fix: exceeds payload size limit as invocation error

docs/advanced/error-handling.md

@@ -98,7 +98,7 @@ The SDK provides several exception types for different failure scenarios.
 | `InvocationError` | Yes (by Lambda) | Lambda retries invocation | Transient infrastructure issues |
 | `CallbackError` | No | Returns FAILED status | Callback handling failures |
 | `StepInterruptedError` | Yes (automatic) | Retries on next invocation | Step interrupted before checkpoint |
-| `CheckpointError` | Depends | Retries if 4xx (except invalid token) | Failed to save execution state |
+| `CheckpointError` | Depends | Permanent on 4xx non-429 (except invalid checkpoint token); retries otherwise | Failed to save execution state |
 | `SerDesError` | No | Returns FAILED status | Serialization failures |
 
 ### Base exceptions

src/aws_durable_execution_sdk_python/exceptions.py

@@ -155,32 +155,25 @@ def from_exception(cls, exception: Exception) -> CheckpointError:
         error: AwsErrorObj | None = base.error
         error_category: CheckpointErrorCategory = CheckpointErrorCategory.INVOCATION
 
-        # InvalidParameterValueException and error message starts with "Invalid Checkpoint Token" is an InvocationError
-        # all other 4xx errors are Execution Errors and should be retried
-        # all 5xx errors are Invocation Errors
+        # 4xx errors (except 429) are permanent failures (EXECUTION), unless it's an
+        # InvalidParameterValueException with "Invalid Checkpoint Token" which is retriable (INVOCATION).
+        # 5xx, 429, and network errors are retriable (INVOCATION).
         status_code: int | None = (metadata and metadata.get("HTTPStatusCode")) or None
         if (
             status_code
-            # if we are in 4xx range (except 429) and is not an InvalidParameterValueException with Invalid Checkpoint Token
-            # then it's an execution error
-            and status_code < SERVICE_ERROR
-            and status_code >= BAD_REQUEST_ERROR
+            and BAD_REQUEST_ERROR <= status_code < SERVICE_ERROR
             and status_code != TOO_MANY_REQUESTS_ERROR
             and error
-            and (
-                # is not InvalidParam => Execution
-                (error.get("Code", "") or "") != "InvalidParameterValueException"
-                # is not Invalid Token => Execution
-                or not (error.get("Message") or "").startswith(
-                    "Invalid Checkpoint Token"
-                )
+            and not (
+                (error.get("Code") or "") == "InvalidParameterValueException"
+                and (error.get("Message") or "").startswith("Invalid Checkpoint Token")
             )
         ):
             error_category = CheckpointErrorCategory.EXECUTION
         return CheckpointError(str(exception), error_category, error, metadata)
 
     def is_retriable(self):
-        return self.error_category == CheckpointErrorCategory.EXECUTION
+        return self.error_category == CheckpointErrorCategory.INVOCATION
 
 
 class ValidationError(DurableExecutionsError):

tests/exceptions_test.py

@@ -67,6 +67,23 @@ def test_checkpoint_error_classification_invalid_token_invocation():
     result = CheckpointError.from_exception(client_error)
 
     assert result.error_category == CheckpointErrorCategory.INVOCATION
+    assert result.is_retriable()
+
+
+def test_checkpoint_error_classification_payload_size_exceeded_execution():
+    """Test 4xx InvalidParameterValueException with STEP output payload size limit exceeded is execution error."""
+    error_response = {
+        "Error": {
+            "Code": "InvalidParameterValueException",
+            "Message": "STEP output payload size must be less than or equal to 262144 bytes.",
+        },
+        "ResponseMetadata": {"HTTPStatusCode": 400},
+    }
+    client_error = ClientError(error_response, "Checkpoint")
+
+    result = CheckpointError.from_exception(client_error)
+
+    assert result.error_category == CheckpointErrorCategory.EXECUTION
     assert not result.is_retriable()
 
 
@@ -81,7 +98,7 @@ def test_checkpoint_error_classification_other_4xx_execution():
     result = CheckpointError.from_exception(client_error)
 
     assert result.error_category == CheckpointErrorCategory.EXECUTION
-    assert result.is_retriable()
+    assert not result.is_retriable()
 
 
 def test_checkpoint_error_classification_429_invocation():
@@ -95,7 +112,7 @@ def test_checkpoint_error_classification_429_invocation():
     result = CheckpointError.from_exception(client_error)
 
     assert result.error_category == CheckpointErrorCategory.INVOCATION
-    assert not result.is_retriable()
+    assert result.is_retriable()
 
 
 def test_checkpoint_error_classification_invalid_param_without_token_execution():
@@ -112,7 +129,7 @@ def test_checkpoint_error_classification_invalid_param_without_token_execution()
     result = CheckpointError.from_exception(client_error)
 
     assert result.error_category == CheckpointErrorCategory.EXECUTION
-    assert result.is_retriable()
+    assert not result.is_retriable()
 
