Person
Discussion
FollowerSet

Outbox

OutboxItem
    outbox    OutboxId
    activity  PersistJSONObject
    published UTCTime

TicketContextLocal
    ticket  TicketId
    accept  OutboxItemId

    UniqueTicketContextLocal       ticket
    UniqueTicketContextLocalAccept accept

Ticket
    number      Int           Maybe
    created     UTCTime
    title       Text                -- HTML
    source      Text                -- Pandoc Markdown
    description Text                -- HTML
    assignee    PersonId      Maybe
    status      TicketStatus
    discuss     DiscussionId
    followers   FollowerSetId
    accept      OutboxItemId

    UniqueTicketDiscuss   discuss
    UniqueTicketFollowers followers