export declare function isMacOS(): boolean;
/** Write a secret, replacing any existing entry for the provider. */
export declare function writeSecret(providerId: string, value: string): void;
/** Read a secret, or undefined when no entry exists. */
export declare function readSecret(providerId: string): string | undefined;
/** Remove a secret. Returns whether an entry was deleted. */
export declare function deleteSecret(providerId: string): boolean;
/**
 * Confirm the Keychain actually works by round-tripping a probe value.
 *
 * Presence of the `security` binary is not enough: the keychain can be locked
 * or access denied, and either would silently drop credentials.
 */
export declare function keychainAvailable(): boolean;