/**
 * SQL Connection Management — PostgreSQL, MySQL, MSSQL, SQLite
 *
 * Singleton pool, connect/close, transactions.
 * Extracted from sql.ts — pure code movement.
 */
export interface PoolOptions {
    pool?: 'high' | 'standard' | 'low';
    label?: string;
}
export interface ResultSet {
    rowCount: number;
    rows?: unknown[];
}
export interface PoolClient {
    query(sql: string, params?: unknown[]): Promise<{
        rows: unknown[];
        rowCount: number;
    }>;
    release(): void;
}
interface Pool {
    query(sql: string, params?: unknown[]): Promise<{
        rows: unknown[];
        rowCount: number;
    }>;
    connect(): Promise<PoolClient>;
    end(): Promise<void>;
}
/**
 * Connect to the SQL database. Auto-detects driver from DATABASE_URL scheme.
 *
 * @param uri - Connection string (defaults to process.env.DATABASE_URL)
 * @param opts - Pool size preset and label
 *
 * @example
 * await connect(); // uses DATABASE_URL from .env
 * await connect(undefined, { pool: 'high', label: 'API' });
 */
export declare function connect(uri?: string, opts?: PoolOptions): Promise<void>;
/** Get the active connection pool. Throws if not connected. */
export declare function getPool(): Pool;
/** Close the connection pool. */
export declare function closePool(): Promise<void>;
/** Idempotent shutdown — safe to call from multiple signal handlers. */
export declare function gracefulShutdown(exitCode?: number): void;
/**
 * Execute a function within a database transaction.
 * Automatically commits on success, rolls back on error.
 *
 * @example
 * const result = await withTransaction(async (client) => {
 *   await client.query('UPDATE accounts SET balance = balance - $1 WHERE id = $2', [100, fromId]);
 *   await client.query('UPDATE accounts SET balance = balance + $1 WHERE id = $2', [100, toId]);
 *   return { success: true };
 * });
 */
export declare function withTransaction<T>(fn: (client: PoolClient) => Promise<T>, dialect?: 'pg' | 'mysql2' | 'mssql' | 'sqlite'): Promise<T>;
export {};
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