I still quite often have even Opus 4.5 generate empty indented lines (regardless of explicit instructions in AGENTS.md not to (besides explicitly referencing the style guide as well), the code not containing any before and the auto-formatter removing them), for example. Trailing whitespace is much rarer but happens as well. Personally I don't care too much, since I've found LLMs to be most efficient when performing roughly the work of a handful commits at most in one thread, so I let the pre-commit hook sort it out after being done with a thread.