/**
 * Warehouse connector contract.
 *
 * FROZEN at v1.0 — any breaking change requires a major version bump and a
 * 6-month deprecation window. See docs/architecture/plugin-api.md.
 */
export interface ColumnSchema {
    name: string;
    type: string;
    nullable?: boolean;
}
export interface TableSchema {
    schema: string;
    name: string;
    columns: ColumnSchema[];
}
export interface QueryRow {
    [column: string]: unknown;
}
export interface QueryResult {
    columns: ColumnSchema[];
    rows: QueryRow[];
    rowCount: number;
    executionTimeMs?: number;
}
export interface QueryCursor extends AsyncIterable<QueryRow> {
    readonly columns: ColumnSchema[];
    close(): Promise<void>;
}
/** Per-driver configuration — opaque to the core. */
export type ConnectorConfig = Record<string, unknown>;
export interface ConnectorMetadata {
    id: string;
    displayName: string;
    supports: {
        streaming: boolean;
        introspection: boolean;
        transactions: boolean;
    };
}
/**
 * Implement this interface and register the module in cdql.yaml under
 * `plugins.connectors`. DQL will instantiate, connect, and close the
 * connector; plugin authors do not need to manage lifecycle.
 */
export interface Connector {
    readonly metadata: ConnectorMetadata;
    /** Open a connection. Called once per session. */
    connect(config: ConnectorConfig): Promise<void>;
    /** Close the connection. Must be idempotent. */
    close(): Promise<void>;
    /** Execute a query to completion and return the full result. */
    query(sql: string, params?: unknown[]): Promise<QueryResult>;
    /**
     * Optional: execute a query as a streaming cursor. Required when
     * `metadata.supports.streaming` is true.
     */
    stream?(sql: string, params?: unknown[]): Promise<QueryCursor>;
    /**
     * Optional: list tables with columns. Required when
     * `metadata.supports.introspection` is true.
     */
    introspect?(): Promise<TableSchema[]>;
    /** Optional: sanity-check the connection is live. */
    ping?(): Promise<void>;
}
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