Problem Understanding Gate：我知道怎么做
请在进入完整作答前写清你的解题理解计划：
- 题目中的数学对象、变量、参数是什么
- 定义域、假设或限制条件是什么
- 题目要求证明或求出的目标结论是什么
- 你计划使用哪些定义、定理、工具或变换
- 是否需要分情况、分支、参数讨论
- 由方程或计算得到的候选结果如何验证为有效结果
- 最后如何检查答案闭合、无遗漏、无无效解
这些点帮助你检查计划是否清楚；可以先修改，也可以在计划足够后进入解题过程。
Design the runtime semantics and gate protocol for Drift, a Minecraft level generation system.
Before implementation, specify how Drift turns a player's natural-language game idea into a Frozen Requirement Contract, how the contract is frozen, how it maps to verified MechanicPrimitives, how generation is blocked when capability coverage fails, and how runtime EventLedger traces are checked against the frozen contract before publishing.
Your design must define formal predicates for RequirementClosed, ContractFrozen, CapabilityCovered, ClosureVerify, and PublishAllowed. It must also specify rejection behavior for empty input, unclosed requirements, unsupported mechanics, and failed closure verification. The goal is to prevent Drift from promising or publishing levels whose mechanics cannot be maintained, observed, verified, and terminally closed.
请在进入完整作答前写清你的解题理解计划：
这些点帮助你检查计划是否清楚；可以先修改，也可以在计划足够后进入解题过程。