Person
Discussion

FollowerSet

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

    UniqueTicketDiscuss discuss

LocalTicket
    ticket    TicketId
    discuss   DiscussionId
    followers FollowerSetId

    UniqueLocalTicket           ticket
    UniqueLocalTicketDiscussion discuss
    UniqueLocalTicketFollowers  followers