[plugins] Additional gating for tool suggest and apps. (#15573)

- [x] Additional gating for tool suggest and apps.

codex-rs/core/src/apps/render.rs

@@ -1,10 +1,72 @@
 use crate::mcp::CODEX_APPS_MCP_SERVER_NAME;
+use codex_app_server_protocol::AppInfo;
 use codex_protocol::protocol::APPS_INSTRUCTIONS_CLOSE_TAG;
 use codex_protocol::protocol::APPS_INSTRUCTIONS_OPEN_TAG;
 
-pub(crate) fn render_apps_section() -> String {
+pub(crate) fn render_apps_section(connectors: &[AppInfo]) -> Option<String> {
+    if !connectors
+        .iter()
+        .any(|connector| connector.is_accessible && connector.is_enabled)
+    {
+        return None;
+    }
+
     let body = format!(
         "## Apps (Connectors)\nApps (Connectors) can be explicitly triggered in user messages in the format `[$app-name](app://{{connector_id}})`. Apps can also be implicitly triggered as long as the context suggests usage of available apps, the available apps will be listed by the `tool_search` tool.\nAn app is equivalent to a set of MCP tools within the `{CODEX_APPS_MCP_SERVER_NAME}` MCP.\nAn installed app's MCP tools are either provided to you already, or can be lazy-loaded through the `tool_search` tool.\nDo not additionally call list_mcp_resources or list_mcp_resource_templates for apps."
     );
-    format!("{APPS_INSTRUCTIONS_OPEN_TAG}\n{body}\n{APPS_INSTRUCTIONS_CLOSE_TAG}")
+    Some(format!(
+        "{APPS_INSTRUCTIONS_OPEN_TAG}\n{body}\n{APPS_INSTRUCTIONS_CLOSE_TAG}"
+    ))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn connector(id: &str, is_accessible: bool, is_enabled: bool) -> AppInfo {
+        AppInfo {
+            id: id.to_string(),
+            name: id.to_string(),
+            description: None,
+            logo_url: None,
+            logo_url_dark: None,
+            distribution_channel: None,
+            branding: None,
+            app_metadata: None,
+            labels: None,
+            install_url: None,
+            is_accessible,
+            is_enabled,
+            plugin_display_names: Vec::new(),
+        }
+    }
+
+    #[test]
+    fn omits_apps_section_without_accessible_and_enabled_apps() {
+        assert_eq!(render_apps_section(&[]), None);
+        assert_eq!(
+            render_apps_section(&[connector(
+                "calendar", /*is_accessible*/ true, /*is_enabled*/ false
+            )]),
+            None
+        );
+        assert_eq!(
+            render_apps_section(&[connector(
+                "calendar", /*is_accessible*/ false, /*is_enabled*/ true
+            )]),
+            None
+        );
+    }
+
+    #[test]
+    fn renders_apps_section_with_an_accessible_and_enabled_app() {
+        let rendered = render_apps_section(&[connector(
+            "calendar", /*is_accessible*/ true, /*is_enabled*/ true,
+        )])
+        .expect("expected apps section");
+
+        assert!(rendered.starts_with(APPS_INSTRUCTIONS_OPEN_TAG));
+        assert!(rendered.contains("## Apps (Connectors)"));
+        assert!(rendered.ends_with(APPS_INSTRUCTIONS_CLOSE_TAG));
+    }
 }