You'll noticeTier: how much it should matter to you
1Useful: my rating, 1 to 5
1Signal: worth watching, 1 to 5
SessionsArea: what it touches
ImprovementsKind: in v2.1.280,
ImprovementsSection of the release
What
When Claude Code hands environment variables to a background or "spare" session, it now checks each one: variables with invalid names, non-string values, or NUL bytes in the value are dropped rather than passed through. A warning is logged naming which keys were dropped, noting that "programs it starts will not see it," and the drop is recorded in telemetry by category.
Why
This prevents malformed environment variables from silently breaking or misbehaving in background sessions, and makes it clear in the logs when and why a variable didn't make it through.
