fix: use .to() for priority reordering when creating new segment overrides in V1

Creating a FeatureSegment with a priority value doesn't trigger reordering
of existing segments. Use .to() after creation to properly reorder.

Author: gagantrivedi

api/features/versioning/versioning_service.py

@@ -198,11 +198,11 @@ def _update_flag_for_versioning_v1(
             feature=feature,
             segment_id=change_set.segment_id,
             environment=environment,
-            priority=change_set.segment_priority
-            if change_set.segment_priority is not None
-            else 0,
         )
 
+        if change_set.segment_priority is not None:
+            feature_segment.to(change_set.segment_priority)
+
         target_feature_state: FeatureState = FeatureState.objects.create(
             feature=feature,
             environment=environment,

api/tests/unit/features/feature_states/test_unit_feature_states_views.py

@@ -391,6 +391,65 @@ def test_update_flag_segment_override_creates_feature_segment_if_not_exists(
     ][0]
     assert segment_override.enabled is True
     assert segment_override.get_feature_state_value() == "premium_feature"
+    assert segment_override.feature_segment is not None
+    assert segment_override.feature_segment.priority == 10
+
+
+def test_create_new_segment_override_reorders_priorities_v1(
+    staff_client: APIClient,
+    feature: Feature,
+    environment: Environment,
+    project: Project,
+    with_environment_permissions: WithEnvironmentPermissionsCallable,
+) -> None:
+    # Given
+    with_environment_permissions([UPDATE_FEATURE_STATE])  # type: ignore[call-arg]
+
+    segment1 = Segment.objects.create(name="segment1", project=project)
+    segment2 = Segment.objects.create(name="segment2", project=project)
+
+    # Create existing segment override at priority 0
+    feature_segment1 = FeatureSegment.objects.create(
+        feature=feature,
+        segment=segment1,
+        environment=environment,
+        priority=0,
+    )
+    FeatureState.objects.create(
+        feature=feature,
+        environment=environment,
+        feature_segment=feature_segment1,
+        enabled=True,
+    )
+
+    url = reverse(
+        "api-experiments:update-flag-v1",
+        kwargs={"environment_key": environment.api_key},
+    )
+
+    # When - Create new segment override at priority 0 (should push segment1 to priority 1)
+    data = {
+        "feature": {"name": feature.name},
+        "segment": {"id": segment2.id, "priority": 0},
+        "enabled": True,
+        "value": {"type": "string", "string_value": "new_segment_value"},
+    }
+    response = staff_client.post(
+        url, data=json.dumps(data), content_type="application/json"
+    )
+
+    # Then
+    assert response.status_code == status.HTTP_204_NO_CONTENT
+
+    # Refresh from DB
+    feature_segment1.refresh_from_db()
+    feature_segment2 = FeatureSegment.objects.get(
+        feature=feature, segment=segment2, environment=environment
+    )
+
+    # segment2 should be at priority 0, segment1 should have been pushed to priority 1
+    assert feature_segment2.priority == 0
+    assert feature_segment1.priority == 1
 
 
 # Update Multiple Feature States Tests