Function isToolExchangeAdjacencyError

packages/kosong/src/errors.ts:218–224

(error: unknown)

] as const;

export function isToolExchangeAdjacencyError(error: unknown): boolean {
  if (!(error instanceof APIStatusError)) return false;
  if (error instanceof APIContextOverflowError) return false;
  if (error.statusCode !== 400 && error.statusCode !== 422) return false;
  const lowerMessage = error.message.toLowerCase();
  return TOOL_EXCHANGE_ADJACENCY_MESSAGE_PATTERNS.some((pattern) => pattern.test(lowerMessage));
}

// The broader family of structural request rejections a strict provider returns
// when the message array itself is malformed — tool_use/tool_result pairing,