import { F as FeatureFlags, E as EmailOptions } from "../../packem_shared/types.d-CyiC9uRC.js";
import 'node:buffer';
/**
 * A single capability that a message uses but the target provider cannot represent.
 */
interface FeatureViolation {
  /**
   * The provider capability flag that is not supported.
   */
  feature: keyof FeatureFlags;
  /**
   * The message field that triggered the check.
   */
  field: string;
  /**
   * Human-readable explanation of the violation.
   */
  message: string;
}
/**
 * Result of a fail-fast provider capability check.
 */
interface FeatureSupportResult {
  /**
   * True when the message uses no capability the provider has explicitly disabled.
   */
  supported: boolean;
  /**
   * The list of capabilities the message uses that the provider cannot represent.
   */
  violations: FeatureViolation[];
}
/**
 * Performs a fail-fast field-support check for a message against a provider's declared capabilities.
 *
 * A capability counts as a violation only when the message actually uses it **and** the provider
 * has explicitly declared it unsupported (`features[capability] === false`). Capabilities left
 * `undefined` are treated as "unknown" and never raise a violation, so providers that publish a
 * partial (or no) {@link FeatureFlags} map are never falsely rejected.
 * @param options The normalized email options about to be sent.
 * @param features The target provider's declared capabilities. When omitted the check is a no-op.
 * @returns A {@link FeatureSupportResult} describing any unsupported capabilities in use.
 * @example
 * ```ts
 * const { supported, violations } = checkFeatureSupport(message, provider.features);
 *
 * if (!supported) {
 *     throw new Error(violations.map((v) => v.message).join(", "));
 * }
 * ```
 */
declare function checkFeatureSupport(options: EmailOptions, features?: FeatureFlags): FeatureSupportResult;
export { FeatureSupportResult, FeatureViolation, checkFeatureSupport as default };