feat: add default limit to checkpoint batching

src/aws_durable_execution_sdk_python/state.py

@@ -45,12 +45,12 @@ class CheckpointBatcherConfig:
     Attributes:
         max_batch_size_bytes: Maximum batch size in bytes (default: 750KB)
         max_batch_time_seconds: Maximum time to wait before flushing batch (default: 1.0 second)
-        max_batch_operations: Maximum number of operations per batch (default: unlimited)
+        max_batch_operations: Maximum number of operations per batch (default: 250)
     """
 
-    max_batch_size_bytes: int = 750 * 1024  # 750KB - private readonly MAX_PAYLOAD_SIZE
-    max_batch_time_seconds: float = 1.0  # 1 second default
-    max_batch_operations: int | float = float("inf")  # No operation limit by default
+    max_batch_size_bytes: int = 750 * 1024  # 750KB
+    max_batch_time_seconds: float = 1.0
+    max_batch_operations: int = 250
 
 
 @dataclass(frozen=True)

tests/state_test.py

@@ -779,7 +779,7 @@ def test_checkpoint_batcher_config_default_values():
 
     assert config.max_batch_size_bytes == 750 * 1024  # 750KB
     assert config.max_batch_time_seconds == 1.0
-    assert config.max_batch_operations == float("inf")
+    assert config.max_batch_operations == 250
 
 
 def test_checkpoint_batcher_config_custom_values():
@@ -803,6 +803,49 @@ def test_checkpoint_batcher_config_immutable():
         config.max_batch_size_bytes = 1000
 
 
+def test_checkpoint_batch_respects_default_max_items_limit():
+    """Test that batch collection respects the default MAX_ITEMS_IN_BATCH (250) limit.
+
+    This ensures consistency across all Durable Execution SDK implementations.
+    """
+    mock_lambda_client = Mock(spec=LambdaClient)
+
+    # Use default config (max_batch_operations=250)
+    config = CheckpointBatcherConfig(
+        max_batch_size_bytes=10 * 1024 * 1024,
+        max_batch_time_seconds=10.0,
+    )
+
+    state = ExecutionState(
+        durable_execution_arn="test_arn",
+        initial_checkpoint_token="token123",  # noqa: S106
+        operations={},
+        service_client=mock_lambda_client,
+        batcher_config=config,
+    )
+
+    # Enqueue 300 small operations (exceeds MAX_ITEMS_IN_BATCH of 250)
+    for i in range(300):
+        operation_update = OperationUpdate(
+            operation_id=f"op_{i}",
+            operation_type=OperationType.STEP,
+            action=OperationAction.START,
+        )
+        state._checkpoint_queue.put(QueuedOperation(operation_update, None))
+
+    # Collect first batch
+    batch1 = state._collect_checkpoint_batch()
+
+    # First batch should have exactly 250 items
+    assert len(batch1) == 250
+
+    # Collect second batch
+    batch2 = state._collect_checkpoint_batch()
+
+    # Second batch should have remaining 50 items
+    assert len(batch2) == 50
+
+
 def test_calculate_operation_size_with_operation():
     """Test _calculate_operation_size with a real operation."""
     operation_update = OperationUpdate(