appendUrl method
Implementation
AccumulatedFileStream appendUrl({required String itemId, required String url, String? turnId, String? senderName}) {
final current = upsert(itemId: itemId, turnId: turnId, senderName: senderName);
final normalizedUrl = url.trim();
final urls = current.urls.toList(growable: true);
if (normalizedUrl.isNotEmpty && !urls.contains(normalizedUrl)) {
urls.add(normalizedUrl);
}
final next = AccumulatedFileStream(
itemId: current.itemId,
turnId: current.turnId,
status: 'in_progress',
urls: List<String>.unmodifiable(urls),
senderName: current.senderName,
);
_items[current.itemId] = next;
return next;
}