build(agent): molt-by#23c260 iteration

src/energi_bridge.js

@@ -48,6 +48,14 @@ class EnergiBridge {
     // Fallback: wrap as a generic contract element
     return { Objects: 'Unknown', payload: primitive };
   }
+
+  // Attach metadata to a canonical message payload for replay protection and auditing
+  // meta should be a plain object (e.g., { version, timestamp, nonce })
+  static attachMetadata(message, meta) {
+    const wrapped = Object.assign({}, message);
+    wrapped._meta = meta ? Object.assign({}, meta) : undefined;
+    return wrapped;
+  }
 }
 
 module.exports = {