feat(nimbus): For complete experiment do not update monitoring data as unenrollment spikes (#15455)

Because

- when the experiment ends clients will all start unenrolling so now
every summary page shows 'unexpectedly high unenrollment' after the
experiment ends because all the clients are unenrolling at the end, we
can do is stop notifying or updating the experiment monitoring data once
the experiment is ended, if we stop updating it, it will never notify it

This commit

- Shows last updated time at summary page
- Does not update monitoring data for the completed experiments.

Fixes #15441

Co-authored-by: Yashika Khurana <yashikakhurana@Yashikas-MBP.home.local>

Author: yashikakhurana

experimenter/experimenter/experiments/migrations/0329_nimbusexperiment_monitoring_data_updated_at.py

@@ -0,0 +1,18 @@
+# Generated by Django 5.2.13 on 2026-04-23
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('experiments', '0328_alter_nimbusexperiment_firefox_labs_group'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='nimbusexperiment',
+            name='monitoring_data_updated_at',
+            field=models.DateTimeField(blank=True, null=True, verbose_name='Monitoring Data Last Updated'),
+        ),
+    ]

experimenter/experimenter/experiments/models.py

@@ -351,6 +351,11 @@ def default_firefox_version_parsed():
             "(enrollment/unenrollment counts, reasons, branches)"
         ),
     )
+    monitoring_data_updated_at = models.DateTimeField(
+        "Monitoring Data Last Updated",
+        blank=True,
+        null=True,
+    )
     risk_partner_related = models.BooleanField(
         "Is a Partner Related Risk Flag", default=None, blank=True, null=True
     )

experimenter/experimenter/experiments/tests/test_changelog_utils.py

@@ -88,6 +88,7 @@ def test_outputs_expected_schema_for_empty_experiment(self):
                 "locales": [],
                 "localizations": None,
                 "monitoring_data": None,
+                "monitoring_data_updated_at": None,
                 "name": "",
                 "next_steps": None,
                 "owner": owner.email,
@@ -220,6 +221,7 @@ def test_outputs_expected_schema_for_complete_experiment(self):
                 "legal_signoff": False,
                 "localizations": experiment.localizations,
                 "monitoring_data": experiment.monitoring_data,
+                "monitoring_data_updated_at": experiment.monitoring_data_updated_at,
                 "name": experiment.name,
                 "next_steps": None,
                 "owner": experiment.owner.email,

experimenter/experimenter/jetstream/tasks.py

@@ -4,6 +4,7 @@
 from celery.utils.log import get_task_logger
 from django.conf import settings
 from django.core.cache import cache
+from django.utils import timezone
 
 from experimenter.celery import app
 from experimenter.experiments.changelog_utils import generate_nimbus_changelog
@@ -149,15 +150,13 @@ def fetch_monitoring_data():
             try:
                 experiment = NimbusExperiment.objects.get(
                     slug=exp_slug,
-                    status__in=[
-                        NimbusConstants.Status.LIVE,
-                        NimbusConstants.Status.COMPLETE,
-                    ],
+                    status=NimbusConstants.Status.LIVE,
                 )
 
                 # Only update if data has changed
                 if experiment.monitoring_data != monitoring_data:
                     experiment.monitoring_data = monitoring_data
+                    experiment.monitoring_data_updated_at = timezone.now()
                     experiment.save()
                     generate_nimbus_changelog(
                         experiment,

experimenter/experimenter/jetstream/tests/test_tasks.py

@@ -3457,15 +3457,9 @@ def test_fetch_monitoring_data_no_data(self, return_value):
 
         self.mock_get_monitoring_data.assert_called_once()
 
-    @parameterized.expand(
-        [
-            (NimbusExperiment.Status.LIVE,),
-            (NimbusExperiment.Status.COMPLETE,),
-        ]
-    )
-    def test_fetch_monitoring_data_updates_live_or_complete_experiment(self, status):
+    def test_fetch_monitoring_data_updates_live_experiment(self):
         experiment = NimbusExperimentFactory.create(
-            status=status,
+            status=NimbusExperiment.Status.LIVE,
             monitoring_data={},
         )
         self.mock_get_monitoring_data.return_value = {
@@ -3476,14 +3470,16 @@ def test_fetch_monitoring_data_updates_live_or_complete_experiment(self, status)
 
         experiment.refresh_from_db()
         self.assertEqual(experiment.monitoring_data, self.monitoring_data)
+        self.assertIsNotNone(experiment.monitoring_data_updated_at)
 
     @parameterized.expand(
         [
             (NimbusExperiment.Status.DRAFT,),
             (NimbusExperiment.Status.PREVIEW,),
+            (NimbusExperiment.Status.COMPLETE,),
         ]
     )
-    def test_fetch_monitoring_data_skips_non_live_or_complete_experiment(self, status):
+    def test_fetch_monitoring_data_skips_non_live_experiment(self, status):
         experiment = NimbusExperimentFactory.create(
             status=status,
             monitoring_data={},
@@ -3496,6 +3492,7 @@ def test_fetch_monitoring_data_skips_non_live_or_complete_experiment(self, statu
 
         experiment.refresh_from_db()
         self.assertEqual(experiment.monitoring_data, {})
+        self.assertIsNone(experiment.monitoring_data_updated_at)
 
     def test_fetch_monitoring_data_skips_nonexistent_experiment(self):
         self.mock_get_monitoring_data.return_value = {

experimenter/experimenter/nimbus_ui/templates/nimbus_experiments/detail_card_monitoring.html

@@ -9,13 +9,23 @@
     <h4 class="mb-0">
       <a href="#monitoring" class="text-decoration-none text-body">{{ NimbusUIConstants.MONITORING_CARD_TITLE }}</a>
     </h4>
-    <a href="{{ NimbusUIConstants.VALIDATING_EXPERIMENTS_URL }}"
-       target="_blank"
-       rel="noopener noreferrer"
-       class="small">Learn more</a>
+    <div class="d-flex align-items-center gap-3">
+      {% if experiment.monitoring_data_updated_at %}
+        <span class="text-muted small">Last updated: {{ experiment.monitoring_data_updated_at|date:"N j, Y" }}</span>
+      {% endif %}
+      <a href="{{ NimbusUIConstants.VALIDATING_EXPERIMENTS_URL }}"
+         target="_blank"
+         rel="noopener noreferrer"
+         class="small">Learn more</a>
+    </div>
   </div>
 {% endblock %}
 {% block card_body %}
+  {% if experiment.is_complete %}
+    <div class="alert alert-secondary mx-3 mt-3 mb-0" role="alert">
+      This experiment has ended. Monitoring data reflects the last update before the experiment concluded.
+    </div>
+  {% endif %}
   {% with summary=experiment.monitoring_summary %}
     <div class="mb-3">
       {% if summary.is_unenrollment_spike %}