/**
 * Work out a column's type from the GENERATOR that feeds it, when `type=` was
 * not declared.
 *
 * This is the reliable middle step of the resolution order: we know a column
 * came from `type="number"` without decimals, so it is an int64 — far safer
 * than guessing from the rendered text, which is how `007` silently becomes 7.
 * When we cannot tell, we return undefined and the caller falls back to string,
 * which never corrupts data.
 * Spec: docs/specs/2026-07-19-typed-output-and-parquet-writer.md §4.
 */
import type { SequenceSpec } from '../sequence/types.js';
import { type ColumnType, type OutputColumnType } from './column-type.js';
/**
 * The single sequence a template refers to, if it is exactly one substitution
 * and nothing else (`${{Id}}`). Composite text has no single source type.
 */
export declare function soleReference(template: string, inject: string): string | undefined;
/**
 * Derive a column type for `name` from the sequence specs, or undefined when it
 * cannot be told confidently.
 */
export declare function deriveColumnType(name: string, specs: readonly SequenceSpec[]): ColumnType | undefined;
/**
 * The type of a column fed by `name`, as a LIST when the generator repeats.
 *
 * A repeating gen puts several values in one cell, so the column is a list of
 * whatever a single value would have been. If the element type cannot be told
 * confidently the whole thing stays text — same safety rule as everywhere else.
 */
export declare function deriveOutputColumnType(name: string, specs: readonly SequenceSpec[]): OutputColumnType | undefined;
/**
 * The `separator` of the generator feeding `name`, or undefined when it does
 * not repeat. This is what a list column splits its rendered text on, so the
 * text view and the typed view can never disagree about where a value ends.
 */
export declare function repeatSeparatorOf(name: string, specs: readonly SequenceSpec[]): string | undefined;
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