import type { TokenStore, StoredToken } from './types.js';
/**
 * In-memory TokenStore implementation used for testing and as a null-object
 * fallback when no persistent store is configured.
 *
 * All operations are synchronous and operate on a plain Map. No I/O, no
 * encryption, no external dependencies. Returned tokens are shallow-copied
 * so callers cannot mutate internal store state through a returned reference.
 */
export declare class NullTokenStore implements TokenStore {
    private readonly store;
    static create(): NullTokenStore;
    get(service: string): StoredToken | null;
    upsert(service: string, token: StoredToken): void;
    delete(service: string): void;
    list(): Array<{
        service: string;
        updatedAt: string;
    }>;
    close(): void;
}
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