UN-2896 [FIX] Don't re-validate unchanged defaults in set_default_triad

The Default Triad UI submits all four defaults on every save, so validating every submitted value locked a user out of changing any default once one of theirs had been deprecated underneath them. Skip unchanged values, matching ProfileManagerSerializer.validate, and cover it with a regression test. Also drops the duplicated adapter name from the deprecation message and promotes the inline logger in serializers to module level.
Deepak-Kesavan · Aug 31, 2026 · Aug 31, 2026 · Sep 1, 2026 · Sep 1, 2026 · Sep 7, 2026
commit 1a5d92c1067cce106cd4b3e7c30d44eb70f04bd1
diff --git a/backend/adapter_processor_v2/adapter_processor.py b/backend/adapter_processor_v2/adapter_processor.py
@@ -219,6 +219,14 @@ def _resolve_selectable_adapter(adapter_pk: str) -> AdapterInstance:
             raise DeprecatedAdapter(get_deprecation_message(adapter.adapter_id))
         return adapter
 
+    # Payload key -> UserDefaultAdapter field backing that default.
+    _DEFAULT_TRIAD_FIELDS = (
+        (AdapterKeys.LLM_DEFAULT, "default_llm_adapter"),
+        (AdapterKeys.EMBEDDING_DEFAULT, "default_embedding_adapter"),
+        (AdapterKeys.VECTOR_DB_DEFAULT, "default_vector_db_adapter"),
+        (AdapterKeys.X2TEXT_DEFAULT, "default_x2text_adapter"),
+    )
+
     @staticmethod
     def set_default_triad(default_triad: dict[str, str], user: User) -> None:
         try:
@@ -230,31 +238,20 @@ def set_default_triad(default_triad: dict[str, str], user: User) -> None:
                 organization_member=organization_member
             )
 
-            if default_triad.get(AdapterKeys.LLM_DEFAULT, None):
-                user_default_adapter.default_llm_adapter = (
-                    AdapterProcessor._resolve_selectable_adapter(
-                        default_triad[AdapterKeys.LLM_DEFAULT]
-                    )
-                )
-            if default_triad.get(AdapterKeys.EMBEDDING_DEFAULT, None):
-                user_default_adapter.default_embedding_adapter = (
-                    AdapterProcessor._resolve_selectable_adapter(
-                        default_triad[AdapterKeys.EMBEDDING_DEFAULT]
-                    )
-                )
-
-            if default_triad.get(AdapterKeys.VECTOR_DB_DEFAULT, None):
-                user_default_adapter.default_vector_db_adapter = (
-                    AdapterProcessor._resolve_selectable_adapter(
-                        default_triad[AdapterKeys.VECTOR_DB_DEFAULT]
-                    )
-                )
-
-            if default_triad.get(AdapterKeys.X2TEXT_DEFAULT, None):
-                user_default_adapter.default_x2text_adapter = (
-                    AdapterProcessor._resolve_selectable_adapter(
-                        default_triad[AdapterKeys.X2TEXT_DEFAULT]
-                    )
+            for payload_key, field in AdapterProcessor._DEFAULT_TRIAD_FIELDS:
+                adapter_pk = default_triad.get(payload_key)
+                # The UI submits all four defaults on every save, so an
+                # unchanged value must not be re-validated -- otherwise a user
+                # whose stored default was deprecated under them could never
+                # change any of the other three.
+                if not adapter_pk or str(adapter_pk) == str(
+                    getattr(user_default_adapter, f"{field}_id", None)
+                ):
+                    continue
+                setattr(
+                    user_default_adapter,
+                    field,
+                    AdapterProcessor._resolve_selectable_adapter(adapter_pk),
                 )
 
             user_default_adapter.save()

diff --git a/backend/adapter_processor_v2/deprecated_adapters.py b/backend/adapter_processor_v2/deprecated_adapters.py
@@ -57,9 +57,12 @@ def is_adapter_selectable(adapter: Any) -> bool:
 
 
 def get_deprecation_message(adapter_id: str | None) -> str:
-    """User-facing reason ``adapter_id`` can no longer be used."""
+    """User-facing reason ``adapter_id`` can no longer be used.
+
+    ``reason`` is surfaced verbatim, so each entry must phrase it as a
+    complete sentence naming the adapter and its replacement.
+    """
     metadata = get_deprecation_metadata(adapter_id)
     if not metadata:
         return "This adapter has been deprecated and can no longer be used."
-    name = metadata.get("adapter_name") or "This adapter"
-    return f"{name} has been deprecated. {metadata['reason']}"
+    return metadata["reason"]
diff --git a/backend/adapter_processor_v2/serializers.py b/backend/adapter_processor_v2/serializers.py
@@ -1,4 +1,5 @@
 import json
+import logging
 from typing import Any
 
