fix(aiand): stay within the basedpyright reportUnknownArgumentType ceiling

- derive exception_provider as the AiandException literal at the aiand
  dispatch (the branch is unreachable for any other provider, so the
  value is unchanged) and narrow model with an isinstance Final, so the
  call stops feeding legacy untyped locals into the typed mapper
- annotate aiand_models as Set[str]

litellm/__init__.py

@@ -686,7 +686,7 @@ qwencloud_models: Set = set()
 qwen_ai_platform_models: Set = set()
 moonshot_models: Set = set()
 publicai_models: Set = set()
-aiand_models: Set = set()
+aiand_models: Set[str] = set()
 darkbloom_models: Set = set()
 v0_models: Set = set()
 morph_models: Set = set()

litellm/litellm_core_utils/exception_mapping_utils.py

@@ -2529,13 +2529,14 @@ def exception_type(
                     body=getattr(original_exception, "body", None),
                 )
             if custom_llm_provider == "aiand":
+                _aiand_model: Final = model if isinstance(model, str) else ""
                 _map_aiand_exception(
-                    model=model,
+                    model=_aiand_model,
                     original_exception=mappable_exception,
                     custom_llm_provider=custom_llm_provider,
                     error_str=error_str,
                     exception_type=exception_type,
-                    exception_provider=exception_provider,
+                    exception_provider="AiandException",
                     extra_information=extra_information,
                 )
             if (