refactor(proxy): build the credential name index and keep-set immutably

Follow the repo's functional conventions on the touched lines: a MappingProxyType
built in one shot for the first-occurrence index, a frozenset for the names to
keep, Sequence parameters and explicit None returns.

litellm/litellm_core_utils/credential_accessor.py

@@ -1,6 +1,7 @@
 """Utils for accessing credentials."""
 
-from collections.abc import Mapping
+from collections.abc import Mapping, Sequence
+from types import MappingProxyType
 from typing import Final
 
 import litellm
@@ -30,16 +31,15 @@ class CredentialAccessor:
         return {} if credential is None else dict(credential_api_key_secret_reference(credential.credential_values))
 
     @staticmethod
-    def upsert_credentials(credentials: list[CredentialItem]):
+    def upsert_credentials(credentials: Sequence[CredentialItem]) -> None:
         """Add credentials to the list, replacing the first existing entry with the same name in place."""
-        index_by_name: Final[dict[str, int]] = {}
-        for i, cred in enumerate(litellm.credential_list):
-            index_by_name.setdefault(cred.credential_name, i)
+        first_index_by_name: Final = MappingProxyType(
+            {cred.credential_name: i for i, cred in reversed(tuple(enumerate(litellm.credential_list)))}
+        )
 
         for credential in credentials:
-            existing_index = index_by_name.get(credential.credential_name)
-            if existing_index is not None:
-                litellm.credential_list[existing_index] = credential
+            if credential.credential_name in first_index_by_name:
+                litellm.credential_list[first_index_by_name[credential.credential_name]] = credential
             else:
                 litellm.credential_list.append(credential)
 

litellm/proxy/proxy_server.py

@@ -9646,7 +9646,7 @@ class ProxyConfig:
         credential_object.credential_values = decrypted_credential_values
         return credential_object
 
-    async def delete_credentials(self, db_credentials: list[CredentialItem]):
+    async def delete_credentials(self, db_credentials: Sequence[CredentialItem]) -> None:
         """
         Create all-up list of db credentials + local credentials
         Compare to the litellm.credential_list
@@ -9657,10 +9657,8 @@ class ProxyConfig:
         credential_list: Final = self.load_credential_list(config=config)
 
         ## DELETE ##
-        names_to_keep: Final = {cred.credential_name for cred in db_credentials} | {
-            cred.credential_name for cred in credential_list
-        }
-        litellm.credential_list[:] = [cred for cred in litellm.credential_list if cred.credential_name in names_to_keep]
+        names_to_keep: Final = frozenset(cred.credential_name for cred in (*db_credentials, *credential_list))
+        litellm.credential_list[:] = (cred for cred in litellm.credential_list if cred.credential_name in names_to_keep)
 
     async def get_credentials(self, prisma_client: PrismaClient):
         try:

tests/unit/proxy/proxy_server/test_proxy_config.py

@@ -2061,11 +2061,6 @@ def test_ProxyConfig_load_credential_list_invalid_entry_raises():
         pc.load_credential_list({"credential_list": [{"missing_required": True}]})
 
 
-# ---------------------------------------------------------------------------
-# ProxyConfig.delete_credentials
-# ---------------------------------------------------------------------------
-
-
 def _credential(name: str) -> CredentialItem:
     return CredentialItem(credential_name=name, credential_values={"api_key": f"key-{name}"}, credential_info={})