When Claude Code runs on Linux, for example on a remote or sandboxed machine, the Write tool now refuses some paths. The Write tool is what Claude uses to create or overwrite a file. A path is refused when it looks like it belongs to your own computer, which means it starts with one of these:
/Users/, a Mac home folder/Volumes/, a Mac drive- a drive letter such as
C:, as on Windows - a UNC path, which is a Windows network share starting with two backslashes
This check runs before Claude Code's existing path checks. When it refuses a path, Claude is told that nothing was written. It is also told to save the file under the outputs directory instead, or to copy the file over.
The check applies only on Linux and only when CLAUDE_CODE_ENVIRONMENT_KIND is not set. It sits behind a server-controlled switch. That switch falls back to on when the server sends nothing, and the check is skipped only when the switch is explicitly off.
A Linux session running somewhere else cannot reach the folders on your computer. A file written to one of these paths would never reach you. Refusing the write stops Claude from reporting that it saved a file you then cannot find.
tengu_hazy_cosmos Not enough to sayNothing here resolved what this flag was doing on this version, so nothing here should be read as on or off.
This account: no value returned · anonymous baseline: no value returned · compiled default in v2.1.300: on
These values were read against a different version of Claude Code, so treat them as the nearest reading available instead of one taken on this release.
Read once, for one account on one subscription tier, against v2.1.300. It isn't a statement about your account. What a flag value here can and cannot tell you
New in this build: tengu_hazy_cosmos