fix: replace datetime.UTC with timezone.utc for Python 3.10 compatibility

datetime.UTC was introduced in Python 3.11. Users on 3.10 get an ImportError.
Also lower ruff/mypy target-version from py313 to py310 to match minimum supported version.

backend/app/api/routes/canvas.py

@@ -1,4 +1,4 @@
-from datetime import UTC, datetime
+from datetime import datetime, timezone
 from typing import Any
 
 from fastapi import APIRouter, Depends
@@ -71,7 +71,7 @@ async def save_canvas(
     state = await db.get(CanvasState, 1)
     if state:
         state.viewport = body.viewport
-        state.saved_at = datetime.now(UTC)
+        state.saved_at = datetime.now(timezone.utc)
     else:
         db.add(CanvasState(id=1, viewport=body.viewport))
 

backend/app/core/scheduler.py

@@ -1,6 +1,6 @@
 """APScheduler setup for background scan and status check jobs."""
 import logging
-from datetime import UTC, datetime
+from datetime import datetime, timezone
 
 from apscheduler.schedulers.asyncio import AsyncIOScheduler
 from sqlalchemy import select
@@ -33,12 +33,12 @@ async def _run_status_checks() -> None:
                 if n:
                     n.status = check_result["status"]
                     n.response_time_ms = check_result["response_time_ms"]
-                    n.last_seen = datetime.now(UTC) if check_result["status"] == "online" else n.last_seen
+                    n.last_seen = datetime.now(timezone.utc) if check_result["status"] == "online" else n.last_seen
                     await db.commit()
             await broadcast_status(
                 node_id=node.id,
                 status=check_result["status"],
-                checked_at=datetime.now(UTC).isoformat(),
+                checked_at=datetime.now(timezone.utc).isoformat(),
                 response_time_ms=check_result["response_time_ms"],
             )
         except Exception as exc:

backend/app/core/security.py

@@ -1,4 +1,4 @@
-from datetime import UTC, datetime, timedelta
+from datetime import datetime, timedelta, timezone
 
 from jose import JWTError, jwt
 from passlib.context import CryptContext
@@ -17,7 +17,7 @@ def hash_password(password: str) -> str:
 
 
 def create_access_token(subject: str) -> str:
-    expire = datetime.now(UTC) + timedelta(minutes=settings.access_token_expire_minutes)
+    expire = datetime.now(timezone.utc) + timedelta(minutes=settings.access_token_expire_minutes)
     payload = {"sub": subject, "exp": expire}
     return str(jwt.encode(payload, settings.secret_key, algorithm=settings.algorithm))
 

backend/app/db/models.py

@@ -1,5 +1,5 @@
 import uuid
-from datetime import UTC, datetime
+from datetime import datetime, timezone
 from typing import Any
 
 from sqlalchemy import JSON, Boolean, DateTime, Float, ForeignKey, Integer, String, Text
@@ -9,7 +9,7 @@ from app.db.database import Base
 
 
 def _now() -> datetime:
-    return datetime.now(UTC)
+    return datetime.now(timezone.utc)
 
 
 def _uuid() -> str:

backend/app/services/scanner.py

@@ -2,7 +2,7 @@
 import asyncio
 import logging
 import socket
-from datetime import UTC, datetime
+from datetime import datetime, timezone
 from typing import Any
 
 from sqlalchemy.ext.asyncio import AsyncSession
@@ -159,7 +159,7 @@ async def run_scan(ranges: list[str], db: AsyncSession, run_id: str) -> None:
         if run:
             run.status = "done"
             run.devices_found = devices_found
-            run.finished_at = datetime.now(UTC)
+            run.finished_at = datetime.now(timezone.utc)
             await db.commit()
 
     except Exception as exc:
@@ -168,5 +168,5 @@ async def run_scan(ranges: list[str], db: AsyncSession, run_id: str) -> None:
         if run:
             run.status = "error"
             run.error = str(exc)
-            run.finished_at = datetime.now(UTC)
+            run.finished_at = datetime.now(timezone.utc)
             await db.commit()

backend/pyproject.toml

@@ -1,5 +1,5 @@
 [tool.ruff]
-target-version = "py313"
+target-version = "py310"
 line-length = 120
 exclude = ["migrations", ".venv"]
 
@@ -11,7 +11,7 @@ ignore = ["B008"]
 "tests/**" = ["E501"]
 
 [tool.mypy]
-python_version = "3.13"
+python_version = "3.10"
 strict = true
 ignore_missing_imports = true
 exclude = ["migrations", ".venv"]