 
 def test_checkpoint_error_classification_5xx_invocation():
@@ -126,7 +143,7 @@ def test_checkpoint_error_classification_5xx_invocation():
     result = CheckpointError.from_exception(client_error)
 
     assert result.error_category == CheckpointErrorCategory.INVOCATION
-    assert not result.is_retriable()
+    assert result.is_retriable()
 
 
 def test_checkpoint_error_classification_unknown_invocation():
@@ -136,7 +153,7 @@ def test_checkpoint_error_classification_unknown_invocation():
     result = CheckpointError.from_exception(unknown_error)
 
     assert result.error_category == CheckpointErrorCategory.INVOCATION
-    assert not result.is_retriable()
+    assert result.is_retriable()
 
 
 def test_validation_error():

tests/execution_test.py

@@ -1066,8 +1066,9 @@ def test_handler(event: Any, context: DurableContext) -> dict:
     # Make the service client checkpoint call fail with CheckpointError
     mock_client.checkpoint.side_effect = failing_checkpoint
 
-    with pytest.raises(CheckpointError, match="Background checkpoint failed"):
-        test_handler(invocation_input, lambda_context)
+    response = test_handler(invocation_input, lambda_context)
+    assert response["Status"] == InvocationStatus.FAILED.value
+    assert response["Error"]["ErrorType"] == "CheckpointError"
 
 
 # endregion durable_execution
@@ -1120,16 +1121,13 @@ def slow_background():
         "aws_durable_execution_sdk_python.state.ExecutionState.checkpoint_batches_forever",
         side_effect=slow_background,
     ):
-        with pytest.raises(CheckpointError, match="Checkpoint system failed"):
-            test_handler(invocation_input, lambda_context)
-
+        response = test_handler(invocation_input, lambda_context)
+        assert response["Status"] == InvocationStatus.FAILED.value
+        assert response["Error"]["ErrorType"] == "CheckpointError"
 
-def test_durable_execution_checkpoint_invocation_error_stops_background():
-    """Test that CheckpointError handler stops background checkpointing.
 
-    When user code raises CheckpointError, the handler should stop the background
-    thread before re-raising to terminate the Lambda.
-    """
+def test_durable_execution_checkpoint_invocation_error_retries():
+    """Test that CheckpointError with INVOCATION category re-raises to trigger Lambda retry."""
     mock_client = Mock(spec=DurableServiceClient)
 
     @durable_execution
@@ -1171,13 +1169,12 @@ def slow_background():
         "aws_durable_execution_sdk_python.state.ExecutionState.checkpoint_batches_forever",
         side_effect=slow_background,
     ):
-        response = test_handler(invocation_input, lambda_context)
-        assert response["Status"] == InvocationStatus.FAILED.value
-        assert response["Error"]["ErrorType"] == "CheckpointError"
+        with pytest.raises(CheckpointError, match="Checkpoint system failed"):
+            test_handler(invocation_input, lambda_context)
 
 
-def test_durable_execution_background_thread_execution_error_retries():
-    """Test that background thread Execution errors are retried (re-raised)."""
+def test_durable_execution_background_thread_execution_error_returns_failed():
+    """Test that background thread Execution errors return FAILED (permanent, no retry)."""
     mock_client = Mock(spec=DurableServiceClient)
 
     def failing_checkpoint(*args, **kwargs):
@@ -1215,12 +1212,13 @@ def test_handler(event: Any, context: DurableContext) -> dict:
 
     mock_client.checkpoint.side_effect = failing_checkpoint
 
-    with pytest.raises(CheckpointError, match="Background checkpoint failed"):
-        test_handler(invocation_input, lambda_context)
+    response = test_handler(invocation_input, lambda_context)
+    assert response["Status"] == InvocationStatus.FAILED.value
+    assert response["Error"]["ErrorType"] == "CheckpointError"
 
 
-def test_durable_execution_background_thread_invocation_error_returns_failed():
-    """Test that background thread Invocation errors return FAILED status."""
+def test_durable_execution_background_thread_invocation_error_retries():
+    """Test that background thread Invocation errors re-raise to trigger Lambda retry."""
     mock_client = Mock(spec=DurableServiceClient)
 
     def failing_checkpoint(*args, **kwargs):
@@ -1258,13 +1256,12 @@ def test_handler(event: Any, context: DurableContext) -> dict:
 
     mock_client.checkpoint.side_effect = failing_checkpoint
 
-    response = test_handler(invocation_input, lambda_context)
-    assert response["Status"] == InvocationStatus.FAILED.value
-    assert response["Error"]["ErrorType"] == "CheckpointError"
+    with pytest.raises(CheckpointError, match="Background checkpoint failed"):
+        test_handler(invocation_input, lambda_context)
 
