import type { Session as SessionDetails } from "../types.js";
import type { RailSession as Session } from "./session-list-entry.js";
export type SessionBranchPage<T extends Session = SessionDetails> = {
    sessions: T[];
    /** Per-row causal generations for rows returned by accepted branch reads. */
    channelGenerations: ReadonlyMap<string, number>;
    nextCursor: string | null;
    loading: boolean;
    /** Whether this load cycle may paint loading or retry feedback in the tree. */
    feedbackVisible: boolean;
    failed: boolean;
    stale: boolean;
    requestId: number | null;
    retryCursor: string | null;
};
export type SessionBranchSummaryDecision = {
    acknowledge: boolean;
    refresh: boolean;
    markStale: boolean;
};
/**
 * Stable summary of the server-owned descendant facts that make an already
 * loaded branch stale. Child creation changes direct/total counts; lifecycle
 * changes advance the status aggregates. Title/content stays owned by the
 * child page or active route projection.
 */
export declare function sessionBranchSummaryKey(session: Session, readRevision?: number): string;
/**
 * Persist a route/lineage child in its already-loaded parent branch. The route
 * owns current lifecycle/content while the cached row retains rail ordering
 * timestamps and may own treeStats.
 */
export declare function upsertSessionBranchChild(pages: ReadonlyMap<string, SessionBranchPage<SessionDetails>>, child: SessionDetails): ReadonlyMap<string, SessionBranchPage<SessionDetails>>;
export declare function upsertSessionBranchChild<T extends Session = SessionDetails>(pages: ReadonlyMap<string, SessionBranchPage<T>>, child: T): ReadonlyMap<string, SessionBranchPage<T>>;
/** Mark one exact branch request active without discarding loaded children. */
export declare function beginSessionBranchRequest<T extends Session = SessionDetails>(pages: ReadonlyMap<string, SessionBranchPage<T>>, parentSessionId: string, requestId: number, cursor?: string, options?: {
    feedbackVisible?: boolean | undefined;
}): ReadonlyMap<string, SessionBranchPage<T>>;
/** Refresh the already-loaded window with bounded, opaque-cursor reads. */
export declare function readLoadedSessionBranchWindow<T extends Session = SessionDetails>(readPage: (cursor?: string) => Promise<{
    sessions: T[];
    pinned: T[];
    nextCursor: string | null;
}>, minimumCount: number, initialCursor?: string): Promise<{
    sessions: T[];
    nextCursor: string | null;
}>;
/** Commit one server child page or a fully refreshed loaded window. */
export declare function commitSessionBranchPage(pages: ReadonlyMap<string, SessionBranchPage<SessionDetails>>, parentSessionId: string, input: {
    sessions: readonly SessionDetails[];
    nextCursor: string | null;
}, options?: {
    append?: boolean | undefined;
    replaceWindow?: boolean | undefined;
    preserve?: readonly SessionDetails[] | undefined;
    requestId?: number | undefined;
    readGeneration?: number | undefined;
}): ReadonlyMap<string, SessionBranchPage<SessionDetails>>;
export declare function commitSessionBranchPage<T extends Session = SessionDetails>(pages: ReadonlyMap<string, SessionBranchPage<T>>, parentSessionId: string, input: {
    sessions: readonly T[];
    nextCursor: string | null;
}, options?: {
    append?: boolean | undefined;
    replaceWindow?: boolean | undefined;
    preserve?: readonly T[] | undefined;
    requestId?: number | undefined;
    readGeneration?: number | undefined;
}): ReadonlyMap<string, SessionBranchPage<T>>;
/** Current branch rows that may own channel filing, with their actual read starts. */
export declare function authoritativeSessionBranchChannels<T extends Session = SessionDetails>(page: SessionBranchPage<T>): Array<readonly [session: T, readGeneration: number]>;
/** Fail only the still-current request and expose its exact retry cursor. */
export declare function failSessionBranchRequest<T extends Session = SessionDetails>(pages: ReadonlyMap<string, SessionBranchPage<T>>, parentSessionId: string, requestId: number): ReadonlyMap<string, SessionBranchPage<T>>;
/** A fresh cached page already owns the active child's parent branch. */
export declare function sessionBranchNeedsHydration<T extends Session = SessionDetails>(page: SessionBranchPage<T> | undefined): boolean;
/** Decide whether a changed parent summary can be acknowledged right now. */
export declare function sessionBranchSummaryDecision(input: {
    previousKey: string | undefined;
    nextKey: string;
    loading: boolean;
    expanded: boolean;
    stale: boolean;
}): SessionBranchSummaryDecision;