 from account_v2.serializer import UserSerializer
@@ -26,6 +27,8 @@
 
 from .models import AdapterInstance, UserDefaultAdapter
 
+logger = logging.getLogger(__name__)
+
 
 class TestAdapterSerializer(serializers.Serializer):
     adapter_id = serializers.CharField(max_length=FLC.ADAPTER_ID_LENGTH)
@@ -155,9 +158,6 @@ def to_representation(self, instance: AdapterInstance) -> dict[str, str]:
                 )
             except Exception as e:
                 # Log error but don't fail serialization
-                import logging
-
-                logger = logging.getLogger(__name__)
                 logger.warning(
                     f"Failed to retrieve icon for adapter {instance.adapter_id}: {e}"
                 )

diff --git a/backend/adapter_processor_v2/tests/test_default_triad_deprecation.py b/backend/adapter_processor_v2/tests/test_default_triad_deprecation.py
@@ -0,0 +1,91 @@
+"""``set_default_triad`` must not re-validate defaults the user did not change.
+
+The Default Triad UI submits all four defaults on every save, so a user whose
+stored default was deprecated underneath them would otherwise be locked out of
+changing any of the other three. Needs a live DB (integration tier).
+"""
+
+from __future__ import annotations
+
+import secrets
+
+import pytest
+from account_v2.models import Organization, User
+from django.test import TestCase
+from tenant_account_v2.models import OrganizationMember
+from utils.user_context import UserContext
+
+from adapter_processor_v2.adapter_processor import AdapterProcessor
+from adapter_processor_v2.exceptions import DeprecatedAdapter
+from adapter_processor_v2.models import AdapterInstance, UserDefaultAdapter
+
+LLM_WHISPERER_V1 = "llmwhisperer|0a1647f0-f65f-410d-843b-3d979c78350e"
+
+
+class SetDefaultTriadDeprecationTest(TestCase):
+    def setUp(self) -> None:
+        self.org = Organization.objects.create(
+            name="org-triad", display_name="Org Triad", organization_id="org-triad"
+        )
+        UserContext.set_organization_identifier(self.org.organization_id)
+        self.user = User.objects.create_user(
+            username="triad@example.com",
+            email="triad@example.com",
+            password=secrets.token_urlsafe(),
+        )
+        self.member = OrganizationMember.objects.create(
+            organization=self.org, user=self.user, role="user"
+        )
+
+        def make(adapter_id: str, name: str, adapter_type: str, available=True):
+            return AdapterInstance.objects.create(
+                adapter_id=adapter_id,
+                adapter_name=name,
+                adapter_type=adapter_type,
+                organization=self.org,
+                created_by=self.user,
+                is_available=available,
+            )
+
+        self.llm_a = make("openai|llm-a", "llm-a", "LLM")
+        self.llm_b = make("openai|llm-b", "llm-b", "LLM")
+        # The user's stored X2TEXT default, deprecated out from under them by
+        # migration 0007.
+        self.stale_x2text = make(LLM_WHISPERER_V1, "old-whisperer", "X2TEXT", False)
+
+        UserDefaultAdapter.objects.create(
+            organization_member=self.member,
+            default_llm_adapter=self.llm_a,
+            default_x2text_adapter=self.stale_x2text,
+        )
+
+    def test_changing_one_default_tolerates_a_stale_deprecated_default(self) -> None:
+        """The regression: resubmitting the unchanged deprecated id must pass."""
+        AdapterProcessor.set_default_triad(
+            {
+                "llm_default": str(self.llm_b.id),
+                "x2text_default": str(self.stale_x2text.id),
+            },
+            self.user,
+        )
+
+        defaults = UserDefaultAdapter.objects.get(organization_member=self.member)
+        assert defaults.default_llm_adapter_id == self.llm_b.id
+        # untouched, still pointing at the deprecated adapter
+        assert defaults.default_x2text_adapter_id == self.stale_x2text.id
+
+    def test_newly_selecting_a_deprecated_adapter_is_still_rejected(self) -> None:
+        """Skipping unchanged values must not weaken the guard itself."""
+        other = AdapterInstance.objects.create(
+            adapter_id=LLM_WHISPERER_V1,
+            adapter_name="another-whisperer",
+            adapter_type="X2TEXT",
+            organization=self.org,
+            created_by=self.user,
+            is_available=False,
+        )
+
+        with pytest.raises(DeprecatedAdapter):
+            AdapterProcessor.set_default_triad(
+                {"x2text_default": str(other.id)}, self.user
+            )