/**
 * The conversation's message versions, as the transcript needs them.
 *
 * Editing a turn forks the conversation on Core: the turn and everything after it are archived, and
 * the replacement continues from the same point. This controller is the read side of that — it
 * holds the version groups the server reports and turns them into the ‹ n/m › pager state for each
 * user turn, and it performs the switch when the visitor pages between versions.
 *
 * Mirrors Core's `useChatMessageBranches`: refresh on session change, refresh again when a turn
 * finishes (the fork is created mid-turn, so the count only settles afterwards), and treat every
 * failure as non-fatal — a conversation with no reachable version state renders with no pager,
 * which is exactly how an unedited conversation renders.
 */
import type { Accessor } from 'solid-js';
import { type WidgetSessionParams } from '@/widget/services/sessions';
import type { MessageType } from '@/widget/types';
import { type BranchPager } from './messageVersions';
type BranchControllerDeps = {
    params: Accessor<WidgetSessionParams>;
    /** The open session, or undefined when the conversation is not server-backed yet. */
    sessionId: Accessor<string | undefined>;
    /** False in preview mounts and wherever the session plane is unreachable. */
    enabled: Accessor<boolean>;
    messages: Accessor<MessageType[]>;
    /** True while a turn is streaming. */
    loading: Accessor<boolean>;
    /** Re-read the live conversation after a switch swapped it out. */
    reloadMessages: (sessionId: string) => Promise<boolean>;
};
export type BranchController = {
    /** Pager state keyed by transcript index; absent for turns that were never edited. */
    pagerByIndex: Accessor<Record<number, BranchPager>>;
    /** True while a switch is in flight — the pager is inert until it settles. */
    isSwitching: Accessor<boolean>;
    refresh: () => Promise<void>;
    switchTo: (index: number, targetBranchIndex: number) => Promise<void>;
};
export declare function createBranchController(deps: BranchControllerDeps): BranchController;
export {};