[codex] Add installed-plugin mention API (#22448)

## Summary
- add app-server `plugin/installed` for mention-oriented plugin loading
- return installed plugins plus explicitly requested install-suggestion
rows
- keep remote handling on installed-state data instead of the broad
catalog listing path

## Why
The `@` mention surface only needs plugins that are usable now, plus a
small product-approved set of install suggestions. It does not need the
full catalog-shaped `plugin/list` payload that the Plugins page uses.

## Validation
- `just write-app-server-schema`
- `just fmt`
- `cargo test -p codex-app-server-protocol`
- `cargo test -p codex-core-plugins`
- `cargo test -p codex-app-server --test all plugin_installed_`

## Notes
- The package-wide `cargo test -p codex-app-server` run still hits an
existing unrelated stack overflow in
`in_process::tests::in_process_start_clamps_zero_channel_capacity`.
- Companion webview PR: https://github.com/openai/openai/pull/915672

codex-rs/core-plugins/src/manager_tests.rs

@@ -7,6 +7,7 @@ use crate::loader::refresh_non_curated_plugin_cache;
 use crate::loader::refresh_non_curated_plugin_cache_force_reinstall;
 use crate::marketplace::MarketplacePluginInstallPolicy;
 use crate::remote::RemoteInstalledPlugin;
+use crate::remote::RemotePluginScope;
 use crate::startup_sync::curated_plugins_repo_path;
 use crate::test_support::TEST_CURATED_PLUGIN_CACHE_VERSION;
 use crate::test_support::TEST_CURATED_PLUGIN_SHA;
@@ -147,6 +148,20 @@ async fn load_config(codex_home: &Path, cwd: &Path) -> PluginsConfigInput {
     load_plugins_config_input(codex_home, cwd).await
 }
 
+fn remote_installed_linear_plugin() -> RemoteInstalledPlugin {
+    RemoteInstalledPlugin {
+        marketplace_name: "chatgpt-global".to_string(),
+        id: "plugins~Plugin_linear".to_string(),
+        name: "linear".to_string(),
+        enabled: true,
+        install_policy: codex_app_server_protocol::PluginInstallPolicy::Available,
+        auth_policy: codex_app_server_protocol::PluginAuthPolicy::OnUse,
+        availability: codex_app_server_protocol::PluginAvailability::Available,
+        interface: None,
+        keywords: Vec::new(),
+    }
+}
+
 #[tokio::test]
 async fn load_plugins_loads_default_skills_and_mcp_servers() {
     let codex_home = TempDir::new().unwrap();
@@ -334,38 +349,6 @@ approval_mode = "approve"
     );
 }
 
-#[tokio::test]
-async fn remote_installed_cache_adds_plugin_skill_roots_without_remote_plugin_flag() {
-    let codex_home = TempDir::new().unwrap();
-    let plugin_base = codex_home
-        .path()
-        .join("plugins/cache/chatgpt-global/linear");
-    write_plugin(&plugin_base, "local", "linear");
-    write_file(
-        &codex_home.path().join(CONFIG_TOML_FILE),
-        r#"[features]
-plugins = true
-"#,
-    );
-
-    let config = load_config(codex_home.path(), codex_home.path()).await;
-    let manager = PluginsManager::new(codex_home.path().to_path_buf());
-    manager.write_remote_installed_plugins_cache(vec![RemoteInstalledPlugin {
-        marketplace_name: "chatgpt-global".to_string(),
-        id: "plugins~Plugin_linear".to_string(),
-        name: "linear".to_string(),
-        enabled: true,
-    }]);
-
-    let outcome = manager.plugins_for_config(&config).await;
-    assert_eq!(
-        outcome.effective_skill_roots(),
-        vec![AbsolutePathBuf::try_from(plugin_base.join("local/skills")).unwrap()]
-    );
-    assert_eq!(outcome.plugins().len(), 1);
-    assert_eq!(outcome.plugins()[0].config_name, "linear@chatgpt-global");
-}
-
 #[tokio::test]
 async fn remote_installed_cache_ignores_plugins_missing_local_cache() {
     let codex_home = TempDir::new().unwrap();
@@ -379,17 +362,85 @@ remote_plugin = true
 
