/**
 * useChat Hook - Layer 1 (Headless)
 *
 * Complete chat state management with zero UI.
 * Consumes AG-UI SSE by default.
 *
 * Supports two inference modes:
 * - cloud: server-side provider inference
 * - server-local: explicit local model on the server
 */
import { handleAgUiStreamingResponse } from "./streaming/index.js";
import type { ChatFilePart, ChatMessage, ChatMessagePart, UseChatOptions, UseChatResult } from "./types.js";
type UseChatStreamHandler = typeof handleAgUiStreamingResponse;
/** A snapshot of messages from a branch point onward */
interface Branch {
    messages: ChatMessage[];
}
/** Tracks branches keyed by the message ID where the edit occurred */
interface BranchState {
    branches: Branch[];
    currentIndex: number;
    baseMessages: ChatMessage[];
}
export declare function isLatestRequest(activeRequestId: number, requestId: number): boolean;
export declare function resolveBranchKey(messageId: string, branchMap: Map<string, BranchState>, branchKeyByMessageId: Map<string, string>): string | undefined;
export declare function findBranchUserMessageIndex(messages: ChatMessage[], branchKey: string, branchKeyByMessageId: Map<string, string>): number;
/**
 * Build the parts for an outgoing user message. File attachments lead (before
 * the text) so the model sees the referenced files first — matching how AI-SDK
 * orders multimodal parts. Exported for unit testing.
 */
export declare function buildUserMessageParts(text: string, files?: ChatFilePart[]): ChatMessagePart[];
/** Extract the text and file payload from a user message for regenerate. */
export declare function userMessagePayload(message: ChatMessage): {
    text: string;
    files?: ChatFilePart[];
} | null;
export declare function resolveUseChatStreamHandler(transport: UseChatOptions["transport"]): UseChatStreamHandler;
interface ResettableUseChatResult extends UseChatResult {
    reset: (messages?: ChatMessage[]) => void;
}
/**
 * The core chat session hook: manages messages, streaming status, input, submit,
 * regenerate, and branch navigation for a conversation. Powers `<Chat>` (L1) and
 * is the L3 headless entry point for building a fully custom chat UI.
 *
 * @example
 * ```tsx
 * import { useChat } from "veryfront/chat";
 *
 * export default function AssistantChat() {
 *   const chat = useChat();
 *   return (
 *     <form onSubmit={chat.handleSubmit}>
 *       <input value={chat.input} onChange={chat.handleInputChange} />
 *       <button disabled={chat.isLoading}>Send</button>
 *     </form>
 *   );
 * }
 * ```
 */
export declare function useChat(options?: UseChatOptions): UseChatResult;
/** @internal Chat session with the reset capability used by conversation hosts. */
export declare function useChatWithSessionReset(options?: UseChatOptions): ResettableUseChatResult;
export {};
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