/** Raised when a voice provider fails, or none is registered for an operation. */
export declare class VoiceProviderError extends Error {
    /** The provider. */
    provider?: string | undefined;
    /** The underlying error. */
    cause?: unknown | undefined;
    constructor(message: string, 
    /** The provider. */
    provider?: string | undefined, 
    /** The underlying error. */
    cause?: unknown | undefined);
}
/** Raised when a provider does not support transcription, speech, or realtime. */
export declare class VoiceCapabilityError extends VoiceProviderError {
    constructor(provider: string, capability: 'transcription' | 'speech' | 'realtime');
}