Gate plugin recommendation cache warming on feature flags (#60721)

## Why

Background plugin cache refreshes fetched recommendations even when plugin recommendations were disabled.

## What changed

Pass the effective recommendation feature state into `PluginsConfigInput` and skip recommendation cache warming unless apps, plugins, and either `tool_suggest` or `recommended_plugins` are enabled. Installed-plugin cache refreshes continue independently.

Disable `tool_suggest` and `recommended_plugins` by default in core and app-server test helpers, with explicit overrides for recommendation tests.

## Testing

Update cache-warming and external-login recommendation tests to opt in explicitly. Update config RPC assertions to verify the test helpers' session flag overrides.

GitOrigin-RevId: dc04e2847c94e2b15842fcd95cc0cf1f104e1fac

codex-rs/core/src/config/mod.rs

@@ -331,6 +331,13 @@ pub(crate) async fn test_config() -> Config {
     Config::load_from_base_config_with_overrides(
         ConfigToml {
             model: Some("gpt-5.5".to_string()),
+            features: Some(
+                BTreeMap::from([
+                    (Feature::ToolSuggest.key().to_string(), false),
+                    (Feature::RecommendedPlugins.key().to_string(), false),
+                ])
+                .into(),
+            ),
             ..Default::default()
         },
         ConfigOverrides::default(),
@@ -1890,6 +1897,7 @@ impl Config {
             self.http_client_factory(),
             self.apps_mcp_product_sku.clone(),
         )
+        .with_plugin_recommendations_enabled(self.features.plugin_recommendations_enabled())
         .with_runtime_auth_mode(
             (self.features.enabled(Feature::RuntimeAgentInstances)
                 && codex_runtime_agent_instance::is_openai_api_url(&self.chatgpt_base_url))

codex-rs/core/tests/common/lib.rs

@@ -17,6 +17,7 @@ use codex_core::config::ConfigBuilder;
 use codex_core::config::ConfigOverrides;
 pub use codex_core::test_support::TestCodexResponsesRequestKind;
 pub use codex_core::test_support::responses_metadata;
+use codex_features::Feature;
 use codex_utils_absolute_path::AbsolutePathBuf;
 pub use codex_utils_absolute_path::test_support::PathBufExt;
 pub use codex_utils_absolute_path::test_support::PathExt;
@@ -213,14 +214,21 @@ pub async fn load_default_config_for_test_with_cloud_config_bundle(
     codex_home: &TempDir,
     cloud_config_bundle: CloudConfigBundleLoader,
 ) -> Config {
-    ConfigBuilder::default()
+    let mut config = ConfigBuilder::default()
         .loader_overrides(LoaderOverrides::without_managed_config_for_tests())
         .codex_home(codex_home.path().to_path_buf())
         .harness_overrides(default_test_overrides())
         .cloud_config_bundle(cloud_config_bundle)
         .build()
         .await
-        .expect("defaults for test should always succeed")
+        .expect("defaults for test should always succeed");
+    for feature in [Feature::ToolSuggest, Feature::RecommendedPlugins] {
+        config
+            .features
+            .disable(feature)
+            .expect("test config should allow disabling plugin recommendations");
+    }
+    config
 }
 
 pub fn managed_network_requirements_loader() -> CloudConfigBundleLoader {

codex-rs/core/tests/suite/builtin_model_catalog.rs

@@ -2,9 +2,9 @@
 #![cfg(test)]
 
 use anyhow::Result;
-use codex_core::config::ConfigBuilder;
 use codex_login::CodexAuth;
 use codex_models_manager::bundled_models_response;
+use core_test_support::load_default_config_for_test;
 use core_test_support::responses;
 use core_test_support::test_codex::test_codex;
 use pretty_assertions::assert_eq;
@@ -49,10 +49,7 @@ model_catalog_url = "https://chatgpt.com/backend-api/codex/models"
             inference.uri(),
         ),
     )?;
-    let mut loaded = ConfigBuilder::default()
-        .codex_home(home.path().to_path_buf())
-        .build()
-        .await?;
+    let mut loaded = load_default_config_for_test(&home).await;
     assert_eq!(
         loaded
             .model_provider