/**
 * The typed output columns declared in a `<block>`.
 *
 * A `<data>` carrying a `name` is a COLUMN; one without is decorative text and
 * is ignored by columnar output. `<line>` structure is irrelevant here — the
 * columns are all named `<data>` in document order. This keeps the text block
 * and the columnar schema the same construct, so nothing new has to be learned
 * and text output is unaffected.
 * Spec: docs/specs/2026-07-19-typed-output-and-parquet-writer.md §1.
 */
import type { DocumentContext } from '../generated/TDCParser.js';
import { type OutputColumnType } from './column-type.js';
export interface DeclaredColumn {
    readonly name: string;
    /** Raw `<data>` body, interpolated per row before being typed. */
    readonly template: string;
    /** Parsed `type="…"`; undefined when the attribute is absent (resolved later). */
    readonly type?: OutputColumnType;
}
/**
 * The columns declared by the document's `<block>`. Empty when the block is a
 * plain text template (no named `<data>`) — that is the normal, untyped path.
 * Throws on a duplicate name or an unparsable `type=`.
 */
export declare function extractDeclaredColumns(doc: DocumentContext): DeclaredColumn[];
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