import type { StairInput, StairResult } from './types.js';
/**
 * Calculate stair dimensions
 *
 * Formulas:
 * - Number of risers = totalRise / riserHeight (rounded)
 * - Number of treads = risers - 1
 * - Tread depth = totalRun / numberOfTreads
 * - Stringer length = sqrt(totalRise² + totalRun²)
 * - 2R + T comfort formula (should be 600-650mm for comfortable stairs)
 * - Total angle = atan2(totalRise, totalRun) × (180 / π)
 *
 * @param input - Stair input parameters
 * @returns Stair calculation results
 * @throws {RangeError} totalRise ≤ 0, totalRun < 0, or riserHeight < 0 (riserHeight 0
 *   means "auto-calculate", the established contract)
 */
export declare function stair(input: StairInput): StairResult;
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