     let config = load_config(codex_home.path(), codex_home.path()).await;
     let manager = PluginsManager::new(codex_home.path().to_path_buf());
-    manager.write_remote_installed_plugins_cache(vec![RemoteInstalledPlugin {
-        marketplace_name: "chatgpt-global".to_string(),
-        id: "plugins~Plugin_linear".to_string(),
-        name: "linear".to_string(),
-        enabled: true,
-    }]);
+    manager.write_remote_installed_plugins_cache(vec![remote_installed_linear_plugin()]);
 
     let outcome = manager.plugins_for_config(&config).await;
     assert_eq!(outcome, PluginLoadOutcome::default());
 }
 
+#[tokio::test]
+async fn build_remote_installed_plugin_marketplaces_from_cache_uses_remote_metadata() {
+    let codex_home = TempDir::new().unwrap();
+    let manager = PluginsManager::new(codex_home.path().to_path_buf());
+    let mut plugin = remote_installed_linear_plugin();
+    plugin.install_policy = codex_app_server_protocol::PluginInstallPolicy::InstalledByDefault;
+    plugin.auth_policy = codex_app_server_protocol::PluginAuthPolicy::OnInstall;
+    plugin.interface = Some(codex_app_server_protocol::PluginInterface {
+        display_name: Some("Linear".to_string()),
+        short_description: Some("Track remote work".to_string()),
+        long_description: None,
+        developer_name: None,
+        category: None,
+        capabilities: Vec::new(),
+        website_url: None,
+        privacy_policy_url: None,
+        terms_of_service_url: None,
+        default_prompt: None,
+        brand_color: Some("#111111".to_string()),
+        composer_icon: None,
+        composer_icon_url: None,
+        logo: None,
+        logo_url: None,
+        screenshots: Vec::new(),
+        screenshot_urls: Vec::new(),
+    });
+    plugin.keywords = vec!["issues".to_string()];
+    manager.write_remote_installed_plugins_cache(vec![plugin]);
+
+    let marketplaces = manager
+        .build_remote_installed_plugin_marketplaces_from_cache(&[RemotePluginScope::Global])
+        .expect("remote installed cache should be present");
+    assert_eq!(marketplaces.len(), 1);
+    assert_eq!(marketplaces[0].name, "chatgpt-global");
+    assert_eq!(marketplaces[0].display_name, "ChatGPT Plugins");
+    assert_eq!(marketplaces[0].plugins.len(), 1);
+    let plugin = &marketplaces[0].plugins[0];
+    assert_eq!(plugin.id, "linear@chatgpt-global");
+    assert_eq!(plugin.remote_plugin_id, "plugins~Plugin_linear");
+    assert_eq!(plugin.name, "linear");
+    assert_eq!(plugin.installed, true);
+    assert_eq!(plugin.enabled, true);
+    assert_eq!(
+        plugin.install_policy,
+        codex_app_server_protocol::PluginInstallPolicy::InstalledByDefault
+    );
+    assert_eq!(
+        plugin.auth_policy,
+        codex_app_server_protocol::PluginAuthPolicy::OnInstall
+    );
+    assert_eq!(plugin.keywords, vec!["issues".to_string()]);
+    assert_eq!(
+        plugin
+            .interface
+            .as_ref()
+            .and_then(|interface| interface.display_name.as_deref()),
+        Some("Linear")
+    );
+    assert_eq!(
+        plugin
+            .interface
+            .as_ref()
+            .and_then(|interface| interface.short_description.as_deref()),
+        Some("Track remote work")
+    );
+    assert_eq!(
+        manager
+            .build_remote_installed_plugin_marketplaces_from_cache(&[RemotePluginScope::Workspace])
+            .expect("remote installed cache should be present"),
+        Vec::new()
+    );
+}
+
 #[tokio::test]
 async fn load_plugins_resolves_disabled_skill_names_against_loaded_plugin_skills() {
     let codex_home = TempDir::new().unwrap();