Function flushPart

packages/kosong/src/generate.ts:294–319

* Append a fully-merged part to the message. * * - ContentPart -> message.content * - ToolCall -> message.toolCalls (the `_streamIndex` routing key is * registered in the map and stripped before storage). * - ToolCallPart -> ignored (orphaned delta without a matching pending

(
  message: Message,
  part: StreamedMessagePart,
  toolCallIndexMap: Map<number | string, number>,
)

 * - ToolCallPart -> ignored (orphaned delta without a matching pending call)
 */
function flushPart(
  message: Message,
  part: StreamedMessagePart,
  toolCallIndexMap: Map<number | string, number>,
): void {
  if (isContentPart(part)) {
    message.content.push(part);
    return;
  }
  if (isToolCall(part)) {
    const streamIndex = part._streamIndex;
    const stored: StoredToolCall = {
      type: 'function',
      id: part.id,
      name: part.name,
      arguments: part.arguments,
      extras: part.extras,
    };
    const ordinal = message.toolCalls.length;
    message.toolCalls.push(stored as ToolCall);
    if (streamIndex !== undefined) {
      toolCallIndexMap.set(streamIndex, ordinal);
    }
  }
  // ToolCallPart: orphaned delta — silently ignore.
}

function formatFinishReasonHint(stream: StreamedMessage): string {
  if (stream.finishReason === null && stream.rawFinishReason === null) return '';