ReviewGuardPower 场景

用一个 guard 场景说明 Power 如何在现有链路里做阻断型检查

场景

你希望在某条运行链路里强制执行一条规则：

  • 如果请求没有带 reviewed = true
  • 就直接阻断后续执行

这类“前置阻断判断”就是最典型的 guard 场景。

示例

import { Power, type PowerHooks } from "@downcity/city/power";

class ReviewGuardPower extends Power {
  readonly name = "review_guard";
  readonly title = "Review Guard";
  readonly description = "Blocks requests that were not reviewed.";

  readonly hooks: PowerHooks = {
    guard: {
      "review.require_checked": [
        async ({ value }) => {
          const body = value as { reviewed?: unknown };
          if (body.reviewed !== true) {
            throw new Error("review is required before continuing");
          }
        },
      ],
    },
  };
}

// City 已登记并把 review_guard 绑定到 entry 的 Agent/Workspace。
await city.powers.scope({ agent_id: agent.id, workspace_id: workspace.id }).guard("review.require_checked", {
  reviewed: true,
});

为什么这里不是 pipeline

因为你不是想“改值”，而是想：

  • 允许继续
  • 或者直接阻断

这正是 guard 的语义。

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