fix: honor __api_exclude__ in async transform path (#1612)

dtmeadows · web-flow · commit 8172232a8bb1 · 2026-03-26T16:51:30.000-04:00
The sync transform path was updated to pass `exclude=getattr(data,
"__api_exclude__", None)` to `model_dump()`, but the async path was
missed. This caused `parsed_output` to leak into API requests when
using the async client for multi-turn structured output conversations,
resulting in a 400 error.

Closes #1610
diff --git a/src/anthropic/_utils/_transform.py b/src/anthropic/_utils/_transform.py
@@ -384,7 +384,7 @@ async def _async_transform_recursive(
         return data
 
     if isinstance(data, pydantic.BaseModel):
-        return model_dump(data, exclude_unset=True, mode="json")
+        return model_dump(data, exclude_unset=True, mode="json", exclude=getattr(data, "__api_exclude__", None))
 
     annotated_type = _get_annotated_type(annotation)
     if annotated_type is None:
