fix(router): guard retry_policy type in update_settings

Mirror Router.__init__ semantics in update_settings: only assign
retry_policy when it is None or a RetryPolicy (after dict coercion).
Previously a non-dict, non-RetryPolicy value (e.g. a YAML typo like
retry_policy: 5 flowing through /config/update) was stored verbatim,
deferring the failure to request time in get_num_retries_from_retry_policy
instead of being dropped at write time.

litellm/router.py

@@ -10217,7 +10217,8 @@ class Router:
                     value = kwargs[var]
                     if isinstance(value, dict):
                         value = RetryPolicy(**value)
-                    setattr(self, var, value)
+                    if value is None or isinstance(value, RetryPolicy):
+                        setattr(self, var, value)
                 else:
                     value = kwargs[var]
                     # only run routing strategy init if it has changed

tests/test_litellm/test_router_retry_policy_update.py

@@ -114,6 +114,24 @@ def test_update_settings_accepts_retry_policy_object_unchanged():
     assert router.retry_policy is policy
 
 
+def test_update_settings_ignores_malformed_retry_policy():
+    """A non-dict, non-``RetryPolicy`` value (e.g. a YAML typo like
+    ``retry_policy: 5`` reaching ``update_settings``) must not land on
+    ``self.retry_policy``. ``Router.__init__`` already drops such inputs;
+    the update path must match so a malformed config can't store garbage
+    that ``get_num_retries_from_retry_policy`` would only choke on at
+    request time."""
+    router = _build_router()
+
+    existing = RetryPolicy(BadRequestErrorRetries=4)
+    router.update_settings(retry_policy=existing)
+    assert router.retry_policy is existing
+
+    for bad_value in (5, "RateLimitErrorRetries=7", ["BadRequestErrorRetries"]):
+        router.update_settings(retry_policy=bad_value)
+        assert router.retry_policy is existing
+
+
 def test_update_settings_get_settings_round_trip_for_retry_policy():
     """``GET /get/config/callbacks`` serializes ``llm_router.get_settings()``
     back to the UI. After updating, the round-trip must reflect the new