Convert timestamps to IST server-side so display is correct regardless of browser cache

app/main.py

@@ -3,7 +3,7 @@ import io
 import json
 import os
 import uuid
-from datetime import timezone
+from datetime import timedelta, timezone
 from pathlib import Path
 from typing import Optional
 
@@ -32,15 +32,16 @@ import logging
 logger = logging.getLogger(__name__)
 
 
-def _isoformat_utc(dt):
-    """Return an ISO-8601 string with explicit +00:00 so the browser can
-    convert to local time.  SQLite strips tzinfo on read, so naive datetimes
-    that we know are UTC need the suffix added back."""
+_IST = timezone(timedelta(hours=5, minutes=30))
+
+
+def _isoformat_ist(dt):
+    """Convert a UTC datetime to IST (GMT+5:30) and return ISO-8601 string."""
     if dt is None:
         return None
     if dt.tzinfo is None:
         dt = dt.replace(tzinfo=timezone.utc)
-    return dt.isoformat()
+    return dt.astimezone(_IST).isoformat()
 
 # Create tables and run migrations without crashing the app (HF Spaces can restart if startup fails)
 try:
@@ -354,7 +355,7 @@ async def detect(
         "beforeThumbUrl": f"/api/overlay/{relative_before_thumb}",
         "afterThumbUrl": f"/api/overlay/{relative_after_thumb}",
         "notificationSent": notification_sent,
-        "createdAt": _isoformat_utc(run.created_at),
+        "createdAt": _isoformat_ist(run.created_at),
     }
 
 
@@ -395,7 +396,7 @@ def history(
             "overlayUrl": f"/api/overlay/{r.overlay_path}" if r.overlay_path else None,
             "beforeThumbUrl": f"/api/overlay/{r.before_thumb_path}" if (getattr(r, "before_thumb_path", None) or "").strip() else None,
             "afterThumbUrl": f"/api/overlay/{r.after_thumb_path}" if (getattr(r, "after_thumb_path", None) or "").strip() else None,
-            "createdAt": _isoformat_utc(r.created_at),
+            "createdAt": _isoformat_ist(r.created_at),
         }
         for r in runs
     ]
@@ -434,7 +435,7 @@ def get_run(
         "beforeFullUrl": f"/api/overlay/{run.before_full_path}" if (getattr(run, "before_full_path", None) or "").strip() else None,
         "beforeThumbUrl": f"/api/overlay/{run.before_thumb_path}" if (getattr(run, "before_thumb_path", None) or "").strip() else None,
         "afterThumbUrl": f"/api/overlay/{run.after_thumb_path}" if (getattr(run, "after_thumb_path", None) or "").strip() else None,
-        "createdAt": _isoformat_utc(run.created_at),
+        "createdAt": _isoformat_ist(run.created_at),
     }