diff --git a/crates/brightstaff/src/handlers/routing_service.rs b/crates/brightstaff/src/handlers/routing_service.rs
index cab18dbc..e5d50fcf 100644
--- a/crates/brightstaff/src/handlers/routing_service.rs
+++ b/crates/brightstaff/src/handlers/routing_service.rs
@@ -27,9 +27,8 @@ pub fn extract_routing_policy(
     let routing_preferences = json_body
         .as_object_mut()
         .and_then(|o| o.remove("routing_preferences"))
-        .and_then(|mut value| {
-            normalize_null_prefer_to_none(&mut value);
-            match serde_json::from_value::<Vec<TopLevelRoutingPreference>>(value) {
+        .and_then(
+            |value| match serde_json::from_value::<Vec<TopLevelRoutingPreference>>(value) {
                 Ok(prefs) => {
                     info!(
                         num_routes = prefs.len(),
@@ -41,43 +40,13 @@ pub fn extract_routing_policy(
                     warn!(error = %err, "failed to parse routing_preferences");
                     None
                 }
-            }
-        });
+            },
+        );
 
     let bytes = Bytes::from(serde_json::to_vec(&json_body).unwrap());
     Ok((bytes, routing_preferences))
 }
 
-fn normalize_null_prefer_to_none(routing_preferences: &mut serde_json::Value) {
-    let Some(preferences) = routing_preferences.as_array_mut() else {
-        return;
-    };
-
-    for preference in preferences {
-        let Some(preference_obj) = preference.as_object_mut() else {
-            continue;
-        };
-
-        let Some(selection_policy) = preference_obj.get_mut("selection_policy") else {
-            continue;
-        };
-
-        let Some(policy_obj) = selection_policy.as_object_mut() else {
-            continue;
-        };
-
-        if policy_obj
-            .get("prefer")
-            .is_some_and(serde_json::Value::is_null)
-        {
-            policy_obj.insert(
-                "prefer".to_string(),
-                serde_json::Value::String("none".to_string()),
-            );
-        }
-    }
-}
-
 #[derive(serde::Serialize)]
 struct RoutingDecisionResponse {
     /// Ranked model list — use first, fall back to next on 429/5xx.
diff --git a/crates/common/src/configuration.rs b/crates/common/src/configuration.rs
index 653f4d8c..e46c06a5 100644
--- a/crates/common/src/configuration.rs
+++ b/crates/common/src/configuration.rs
@@ -1,5 +1,5 @@
 use hermesllm::apis::openai::{ModelDetail, ModelObject, Models};
-use serde::{Deserialize, Serialize};
+use serde::{Deserialize, Deserializer, Serialize};
 use std::collections::HashMap;
 use std::fmt::Display;
 
@@ -116,9 +116,19 @@ pub enum SelectionPreference {
 
 #[derive(Debug, Clone, Default, Serialize, Deserialize)]
 pub struct SelectionPolicy {
+    #[serde(default, deserialize_with = "deserialize_selection_preference")]
     pub prefer: SelectionPreference,
 }
 
+fn deserialize_selection_preference<'de, D>(
+    deserializer: D,
+) -> Result<SelectionPreference, D::Error>
+where
+    D: Deserializer<'de>,
+{
+    Ok(Option::<SelectionPreference>::deserialize(deserializer)?.unwrap_or_default())
+}
+
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct TopLevelRoutingPreference {
     pub name: String,