Rules

Rules apply temporary overlays to server-side curing behavior. They are useful for conditions such as a class matchup, target state, room state, or a short combat window where the normal baseline should be adjusted.

A rule has a stable id and an evaluate(ctx) function. When its condition is not met, return null. When it is met, return only the patch the rule owns.

const rule = {
  id: "prioritize-asthma",
  evaluate(ctx) {
    if (!ctx.haveAff("slickness")) return null;
    return {
      affPriorities: { asthma: 1 },
    };
  },
};

nexSys.api.rules.add(rule);

Lifecycle

Rules can be added, removed, enabled, disabled, ordered, and grouped into packs. Evaluation is deterministic: enabled rules are evaluated in configured order and later contributions win for overlapping keys unless a terminal rule stops evaluation.

Keep side effects outside evaluate. Use transition handlers when an integration must react to activation or deactivation:

const dispose = nexSys.api.rules.bindTransition("prioritize-asthma", {
  onActivate(payload) {},
  onDeactivate(payload) {},
});

The caller owns the disposer returned by bindTransition.