fix: reload legacy session rows

openviking/message/message.py

@@ -11,7 +11,6 @@
 from typing import List, Literal, Optional
 
 from openviking.message.part import ContextPart, Part, TextPart, ToolPart
-from openviking.utils.time_utils import format_iso8601, parse_iso_datetime
 
 
 @dataclass
@@ -65,6 +64,12 @@ def estimated_tokens(self) -> int:
     def to_dict(self) -> dict:
         """Serialize to JSONL."""
         created_at_val = self.created_at or datetime.now(timezone.utc).isoformat()
+        if isinstance(created_at_val, datetime):
+            created_at_val = (
+                created_at_val.astimezone(timezone.utc)
+                .isoformat(timespec="milliseconds")
+                .replace("+00:00", "Z")
+            )
         return {
             "id": self.id,
             "role": self.role,
@@ -108,7 +113,15 @@ def _part_to_dict(self, part: Part) -> dict:
     def from_dict(cls, data: dict) -> "Message":
         """Deserialize from JSONL."""
         parts = []
-        for p in data.get("parts", []):
+        raw_parts = data.get("parts")
+        if raw_parts is None:
+            legacy_content = data.get("content")
+            if legacy_content is not None:
+                raw_parts = [{"type": "text", "text": legacy_content}]
+            else:
+                raw_parts = []
+
+        for p in raw_parts:
             if p["type"] == "text":
                 parts.append(TextPart(text=p.get("text", "")))
             elif p["type"] == "context":
@@ -138,7 +151,7 @@ def from_dict(cls, data: dict) -> "Message":
             id=data["id"],
             role=data["role"],
             parts=parts,
-            created_at=data["created_at"],
+            created_at=data.get("created_at"),
         )
 
     @classmethod
@@ -193,7 +206,7 @@ def create_assistant(
             id=msg_id or f"msg_{uuid4().hex}",
             role="assistant",
             parts=parts,
-            created_at=datetime.now(timezone.utc).isoformat()
+            created_at=datetime.now(timezone.utc).isoformat(),
         )
 
     def get_context_parts(self) -> List[ContextPart]:

tests/unit/test_message.py

@@ -514,6 +514,24 @@ def test_from_dict_with_tool_part(self):
         assert isinstance(msg.parts[0], ToolPart)
         assert msg.parts[0].tool_id == "call-1"
 
+    def test_from_dict_supports_legacy_content_only_messages(self):
+        """Legacy messages with only content should load as a TextPart."""
+        d = {
+            "id": "msg-legacy",
+            "role": "user",
+            "content": "Hello from legacy storage",
+        }
+
+        msg = Message.from_dict(d)
+
+        assert msg.id == "msg-legacy"
+        assert msg.role == "user"
+        assert len(msg.parts) == 1
+        assert isinstance(msg.parts[0], TextPart)
+        assert msg.parts[0].text == "Hello from legacy storage"
+        assert msg.content == "Hello from legacy storage"
+        assert msg.created_at is None
+
     def test_roundtrip(self):
         """Test to_dict -> from_dict roundtrip."""
         original = Message(
@@ -534,6 +552,29 @@ def test_roundtrip(self):
         assert isinstance(restored.parts[0], TextPart)
         assert isinstance(restored.parts[1], ContextPart)
 
+    def test_legacy_message_can_be_reloaded_and_extended(self):
+        """Legacy content-only rows should survive reload before appending new messages."""
+        legacy_row = {
+            "id": "msg-legacy",
+            "role": "user",
+            "content": "Legacy message",
+            "created_at": "2026-03-26T10:30:00Z",
+        }
+        fresh = Message.create_user("Fresh message", msg_id="msg-fresh")
+
+        reloaded_messages = [Message.from_dict(legacy_row), Message.from_dict(fresh.to_dict())]
+
+        assert [message.content for message in reloaded_messages] == [
+            "Legacy message",
+            "Fresh message",
+        ]
+        assert [
+            json.loads(message.to_jsonl())["parts"][0]["text"] for message in reloaded_messages
+        ] == [
+            "Legacy message",
+            "Fresh message",
+        ]
+
 
 class TestMessageFactoryMethods:
     """Test Message factory methods."""