remove commented out code

src/pretix/base/migrations/0302_customerssoprovider_allow_convert_to_sso.py

@@ -0,0 +1,18 @@
+# Generated by Django 5.2.12 on 2026-07-01 08:34
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("pretixbase", "0301_reusablemedium_remove_orderposition"),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name="customerssoprovider",
+            name="allow_convert_to_sso",
+            field=models.BooleanField(default=False),
+        ),
+    ]

src/pretix/base/models/customers.py

@@ -73,6 +73,13 @@ class CustomerSSOProvider(LoggedModel):
         null=False, blank=False,
         choices=METHODS,
     )
+    allow_convert_to_sso = models.BooleanField(
+        default=False,
+        verbose_name=_("Convert existing customers to single-sign-on accounts on login"),
+        help_text=_(
+            "If enabled, when an existing customer registered with email and password tries to login through this SSO provider, pretix changes the account to single-sign-on. Otherwise pretix does not allow to log in."
+        ),
+    )
     configuration = models.JSONField()
 
     def allow_delete(self):

src/pretix/control/forms/organizer.py

@@ -1244,7 +1244,7 @@ class SSOProviderForm(I18nModelForm):
 
     class Meta:
         model = CustomerSSOProvider
-        fields = ['is_active', 'name', 'button_label', 'method']
+        fields = ['is_active', 'name', 'button_label', 'method', 'allow_convert_to_sso']
         widgets = {
             'method': forms.RadioSelect,
         }

src/pretix/control/templates/pretixcontrol/organizers/edit.html

@@ -132,6 +132,7 @@
                         <legend>{% trans "Customer accounts" %}</legend>
                         {% bootstrap_field sform.customer_accounts layout="control" %}
                         {% bootstrap_field sform.customer_accounts_native layout="control" %}
+                        {% bootstrap_field sform.customer_accounts_to_oidc layout="control" %}
                         {% bootstrap_field sform.customer_accounts_require_login_for_order_access layout="control" %}
                         {% bootstrap_field sform.customer_accounts_link_by_email layout="control" %}
                         {% bootstrap_field sform.name_scheme layout="control" %}

src/pretix/presale/views/customer.py

@@ -864,11 +864,33 @@ class SSOLoginReturnView(RedirectBackMixin, View):
                         identifier=identifier,
                     )
                 except Customer.DoesNotExist:
-                    return self._fail(
-                        _('We were unable to use your login since the email address {email} is already used for a '
-                          'different account in this system.').format(email=profile['email']),
-                        popup_origin,
-                    )
+                    # no race-condition, try to convert to oidc?
+                    if self.provider.allow_convert_to_sso:
+                        try:
+                            customer = self.request.organizer.customers.get(
+                                email=profile['email'],
+                            )
+                            customer.set_unusable_password()
+                            customer.provider = self.provider
+                            customer.external_identifier = str(profile['uid'])
+                            customer.is_verified = True
+                            if name_parts:
+                                customer.name_parts = name_parts
+                            if profile.get('phone'):
+                                customer.phone = profile.get('phone')
+                            customer.save()
+                        except Customer.DoesNotExist:
+                            # should actually never happen
+                            return self._fail(
+                                _('We were unable to use your login since either the email address is unknown in this system.'),
+                                popup_origin,
+                            )
+                    else:
+                        return self._fail(
+                            _('We were unable to use your login since the email address {email} is already used for a '
+                              'different account in this system.').format(email=profile['email']),
+                            popup_origin,
+                        )
         else:
             if customer.is_active and customer.email != profile['email']:
                 customer.email = profile['email']

src/tests/presale/test_customer.py

@@ -438,6 +438,24 @@ def test_org_sso_login_new_customer_email_conflict(env, client, provider):
     _sso_login(client, provider, 'new@example.net', expect_fail=True)
 
 
+@pytest.mark.django_db(transaction=True)
+def test_org_sso_convert_customer_on_login(env, client, provider):
+    organizer = env[0]
+    provider.allow_convert_to_sso = True
+    provider.save()
+    with scopes_disabled():
+        customer = organizer.customers.create(email='new@example.net', is_verified=True, is_active=False)
+        customer.set_password('foo')
+        customer.save()
+
+    _sso_login(client, provider, 'new@example.net')
+
+    customer.refresh_from_db()
+    assert customer.provider
+    assert customer.identifier
+    assert not customer.has_usable_password()
+
+
 @pytest.mark.django_db
 @pytest.mark.parametrize("url", [
     "account/change",