fix: address Greptile P1s — CLI-safe timezone import + DB connection leak

P1: `from django.utils import timezone` at module level crashes when
    visitran is used as a standalone CLI without Django installed.
    Wrapped in try/except with a minimal fallback that provides
    timezone.now() via stdlib datetime.

P1: close_db_connection() was only called in the success path of
    execute_run_command. On exception the connection leaked. Moved
    to a finally block so it always runs regardless of outcome.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: abhizipstack

backend/backend/core/routers/execute/views.py

@@ -59,7 +59,6 @@ def execute_run_command(request: Request, project_id: str) -> Response:
     app = ApplicationContext(project_id=project_id)
     try:
         app.execute_visitran_run_command(current_model=file_name, environment_id=environment_id)
-        app.visitran_context.close_db_connection()
         app.backup_current_no_code_model()
         logger.info(f"[execute_run_command] Completed successfully for file_name={file_name}")
         _data = {"status": "success"}
@@ -68,6 +67,8 @@ def execute_run_command(request: Request, project_id: str) -> Response:
         logger.exception(f"[execute_run_command] DAG execution failed for file_name={file_name}")
         _data = {"status": "failed", "error_message": "Model execution failed. Check server logs for details."}
         return Response(data=_data, status=status.HTTP_400_BAD_REQUEST)
+    finally:
+        app.visitran_context.close_db_connection()
 
 
 

backend/visitran/visitran.py

@@ -16,7 +16,15 @@
 
 import ibis
 import networkx as nx
-from django.utils import timezone
+try:
+    from django.utils import timezone
+except ImportError:
+    from datetime import datetime, timezone as _tz
+
+    class timezone:
+        @staticmethod
+        def now():
+            return datetime.now(_tz.utc)
 from visitran import utils
 from visitran.adapters.adapter import BaseAdapter
 from visitran.adapters.seed import BaseSeed