[apps] Improve app loading. (#10994)

There are two concepts of apps that we load in the harness:

- Directory apps, which is all the apps that the user can install.
- Accessible apps, which is what the user actually installed and can be
$ inserted and be used by the model. These are extracted from the tools
that are loaded through the gateway MCP.

Previously we wait for both sets of apps before returning the full apps
list. Which causes many issues because accessible apps won't be
available to the UI or the model if directory apps aren't loaded or
failed to load.

In this PR we are separating them so that accessible apps can be loaded
separately and are instantly available to be shown in the UI and to be
provided in model context. We also added an app-server event so that
clients can subscribe to also get accessible apps without being blocked
on the full app list.

- [x] Separate accessible apps and directory apps loading.
- [x] `app/list` request will also emit `app/list/updated` notifications
that app-server clients can subscribe. Which allows clients to get
accessible apps list to render in the $ menu without being blocked by
directory apps.
- [x] Cache both accessible and directory apps with 1 hour TTL to avoid
reloading them when creating new threads.
- [x] TUI improvements to redraw $ menu and /apps menu when app list is
updated.

codex-rs/tui/src/chatwidget/tests.rs

@@ -1074,6 +1074,7 @@ async fn make_chatwidget_manual(
         agent_turn_running: false,
         mcp_startup_status: None,
         connectors_cache: ConnectorsCacheState::default(),
+        connectors_prefetch_in_flight: false,
         interrupts: InterruptManager::new(),
         reasoning_buffer: String::new(),
         full_reasoning_buffer: String::new(),
@@ -3667,6 +3668,74 @@ fn render_bottom_popup(chat: &ChatWidget, width: u16) -> String {
     lines.join("\n")
 }
 
+#[tokio::test]
+async fn apps_popup_refreshes_when_connectors_snapshot_updates() {
+    let (mut chat, _rx, _op_rx) = make_chatwidget_manual(None).await;
+    chat.config.features.enable(Feature::Apps);
+    chat.bottom_pane.set_connectors_enabled(true);
+
+    chat.on_connectors_loaded(
+        Ok(ConnectorsSnapshot {
+            connectors: vec![codex_chatgpt::connectors::AppInfo {
+                id: "connector_1".to_string(),
+                name: "Notion".to_string(),
+                description: Some("Workspace docs".to_string()),
+                logo_url: None,
+                logo_url_dark: None,
+                distribution_channel: None,
+                install_url: Some("https://example.test/notion".to_string()),
+                is_accessible: true,
+            }],
+        }),
+        false,
+    );
+    chat.add_connectors_output();
+
+    let before = render_bottom_popup(&chat, 80);
+    assert!(
+        before.contains("Installed 1 of 1 available apps."),
+        "expected initial apps popup snapshot, got:\n{before}"
+    );
+
+    chat.on_connectors_loaded(
+        Ok(ConnectorsSnapshot {
+            connectors: vec![
+                codex_chatgpt::connectors::AppInfo {
+                    id: "connector_1".to_string(),
+                    name: "Notion".to_string(),
+                    description: Some("Workspace docs".to_string()),
+                    logo_url: None,
+                    logo_url_dark: None,
+                    distribution_channel: None,
+                    install_url: Some("https://example.test/notion".to_string()),
+                    is_accessible: true,
+                },
+                codex_chatgpt::connectors::AppInfo {
+                    id: "connector_2".to_string(),
+                    name: "Linear".to_string(),
+                    description: Some("Project tracking".to_string()),
+                    logo_url: None,
+                    logo_url_dark: None,
+                    distribution_channel: None,
+                    install_url: Some("https://example.test/linear".to_string()),
+                    is_accessible: true,
+                },
+            ],
+        }),
+        true,
+    );
+
+    let after = render_bottom_popup(&chat, 80);
+    assert!(
+        after.contains("Installed 2 of 2 available apps."),
+        "expected refreshed apps popup snapshot, got:\n{after}"
+    );
+    assert!(
+        after.contains("Linear"),
+        "expected refreshed popup to include new connector, got:\n{after}"
+    );
+}
+
 #[tokio::test]
 async fn experimental_features_popup_snapshot() {
     let (mut chat, _rx, _op_rx) = make_chatwidget_manual(None).await;