@pegma/flags-launchdarkly

LaunchDarkly FlagProvider for Pegma hosts.

[!IMPORTANT] Pegma is in early 0.x development. This package's public API is unstable.

The host constructs and injects a LaunchDarkly reader. This package never imports the LaunchDarkly SDK, never owns a client singleton, and does not evaluate targeting rules or percentage rollouts. It translates an already evaluated variationDetail result into a FlagResolution.

import {
  createLaunchDarklyFlagProvider,
  launchDarklyUserContext,
} from "@pegma/flags-launchdarkly";
import { createFlagsClient, declareFlags, flag } from "@pegma/flags-core";
import type { Logger } from "@pegma/spine";

const schema = declareFlags({
  checkoutEnabled: flag.boolean({ defaultValue: false }),
});

const logger: Logger = {
  log(level, message, fields) {
    console.log(level, message, fields);
  },
};

const provider = createLaunchDarklyFlagProvider({
  reader: {
    async variationDetail({ flagKey, context, defaultValue }) {
      return ldClient.variationDetail(
        flagKey,
        launchDarklyUserContext(context),
        defaultValue,
      );
    },
    close() {
      return ldClient.close();
    },
  },
});

const client = createFlagsClient({ schema, logger, provider });

Import launchDarklyUserContext from this package when the host wants the documented single-kind user context (kind: "user", key = targeting key). Hosts that need a multi-kind context can map EvaluationContext themselves inside the reader.

A missing flag (undefined from the reader, or LaunchDarkly FLAG_NOT_FOUND) is DEFAULT_FALLBACK. OFF and PREREQUISITE_FAILED are DISABLED. TARGET_MATCH, RULE_MATCH, and FALLTHROUGH are TARGETING_MATCH — LaunchDarkly already evaluated those rules. Other LaunchDarkly ERROR kinds propagate so the flags client can record ERROR.