/**
 * Provider key resolution utilities.
 * Supports user-supplied overrides (USER_<KEY>) with environment fallbacks.
 * If neither is set, reports as missing so the runtime can prompt the user.
 */
export type KeySource = 'user' | 'env' | 'missing';
export interface ResolvedKey {
    name: string;
    value?: string;
    source: KeySource;
}
/**
 * Resolves a list of keys, preferring user-supplied overrides.
 */
export declare function resolveKeys(names: string[]): ResolvedKey[];
/**
 * Builds a user-facing message listing missing keys and how to provide them.
 */
export declare function buildMissingKeyMessage(names: string[]): string | null;
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