feat: empty role ok (#16999)

codex-rs/core/src/agent/role.rs

@@ -64,6 +64,12 @@ async fn apply_role_to_config_inner(
         return Ok(());
     };
     let role_layer_toml = load_role_layer_toml(config, config_file, is_built_in, role_name).await?;
+    if role_layer_toml
+        .as_table()
+        .is_some_and(toml::map::Map::is_empty)
+    {
+        return Ok(());
+    }
     let (preserve_current_profile, preserve_current_provider) =
         preservation_policy(config, &role_layer_toml);
 

codex-rs/core/src/agent/role_tests.rs

@@ -87,6 +87,22 @@ async fn apply_explorer_role_sets_model_and_adds_session_flags_layer() {
     assert_eq!(session_flags_layer_count(&config), before_layers + 1);
 }
 
+#[tokio::test]
+async fn apply_empty_explorer_role_preserves_current_model_and_reasoning_effort() {
+    let (_home, mut config) = test_config_with_cli_overrides(Vec::new()).await;
+    let before_layers = session_flags_layer_count(&config);
+    config.model = Some("gpt-5.4-mini".to_string());
+    config.model_reasoning_effort = Some(ReasoningEffort::High);
+
+    apply_role_to_config(&mut config, Some("explorer"))
+        .await
+        .expect("explorer role should apply");
+
+    assert_eq!(config.model.as_deref(), Some("gpt-5.4-mini"));
+    assert_eq!(config.model_reasoning_effort, Some(ReasoningEffort::High));
+    assert_eq!(session_flags_layer_count(&config), before_layers);
+}
+
 #[tokio::test]
 async fn apply_role_returns_unavailable_for_missing_user_role_file() {
     let (_home, mut config) = test_config_with_cli_overrides(Vec::new()).await;