/**
 * Canvas helpers shared by the session bridge (session-proxy.ts) and the app
 * catalog (canvas-app-catalog.ts). Kept in their own module so the catalog
 * can be exercised without importing the whole bridge, and so the bridge and
 * the catalog can never disagree about slot names or revision derivation.
 *
 * The session canvas: one reserved artifact per session slot, drawn by the
 * agent with draw_canvas and rendered live in the portal. The revision is
 * derived from the durable session.canvas_updated event log, not a counter
 * column — see docs/proposals/session-canvas.md.
 */
export declare const CANVAS_ARTIFACT_FILENAME = "canvas.html";
/** Slot 1 keeps the historical name; 2-5 are canvas2.html .. canvas5.html. */
export declare function canvasArtifactFilename(slot: number): string;
/** 1-5, defaulting absent to 1. Returns null for anything else. */
export declare function normalizeCanvasSlot(value: unknown): number | null;
/** Event rows predate slots; a missing slot means slot 1. */
export declare function eventSlot(row: any): number;
/**
 * Latest canvas draw's full data (rev + armed contract) from the durable
 * event log — the single authority. Reads a bounded window rather than
 * exactly one row and takes the max of the VALID revs it finds, so one
 * garbage event (rev missing, NaN, negative — injectable via
 * send_session_event, which validates nothing) cannot reset the sequence.
 *
 * No empty-coerce on failure: a transient read error that reads as "no
 * canvas" would mint rev 1 over a live rev-12 canvas. Callers route the
 * throw to a structured { error }.
 *
 * Window 30, not 5: five interleaved slots can push one slot's latest draw
 * well past a five-event window. The session_canvases table is the fast
 * path; this scan is the durable fallback.
 */
export declare function latestCanvasEventData(catalog: any, sessionId: string, slot?: number): Promise<{
    rev: number;
    responseContract?: Record<string, any>;
}>;
/** The current canvas revision: table first (migration 0045), event scan as the durable fallback. */
export declare function latestCanvasRev(catalog: any, sessionId: string, slot?: number): Promise<number>;
//# sourceMappingURL=canvas-support.d.ts.map