fix(router): answer a context window error when the request num_retries cannot be read

A request num_retries the retry loop cannot compare raised the loop's
TypeError as a 500 once a context window error became retryable. Hand the
context window error on instead, as the request got before.

litellm-rust/crates/router-core/src/call.rs

@@ -1098,17 +1098,20 @@ impl Core {
                 });
             }
             if uncounted == Some(UncountedRetries::Raises) {
+                if let Some(refusal) = refusal {
+                    return Err(refusal);
+                }
                 self.host.observe(&RouterEvent::RetryCountRaised {
                     level: at.level,
                     model: target.group.clone(),
                     cause: RetryCause::of(&failed.error),
                 });
-                return Err(refusal.unwrap_or(Failed {
+                return Err(Failed {
                     error: Box::new(Error::Attempt(AttemptError::host_raised(&["Exception"]))),
                     deployment_id: None,
                     routed: None,
                     served_as: None,
-                }));
+                });
             }
             if num_retries == 0 {
                 return Err(refusal.unwrap_or(failed));

litellm-rust/crates/router-core/tests/call_loop.rs

@@ -1106,6 +1106,29 @@ async fn a_retry_that_fails_after_a_context_window_error_raises_that_error(confi
     assert_eq!(host.selected().len(), 3);
 }
 
+#[rstest]
+#[tokio::test]
+async fn a_num_retries_that_raises_leaves_a_context_window_error_standing(config: RouterConfig) {
+    let host = Arc::new(ScriptedHost::failing("primary", vec![context_window()]));
+    let router = router(config, json!({"num_retries": 2}), host.clone());
+    let request = RouterRequest {
+        uncounted_retries: Some(UncountedRetries::Raises),
+        ..request()
+    };
+    let refused = router.call(Op::from("acompletion"), request).await;
+    assert!(
+        matches!(refused, Err(Error::Attempt(failed)) if failed.kind == FailureKind::ContextWindowExceeded)
+    );
+    assert!(
+        !host
+            .events
+            .lock()
+            .iter()
+            .any(|event| matches!(event, RouterEvent::RetryCountRaised { .. }))
+    );
+    assert_eq!(host.selected().len(), 1);
+}
+
 #[rstest]
 #[tokio::test]
 async fn a_failed_agentic_followup_is_not_retried_but_still_falls_back(config: RouterConfig) {