refactor: daily fresh tech debt cleanup, rolling PR (2026-09-25) (#43151)

* refactor: clean up fresh tech debt from 2026-09-24 (stacked comprehensions, getattr, bare dict)

Co-Authored-By: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>

* chore: drop the budget ratchet from the PR branch, the default-branch automation owns it

Co-Authored-By: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>

---------

Co-authored-by: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>

litellm/batches/batch_utils.py

@@ -43,7 +43,7 @@ def _uses_native_vertex_output(
 ) -> bool:
     if custom_llm_provider != "vertex_ai":
         return False
-    if model_name and getattr(litellm, "disable_vertex_batch_output_transformation", False):
+    if model_name and litellm.disable_vertex_batch_output_transformation:
         return True
     return first_row is not None and is_native_vertex_batch_output_row(first_row)
 

litellm/integrations/langfuse/langfuse_sdk.py

@@ -684,7 +684,7 @@ class LangfuseSpanExporter(SpanExporter):
     def _round(self, halving: _Halving) -> _Halving:
         sent: Final = tuple((batch, self._send_batch(batch)) for batch in halving.pending)
         return _Halving(
-            pending=tuple(part for batch, outcome in sent if outcome == "too_large" for part in _smaller(batch)),
+            pending=tuple(chain.from_iterable(_smaller(batch) for batch, outcome in sent if outcome == "too_large")),
             settled=halving.settled
             + tuple(
                 SpanExportResult.SUCCESS if outcome == "delivered" else SpanExportResult.FAILURE

litellm/llms/openai/organization_costs.py

@@ -3,6 +3,7 @@
 from collections.abc import Awaitable, Callable, Mapping, Sequence
 from dataclasses import dataclass
 from datetime import date, datetime, timedelta, timezone
+from itertools import chain
 from types import MappingProxyType
 from typing import Final, Literal, TypeAlias
 
@@ -126,7 +127,8 @@ async def fetch_openai_daily_costs(
     return MappingProxyType(
         {
             day: sum(
-                result.amount.value for bucket in buckets if _bucket_day(bucket) == day for result in bucket.results
+                result.amount.value
+                for result in chain.from_iterable(bucket.results for bucket in buckets if _bucket_day(bucket) == day)
             )
             for day in days
         }

litellm/proxy/_experimental/mcp_server/mcp_server_manager.py

@@ -6855,12 +6855,13 @@ class MCPServerManager:
         if not tool_permissions:
             return {}
         expanded: Final = tuple(
-            (server_id, tuple(tools or ()))
-            for key, tools in tool_permissions.items()
-            for server_id in self.expand_permission_list([key])
+            chain.from_iterable(
+                ((server_id, tuple(tools or ())) for server_id in self.expand_permission_list([key]))
+                for key, tools in tool_permissions.items()
+            )
         )
         return {
-            server_id: list(dict.fromkeys(tool for _, tools in group for tool in tools))
+            server_id: list(dict.fromkeys(chain.from_iterable(tools for _, tools in group)))
             for server_id, group in groupby(sorted(expanded, key=itemgetter(0)), key=itemgetter(0))
         }
 

litellm/proxy/common_utils/model_listing_utils.py

@@ -14,6 +14,7 @@ import re
 from collections.abc import Container, Mapping, Sequence
 from dataclasses import dataclass
 from functools import reduce
+from itertools import chain
 from types import MappingProxyType
 from typing import TYPE_CHECKING, Final, cast
 
@@ -191,7 +192,7 @@ def alias_map(aliases: object) -> Mapping[str, str]:
 
 
 def _alias_names(alias_maps: Sequence[Mapping[str, str]]) -> tuple[str, ...]:
-    return tuple(dict.fromkeys(alias for aliases in alias_maps for alias in aliases))
+    return tuple(dict.fromkeys(chain.from_iterable(alias_maps)))
 
 
 def _rewrite(model_id: str, alias_maps: Sequence[Mapping[str, str]]) -> str | None:

litellm/proxy/hooks/proxy_track_cost_callback.py

@@ -474,7 +474,9 @@ class _ProxyDBLogger(CustomLogger):
             spend_log_error("Error in tracking cost callback - %s", str(e), exc=e)
 
     @staticmethod
-    async def _enrich_failure_metadata_unless_db_stalled(metadata: dict, original_exception: Exception) -> dict:
+    async def _enrich_failure_metadata_unless_db_stalled(
+        metadata: dict[str, object], original_exception: Exception
+    ) -> dict[str, object]:
         if isinstance(original_exception, DBLookupDeadlineExceeded):
             return metadata
         return await _ProxyDBLogger._enrich_failure_metadata_with_key_info(metadata=metadata)

litellm/proxy/spend_tracking/key_metadata_recovery.py

@@ -215,17 +215,23 @@ def _meta_with_user_details(
     return updated
 
 
+def _user_id_needing_details(api_key: str, meta: KeyMetadataDict) -> str | None:
+    user_id: Final = meta.get("user_id")
+    if not isinstance(user_id, str) or not user_id:
+        return None
+    if meta.get("user_email") and not (_is_cli_session_key(api_key) and not meta.get("team_id")):
+        return None
+    return user_id
+
+
 async def attach_user_details(
     prisma_client: PrismaClient,
     recovered: Mapping[str, KeyMetadataDict],
 ) -> Mapping[str, KeyMetadataDict]:
     needing_details: Final = frozenset(
         user_id
-        for api_key, meta in recovered.items()
-        for user_id in (meta.get("user_id"),)
-        if isinstance(user_id, str)
-        and user_id
-        and (not meta.get("user_email") or (_is_cli_session_key(api_key) and not meta.get("team_id")))
+        for user_id in (_user_id_needing_details(api_key, meta) for api_key, meta in recovered.items())
+        if user_id is not None
     )
     details: Final = await _details_for_user_ids(prisma_client, needing_details)
     if not details:

litellm/types/litellm_params.py

@@ -3,6 +3,7 @@ models and KWARG_ARTIFACTS into all_litellm_params."""
 
 from collections.abc import Callable, Iterator, Mapping, MutableMapping, Sequence
 from dataclasses import dataclass, field, fields, is_dataclass
+from itertools import chain
 from types import MappingProxyType
 from typing import TYPE_CHECKING, Final, Literal, TypeAlias
 
@@ -359,6 +360,6 @@ def owned_wire_names(root: type) -> tuple[str, ...]:
     return tuple(names())
 
 
-OWNED_KWARG_NAMES: Final = tuple(name for root in LITELLM_OWNED_ROOTS for name in owned_wire_names(root))
+OWNED_KWARG_NAMES: Final = tuple(chain.from_iterable(owned_wire_names(root) for root in LITELLM_OWNED_ROOTS))
 AGENTIC_LOOP_KWARG_NAMES: Final = (*wire_names(AgenticLoopState), *wire_names(AgenticLoopOptions))
 BEDROCK_BATCH_KWARG_NAMES: Final = wire_names(BedrockBatchConnection)