diff --git a/sgl-router/src/protocols/spec.rs b/sgl-router/src/protocols/spec.rs
index 672876c6c..a441bbf7f 100644
--- a/sgl-router/src/protocols/spec.rs
+++ b/sgl-router/src/protocols/spec.rs
@@ -1911,6 +1911,8 @@ pub struct SamplingParams {
     #[serde(skip_serializing_if = "Option::is_none")]
     pub no_stop_trim: Option<bool>,
     #[serde(skip_serializing_if = "Option::is_none")]
+    pub n: Option<u32>,
+    #[serde(skip_serializing_if = "Option::is_none")]
     pub sampling_seed: Option<u64>,
 }