diff --git a/api/src/backend/api/v1/serializers.py b/api/src/backend/api/v1/serializers.py
index 5b9d458ef9..182f349820 100644
--- a/api/src/backend/api/v1/serializers.py
+++ b/api/src/backend/api/v1/serializers.py
@@ -6,6 +6,7 @@ from django.conf import settings
 from django.contrib.auth import authenticate
 from django.contrib.auth.models import update_last_login
 from django.contrib.auth.password_validation import validate_password
+from django.db import IntegrityError
 from drf_spectacular.utils import extend_schema_field
 from jwt.exceptions import InvalidKeyError
 from rest_framework.reverse import reverse
@@ -18,7 +19,7 @@ from rest_framework_simplejwt.serializers import TokenObtainPairSerializer
 from rest_framework_simplejwt.tokens import RefreshToken
 
 from api.db_router import MainRouter
-from api.exceptions import ConflictException, ModelValidationError
+from api.exceptions import ConflictException
 from api.models import (
     Finding,
     Integration,
@@ -2964,9 +2965,12 @@ class LighthouseProviderConfigSerializer(RLSSerializer):
             "inserted_at": {"read_only": True},
             "updated_at": {"read_only": True},
             "is_active": {"read_only": True},
-            "url": {"read_only": True},
+            "url": {"read_only": True, "view_name": "lighthouse-providers-detail"},
         }
 
+    class JSONAPIMeta:
+        resource_name = "lighthouse-providers"
+
     def to_representation(self, instance):
         data = super().to_representation(instance)
         # Support JSON:API fields filter: fields[lighthouse-providers]=credentials
@@ -2990,7 +2994,12 @@ class LighthouseProviderConfigSerializer(RLSSerializer):
                     return [mask_value(v) for v in value]
                 return value
 
-            data["credentials"] = mask_value(creds) if creds is not None else None
+            # Always return masked credentials, even if creds is None
+            if creds is not None:
+                data["credentials"] = mask_value(creds)
+            else:
+                # If credentials_decoded returns None, return None for credentials field
+                data["credentials"] = None
 
         return data
 
@@ -3001,7 +3010,7 @@ class LighthouseProviderConfigCreateSerializer(RLSSerializer, BaseWriteSerialize
     Accepts credentials as JSON; stored encrypted via credentials_decoded.
     """
 
-    credentials = serializers.JSONField(write_only=True)
+    credentials = serializers.JSONField(write_only=True, required=True)
 
     class Meta:
         model = LighthouseProviderConfiguration
@@ -3016,25 +3025,22 @@ class LighthouseProviderConfigCreateSerializer(RLSSerializer, BaseWriteSerialize
             "base_url": {"required": False, "allow_null": True},
         }
 
-    def validate(self, attrs):
-        tenant_id = self.context.get("tenant_id")
-        provider_type = attrs.get("provider_type")
-        if LighthouseProviderConfiguration.objects.filter(
-            tenant_id=tenant_id, provider_type=provider_type
-        ).exists():
-            raise ValidationError(
-                {
-                    "provider_type": "Configuration for this provider already exists for the tenant.",
-                }
-            )
-        return super().validate(attrs)
-
     def create(self, validated_data):
         credentials = validated_data.pop("credentials")
-        instance = super().create(validated_data)
+
+        instance = LighthouseProviderConfiguration(**validated_data)
+        instance.tenant_id = self.context.get("tenant_id")
         instance.credentials_decoded = credentials
-        instance.save()
-        return instance
+
+        try:
+            instance.save()
+            return instance
+        except IntegrityError:
+            raise ValidationError(
+                {
+                    "provider_type": "Configuration for this provider already exists for the tenant."
+                }
+            )
 
 
 class LighthouseProviderConfigUpdateSerializer(BaseWriteSerializer):
@@ -3062,10 +3068,14 @@ class LighthouseProviderConfigUpdateSerializer(BaseWriteSerializer):
 
     def update(self, instance, validated_data):
         credentials = validated_data.pop("credentials", None)
-        instance = super().update(instance, validated_data)
+
+        for attr, value in validated_data.items():
+            setattr(instance, attr, value)
+
         if credentials is not None:
             instance.credentials_decoded = credentials
-            instance.save()
+
+        instance.save()
         return instance
 
 
@@ -3106,7 +3116,8 @@ class LighthouseTenantConfigSerializer(RLSSerializer):
 class LighthouseTenantConfigCreateSerializer(RLSSerializer, BaseWriteSerializer):
     """
     Create serializer for LighthouseTenantConfiguration.
-    Ensures one record per tenant.
+
+    Note: One record per tenant constraint is enforced by database and model.clean().
     """
 
     class Meta:
@@ -3117,13 +3128,13 @@ class LighthouseTenantConfigCreateSerializer(RLSSerializer, BaseWriteSerializer)
             "default_models",
         ]
 
-    def validate(self, attrs):
-        tenant_id = self.context.get("tenant_id")
-        if LighthouseTenantConfiguration.objects.filter(tenant_id=tenant_id).exists():
+    def create(self, validated_data):
+        try:
+            return super().create(validated_data)
+        except IntegrityError:
             raise ValidationError(
                 {"tenant_id": "Tenant Lighthouse configuration already exists."}
             )
-        return super().validate(attrs)
 
 
 class LighthouseTenantConfigUpdateSerializer(BaseWriteSerializer):
@@ -3139,47 +3150,6 @@ class LighthouseTenantConfigUpdateSerializer(BaseWriteSerializer):
             "id": {"read_only": True},
         }
 
-    def validate(self, attrs):
-        """
-        Validate only that default_provider (if supplied):
-        - is a supported provider type, and
-        - has an active provider configuration for this tenant.
-        """
-        validated_attrs = super().validate(attrs)
-
-        default_provider = validated_attrs.get("default_provider", None)
-
-        # To set a default provider, it must be one of the supported provider types and have an active configuration for this tenant
-        if default_provider is not None and default_provider != "":
-            supported_providers = [
-                choice[0]
-                for choice in LighthouseProviderConfiguration.ProviderChoices.choices
-            ]
-            if default_provider not in supported_providers:
-                raise ModelValidationError(
-                    detail=f"Unsupported provider '{default_provider}'",
-                    code="unsupported_default_provider",
-                    pointer="/data/attributes/default_provider",
-                )
-
-            tenant_id = (
-                self.instance.tenant_id
-                if self.instance
-                else self.context.get("tenant_id")
-            )
-            if not LighthouseProviderConfiguration.objects.filter(
-                tenant_id=tenant_id,
-                provider_type=default_provider,
-                is_active=True,
-            ).exists():
-                raise ModelValidationError(
-                    detail=f"No active configuration found for provider '{default_provider}'",
-                    code="invalid_default_provider",
-                    pointer="/data/attributes/default_provider",
-                )
-
-        return validated_attrs
-
 
 # Lighthouse: Provider models