fix(proxy): make the lazy OpenAPI snapshot byte-identical on every Python version (#42519)

Python 3.13+ strips the common indentation of docstrings at compile time and 3.12
keeps it, and the 429 error description in ERROR_RESPONSES came straight from
RateLimitError.__doc__, so regenerating litellm/proxy/_lazy_openapi_snapshot.json
on a 3.13+ venv produced a one-line diff that the check-ui-api-types job (Python
3.12) rejected. Run the docstring through inspect.cleandoc before it lands in the
spec, regenerate the snapshot once, and pin the behavior with a test

Co-authored-by: mateo-berri <277851410+mateo-berri@users.noreply.github.com>

litellm/proxy/_lazy_openapi_snapshot.json

@@ -19919,7 +19919,7 @@
                   }
                 }
               },
-              "description": "\n    Unified rate-limit error.\n\n    Every rate-limit condition surfaced by litellm \u2014 whether it originated from\n    an upstream LLM provider, a vendor batch endpoint, or one of litellm's own\n    proxy-side limiters (parallel-requests, dynamic-rate, batch-rate, budget,\n    max-iterations, etc.) \u2014 is raised as an instance of this class.\n\n    The :attr:`category` attribute lets callers distinguish the source. See\n    :class:`RateLimitErrorCategory` for the available values.\n    "
+              "description": "Unified rate-limit error.\n\nEvery rate-limit condition surfaced by litellm \u2014 whether it originated from\nan upstream LLM provider, a vendor batch endpoint, or one of litellm's own\nproxy-side limiters (parallel-requests, dynamic-rate, batch-rate, budget,\nmax-iterations, etc.) \u2014 is raised as an instance of this class.\n\nThe :attr:`category` attribute lets callers distinguish the source. See\n:class:`RateLimitErrorCategory` for the available values."
             },
             "500": {
               "content": {

litellm/proxy/common_utils/swagger_utils.py

@@ -1,3 +1,4 @@
+import inspect
 from typing import Any, Final
 
 from pydantic import BaseModel, Field
@@ -31,11 +32,15 @@ def get_status_code(exception):
     return 500  # Internal Server Error as default
 
 
+def _error_description(exception: type[Exception]) -> str:
+    return inspect.cleandoc(exception.__doc__) if exception.__doc__ else exception.__name__
+
+
 # Create error responses
 ERROR_RESPONSES: Final = {
     get_status_code(exception): {
         "model": ErrorResponse,
-        "description": exception.__doc__ or exception.__name__,
+        "description": _error_description(exception),
     }
     for exception in LITELLM_EXCEPTION_TYPES
 }

tests/test_litellm/proxy/common_utils/test_swagger_utils.py

@@ -0,0 +1,18 @@
+import inspect
+
+from litellm.exceptions import RateLimitError
+from litellm.proxy.common_utils.swagger_utils import ERROR_RESPONSES, _error_description
+
+
+class _ChildWithoutDoc(RateLimitError):
+    pass
+
+
+def test_error_response_descriptions_carry_no_docstring_indentation():
+    assert ERROR_RESPONSES[429]["description"] == inspect.cleandoc(RateLimitError.__doc__ or "")
+    for response in ERROR_RESPONSES.values():
+        assert response["description"] == inspect.cleandoc(response["description"])
+
+
+def test_error_description_falls_back_to_the_class_name_without_an_own_docstring():
+    assert _error_description(_ChildWithoutDoc) == "_ChildWithoutDoc"