feat(nimbus): Add subscribers field to feature config model. (#13787)

Because

- We want to allow a user to subscribe to a feature and get
notifications when that feature is used

This commit

- Adds the subscribers field to the Feature Config class.

Fixes #13783

Author: b4handjr

experimenter/experimenter/experiments/migrations/0297_nimbusfeatureconfig_subscribers.py

@@ -0,0 +1,24 @@
+# Generated by Django 5.2.7 on 2025-10-27 15:00
+
+from django.conf import settings
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("experiments", "0296_nimbusexperiment_qa_run_date_and_more"),
+        migrations.swappable_dependency(settings.AUTH_USER_MODEL),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name="nimbusfeatureconfig",
+            name="subscribers",
+            field=models.ManyToManyField(
+                blank=True,
+                related_name="subscribed_nimbus_features",
+                to=settings.AUTH_USER_MODEL,
+                verbose_name="Subscribers",
+            ),
+        ),
+    ]

experimenter/experimenter/experiments/models.py

@@ -2291,6 +2291,12 @@ class NimbusFeatureConfig(models.Model):
     )
     owner_email = models.EmailField(blank=True, null=True)
     enabled = models.BooleanField(default=True)
+    subscribers = models.ManyToManyField(
+        User,
+        related_name="subscribed_nimbus_features",
+        blank=True,
+        verbose_name="Subscribers",
+    )
 
     class Meta:
         verbose_name = "Nimbus Feature Config"

experimenter/experimenter/experiments/tests/factories.py

@@ -108,6 +108,18 @@ def schemas(self, create, extracted, **kwargs):
                 )
             )
 
+    @factory.post_generation
+    def subscribers(self, create, extracted, **kwargs):
+        if not create:
+            return
+
+        if isinstance(extracted, Iterable):
+            for subscriber in extracted:
+                self.subscribers.add(subscriber)
+        else:
+            for _ in range(3):
+                self.subscribers.add(UserFactory.create())
+
     @classmethod
     def create_desktop_prefflips_feature(cls, **kwargs):
         """Create a feature for Firefox Desktop with the slug "prefFlips"."""

experimenter/experimenter/experiments/tests/test_changelog_utils.py

@@ -277,6 +277,7 @@ def test_outputs_expected_schema_for_complete_experiment(self):
                     "schema": feature_config.schemas.get(version=None).schema,
                     "slug": feature_config.slug,
                     "enabled": feature_config.enabled,
+                    "subscribers": [user.id for user in feature_config.subscribers.all()],
                 },
                 feature_configs_data,
             )

experimenter/experimenter/experiments/tests/test_models.py

@@ -5516,6 +5516,27 @@ def test_get_versioned_schema_range(self):
             ),
         )
 
+    def test_feature_config_can_have_subscribers(self):
+        user1 = UserFactory.create()
+        user2 = UserFactory.create()
+        feature = NimbusFeatureConfigFactory.create()
+        feature.subscribers.add(user1, user2)
+
+        self.assertEqual(feature.subscribers.count(), 5)
+        self.assertIn(user1, feature.subscribers.all())
+        self.assertIn(user2, feature.subscribers.all())
+
+    def test_user_can_subscribe_to_multiple_feature_configs(self):
+        user = UserFactory.create()
+        feature1 = NimbusFeatureConfigFactory.create()
+        feature2 = NimbusFeatureConfigFactory.create()
+        feature1.subscribers.add(user)
+        feature2.subscribers.add(user)
+
+        self.assertEqual(user.subscribed_nimbus_features.count(), 2)
+        self.assertIn(feature1, user.subscribed_nimbus_features.all())
+        self.assertIn(feature2, user.subscribed_nimbus_features.all())
+
 
 class ApplicationConfigTests(TestCase):
     application_config = experimenter.experiments.constants.APPLICATION_CONFIG_DESKTOP