fix(redis): unwrap decorated __init__s when deriving the from_url kwargs allowlist

redis-py >= 7.4 decorates AbstractConnection.__init__ with @deprecated_args,
whose wrapper is declared (self, *args, **kwargs). _init_arg_names introspects
the wrapper directly, so from redis-py 7.4 the MRO walk loses every real
connection parameter and the from_url allowlist silently drops socket_timeout
and socket_connect_timeout again - the exact regression the allowlist rework
fixed, reintroduced one dependency version later. A url-configured Redis that
blackholes packets then blocks callers indefinitely instead of timing out.

Follow the __wrapped__ chain with inspect.unwrap before introspecting; a no-op
for undecorated __init__s.

Measured across redis-py lines (socket_timeout present in the allowlist):
6.4.0 before/after: yes/yes. 7.1.0: yes/yes. 7.4.1: NO/yes. 8.1.0: NO/yes.
tests/test_litellm/test_redis.py at redis-py 8.1.0: 10 failures before, 3
after (the residual trio is sentinel/cluster password handling, failing
identically without this change).

Two tests: a decorated-fake proving the unwrap mechanism, and a live-invariant
assertion that the installed redis-py's allowlist carries the socket timeouts -
the first thing to go red if a future redis-py changes signature declaration
again.

litellm/_redis.py

@@ -67,12 +67,20 @@ def _init_arg_names(cls: type) -> frozenset[str]:
 
     Keyword-only parameters are included, and the MRO is walked because redis-py splits a
     connection's parameters between ``AbstractConnection`` and its concrete subclasses.
+
+    Each ``__init__`` is unwrapped before introspection: redis-py >= 7.4 decorates
+    ``AbstractConnection.__init__`` with ``@deprecated_args``, whose wrapper is declared
+    ``(self, *args, **kwargs)`` — introspecting the wrapper directly loses every real
+    parameter (``socket_timeout`` included), which silently emptied this allowlist and
+    dropped the socket timeouts from url-configured connections. ``inspect.unwrap``
+    follows the ``__wrapped__`` chain to the true signature and is a no-op on
+    undecorated ``__init__``s.
     """
     return frozenset(
         name
         for klass in inspect.getmro(cls)
         if klass is not object
-        for spec in (inspect.getfullargspec(klass.__init__),)
+        for spec in (inspect.getfullargspec(inspect.unwrap(klass.__init__)),)
         for name in spec.args + spec.kwonlyargs
     )
 

tests/test_litellm/test_redis.py

@@ -864,3 +864,49 @@ def test_redis_uses_the_hiredis_response_parser():
     client = get_redis_client(host="redis-host", port=6379)
     connection = client.connection_pool.make_connection()
     assert isinstance(connection._parser, _HiredisParser)
+
+
+def test_init_arg_names_sees_through_decorated_inits():
+    """redis-py >= 7.4 wraps AbstractConnection.__init__ with @deprecated_args, whose
+    wrapper is declared (self, *args, **kwargs). Introspecting the wrapper directly
+    yields no real parameters, which silently emptied the from_url allowlist and
+    dropped socket_timeout from url-configured connections. The MRO walk must follow
+    __wrapped__ to the true signature.
+    """
+    import functools
+
+    from litellm._redis import _init_arg_names
+
+    def deprecating(fn):
+        @functools.wraps(fn)
+        def wrapper(self, *args, **kwargs):
+            return fn(self, *args, **kwargs)
+
+        return wrapper
+
+    class Base:
+        @deprecating
+        def __init__(self, socket_timeout=None, socket_connect_timeout=None):
+            pass
+
+    class Concrete(Base):
+        def __init__(self, host=None, **kwargs):
+            super().__init__(**kwargs)
+
+    names = _init_arg_names(Concrete)
+    assert "socket_timeout" in names
+    assert "socket_connect_timeout" in names
+    assert "host" in names
+
+
+def test_url_allowlist_always_carries_socket_timeouts():
+    """The load-bearing invariant behind test_url_config_* against the INSTALLED
+    redis-py, whatever its version: if a redis-py release changes how its __init__
+    signatures are declared (7.4 did, via @deprecated_args), this is the first
+    assertion that goes red.
+    """
+    from litellm._redis import _get_redis_url_kwargs
+
+    allowed = _get_redis_url_kwargs()
+    assert "socket_timeout" in allowed
+    assert "socket_connect_timeout" in allowed