fix(proxy): cleandoc exception docstrings used in OpenAPI ERROR_RESPONSES

The Swagger error descriptions wired up in swagger_utils.ERROR_RESPONSES
were taken straight from exception.__doc__, which preserves the leading
whitespace from the Python source (4 spaces per body line for any
multi-line docstring). openapi-typescript renders that into JSDoc
verbatim, so when RateLimitError grew a real multi-line docstring in
#27687, every regenerated schema.d.ts now has a different indentation
than the file committed by #29885. CI's Check UI API Types Sync flips
back and forth between rebases on any PR that doesn't touch
schema.d.ts itself.

Pass __doc__ through inspect.cleandoc so the description stored in the
OpenAPI spec is dedented at the source. The committed schema.d.ts is
exactly what gen:api now produces, so no schema regen is needed in this
commit; future docstrings on litellm exceptions won't reintroduce the
drift either. Inherited docstrings from openai/Exception are still
ignored (we keep the existing __doc__-not-getdoc fallback to the class
name) so the description of every other 4xx/5xx response stays the
class name like 'AuthenticationError'.

Co-authored-by: Krrish Dholakia <krrish-berri-2@users.noreply.github.com>

litellm/proxy/common_utils/swagger_utils.py

@@ -1,3 +1,4 @@
+import inspect
 from typing import Any, Dict
 
 from pydantic import BaseModel, Field
@@ -31,11 +32,25 @@ def get_status_code(exception):
     return 500  # Internal Server Error as default
 
 
-# Create error responses
+def _exception_description(exception):
+    """Return a normalized description for OpenAPI / JSDoc consumers.
+
+    Uses the class's own docstring (not an inherited one) so the rendered Swagger
+    description matches the historical short-form (the class name) when only an
+    upstream library defined a docstring. ``cleandoc`` strips the source-code
+    indentation that would otherwise leak into the generated JSDoc comment in
+    ``ui/litellm-dashboard/src/lib/http/schema.d.ts``.
+    """
+    doc = exception.__doc__
+    if not doc:
+        return exception.__name__
+    return inspect.cleandoc(doc)
+
+
 ERROR_RESPONSES = {
     get_status_code(exception): {
         "model": ErrorResponse,
-        "description": exception.__doc__ or exception.__name__,
+        "description": _exception_description(exception),
     }
     for exception in LITELLM_EXCEPTION_TYPES
 }

tests/test_litellm/proxy/common_utils/test_swagger_utils.py

@@ -0,0 +1,33 @@
+import inspect
+
+from litellm.exceptions import RateLimitError
+from litellm.proxy.common_utils.swagger_utils import (
+    ERROR_RESPONSES,
+    _exception_description,
+)
+
+
+class _ChildWithoutDoc(RateLimitError):
+    pass
+
+
+def test_exception_description_dedents_multiline_docstring():
+    description = _exception_description(RateLimitError)
+
+    assert RateLimitError.__doc__ is not None
+    assert RateLimitError.__doc__.startswith("\n    ")
+    assert description == inspect.cleandoc(RateLimitError.__doc__)
+    assert "\n    " not in description
+
+
+def test_exception_description_falls_back_to_name_when_no_own_doc():
+    assert _ChildWithoutDoc.__doc__ is None
+    assert _exception_description(_ChildWithoutDoc) == "_ChildWithoutDoc"
+
+
+def test_rate_limit_error_response_description_is_dedented():
+    rate_limit_response = ERROR_RESPONSES[429]
+
+    description = rate_limit_response["description"]
+    assert description.startswith("Unified rate-limit error.")
+    assert "\n    " not in description