export interface UseHostFeatureFlagOptions {
    /**
     * Value returned when the feature flags have loaded but the requested flag is
     * not present in the loaded set. When omitted, a missing flag resolves to
     * `null` (the historical behaviour).
     *
     * Note: this only applies once flags are loaded. While flags are still
     * loading the hook always returns `null` regardless of this option.
     */
    defaultValueWhenMissing?: boolean;
}
/**
 * Reads a host feature flag by key.
 *
 * Return values:
 * - `null` while the host feature flags have not loaded yet.
 * - the flag's boolean `state` when the flag exists in the loaded set.
 * - `null` when the flags are loaded but the requested flag is not present,
 *   unless `options.defaultValueWhenMissing` is provided, in which case that
 *   value is returned.
 *
 * The hook is generic so callers can narrow the accepted key. Internal callers
 * pass the strongly-typed `Flag` union for type safety, e.g.
 * `useHostFeatureFlag<Flag>(Flags.SOME_FLAG, { defaultValueWhenMissing: true })`.
 * External callers may pass any string.
 *
 * Must be used within a `FeatureFlagContext` (provided by `TrackunitProviders`).
 *
 * @example
 * import { useHostFeatureFlag } from "@trackunit/react-core-hooks";
 * const isEnabled = useHostFeatureFlag("my_flag", { defaultValueWhenMissing: true });
 * @see useFeatureFlags
 */
export declare const useHostFeatureFlag: <TFlag extends string = string>(flag: TFlag, options: UseHostFeatureFlagOptions) => boolean | null;