chore: refactor lighthouse config singleton code

api/src/backend/api/v1/serializers.py

@@ -3187,82 +3187,6 @@ class LighthouseTenantConfigSerializer(RLSSerializer):
         }
 
 
-class LighthouseTenantConfigCreateSerializer(RLSSerializer, BaseWriteSerializer):
-    """
-    Create serializer for LighthouseTenantConfiguration.
-
-    Note: One record per tenant constraint is enforced by database and model.clean().
-    """
-
-    class Meta:
-        model = LighthouseTenantConfiguration
-        fields = [
-            "business_context",
-            "default_provider",
-            "default_models",
-        ]
-
-    def validate(self, attrs):
-        request = self.context.get("request")
-        tenant_id = self.context.get("tenant_id") or (
-            getattr(request, "tenant_id", None) if request else None
-        )
-
-        default_provider = attrs.get("default_provider", "")
-        default_models = attrs.get("default_models", {})
-
-        if default_provider:
-            supported = set(LighthouseProviderConfiguration.LLMProviderChoices.values)
-            if default_provider not in supported:
-                raise ValidationError(
-                    {"default_provider": f"Unsupported provider '{default_provider}'."}
-                )
-            if not LighthouseProviderConfiguration.objects.filter(
-                tenant_id=tenant_id, provider_type=default_provider, is_active=True
-            ).exists():
-                raise ValidationError(
-                    {
-                        "default_provider": f"No active configuration found for '{default_provider}'."
-                    }
-                )
-
-        if default_models is not None and not isinstance(default_models, dict):
-            raise ValidationError(
-                {"default_models": "Must be an object mapping provider -> model_id."}
-            )
-
-        for provider_type, model_id in (default_models or {}).items():
-            provider_cfg = LighthouseProviderConfiguration.objects.filter(
-                tenant_id=tenant_id, provider_type=provider_type, is_active=True
-            ).first()
-            if not provider_cfg:
-                raise ValidationError(
-                    {
-                        "default_models": f"No active configuration for provider '{provider_type}'."
-                    }
-                )
-            if not LighthouseProviderModels.objects.filter(
-                tenant_id=tenant_id,
-                provider_configuration=provider_cfg,
-                model_id=model_id,
-            ).exists():
-                raise ValidationError(
-                    {
-                        "default_models": f"Invalid model '{model_id}' for provider '{provider_type}'."
-                    }
-                )
-
-        return super().validate(attrs)
-
-    def create(self, validated_data):
-        try:
-            return super().create(validated_data)
-        except IntegrityError:
-            raise ValidationError(
-                {"tenant_id": "Tenant Lighthouse configuration already exists."}
-            )
-
-
 class LighthouseTenantConfigUpdateSerializer(BaseWriteSerializer):
     class Meta:
         model = LighthouseTenantConfiguration

api/src/backend/api/v1/urls.py

@@ -37,12 +37,12 @@ from api.v1.views import (
     ScheduleViewSet,
     SchemaView,
     TaskViewSet,
+    TenantApiKeyViewSet,
     TenantFinishACSView,
     TenantMembersViewSet,
     TenantViewSet,
     UserRoleRelationshipView,
     UserViewSet,
-    TenantApiKeyViewSet,
 )
 
 router = routers.DefaultRouter(trailing_slash=False)
@@ -154,7 +154,7 @@ urlpatterns = [
     path(
         "lighthouse/config",
         LighthouseTenantConfigViewSet.as_view(
-            {"get": "retrieve", "post": "create", "patch": "partial_update"}
+            {"get": "list", "patch": "partial_update"}
         ),
         name="lighthouse-config",
     ),

api/src/backend/api/v1/views.py

@@ -171,7 +171,6 @@ from api.v1.serializers import (
     LighthouseProviderConfigSerializer,
     LighthouseProviderConfigUpdateSerializer,
     LighthouseProviderModelsSerializer,
-    LighthouseTenantConfigCreateSerializer,
     LighthouseTenantConfigSerializer,
     LighthouseTenantConfigUpdateSerializer,
     MembershipSerializer,
@@ -4354,35 +4353,29 @@ class LighthouseProviderConfigViewSet(BaseRLSViewSet):
 
 @extend_schema_view(
     list=extend_schema(
-        tags=["Lighthouse AI"],
-        summary="List tenant config",
-        description="List Lighthouse AI tenant-level settings for the current tenant.",
-    ),
-    retrieve=extend_schema(
         tags=["Lighthouse AI"],
         summary="Get tenant config",
-        description="Retrieve tenant Lighthouse AI settings by ID.",
-    ),
-    create=extend_schema(
-        tags=["Lighthouse AI"],
-        summary="Create tenant config",
-        description="Create Lighthouse AI tenant-level settings. Only one configuration is allowed per tenant.",
+        description="Retrieve current tenant-level Lighthouse AI settings. Returns a single configuration object.",
     ),
     partial_update=extend_schema(
         tags=["Lighthouse AI"],
         summary="Update tenant config",
-        description="Update tenant-level settings. Validates that the default provider is configured and active and that default model IDs exist for the chosen providers.",
-    ),
-    destroy=extend_schema(
-        tags=["Lighthouse AI"],
-        summary="Delete tenant config",
-        description="Delete tenant Lighthouse AI settings for the current tenant.",
+        description="Update tenant-level settings. Validates that the default provider is configured and active and that default model IDs exist for the chosen providers. Auto-creates configuration if it doesn't exist.",
     ),
 )
 class LighthouseTenantConfigViewSet(BaseRLSViewSet):
+    """
+    Singleton endpoint for tenant-level Lighthouse AI configuration.
+
+    This viewset implements a true singleton pattern:
+    - GET returns the single configuration object (or 404 if not found)
+    - PATCH updates/creates the configuration (upsert semantics)
+    - No ID is required in the URL
+    """
+
     queryset = LighthouseTenantConfiguration.objects.all()
     serializer_class = LighthouseTenantConfigSerializer
-    http_method_names = ["get", "post", "patch", "delete"]
+    http_method_names = ["get", "patch"]
 
     def get_queryset(self):
         if getattr(self, "swagger_fake_view", False):
@@ -4392,9 +4385,7 @@ class LighthouseTenantConfigViewSet(BaseRLSViewSet):
         )
 
     def get_serializer_class(self):
-        if self.action == "create":
-            return LighthouseTenantConfigCreateSerializer
-        elif self.action == "partial_update":
+        if self.action == "partial_update":
             return LighthouseTenantConfigUpdateSerializer
         return super().get_serializer_class()
 
@@ -4408,8 +4399,8 @@ class LighthouseTenantConfigViewSet(BaseRLSViewSet):
         self.check_object_permissions(self.request, obj)
         return obj
 
-    def retrieve(self, request, *args, **kwargs):
-        """GET endpoint for singleton - no pk required."""
+    def list(self, request, *args, **kwargs):
+        """GET endpoint for singleton - returns single object, not an array."""
         instance = self.get_object()
         serializer = self.get_serializer(instance)
         return Response(serializer.data)