xo-interpreter2: scaffold repl + alloc measurement frameowkr

xo-arena/src/arena/ErrorArena.cpp

@@ -0,0 +1,43 @@
+/** @file ErrorArena.cpp
+*
+ *  @author Roland Conybeare, Feb 2026
+ **/
+
+#include "ErrorArena.hpp"
+
+namespace xo {
+    namespace mm {
+        DArena
+        ErrorArena::s_instance;
+
+        ArenaConfig
+        ErrorArena::default_config()
+        {
+            return ArenaConfig().with_name("error-arena").with_size(16 * 1024);
+        }
+
+        namespace  {
+            bool s_init_done = false;
+        }
+
+        void
+        ErrorArena::init_once(const ArenaConfig & cfg)
+        {
+            if (!s_init_done) {
+                s_init_done = true;
+                s_instance = DArena::map(cfg);
+            }
+        }
+
+        DArena *
+        ErrorArena::instance()
+        {
+            init_once(default_config());
+
+            return &s_instance;
+        }
+        
+    } /*namespace mm*/
+} /*namespace xo*/
+
+/* end ErrorArena.cpp */