saveCheckpoint method

@override Future<void> saveCheckpoint(StepCheckpoint checkpoint)

Persists a step checkpoint.

If a checkpoint with the same (workflowExecutionId, stepIndex, attempt) already exists, it should be updated.

Implementation

@override
Future<void> saveCheckpoint(StepCheckpoint checkpoint) async {
  final key = checkpoint.workflowExecutionId;
  final list = _checkpoints.putIfAbsent(key, () => []);

  // Update existing checkpoint with same (executionId, stepIndex, attempt)
  final existingIndex = list.indexWhere(
    (cp) =>
        cp.stepIndex == checkpoint.stepIndex &&
        cp.attempt == checkpoint.attempt,
  );

  final saved = checkpoint.id != null
      ? checkpoint
      : checkpoint.copyWith(id: _nextCheckpointId++);

  if (existingIndex >= 0) {
    list[existingIndex] = saved;
  } else {
    list.add(saved);
  }
}