import type * as z from "zod";
import { type UdlAnyFamily } from "./schema.js";
/**
 * How this engine reads one UDL format. A Build is bytecode and keeps the
 * format it compiled to. The current format parses straight into the engine's
 * document; an older one parses with its own schema, then `upgrade`, a pure
 * and deterministic step, turns it into the next format.
 */
export interface UdlFormatReader {
    readonly schema: z.ZodType;
    readonly upgrade?: (document: unknown) => unknown;
}
/**
 * One reader per format a stored Build uses, keyed by `document.udl`. A format
 * bump adds its schema here and gives the previous format an upgrade step. A
 * new Build admits only `UDL_FORMAT_VERSION` (`validateNewBuildUdl`).
 */
export declare const udlFormatReaders: Map<number, UdlFormatReader>;
/**
 * Whether two families name the same std declaration. Two format 2 families
 * compare digests. When either is format 1, module and export path decide,
 * which is what a stored revision decided: every stored revision is 1.
 */
export declare function sameFamily(a: UdlAnyFamily | undefined, b: UdlAnyFamily): boolean;
/** The format a stored document declares, when this engine can read it. */
export declare function readableUdlFormat(document: unknown): number | undefined;
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