Unclear It is not clear whether the removed step actually locked the file or did nothing at all.
What
Claude Code can rewrite a session's transcript file to make it smaller, called compacting. It can also mark individual messages in it as removed. Both operations used to begin by waiting on the file. That step is gone, and both now start their work straight away.
Compacting still checks whether the file changed underneath it, or was caught partway through a line, before it finishes. Message removal still refuses to run on a session file that is too large.
Why
If the removed step was a lock, other writes to the same transcript could now overlap with compacting or message removal. The checks that remain may be what guards against that now.
Something disagreesSomething we can check disagrees with this entry, or the writer said they could not settle it.
The writer flagged doubt
It is not clear whether the removed step actually locked the file or did nothing at all.