My first Opus 5.5 session ran `pkill -f "cat" -U <user> -n` when it wanted "to stop a stuck cat" (the explanation it gave when I asked why). On MacOS the command kills every process with "cat" in it. I was using effort high and auto mode.

That's the first time since I started running Claude Code nine months ago that a session causes actual harm to other work on the same machine. Can still be a coincidence.