@coduckai/flags-core

The zero-dependency evaluation engine for CoDuck Flags. It validates versioned rulesets, evaluates typed flags, matches ordered targeting rules and produces stable percentage assignments without network access.

npm install @coduckai/flags-core

import { defineRuleset, evaluateBoolean } from "@coduckai/flags-core";

const ruleset = defineRuleset(rawConfiguration);
const result = evaluateBoolean(
  ruleset,
  "new-checkout",
  { targetingKey: account.id, plan: account.plan },
  false
);

console.log(result.value, result.variant, result.reason, result.metadata.revision);

defineRuleset() throws with precise validation issues at configuration boundaries. evaluateFlag() and the typed evaluators never throw; they return the caller default with an error reason if evaluation cannot complete. Import the published JSON Schema from @coduckai/flags-core/ruleset.schema.json.

See the v1 contract for evaluation order and the normative bucketing algorithm.