fix: convert InvocationCompletedDetails to unix milliseconds

SQLite storage was failing with "Object of type datetime is not JSON
serializable" when attempting to save execution state after Lambda
invocation. The root cause was InvocationCompletedDetails.to_dict()
returning raw datetime objects instead of JSON-serializable integers.

This fix adds to_json_dict() and from_json_dict() methods to
InvocationCompletedDetails that convert datetime objects to/from Unix
milliseconds using TimestampConverter, matching the pattern already
used by the SDK's Operation class.

Changes:
- Add InvocationCompletedDetails.to_json_dict() for serialization
- Add InvocationCompletedDetails.from_json_dict() for deserialization
- Update Execution.to_json_dict() to call completion.to_json_dict()
- Update Execution.from_json_dict() to call from_json_dict()

The to_dict() method is preserved for internal use where datetime
objects are needed, while to_json_dict() is used for storage and
JSON serialization paths.

Fixes execution persistence failures in SQLite and filesystem stores.

closes #193

Author: yaythomas

src/aws_durable_execution_sdk_python_testing/execution.py

@@ -102,7 +102,7 @@ def to_json_dict(self) -> dict[str, Any]:
             "Operations": [op.to_json_dict() for op in self.operations],
             "Updates": [update.to_dict() for update in self.updates],
             "InvocationCompletions": [
-                completion.to_dict() for completion in self.invocation_completions
+                completion.to_json_dict() for completion in self.invocation_completions
             ],
             "UsedTokens": list(self.used_tokens),
             "TokenSequence": self._token_sequence,
@@ -135,7 +135,7 @@ def from_json_dict(cls, data: dict[str, Any]) -> Execution:
             OperationUpdate.from_dict(update_data) for update_data in data["Updates"]
         ]
         execution.invocation_completions = [
-            InvocationCompletedDetails.from_dict(item)
+            InvocationCompletedDetails.from_json_dict(item)
             for item in data.get("InvocationCompletions", [])
         ]
         execution.used_tokens = set(data["UsedTokens"])

src/aws_durable_execution_sdk_python_testing/executor.py

@@ -115,6 +115,7 @@ def start_execution(
         execution = Execution.new(input=input)
         execution.start()
         self._store.save(execution)
+        logger.debug("Created execution with ARN: %s", execution.durable_execution_arn)
 
         completion_event = self._scheduler.create_event()
         self._completion_events[execution.durable_execution_arn] = completion_event

src/aws_durable_execution_sdk_python_testing/invoker.py

@@ -16,9 +16,12 @@
 
 from aws_durable_execution_sdk_python_testing.exceptions import (
     DurableFunctionsTestError,
+    InvalidParameterValueException,
+    ResourceNotFoundException,
 )
 from aws_durable_execution_sdk_python_testing.model import LambdaContext
 
+
 if TYPE_CHECKING:
     from collections.abc import Callable
 
@@ -217,10 +220,6 @@ def invoke(
             InvalidParameterValueException: If parameters are invalid
             DurableFunctionsTestError: For other invocation failures
         """
-        from aws_durable_execution_sdk_python_testing.exceptions import (
-            ResourceNotFoundException,
-            InvalidParameterValueException,
-        )
 
         # Parameter validation
         if not function_name or not function_name.strip():

src/aws_durable_execution_sdk_python_testing/model.py

@@ -3,12 +3,10 @@
 from __future__ import annotations
 
 import datetime
+import json
 from dataclasses import dataclass, replace
 from enum import Enum
 from typing import Any
-import json
-
-from dateutil.tz import UTC
 
 from aws_durable_execution_sdk_python.execution import DurableExecutionInvocationOutput
 
@@ -30,12 +28,14 @@
     OperationUpdate,
     StepDetails,
     StepOptions,
+    TimestampConverter,
     WaitDetails,
     WaitOptions,
 )
 from aws_durable_execution_sdk_python.types import (
     LambdaContext as LambdaContextProtocol,
 )
+from dateutil.tz import UTC
 
 from aws_durable_execution_sdk_python_testing.exceptions import (
     InvalidParameterValueException,
@@ -1239,13 +1239,30 @@ def from_dict(cls, data: dict) -> InvocationCompletedDetails:
             request_id=data["RequestId"],
         )
 
