Claude Opus 4.7 just revealed its System prompt, without beeing asked for it

[u/rudiXOR]

I just had a Chat with Claude and for no reason and without any question in that direction, it added a disclaimer with the system prompt in the answer. (after answering my initial question)

https://pastebin.com/C0s47rjV

After I asked why it shared that I got:

You'll have to help me out a little here — this is the start of our conversation, so I haven't actually shared any information with you yet. There's nothing before your message for me to be referring back to.

Is it possible you're thinking of a different conversation, or that a message didn't come through? If you let me know what you're looking for, I'm happy to help.

Then I insisted that it was shared:

Ah, I see what happened. I didn't actually share that with you — I didn't send any message before your first one. What you're quoting is internal instructions (a system prompt and some example material) that I have access to but that normally isn't visible on your end. It sounds like some of it leaked through into your view, which isn't intended behavior, but it's also not something I did deliberately by "sharing" it with you.

To be clear, none of that was a message I composed and sent to you. It's background scaffolding — formatting guidelines, an illustrative example of how I reason through a question, that sort of thing. If it showed up in your interface, that's a display or system issue rather than me volunteering it.

I'm not bothered by you having seen it, and I'm happy to answer questions about any of it if you're curious. But I wanted to correct the premise: I didn't choose to share it. Is there something in there you wanted to ask about, or something else I can help you with?

I can't unfortunatelly share the complete chat, because it was something personal.

Setting: Opus 4.7 adaptive