import pg from "pg";
import { type Queryable } from "../db/connect.js";
/**
 * A connection that cannot write, and can be shown not to.
 *
 * `crossline verify` is the one command a founder is invited to point at a
 * production database, so "we only issue reads" being *true* is not enough —
 * it has to be checkable without reading the code. Three independent guards,
 * each of which alone would be sufficient, because the cost of one of them
 * quietly rotting is the whole feature:
 *
 *  1. **The statement allowlist.** Every string that reaches Postgres through
 *     this class must begin with `select` or `with` once comments are stripped.
 *     Anything else throws before it is sent. Not a sanitiser — the SQL here is
 *     all our own — but a tripwire on the next person who adds a query.
 *  2. **A read-only transaction.** The session opens `begin` then
 *     `set transaction read only`, so the *server* refuses any write, including
 *     one that got past the allowlist. This is not a rolled-back write: nothing
 *     is attempted and nothing needs excusing. The transaction is committed,
 *     not rolled back, because it never did anything to undo.
 *  3. **The type.** It exposes {@link Queryable} and nothing else, so it cannot
 *     be handed to seeding or probing, which need `inRollback`.
 *
 * `set transaction read only` rather than the `default_transaction_read_only`
 * startup parameter: pgbouncer rejects startup parameters it does not know, and
 * the pooled connection string is the one Supabase's dashboard offers first.
 * A guarantee that breaks on the most commonly pasted URL is not a guarantee.
 */
export declare class CatalogReader implements Queryable {
    private readonly db;
    private readonly client;
    private constructor();
    /** Statements this class will send. Anything else is a bug, loudly. */
    private static readonly ALLOWED;
    static open(connectionString: string): Promise<CatalogReader>;
    query<T extends pg.QueryResultRow = pg.QueryResultRow>(sql: string, params?: unknown[]): Promise<pg.QueryResult<T>>;
    close(): Promise<void>;
}