GitHub has a somewhat limited ticketing functionality (GitHub calls tickets "issues").
Tickets have two states: open or closed.
Once a ticket is created, the following modifications can be made to it: - edit ticket body/title - add a new comment - edit a comment's body - close a ticket (or reopen)
Thus, there is no "history" API call---we just get the current state, and we can formulate our own history based on the list of comments, updated_at timestamps, and comparing our state with the current state.
GitHub issues can also have arbitrary "labels" applied to them, but we're currently ignoring this functionality.