You'll noticeTier: how much it should matter to you
2Useful: my rating, 1 to 5
0Signal: worth watching, 1 to 5
SandboxArea: what it touches
ImprovementsKind: in v2.1.221,
ImprovementsSection of the release
What
The sandbox section of the Bash tool description now only tells Claude to use $TMPDIR when the sandbox actually exports it, and otherwise tells it to create its own scratch directory.
Details
the old "always use the $TMPDIR environment variable" text is kept when the helper returns true, meaning the platform is Windows or the sandbox profile is not "relaxed"
otherwise the model is told to make its own scratch dir with mktemp -d
so a relaxed non-Windows sandbox profile now gets the mktemp guidance
Evidence
the sandbox does not export it in this configuration
Strings lifted out of the shipped bundle, so the claim above can be checked against them.
