/**
 * A conservative invoice triage example. A clear result still needs the
 * application's business checks; this function never authorizes payment.
 * @param {unknown} response
 */
function routeInvoice(response) {
	/** @param {unknown} value @returns {value is Record<string, unknown>} */
	function isRecord(value) {
		return typeof value === 'object' && value !== null && !Array.isArray(value);
	}
	if (!isRecord(response) || !isRecord(response.data) || !isRecord(response.fields)) {
		throw new Error('Expected an extraction response with data and fields');
	}
	const required = ['/invoice_number', '/total', '/currency'];
	const pointers = new Set([...required, ...Object.keys(response.fields)]);
	const reasons = [];
	for (const pointer of pointers) {
		const field = response.fields[pointer];
		if (!isRecord(field)) {
			reasons.push({ pointer, reason: 'metadata_absent' });
			continue;
		}
		if (field.state !== 'present') {
			// This example reviews null and missing optional fields too.
			reasons.push({ pointer, reason: 'not_present' });
			continue;
		}
		if (field.conflict === true) reasons.push({ pointer, reason: 'conflict' });
		if (
			typeof field.confidence !== 'number' ||
			!Number.isFinite(field.confidence) ||
			field.confidence < 0 ||
			field.confidence > 1
		) {
			reasons.push({ pointer, reason: 'score_absent_or_invalid' });
		}
		if (field.grounding !== 'verified' || !isRecord(field.anchor)) {
			reasons.push({ pointer, reason: 'source_review' });
		}
	}
	const data = response.data;
	if (
		typeof data.invoice_number !== 'string' ||
		data.invoice_number.length === 0 ||
		typeof data.total !== 'number' ||
		!Number.isFinite(data.total) ||
		(data.currency !== 'USD' && data.currency !== 'EUR')
	) {
		reasons.push({ pointer: '', reason: 'data_contract' });
	}
	return {
		route: reasons.length ? 'exception_review' : 'business_checks',
		reasons,
		// Preserve source references for the reviewer; do not put them in logs.
		extraction: response,
	};
}

return $input.all().map((item, index) => ({
  json: routeInvoice(item.json), pairedItem: { item: index }
}));