Support-ticket lifecycle with a reopen path

support_ticket.cell

// Support-ticket lifecycle with a reopen path.
// open -> in_progress -> resolved -> closed, with a resolved -> reopened
// loop that funnels back to in_progress. The * -> closed catch-all and the
// reopened -> in_progress arrow keep the machine live: every state can
// still reach the terminal `closed`. assert_fails guards illegal skips.

cell TicketDesk {
    face {
        signal file(id: String) -> String
        signal assign(id: String) -> String
        signal resolve(id: String) -> String
        signal reopen(id: String) -> String
        signal close(id: String) -> String
        signal status(id: String) -> String
        signal next(id: String) -> List<String>
    }

    state ticket {
        initial: open
        open        -> in_progress
        in_progress -> resolved
        resolved    -> reopened
        reopened    -> in_progress
        resolved    -> closed
        *           -> closed
    }

    on file(id: String)    { return get_status(id) }
    on assign(id: String)  { transition(id, "in_progress")  return get_status(id) }
    on resolve(id: String) { transition(id, "resolved")  return get_status(id) }
    on reopen(id: String)  { transition(id, "reopened")  return get_status(id) }
    on close(id: String)   { transition(id, "closed")  return get_status(id) }
    on status(id: String)  { return get_status(id) }
    on next(id: String)    { return valid_transitions(id) }
}

cell test TicketTests {
    rules {
        // happy path
        assert file("k1") == "open"
        assert assign("k1") == "in_progress"
        assert resolve("k1") == "resolved"
        assert close("k1") == "closed"

        // reopen loop: resolved -> reopened -> in_progress
        assert assign("k2") == "in_progress"
        assert resolve("k2") == "resolved"
        assert reopen("k2") == "reopened"
        assert assign("k2") == "in_progress"

        // any ticket can be closed via the * catch-all (here from open)
        assert close("k3") == "closed"

        // illegal: cannot resolve a ticket nobody has picked up (open)
        assert_fails resolve("k4")
        // illegal: cannot reopen something that was never resolved
        assert_fails reopen("k5")
    }
}