FEATURE: hide bookmarks but always show if post is bookmarked

app/assets/javascripts/discourse/views/post-menu.js.es6

@@ -97,6 +97,10 @@ export default Discourse.View.extend({
       }
     }
 
+    if(post.get("bookmarked")){
+      hiddenButtons.removeObject("bookmark");
+    }
+
     var yours = post.get('yours');
     Discourse.SiteSettings.post_menu.split("|").forEach(function(i) {
       var creator = self["buttonFor" + i.replace(/\+/, '').capitalize()];

config/site_settings.yml

@@ -108,7 +108,7 @@ basic:
   post_menu_hidden_items:
     client: true
     type: list
-    default: 'edit|delete|admin'
+    default: 'bookmark|edit|delete|admin'
     choices:
      - like
      - edit