ChatAppend:
  type: world
  events:
    on player chats:
      - if <context.message.ends_with[--]>:
          - define message <context.message.before_last[--]>
          - flag <player> messages:->:<[message]>
          - narrate "You have <player.flag[messages].size> appended messages."
          - determine cancelled
      - else if <player.has_flag[messages]> && !<context.message.ends_with[--]>:
          - flag <player> messages:->:<context.message>
          - define appended_message <proc[CombineMessages].context[<player.flag[messages].space_separated>]><context.message>
          - determine <[appended_message]> passively
          - flag <player> messages:!
          - determine <[appended_message]>