also their api pricing is a little misleading - it only matches sonnet 4 pricing ($3/$15) only "for request under 128k" (whatever it means) but above that it's 2x more.
That 128k is a reference to the context window — how many tokens you put in to the start. Presumably Grok 4 with 128k context window is running on less hardware (it needs much less RAM than 256k) and they route it accordingly internally.
