export type StoredMessage = {
    type?: string;
    message?: string;
    isFailed?: boolean;
    streamError?: string;
    action?: unknown;
    artifacts?: unknown[];
    sourceDocuments?: unknown[];
    agentReasoning?: unknown;
    fileUploads?: unknown[];
    followUpPrompts?: unknown;
    usedTools?: unknown[];
    agentFlowExecutedData?: unknown;
    blocks?: unknown[];
    dynamicUiBlocks?: unknown[];
    activity?: {
        steps?: unknown[];
    } | null;
    artifactGenerations?: unknown[];
    ttsAudio?: unknown;
    runtimeCredentialStates?: unknown[];
};
export declare function replaceAt<T>(list: readonly T[], index: number, next: T): T[];
export declare function updateAt<T>(list: readonly T[], index: number, updater: (item: T) => T): T[];
export declare function hasRenderableContent(message: StoredMessage | null | undefined): boolean;
export declare function isEmptyAssistantPlaceholder(message: StoredMessage | null | undefined): boolean;
export declare function pruneEmptyAssistantPlaceholders<T extends StoredMessage>(list: readonly T[]): T[];