You'll noticeTier: how much it should matter to you
3Useful: my rating, 1 to 5
3Signal: worth watching, 1 to 5
SDKArea: what it touches
ImprovementsKind: in v2.1.299,
ImprovementsSection of the release
Unclear Which setting under apply_flag_settings takes this value is not named.
What
A program that drives Claude Code can change session settings through apply_flag_settings. One of those settings takes a list of models. It used to accept a plain list of one to three model IDs, or null. It now has to be null or an object with exactly two keys, "for" and "models". Any other shape produces a warning.
Why
Programs that send the old plain list will now get a warning and need to switch to the new shape.
