What
The list of settings recognized when serializing an agent's spawn configuration (for example, for the SDK) now includes isolation, alongside existing settings like background and omitClaudeMd. Separately, the schema validating spawn options for isolation, observer, and observer message was refactored to use shared helper definitions instead of separate inline ones.
Why
This lets an agent's isolation setting actually be carried through when its configuration is passed along, rather than being dropped during serialization.
Names in the bundleisolation
The entry above is what we published on the day. These lines were added later, as Anthropic's own pages caught up, and they sit beside the original rather than replacing it.
Confirmed since
Anthropic's documentation has since written up isolation, on Configure the sandboxed Bash tool.
The session temp directory is writable inside the sandbox by default, alongside the working directory. Unless you [disable filesystem isolation](#disable-filesystem-isolation), Claude Code sets `$TMPDIR` to this directory for sandboxed com…sandboxing see the edit
Added since
A small documentation edit on Configure cloud environments touched a line naming isolation after this was published.
MCP connectors you enable on a session or routine work without adding their hosts to **Allowed domains**, because connector traffic travels through Anthropic's servers rather than the session's network. This relies on the same Anthropic-bo…cloud-environments see the edit
One source agreesOne thing we can check says the same as this entry.
Anthropic's documentation agrees
A small documentation edit on Configure cloud environments touched a line naming isolation after this was published.