Constant MAX_LIVE_TRANSACTIONS 

pub const MAX_LIVE_TRANSACTIONS: usize = _; // 40usize

The most transactions that can be in flight at once, whatever the program does.

Two branch spaces (client and server), SLOTS branches in each, and five keys per branch — six methods, of which ACK folds onto INVITE. This is the bound behind Invariant::StoreGrowth: it depends on the vocabulary and not on the program’s length, which is what “does not grow without bound over a bounded sequence” has to mean if it is to mean anything. The vocabulary’s ceiling, kept because the doc below reads off it: the two HashMaps can hold at most SLOTS × FOLDED_METHODS keys each. The store-growth invariant no longer asserts against it, because it cannot fire — see the X-31 note in check_bound.