That tweet says:

> Opus 5 can silently fallback to Opus 4.8 (without any notice) on the serverside if you hit a guardrail

But https://support.claude.com/en/articles/16049681-why-claude-s... says (emphasis mine):

> These checks cause Claude to _visibly_ fallback from Opus 5 to Opus 4.8 [...] You'll see a notice explaining that the model switched, and the response will be labeled with the model that answered.

So who is right? I know for Fable I am visibly told, is this tweet trying to say it is silent against what Anthropic is saying?

So, announcing the fallback is better than doing it silently, but the fact that Fable falls back frequently for the kind of work I do (a lot of security oriented stuff lately, but it falls back on seemingly random stuff, sometimes, too), means I reach for it less. Getting interrupted mid-task makes it much less valuable. If I have any suspicion I'm going to hit the guardrails, I'll use something else.

Is some random guy on Twitter right, or official support docs that explicitly describe this scenario?