But your private key should never leave your secure storage to be put anywhere. If you somehow export it and then also give someone or an LLM access to it, then this is ofc very stupid. But this attack vector is possible with every authentication.

I mean it’s probably a good idea to have some kind of limit in place, because you really don’t want to deal with attackers trying to transfer megabytes worth of text in the password field and triggering an OOM on your end. But this limit should still be pretty high ofc.

Maybe write freely would be an option? There is also a hosted version of it on write.as. It also speaks Activity Pub so it would be published on the fediverse too. I’ve not looked super deeply into the technology, but considered using it for my (future) blog.