it is done

core/src/mindustry/entities/traits/BuilderMinerTrait.java

@@ -0,0 +1,22 @@
+package mindustry.entities.traits;
+
+/** A class for gracefully merging mining and building traits.*/
+public interface BuilderMinerTrait extends MinerTrait, BuilderTrait{
+
+    default void updateMechanics(){
+        updateBuilding();
+
+        //mine only when not building
+        if(buildRequest() == null){
+            updateMining();
+        }
+    }
+
+    default void drawMechanics(){
+        if(isBuilding()){
+            drawBuilding();
+        }else{
+            drawMining();
+        }
+    }
+}