It sometimes happens with simple things. I once pasted the announcement for an event in Claude to check for spelling and grammar.

It had a small suggestion for the last sentence and repeated the whole corrected version for me to copy and paste.

Only last sentence slightly modified - or so I thought because it had moved the date of the event in the first sentence by one day.

Luckily I caught it before posting, but it was a close call.

Yup, I always take editing suggestions and implement them manually, then re-feed the edited version back in for new suggestions if needed. Never let it edit your stuff directly —— the risk of stealth random errors sneaking in is too great.

Just because every competent human we know would edit ONLY the specified parts, or move only the specified columns with a cut/paste operation (or similar deterministically reliable operation), does not mean an LLM will do the same, in fact, it seems to prefer to regenerate everything on the fly. NO, just NO.