fix: replace deprecated datetime.utcnow with timezone-aware

backend/app/agents/coordinator.py

@@ -1,7 +1,7 @@
 """Agent coordinator for orchestrating multiple agents with message passing."""
 
 import asyncio
-from datetime import datetime
+from datetime import datetime, timezone
 from enum import Enum
 from typing import Any
 
@@ -43,7 +43,7 @@ class Message:
         self.message_type = message_type
         self.content = content
         self.priority = priority
-        self.timestamp = datetime.utcnow()
+        self.timestamp = datetime.now(timezone.utc)
 
     def to_dict(self) -> dict[str, Any]:
         """Convert to dictionary."""

backend/app/agents/memory_agent.py

@@ -1,6 +1,6 @@
 """Memory agent for memory operations and knowledge management."""
 
-from datetime import datetime
+from datetime import datetime, timezone
 from typing import Any
 
 from app.core.action import Action, ActionType
@@ -26,20 +26,20 @@ class MemoryEntry:
         self.memory_type = memory_type
         self.ttl_seconds = ttl_seconds
         self.metadata = metadata or {}
-        self.created_at = datetime.utcnow()
-        self.accessed_at = datetime.utcnow()
+        self.created_at = datetime.now(timezone.utc)
+        self.accessed_at = datetime.now(timezone.utc)
         self.access_count = 0
 
     def is_expired(self) -> bool:
         """Check if the memory entry has expired."""
         if self.ttl_seconds is None:
             return False
-        elapsed = (datetime.utcnow() - self.created_at).total_seconds()
+        elapsed = (datetime.now(timezone.utc) - self.created_at).total_seconds()
         return elapsed > self.ttl_seconds
 
     def access(self) -> Any:
         """Access the memory and update metadata."""
-        self.accessed_at = datetime.utcnow()
+        self.accessed_at = datetime.now(timezone.utc)
         self.access_count += 1
         return self.value
 

backend/app/memory/long_term.py

@@ -5,7 +5,7 @@ from __future__ import annotations
 import asyncio
 import hashlib
 import logging
-from datetime import datetime
+from datetime import datetime, timezone
 from typing import Any
 from uuid import uuid4
 
@@ -170,7 +170,7 @@ class LongTermMemory:
 
         async with self._lock:
             doc_id = document_id or self._generate_id(content)
-            now = datetime.utcnow()
+            now = datetime.now(timezone.utc)
 
             document = Document(
                 id=doc_id,

backend/app/memory/short_term.py

@@ -4,7 +4,7 @@ from __future__ import annotations
 
 import asyncio
 from collections import OrderedDict
-from datetime import datetime
+from datetime import datetime, timezone
 from typing import Any, Generic, TypeVar
 
 from pydantic import BaseModel, Field
@@ -12,12 +12,17 @@ from pydantic import BaseModel, Field
 T = TypeVar("T")
 
 
+def _utc_now() -> datetime:
+    """Return current UTC datetime."""
+    return datetime.now(timezone.utc)
+
+
 class MemoryEntry(BaseModel, Generic[T]):
     """A single memory entry with metadata."""
 
     key: str
     value: Any
-    created_at: datetime = Field(default_factory=datetime.utcnow)
+    created_at: datetime = Field(default_factory=_utc_now)
     updated_at: datetime = Field(default_factory=datetime.utcnow)
     access_count: int = 0
     tags: list[str] = Field(default_factory=list)
@@ -94,7 +99,7 @@ class ShortTermMemory:
             ValueError: If max_size would be exceeded for a new key.
         """
         async with self._lock:
-            now = datetime.utcnow()
+            now = datetime.now(timezone.utc)
 
             if key in self._store:
                 entry = self._store[key]

backend/app/memory/working.py

@@ -4,20 +4,25 @@ from __future__ import annotations
 
 import asyncio
 from collections import OrderedDict
-from datetime import datetime
+from datetime import datetime, timezone
 from typing import Any
 
 from pydantic import BaseModel, Field
 
 
+def _utc_now() -> datetime:
+    """Return current UTC datetime."""
+    return datetime.now(timezone.utc)
+
+
 class WorkingMemoryItem(BaseModel):
     """A single item in working memory."""
 
     id: str
     content: Any
     priority: float = 0.0
-    created_at: datetime = Field(default_factory=datetime.utcnow)
-    last_accessed: datetime = Field(default_factory=datetime.utcnow)
+    created_at: datetime = Field(default_factory=_utc_now)
+    last_accessed: datetime = Field(default_factory=_utc_now)
     access_count: int = 0
     metadata: dict[str, Any] = Field(default_factory=dict)
 
@@ -86,7 +91,7 @@ class WorkingMemory:
                 self._counter += 1
                 item_id = f"wm_{self._counter}"
 
-            now = datetime.utcnow()
+            now = datetime.now(timezone.utc)
 
             # Check if item already exists (update it)
             if item_id in self._items:
@@ -170,7 +175,7 @@ class WorkingMemory:
             # Get last item
             item_id = next(reversed(self._items))
             item = self._items[item_id]
-            item.last_accessed = datetime.utcnow()
+            item.last_accessed = datetime.now(timezone.utc)
             item.access_count += 1
             return item
 
@@ -187,7 +192,7 @@ class WorkingMemory:
         async with self._lock:
             item = self._items.get(item_id)
             if item:
-                item.last_accessed = datetime.utcnow()
+                item.last_accessed = datetime.now(timezone.utc)
                 item.access_count += 1
                 # Move to end (mark as recently accessed)
                 self._items.move_to_end(item_id)

backend/app/models/router.py

@@ -3,7 +3,7 @@
 import asyncio
 import logging
 from dataclasses import dataclass, field
-from datetime import datetime
+from datetime import datetime, timezone
 from enum import Enum
 from typing import Any
 
@@ -123,7 +123,7 @@ class CostTracker:
         self.cost_by_model = {}
         self.request_count = 0
         self.total_tokens = TokenUsage()
-        self.start_time = datetime.utcnow()
+        self.start_time = datetime.now(timezone.utc)
 
 
 class SmartModelRouter: