chore: spawn MCP for memories (#21214)

Co-authored-by: Codex <noreply@openai.com>

codex-rs/features/src/tests.rs

@@ -129,6 +129,13 @@ fn remote_compaction_v2_is_under_development() {
     );
 }
 
+#[test]
+fn builtin_mcp_is_under_development() {
+    assert_eq!(Feature::BuiltInMcp.stage(), Stage::UnderDevelopment);
+    assert_eq!(Feature::BuiltInMcp.default_enabled(), false);
+    assert_eq!(feature_for_key("builtin_mcp"), Some(Feature::BuiltInMcp));
+}
+
 #[test]
 fn terminal_resize_reflow_is_experimental_and_enabled_by_default() {
     assert_eq!(