/**
 * Main-view Session derivation for the multi-instance Client Session model.
 *
 * The Client Session Controller carries no global "current" selection: view
 * selection belongs to the workspace UI, which owns the main-area reference and
 * publishes it through the catalog's per-source ownership counts
 * (`SessionSummary.retainedBy.mainView`). A plugin that needs the Session the
 * main view shows derives it from that marker instead of the removed
 * `SessionListState.current` field.
 *
 * The marker describes view ownership, not authority. It is the right input for
 * presentation and for deciding which view a navigation targets; it is not a
 * business fallback, because source counts never imply visibility or success.
 * @module dsh-web/shared/main-session
 */
/** The catalog row subset this helper reads (a `SessionSummary` projection). */
export interface MainViewOwnedRow<Id extends string = string> {
    /** Catalog row identity. */
    readonly id: Id;
    /** Per-source local ownership counts; absent rows are never owned. */
    readonly retainedBy?: Readonly<Partial<Record<string, number>>> | undefined;
}
/**
 * Resolve the Session the main view currently shows.
 *
 * Reads the catalog's rows rather than a per-id retain-info source: ownership
 * counts ride the list snapshot, so this neither allocates observers nor opens
 * history, and a subscription to the list still fires when the selection moves.
 * @param byId - the session catalog's rows (`SessionListState.byId`), when available.
 * @returns the main-view session id, or undefined when the main view shows none.
 */
export declare function mainViewSessionId<Id extends string>(byId: Readonly<Record<Id, MainViewOwnedRow<Id> | undefined>> | undefined | null): Id | undefined;