Action might work?

src/main/java/mod/treestar/shopmod/ShopMod.java

@@ -2,9 +2,11 @@ package mod.treestar.shopmod;
 
 import mod.treestar.shopmod.categoryprovider.JsonShopCategoryProvider;
 import mod.treestar.shopmod.itemprovider.JsonShopItemProvider;
+import mod.treestar.shopmod.ShopOpenAction;
 import org.gotti.wurmunlimited.modloader.interfaces.Configurable;
 import org.gotti.wurmunlimited.modloader.interfaces.Initable;
 import org.gotti.wurmunlimited.modloader.interfaces.WurmServerMod;
+import org.gotti.wurmunlimited.modsupport.actions.ModActions;
 
 import java.util.Properties;
 import java.util.logging.Level;
@@ -33,11 +35,15 @@ public class ShopMod implements WurmServerMod, Initable, Configurable {
 
     @Override
     public void init() {
+        ModActions.init();
+
         ShopService shopService = ShopService.getInstance();
 
         shopService.registerCategoryProvider(new JsonShopCategoryProvider(categoryJsonPath));
         shopService.registerItemProvider(new JsonShopItemProvider(itemJsonPath));
 
+        new ShopOpenAction(shopService, shopName, enableTokenAccess, enableMailboxAccess);
+
         logger.log(Level.INFO, String.format("Initialized shop '%s' (token access: %s, mailbox access: %s)", shopName, enableTokenAccess, enableMailboxAccess));
     }
 

src/main/java/mod/treestar/shopmod/ShopOpenAction.java

@@ -0,0 +1,92 @@
+package mod.treestar.shopmod;
+
+import com.wurmonline.server.NoSuchPlayerException;
+import com.wurmonline.server.behaviours.Action;
+import com.wurmonline.server.behaviours.ActionEntry;
+import com.wurmonline.server.creatures.Creature;
+import com.wurmonline.server.items.Item;
+import com.wurmonline.server.items.ItemList;
+import org.gotti.wurmunlimited.modsupport.actions.ActionPerformer;
+import org.gotti.wurmunlimited.modsupport.actions.BehaviourProvider;
+import org.gotti.wurmunlimited.modsupport.actions.ModActions;
+import com.wurmonline.server.questions.ShopQuestion;
+
+import java.util.Collections;
+import java.util.List;
+
+/**
+ * Adds an action to open the shop from supported interactables (village tokens, mailboxes).
+ */
+public class ShopOpenAction implements ActionPerformer, BehaviourProvider {
+    private final ShopService shopService;
+    private final String shopName;
+    private final boolean allowTokens;
+    private final boolean allowMailboxes;
+    private final ActionEntry actionEntry;
+
+    public ShopOpenAction(ShopService shopService, String shopName, boolean allowTokens, boolean allowMailboxes) {
+        this.shopService = shopService;
+        this.shopName = shopName;
+        this.allowTokens = allowTokens;
+        this.allowMailboxes = allowMailboxes;
+        this.actionEntry = ActionEntry.createEntry(
+                (short) ModActions.getNextActionId(),
+                "Open shop",
+                "opening shop",
+                new int[] { 23 }
+        );
+        ModActions.registerAction(this.actionEntry);
+        ModActions.registerActionPerformer(this);
+        ModActions.registerBehaviourProvider(this);
+    }
+
+    @Override
+    public short getActionId() {
+        return actionEntry.getNumber();
+    }
+
+    @Override
+    public boolean action(Action action, Creature performer, Item target, short actionId, float counter) {
+        if (actionId != getActionId()) {
+            return false;
+        }
+        if (!isValidTarget(target)) {
+            return true;
+        }
+        try {
+            new ShopQuestion(performer.getWurmId(), shopName, shopService).sendQuestion();
+        } catch (NoSuchPlayerException e) {
+            performer.getCommunicator().sendNormalServerMessage("Unable to open shop right now.");
+        }
+        return true;
+    }
+
+    @Override
+    public boolean action(Action action, Creature performer, Creature target, short actionId, float counter) {
+        return false; // not supported
+    }
+
+    @Override
+    public List<ActionEntry> getBehavioursFor(Creature performer, Item target) {
+        if (isValidTarget(target)) {
+            return Collections.singletonList(actionEntry);
+        }
+        return null;
+    }
+
+    @Override
+    public List<ActionEntry> getBehavioursFor(Creature performer, Creature target) {
+        return null;
+    }
+
+    private boolean isValidTarget(Item target) {
+        if (target == null) return false;
+        if (allowTokens && target.getTemplateId() == ItemList.villageToken) {
+            return true;
+        }
+        if (allowMailboxes && target.isMailBox()) {
+            return true;
+        }
+        return false;
+    }
+}