import type { BrokerToClient, ClientRole, RpcExtensionUIRequest, RpcSessionState, WelcomeFrame } from '../runtime/broker-protocol.js';
/** A retained `ctx.ui.setWidget` entry. */
export interface DisplayWidget {
    lines: string[];
    placement: 'aboveEditor' | 'belowEditor';
}
/** The broker-owned display levels (`ctx.ui.setStatus/setWidget/setTitle`),
 *  insertion-ordered per key exactly as the broker retains them. */
export interface DisplayState {
    statuses: Record<string, string>;
    widgets: Record<string, DisplayWidget>;
    title: string | undefined;
}
export interface SessionState {
    /** This viewer's broker-assigned role. */
    role: ClientRole;
    /** The client_id currently holding control, or null when nobody does. */
    controllerId: string | null;
    /** The broker process's pi agent dir, from `welcome` — lets a viewer point an
     *  AuthStorage/ModelRegistry at the SAME auth.json. */
    agentDir: string | undefined;
    /** pi's own `get_state` payload. `undefined` until the first welcome. */
    engine: RpcSessionState | undefined;
    /** Live context occupancy in prompt tokens: seeded from the snapshot's
     *  contextUsage, then tracked off each assistant `message_end`. */
    contextTokens: number | undefined;
    /** Queued steering + follow-up message TEXT, from `queue_update`. A fresh
     *  broker with an empty queue emits no `queue_update`, so every welcome resets
     *  this rather than leaving a dead broker's rows on screen. */
    queued: string[];
    display: DisplayState;
    /** The blocking dialog awaiting an answer, or null. Only a controller is ever
     *  sent one; `welcome.pending_dialog` carries one in flight at attach time, and
     *  a welcome is a COMPLETE catch-up, so a welcome naming none clears it.
     *  (The terminal viewer does not read this field: its overlay is owned by
     *  `InputController`, which holds a live TUI handle rather than data. The field
     *  is still session state — it is derived solely from broker frames — and the
     *  web SPA renders straight off it.) */
    dialog: RpcExtensionUIRequest | null;
}
export declare function initialSessionState(role?: ClientRole): SessionState;
/** The whole session state a `welcome` determines, in ONE step. This is why D1
 *  had to land first: before the broker carried its retained display levels in
 *  `snapshot.display`, catch-up was `welcome` plus N replayed edges and this
 *  function could not be total. */
export declare function applySnapshot(frame: WelcomeFrame): SessionState;
/** Fold one broker frame into the session state. Pure and total: a frame that
 *  carries no session state returns `state` UNCHANGED (same reference). */
export declare function reduce(state: SessionState, frame: BrokerToClient, clientId: string): SessionState;