régler erreur 500 sur changement de role par admin

app/routes/users.py

@@ -112,14 +112,19 @@ def edit_user(user_id):
         discord_user_id = request.form.get('discord_user_id', '').strip()
         league_os_profile = request.form.get('league_os_profile', '').strip()
 
-        # Change role via raw SQL to avoid polymorphic identity corruption
+        # Change role via raw SQL to avoid polymorphic identity corruption.
+        # Must discard the entire session because the polymorphic discriminator
+        # change invalidates the identity map for this instance and anything
+        # that references it via relationships.
         if user.role != role:
+            user_id_local = user.id
             db.session.execute(
                 db.text("UPDATE users SET role = :role WHERE id = :id"),
-                {"role": role, "id": user.id}
+                {"role": role, "id": user_id_local}
             )
             db.session.commit()
-            user = User.query.get(user_id)  # re-fetch with correct polymorphic class
+            db.session.remove()  # discard stale session entirely
+            user = User.query.get(user_id_local)  # fresh session, correct class
 
         user.full_name = full_name
         user.email = email