Change triaged_at for existing reports

Author: ksy36

server/reportmanager/migrations/0019_migrate_hide_until_to_triage_status.py

@@ -1,18 +1,24 @@
 # Generated by Django 6.0.4 on 2026-04-24 17:02
 
+from datetime import timedelta
+
 from django.db import migrations
-from django.utils import timezone
+from django.db.models import ExpressionWrapper, F
+from django.db.models.fields import DateTimeField
 
 
 def migrate_triage_data(apps, schema_editor):
     """Migrate hide_until data to triage_status field."""
     Bucket = apps.get_model('reportmanager', 'Bucket')
-    now = timezone.now()
 
     # All currently triaged buckets (hide_until is not NULL) → 'worksforme'
+    # triaged_at is set to hide_until - 4 weeks to approximate when triage happened
     triaged_count = Bucket.objects.filter(hide_until__isnull=False).update(
         triage_status='worksforme',
-        triaged_at=now
+        triaged_at=ExpressionWrapper(
+            F('hide_until') - timedelta(weeks=4),
+            output_field=DateTimeField(),
+        ),
     )
 
     print(f"Migrated {triaged_count} triaged buckets to 'worksforme' status")