What probably matters to youSection of the release
What
In headless mode, Claude Code runs without its interactive screen and is driven by another program. A turn is one exchange where Claude handles a message. Sometimes a turn begins before the startup message has been sent. When that happens, the session now calls an optional onTurnBeganBeforeInit callback, which is a function the controlling program can supply. If that function fails, the error is logged and the turn carries on.
Why
Programs that run Claude Code can measure when turns begin before startup has finished. A fault in their own callback will not stop the turn.
