diff --git a/codex-rs/codex-api/src/endpoint/realtime_client_secrets.rs b/codex-rs/codex-api/src/endpoint/realtime_client_secrets.rs
index 16b2adb4ec..1c3ac0ef5d 100644
--- a/codex-rs/codex-api/src/endpoint/realtime_client_secrets.rs
+++ b/codex-rs/codex-api/src/endpoint/realtime_client_secrets.rs
@@ -1,7 +1,6 @@
 use crate::auth::AuthProvider;
 use crate::endpoint::realtime_websocket::RealtimeSessionConfig;
-use crate::endpoint::realtime_websocket::methods_common::normalized_session_mode;
-use crate::endpoint::realtime_websocket::methods_common::session_update_session;
+use crate::endpoint::realtime_websocket::session_update_session_json;
 use crate::endpoint::session::EndpointSession;
 use crate::error::ApiError;
 use crate::provider::Provider;
@@ -61,13 +60,11 @@ impl<T: HttpTransport, A: AuthProvider> RealtimeClientSecretsClient<T, A> {
 }
 
 fn realtime_client_secret_request_body(config: &RealtimeSessionConfig) -> Result<Value, ApiError> {
-    let session_mode = normalized_session_mode(config.event_parser, config.session_mode);
-    let mut session = serde_json::to_value(session_update_session(
+    let mut session = session_update_session_json(
         config.event_parser,
         config.instructions.clone(),
-        session_mode,
-    ))
-    .map_err(|err| ApiError::Stream(format!("failed to encode realtime session config: {err}")))?;
+        config.session_mode,
+    )?;
     if let Some(model) = config.model.as_ref()
         && let Some(session_object) = session.as_object_mut()
     {
diff --git a/codex-rs/codex-api/src/endpoint/realtime_websocket/methods_common.rs b/codex-rs/codex-api/src/endpoint/realtime_websocket/methods_common.rs
index ce9a3c325d..048ea6127a 100644
--- a/codex-rs/codex-api/src/endpoint/realtime_websocket/methods_common.rs
+++ b/codex-rs/codex-api/src/endpoint/realtime_websocket/methods_common.rs
@@ -10,11 +10,13 @@ use crate::endpoint::realtime_websocket::protocol::RealtimeEventParser;
 use crate::endpoint::realtime_websocket::protocol::RealtimeOutboundMessage;
 use crate::endpoint::realtime_websocket::protocol::RealtimeSessionMode;
 use crate::endpoint::realtime_websocket::protocol::SessionUpdateSession;
+use crate::error::ApiError;
+use serde_json::Value;
 
 pub(super) const REALTIME_AUDIO_SAMPLE_RATE: u32 = 24_000;
 const AGENT_FINAL_MESSAGE_PREFIX: &str = "\"Agent Final Message\":\n\n";
 
-pub(crate) fn normalized_session_mode(
+fn normalized_session_mode(
     event_parser: RealtimeEventParser,
     session_mode: RealtimeSessionMode,
 ) -> RealtimeSessionMode {
@@ -48,7 +50,7 @@ pub(super) fn conversation_handoff_append_message(
     }
 }
 
-pub(crate) fn session_update_session(
+fn session_update_session(
     event_parser: RealtimeEventParser,
     instructions: String,
     session_mode: RealtimeSessionMode,
@@ -60,6 +62,19 @@ pub(crate) fn session_update_session(
     }
 }
 
+pub(crate) fn session_update_session_json(
+    event_parser: RealtimeEventParser,
+    instructions: String,
+    session_mode: RealtimeSessionMode,
+) -> Result<Value, ApiError> {
+    serde_json::to_value(session_update_session(
+        event_parser,
+        instructions,
+        session_mode,
+    ))
+    .map_err(|err| ApiError::Stream(format!("failed to encode realtime session config: {err}")))
+}
+
 pub(super) fn websocket_intent(event_parser: RealtimeEventParser) -> Option<&'static str> {
     match event_parser {
         RealtimeEventParser::V1 => v1_websocket_intent(),
diff --git a/codex-rs/codex-api/src/endpoint/realtime_websocket/mod.rs b/codex-rs/codex-api/src/endpoint/realtime_websocket/mod.rs
index 67f7dd4148..1e0dfdd686 100644
--- a/codex-rs/codex-api/src/endpoint/realtime_websocket/mod.rs
+++ b/codex-rs/codex-api/src/endpoint/realtime_websocket/mod.rs
@@ -1,5 +1,5 @@
 pub mod methods;
-pub(crate) mod methods_common;
+mod methods_common;
 mod methods_v1;
 mod methods_v2;
 pub mod protocol;
@@ -13,6 +13,7 @@ pub use methods::RealtimeWebsocketClient;
 pub use methods::RealtimeWebsocketConnection;
 pub use methods::RealtimeWebsocketEvents;
 pub use methods::RealtimeWebsocketWriter;
+pub(crate) use methods_common::session_update_session_json;
 pub use protocol::RealtimeEventParser;
 pub use protocol::RealtimeSessionConfig;
 pub use protocol::RealtimeSessionMode;