applyCacheBreakpoints function

List<Map<String, dynamic>> applyCacheBreakpoints(List<Map<String, dynamic>> messages, CacheConfig config)

Apply cache breakpoints to a list of message maps destined for the API.

Inserts cache_control: {"type": "ephemeral"} on the last content block of each message at the specified breakpoint indices.

Implementation

List<Map<String, dynamic>> applyCacheBreakpoints(
  List<Map<String, dynamic>> messages,
  CacheConfig config,
) {
  if (!config.enabled || config.breakpoints.isEmpty) return messages;

  // Deep copy to avoid mutating the originals.
  final result = messages.map((m) => Map<String, dynamic>.from(m)).toList();

  for (final idx in config.breakpoints) {
    if (idx < 0 || idx >= result.length) continue;

    final message = result[idx];
    final content = message['content'];
    if (content is List && content.isNotEmpty) {
      final contentList = List<Map<String, dynamic>>.from(
        content.map((c) => Map<String, dynamic>.from(c as Map)),
      );
      // Mark the last content block.
      contentList.last['cache_control'] = {'type': 'ephemeral'};
      message['content'] = contentList;
    } else if (content is String) {
      // If content is a plain string, wrap it in a block with cache_control.
      message['content'] = [
        {
          'type': 'text',
          'text': content,
          'cache_control': {'type': 'ephemeral'},
        },
      ];
    }
  }

  return result;
}