diff --git a/codex-rs/app-server/src/models.rs b/codex-rs/app-server/src/models.rs
index a58bfe284d..502fd60281 100644
--- a/codex-rs/app-server/src/models.rs
+++ b/codex-rs/app-server/src/models.rs
@@ -4,13 +4,13 @@ use codex_app_server_protocol::ReasoningEffortOption;
 use codex_common::model_presets::ModelPreset;
 use codex_common::model_presets::ReasoningEffortPreset;
 use codex_common::model_presets::builtin_model_presets;
-use codex_common::model_presets::default_model_id_for_auth;
+use codex_core::config::default_model_for_auth;
 
 pub fn supported_models(auth_mode: Option<AuthMode>) -> Vec<Model> {
-    let default_model_id = default_model_id_for_auth(auth_mode);
+    let default_model_id = default_model_for_auth(auth_mode);
     builtin_model_presets(auth_mode)
         .into_iter()
-        .map(|preset| model_from_preset(preset, default_model_id))
+        .map(|preset| model_from_preset(preset, &default_model_id))
         .collect()
 }
 
diff --git a/codex-rs/common/src/model_presets.rs b/codex-rs/common/src/model_presets.rs
index 8326f976dd..a031f23b1d 100644
--- a/codex-rs/common/src/model_presets.rs
+++ b/codex-rs/common/src/model_presets.rs
@@ -256,13 +256,6 @@ pub fn builtin_model_presets(auth_mode: Option<AuthMode>) -> Vec<ModelPreset> {
         .collect()
 }
 
-pub fn default_model_id_for_auth(auth_mode: Option<AuthMode>) -> &'static str {
-    match auth_mode {
-        Some(AuthMode::ApiKey) => "gpt-5.1-codex",
-        _ => "gpt-5.1-codex-max",
-    }
-}
-
 pub fn all_model_presets() -> &'static Vec<ModelPreset> {
     &PRESETS
 }
@@ -287,17 +280,4 @@ mod tests {
                 .all(|preset| preset.id != "gpt-5.1-codex-max")
         );
     }
-
-    #[test]
-    fn default_model_depends_on_auth_mode() {
-        assert_eq!(
-            default_model_id_for_auth(Some(AuthMode::ChatGPT)),
-            "gpt-5.1-codex-max"
-        );
-        assert_eq!(
-            default_model_id_for_auth(Some(AuthMode::ApiKey)),
-            "gpt-5.1-codex"
-        );
-        assert_eq!(default_model_id_for_auth(None), "gpt-5.1-codex-max");
-    }
 }
diff --git a/codex-rs/core/src/config/mod.rs b/codex-rs/core/src/config/mod.rs
index ad8eeadff9..10d30e064b 100644
--- a/codex-rs/core/src/config/mod.rs
+++ b/codex-rs/core/src/config/mod.rs
@@ -1349,7 +1349,7 @@ fn default_model() -> String {
     OPENAI_DEFAULT_MODEL.to_string()
 }
 
-fn default_model_for_auth(auth_mode: Option<AuthMode>) -> String {
+pub fn default_model_for_auth(auth_mode: Option<AuthMode>) -> String {
     match auth_mode {
         Some(AuthMode::ApiKey) => OPENAI_DEFAULT_MODEL_API_KEY.to_string(),
         _ => default_model(),