diff --git a/alias/src/alias/agent/mock/mock_message_models.py b/alias/src/alias/agent/mock/mock_message_models.py
index d7be0dc9..c13eecfe 100644
--- a/alias/src/alias/agent/mock/mock_message_models.py
+++ b/alias/src/alias/agent/mock/mock_message_models.py
@@ -3,10 +3,15 @@
 import uuid
 from enum import Enum
 from typing import Any, Optional, Literal
-from dataclasses import dataclass
+from dataclasses import dataclass, field
+from datetime import datetime, timezone
 from pydantic import BaseModel, Field
 
 
+def _get_utc_now_iso():
+    return datetime.now(timezone.utc).isoformat()
+
+
 @dataclass
 class MockFileBase:
     filename: str
@@ -15,8 +20,8 @@ class MockFileBase:
     storage_path: str
     size: int = -1
     storage_type: str = "unknown"
-    create_time: str = "xxxyyy"
-    update_time: str = "xxxyyy"
+    create_time: str = field(default_factory=_get_utc_now_iso)
+    update_time: str = field(default_factory=_get_utc_now_iso)
     user_id: uuid.UUID = uuid.uuid4()
 
 
@@ -62,12 +67,13 @@ class UserMessage(BaseMessage):
     name: str = "User"
 
 
+@dataclass
 class MockMessage:
-    id: uuid.UUID = uuid.uuid4()
+    id: uuid.UUID = field(default_factory=uuid.uuid4)
     message: Optional[dict] = None
-    files: list[Any] = []
-    create_time: str = "xxxyyy"
-    update_time: str = "xxxyyy"
+    files: list[Any] = field(default_factory=list)
+    create_time: str = field(default_factory=_get_utc_now_iso)
+    update_time: str = field(default_factory=_get_utc_now_iso)
 
 
 class SubTaskToPrint(BaseModel):