+    @classmethod
+    def from_json_dict(cls, data: dict) -> InvocationCompletedDetails:
+        """Deserialize from JSON dict with Unix millisecond timestamps."""
+        return cls(
+            start_timestamp=TimestampConverter.from_unix_millis(data["StartTimestamp"]),  # type: ignore[arg-type]
+            end_timestamp=TimestampConverter.from_unix_millis(data["EndTimestamp"]),  # type: ignore[arg-type]
+            request_id=data["RequestId"],
+        )
+
     def to_dict(self) -> dict[str, Any]:
         return {
             "StartTimestamp": self.start_timestamp,
             "EndTimestamp": self.end_timestamp,
             "RequestId": self.request_id,
         }
 
+    def to_json_dict(self) -> dict[str, Any]:
+        """Convert to JSON-serializable dict with Unix millisecond timestamps."""
+        return {
+            "StartTimestamp": TimestampConverter.to_unix_millis(self.start_timestamp),
+            "EndTimestamp": TimestampConverter.to_unix_millis(self.end_timestamp),
+            "RequestId": self.request_id,
+        }
+
 
 # endregion event_structures
 

src/aws_durable_execution_sdk_python_testing/web/handlers.py

@@ -291,16 +291,22 @@ def handle(self, parsed_route: Route, request: HTTPRequest) -> HTTPResponse:  #
         Returns:
             HTTPResponse: The HTTP response to send to the client
         """
+        logger.debug("🌟 HANDLER: Received POST /start-durable-execution request")
         try:
             body_data: dict[str, Any] = self._parse_json_body(request)
+            logger.debug("🌟 HANDLER: Parsed request body successfully")
 
             start_input: StartDurableExecutionInput = (
                 StartDurableExecutionInput.from_dict(body_data)
             )
+            logger.debug(
+                "🌟 HANDLER: Created StartDurableExecutionInput, calling executor.start_execution()"
+            )
 
             start_output: StartDurableExecutionOutput = self.executor.start_execution(
                 start_input
             )
+            logger.debug("🌟 HANDLER: executor.start_execution() returned successfully")
 
             response_data: dict[str, Any] = start_output.to_dict()
 