 
-def test_durable_execution_final_success_checkpoint_execution_error_retries():
-    """Test that execution errors on final success checkpoint trigger retry."""
+def test_durable_execution_final_success_checkpoint_execution_error_returns_failed():
+    """Test that execution errors on final success checkpoint return FAILED (permanent, no retry)."""
     mock_client = Mock(spec=DurableServiceClient)
 
     def failing_final_checkpoint(*args, **kwargs):
@@ -1303,12 +1300,13 @@ def test_handler(event: Any, context: DurableContext) -> dict:
 
     mock_client.checkpoint.side_effect = failing_final_checkpoint
 
-    with pytest.raises(CheckpointError, match="Final checkpoint failed"):
-        test_handler(invocation_input, lambda_context)
+    response = test_handler(invocation_input, lambda_context)
+    assert response["Status"] == InvocationStatus.FAILED.value
+    assert response["Error"]["ErrorType"] == "CheckpointError"
 
 
-def test_durable_execution_final_success_checkpoint_invocation_error_returns_failed():
-    """Test that invocation errors on final success checkpoint return FAILED."""
+def test_durable_execution_final_success_checkpoint_invocation_error_retries():
+    """Test that invocation errors on final success checkpoint re-raise to trigger Lambda retry."""
     mock_client = Mock(spec=DurableServiceClient)
 
     def failing_final_checkpoint(*args, **kwargs):
@@ -1348,14 +1346,12 @@ def test_handler(event: Any, context: DurableContext) -> dict:
 
     mock_client.checkpoint.side_effect = failing_final_checkpoint
 
-    response = test_handler(invocation_input, lambda_context)
-    assert response["Status"] == InvocationStatus.FAILED.value
-    assert response["Error"]["ErrorType"] == "CheckpointError"
-    assert response["Error"]["ErrorMessage"] == "Final checkpoint failed"
+    with pytest.raises(CheckpointError, match="Final checkpoint failed"):
+        test_handler(invocation_input, lambda_context)
 
 
-def test_durable_execution_final_failure_checkpoint_execution_error_retries():
-    """Test that execution errors on final failure checkpoint trigger retry."""
+def test_durable_execution_final_failure_checkpoint_execution_error_returns_failed():
+    """Test that execution errors on final failure checkpoint return FAILED (permanent, no retry)."""
     mock_client = Mock(spec=DurableServiceClient)
 
     def failing_final_checkpoint(*args, **kwargs):
@@ -1396,12 +1392,13 @@ def test_handler(event: Any, context: DurableContext) -> dict:
 
     mock_client.checkpoint.side_effect = failing_final_checkpoint
 
-    with pytest.raises(CheckpointError, match="Final checkpoint failed"):
-        test_handler(invocation_input, lambda_context)
+    response = test_handler(invocation_input, lambda_context)
+    assert response["Status"] == InvocationStatus.FAILED.value
+    assert response["Error"]["ErrorType"] == "CheckpointError"
 
 
-def test_durable_execution_final_failure_checkpoint_invocation_error_returns_failed():
-    """Test that invocation errors on final failure checkpoint return FAILED."""
+def test_durable_execution_final_failure_checkpoint_invocation_error_retries():
+    """Test that invocation errors on final failure checkpoint re-raise to trigger Lambda retry."""
     mock_client = Mock(spec=DurableServiceClient)
 
     def failing_final_checkpoint(*args, **kwargs):
@@ -1442,10 +1439,8 @@ def test_handler(event: Any, context: DurableContext) -> dict:
 
     mock_client.checkpoint.side_effect = failing_final_checkpoint
 
-    response = test_handler(invocation_input, lambda_context)
-    assert response["Status"] == InvocationStatus.FAILED.value
-    assert response["Error"]["ErrorType"] == "CheckpointError"
-    assert response["Error"]["ErrorMessage"] == "Final checkpoint failed"
+    with pytest.raises(CheckpointError, match="Final checkpoint failed"):
+        test_handler(invocation_input, lambda_context)
 
 
 def test_durable_handler_background_thread_failure_on_succeed_checkpoint():
@@ -1809,8 +1804,9 @@ def test_handler(event: Any, context: DurableContext) -> dict:
     mock_client.checkpoint.side_effect = failing_checkpoint
 
     with patch("aws_durable_execution_sdk_python.execution.logger", mock_logger):
-        with pytest.raises(CheckpointError):
-            test_handler(invocation_input, lambda_context)
+        response = test_handler(invocation_input, lambda_context)
+        assert response["Status"] == InvocationStatus.FAILED.value
+        assert response["Error"]["ErrorType"] == "CheckpointError"
 
     mock_logger.exception.assert_called_once()
     call_args = mock_logger.exception.call_args
@@ -1922,8 +1918,9 @@ def test_handler(event: Any, context: DurableContext) -> dict:
     lambda_context.tenant_id = None
 
     with patch("aws_durable_execution_sdk_python.execution.logger", mock_logger):
-        with pytest.raises(CheckpointError):
-            test_handler(invocation_input, lambda_context)
+        response = test_handler(invocation_input, lambda_context)
+        assert response["Status"] == InvocationStatus.FAILED.value
+        assert response["Error"]["ErrorType"] == "CheckpointError"
 
     mock_logger.exception.assert_called_once()
     call_args = mock_logger.exception.call_args