anchor.diff:                  // no transition
                   | None -> just field
   
  +            | UpdateProp prop ->
  +                let field = Field.updateProp (constant prop) prop.PropId field
  +                just field
  +
               | MenuTeamOpen ->
                   let state = MenuTeam { TeamIndex = 0; TeamIndices = Map.toKeyList field.Team }
                   let field = Field.updateMenu (fun menu -> { menu with MenuState = state }) field
  
positive.code:                  // props
                   Content.entities field (fun field _ -> field.Props) (fun props _ -> props) $ fun _ prop _ ->
                      Content.entity<PropDispatcher> Gen.name
                          [Entity.Prop <== prop]
  
                   // spirit orb
                   Content.entityIf field (fun field _ -> Field.hasEncounters field) $ fun field _ ->
  
negative.code:         | Update
          | UpdateAvatar of Avatar
          | UpdateFieldTransition
          | UpdateProp of Prop
          | MenuTeamOpen
          | MenuTeamAlly of int
          | MenuItemOpen
  