CLAUDE_CODE_SHELL_PREFIX

A Claude Code environment variable, read out of the shipped bundle. It has been in the build since v2.1.138, including the newest one read.

Releases whose published page names CLAUDE_CODE_SHELL_PREFIX.

1. v2.1.301 15 Oct 2026
   How local MCP servers get their shell prefix and environment has changed

   For MCP servers started as local programs, the shell prefix and starting environment are now worked out in one place and adjusted by config scope

   found in this entry's text, named in this entry

2. v2.1.301 15 Oct 2026
   Simpler check for which hooks get the organization's shell prefix

   Whether a hook counts as your organization's, and so gets CLAUDE_CODE_SHELL_PREFIX, no longer depends on the hook's type or its plugin

   found in this entry's text, named in this entry

3. v2.1.299 14 Oct 2026
   Hooks that can't run in cloud sessions now say why

   Hooks that can't run in a cloud session or fail on another machine now return a clear reason, and shell prefix handling for plugin and skill hooks changed

   found in this entry's text

4. v2.1.288 2 Oct 2026
   Claude Code says why a hook was not registered

   Hooks that are skipped now come with a reason, such as a missing script or a script in an unread dot-folder

   found in this entry's text, named in this entry

5. v2.1.288 2 Oct 2026
   Shorter reasons when a hook is not sent to a cloud session

   With claude --cloud, notices about hooks held back are shorter and give a cause, with a warning when a changed guard hook blocks tool calls

   found in this entry's text

6. v2.1.281 23 Sep 2026
   Cloud device hooks: CLAUDE_CODE_SHELL_PREFIX and writable-root checks now understand Windows paths

   Checks on CLAUDE_CODE_SHELL_PREFIX for cloud device hooks now understand Windows paths

   found in this entry's text, named in this entry

7. v2.1.248 27 Aug 2026
   Ink app shell, MCP client and Skill tool moved to top-level definitions

   The Ink shell, MCP client and Skill tool are now defined at load time.

   found in this entry's text

8. v2.1.247 26 Aug 2026
   Hook inventory sent to a cloud worker includes the repo root

   The hook list sent to a cloud session now includes your repo root and a composed shell prefix.

   named in this entry, found in this entry's text

9. v2.1.247 26 Aug 2026
   Device hooks get a full child environment, and an untrustworthy shell prefix is dropped

   Hooks run for cloud sessions get a full environment, and an untrusted CLAUDE_CODE_SHELL_PREFIX is dropped with a warning.

   named in this entry, found in this entry's text

10. v2.1.247 26 Aug 2026
    Stricter vetting of hooks forwarded to a cloud session

    Hooks forwarded to a cloud session are vetted harder, and refused if their program lives somewhere the session can write.

    found in this entry's text

11. v2.1.246 25 Aug 2026
    Hooks run under the calling side's shell prefix and environment

    Hooks now run with the shell prefix and environment of whichever side made the call.

    named in this entry, found in this entry's text

12. v2.1.246 25 Aug 2026
    Hook and MCP program trust checks look at a second PATH

    Hook and MCP programs are checked against two PATHs, and any mismatch counts as risky.

    found in this entry's text

The earliest release whose published evidence quoted CLAUDE_CODE_SHELL_PREFIX was v2.1.247, 26 Aug 2026. That is the oldest release this project wrote about it, so it is a floor on the name's age and not the release that introduced it. It is not a presence reading: which builds carried the name is the table below.

One row per release since the first build this name was read out of. Absent means the build was read and the name was not in it, never mined means no bundle for that release was ever archived, and a declared type or a default is only ever what that release's own bundle stated.

Read out of the published npm bundle release by release, and out of Anthropic's own documentation as this site captured it. Nothing on this page is a description anybody here wrote about what the environment variable does. All environment variables.