The vocabulary a lobby's state commonly uses.

Core does not model a state machine — it does not know when a match starts, ends, drafts, pauses or goes to overtime. It knows a lobby was created, and nothing more. So the values below are documentation, not an enum: core accepts any state word, any state may follow any other, and a game that needs a vocabulary or an ordering enforces both in before_lobby_state_change — the same callback that already gates who may move to what:

def before_lobby_state_change(_lobby, _from, to)
    when to not in ["created", "starting", "playing", "ended"],
    do: {:error, :unknown_state}

A state is a word, not a lifecycle: core attaches no meaning to any of them, including whether one ends the lobby. A game that finishes a match deletes the lobby itself; retention only reaps lobbies everyone has gone quiet in.