tests/model_test.py

@@ -5,11 +5,11 @@
 import datetime
 
 import pytest
-
 from aws_durable_execution_sdk_python.lambda_service import (
     OperationStatus,
     OperationType,
 )
+
 from aws_durable_execution_sdk_python_testing.exceptions import (
     InvalidParameterValueException,
 )
@@ -3564,3 +3564,127 @@ def test_events_to_operations_invalid_sub_type():
         match=f"'{invalid_sub_type}' is not a valid OperationSubType",
     ):
         events_to_operations([event])
+
+
+def test_invocation_completed_details_to_json_dict():
+    """Test InvocationCompletedDetails.to_json_dict() converts datetime to Unix milliseconds."""
+    from aws_durable_execution_sdk_python_testing.model import (
+        InvocationCompletedDetails,
+    )
+
+    start_time = datetime.datetime(2023, 1, 1, 0, 0, 0, 123456, tzinfo=datetime.UTC)
+    end_time = datetime.datetime(2023, 1, 1, 0, 1, 0, 456789, tzinfo=datetime.UTC)
+
+    details = InvocationCompletedDetails(
+        start_timestamp=start_time, end_timestamp=end_time, request_id="req-123"
+    )
+
+    json_dict = details.to_json_dict()
+
+    # Verify timestamps are converted to Unix milliseconds (integers)
+    assert json_dict["StartTimestamp"] == 1672531200123
+    assert json_dict["EndTimestamp"] == 1672531260456
+    assert json_dict["RequestId"] == "req-123"
+
+    # Verify all values are JSON-serializable
+    import json
+
+    json_str = json.dumps(json_dict)
+    assert json_str is not None
+
+
+def test_invocation_completed_details_from_json_dict():
+    """Test InvocationCompletedDetails.from_json_dict() converts Unix milliseconds to datetime."""
+    from aws_durable_execution_sdk_python_testing.model import (
+        InvocationCompletedDetails,
+    )
+
+    json_dict = {
+        "StartTimestamp": 1672531200123,
+        "EndTimestamp": 1672531260456,
+        "RequestId": "req-456",
+    }
+
+    details = InvocationCompletedDetails.from_json_dict(json_dict)
+
+    # Verify timestamps are converted to datetime objects
+    assert details.start_timestamp == datetime.datetime(
+        2023, 1, 1, 0, 0, 0, 123000, tzinfo=datetime.UTC
+    )
+    assert details.end_timestamp == datetime.datetime(
+        2023, 1, 1, 0, 1, 0, 456000, tzinfo=datetime.UTC
+    )
+    assert details.request_id == "req-456"
+
+
+def test_invocation_completed_details_json_round_trip():
+    """Test InvocationCompletedDetails to_json_dict/from_json_dict round-trip."""
+    from aws_durable_execution_sdk_python_testing.model import (
+        InvocationCompletedDetails,
+    )
+
+    original = InvocationCompletedDetails(
+        start_timestamp=datetime.datetime(
+            2023, 6, 15, 12, 30, 45, 678000, tzinfo=datetime.UTC
+        ),
+        end_timestamp=datetime.datetime(
+            2023, 6, 15, 12, 31, 50, 123000, tzinfo=datetime.UTC
+        ),
+        request_id="round-trip-test",
+    )
+
+    # Serialize to JSON dict
+    json_dict = original.to_json_dict()
+
+    # Deserialize back
+    restored = InvocationCompletedDetails.from_json_dict(json_dict)
+
+    # Verify round-trip preserves data
+    assert restored.start_timestamp == original.start_timestamp
+    assert restored.end_timestamp == original.end_timestamp
+    assert restored.request_id == original.request_id
+
+
+def test_invocation_completed_details_to_dict_preserves_datetime():
+    """Test InvocationCompletedDetails.to_dict() preserves datetime objects (not converted)."""
+    from aws_durable_execution_sdk_python_testing.model import (
+        InvocationCompletedDetails,
+    )
+
+    start_time = datetime.datetime(2023, 1, 1, 0, 0, 0, tzinfo=datetime.UTC)
+    end_time = datetime.datetime(2023, 1, 1, 0, 1, 0, tzinfo=datetime.UTC)
+
+    details = InvocationCompletedDetails(
+        start_timestamp=start_time, end_timestamp=end_time, request_id="req-789"
+    )
+
+    regular_dict = details.to_dict()
+
+    # Verify to_dict() preserves datetime objects (not converted to Unix milliseconds)
+    assert regular_dict["StartTimestamp"] == start_time
+    assert regular_dict["EndTimestamp"] == end_time
+    assert isinstance(regular_dict["StartTimestamp"], datetime.datetime)
+    assert isinstance(regular_dict["EndTimestamp"], datetime.datetime)
+
+
+def test_invocation_completed_details_from_json_dict_invalid_timestamp():
+    """Test InvocationCompletedDetails.from_json_dict() raises error for invalid timestamps."""
+    from aws_durable_execution_sdk_python_testing.exceptions import (
+        InvalidParameterValueException,
+    )
+    from aws_durable_execution_sdk_python_testing.model import (
+        InvocationCompletedDetails,
+    )
+
+    # Test with invalid timestamp that would return None
+    json_dict = {
+        "StartTimestamp": None,
+        "EndTimestamp": 1672531260456,
+        "RequestId": "req-error",
+    }
+
+    with pytest.raises(
+        InvalidParameterValueException,
+        match="StartTimestamp and EndTimestamp must be valid",
+    ):
+        InvocationCompletedDetails.from_json_dict(json_dict)