What
A user message can now carry an optional classifierBoundary marker. The auto-mode classifier checks for this marker when it decides which parts of the conversation to look at. This classifier is the check that decides whether actions can go ahead without asking you.
Why
It gives Claude Code a way to mark a point in the conversation that changes what the classifier looks at.
Something disagreesSomething we can check disagrees with this entry, or the writer said they could not settle it.
The writer flagged doubt
The finding does not say what sets the marker or how it changes the context the classifier receives.