make some things more explicit

app/models/user.rb

@@ -66,6 +66,7 @@ class User < ApplicationRecord
   end
   
   def all_accessible_maps
+    #TODO: is there a way to keep this an ActiveRecord relation?
     maps + shared_maps
   end
 

app/policies/mapping_policy.rb

@@ -10,6 +10,8 @@ class MappingPolicy < ApplicationPolicy
       permission = 'maps.permission IN (?)'
       return scope.joins(:map).where(permission, visible) unless user
 
+      # if this is getting changed, the policy_scope for messages should also be changed
+      # as it is based entirely on the map to which it belongs
       scope.joins(:map).where(permission, visible)
            .or(scope.joins(:map).where('maps.id IN (?)', user.shared_maps.map(&:id)))
            .or(scope.joins(:map).where('maps.user_id = ?', user.id))

app/policies/message_policy.rb

@@ -6,6 +6,8 @@ class MessagePolicy < ApplicationPolicy
       permission = 'maps.permission IN (?)'
       return scope.joins(:map).where(permission, visible) unless user
 
+      # if this is getting changed, the policy_scope for mappings should also be changed
+      # as it is based entirely on the map to which it belongs
       scope.joins(:map).where(permission, visible)
            .or(scope.joins(:map).where('maps.id IN (?)', user.shared_maps.map(&:id)))
            .or(scope.joins(:map).where('maps.user_id = ?', user.id))

app/policies/synapse_policy.rb

@@ -3,11 +3,10 @@ class SynapsePolicy < ApplicationPolicy
   class Scope < Scope
     def resolve
       visible = %w(public commons)
-
       return scope.where(permission: visible) unless user
 
       scope.where(permission: visible)
-           .or(scope.where(defer_to_map_id: user.all_accessible_maps.map(&:id)))
+           .or(scope.where.not(defer_to_map_id: nil).where(defer_to_map_id: user.all_accessible_maps.map(&:id)))
            .or(scope.where(user_id: user.id))
     end
   end

app/policies/topic_policy.rb

@@ -6,7 +6,7 @@ class TopicPolicy < ApplicationPolicy
       return scope.where(permission: visible) unless user
 
       scope.where(permission: visible)
-           .or(scope.where(defer_to_map_id: user.all_accessible_maps.map(&:id)))
+           .or(scope.where.not(defer_to_map_id: nil).where(defer_to_map_id: user.all_accessible_maps.map(&:id)))
            .or(scope.where(user_id: user.id))
     end
   end