/**
 * Import staging: validating an uploaded archive before any of it reaches the live data
 * directory, and serialising concurrent imports of the same database.
 */
/** Thrown when an upload is not a genuine AxioDB export. Callers answer 400. */
export declare class InvalidExportError extends Error {
    constructor(message: string);
}
/** Thrown when the same database is already present or already being imported. Answer 409. */
export declare class ImportConflictError extends Error {
    constructor(message: string);
}
/**
 * Confirms that a staged directory holds one AxioDB database export, and returns its name.
 *
 * The database name comes from the archive's own contents, never from the uploaded
 * filename - two people can export the same database and rename the file to anything, so
 * the filename says nothing about what is inside.
 *
 * `tarGzFolder` archives `{root}/{dbName}`, so a genuine export is exactly one top-level
 * directory containing recognisable AxioDB artefacts.
 *
 * @param stagingDir - Directory the archive was extracted into.
 * @returns The database name the archive contains.
 * @throws {InvalidExportError} When the contents are not an AxioDB export.
 */
export declare function readExportedDatabaseName(stagingDir: string): string;
/**
 * Claims the right to import `databaseName`.
 *
 * @param databaseName - Name read from the archive's contents.
 * @param username - Who is importing, so a clash can name them.
 * @throws {ImportConflictError} When another import of the same database is in flight.
 */
export declare function claimImport(databaseName: string, username: string): void;
/** Releases the claim. Always call from a `finally`. */
export declare function releaseImport(databaseName: string): void;