FIX: Don't allow editing seeded category security settings

app/assets/javascripts/discourse/components/edit-category-security.js.es6

@@ -7,16 +7,24 @@ export default buildCategoryPanel('security', {
 
   actions: {
     editPermissions() {
-      this.set('editingPermissions', true);
+      if (!this.get('category.is_special')) {
+        this.set('editingPermissions', true);
+      }
     },
 
     addPermission(group, id) {
-      this.get('category').addPermission({group_name: group + "",
-                                       permission: Discourse.PermissionType.create({id})});
+      if (!this.get('category.is_special')) {
+        this.get('category').addPermission({
+          group_name: group + "",
+          permission: Discourse.PermissionType.create({id})
+        });
+      }
     },
 
     removePermission(permission) {
-      this.get('category').removePermission(permission);
+      if (!this.get('category.is_special')) {
+        this.get('category').removePermission(permission);
+      }
     },
   }
 });

app/assets/javascripts/discourse/templates/components/edit-category-security.hbs

@@ -1,4 +1,9 @@
 <section class='field'>
+  {{#if category.is_special}}
+    <p class="warning">{{i18n 'category.special_warning'}}</p>
+  {{else}}
+
+  {{/if}}
   <ul class='permission-list'>
     {{#each category.permissions as |p|}}
       <li>
@@ -16,6 +21,8 @@
     {{view 'select' class="permission-selector" optionValuePath="content.id" optionLabelPath="content.description" content=category.availablePermissions value=selectedPermission}}
     <button {{action "addPermission" selectedGroup selectedPermission}} class="btn btn-small">{{i18n 'category.add_permission'}}</button>
   {{else}}
-    <button {{action "editPermissions"}} class="btn btn-small">{{i18n 'category.edit_permissions'}}</button>
+    {{#unless category.is_special}}
+      <button {{action "editPermissions"}} class="btn btn-small">{{i18n 'category.edit_permissions'}}</button>
+    {{/unless}}
   {{/if}}
 </section>

app/serializers/category_serializer.rb

@@ -11,6 +11,7 @@ class CategorySerializer < BasicCategorySerializer
              :suppress_from_homepage,
              :can_delete,
              :cannot_delete_reason,
+             :is_special,
              :allow_badges,
              :custom_fields
 
@@ -37,6 +38,11 @@ class CategorySerializer < BasicCategorySerializer
     true
   end
 
+  def is_special
+    [SiteSetting.lounge_category_id, SiteSetting.meta_category_id, SiteSetting.staff_category_id, SiteSetting.uncategorized_category_id]
+    .include? object.id
+  end
+
   def include_can_delete?
     scope && scope.can_delete?(object)
   end

config/locales/client.en.yml

@@ -1539,6 +1539,7 @@ en:
       change_in_category_topic: "Edit Description"
       already_used: 'This color has been used by another category'
       security: "Security"
+      special_warning: "Warning: This category is a pre-seeded category and the security settings cannot be edited. If you do not wish to use this category, delete it instead of repurposing it."
       images: "Images"
       auto_close_label: "Auto-close topics after:"
       auto_close_units: "hours"

config/site_settings.yml

@@ -418,9 +418,6 @@ posting:
   newuser_max_attachments:
     client: true
     default: 0
-  uncategorized_category_id:
-    default: -1
-    hidden: true
   post_excerpt_maxlength: 300
   display_name_on_posts:
     client: true
@@ -922,14 +919,15 @@ uncategorized:
   lounge_category_id:
     default: -1
     hidden: true
-
   meta_category_id:
     default: -1
     hidden: true
-
   staff_category_id:
     default: -1
     hidden: true
+  uncategorized_category_id:
+    default: -1
+    hidden: true
 
   performance_report_topic_id:
     default: -1