pairs of DAG commit rules that share a committee; we instantiate it with Mysticeti and Mahi-Mahi at n >= 3f+1 and with the two variants of BlueBottle at n >= 5f+1. We prove it safe and live, and provide mechanized proofs in Lean 4. In simulation, Steelhead matches the partially synchronous protocol in a healthy network, stays close to the asynchronous one when network conditions stall the partially synchronous one, and adapts quickly in both directions.
