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MGS2006: likely PATH-shim manager stripped

A subprocess failed and magus suspects the cause is sandbox stripping the env vars that a PATH-shim runtime manager (mise, asdf, direnv) relies on.

[MGS2006] mise shims appear stripped from PATH; the build is using system tools instead
  cmd=go missing_var=MISE_DATA_DIR

Why

mise, asdf, and direnv work by injecting a shim directory into PATH and reading a tool-version file from the workspace. The shim binary is invoked when the user runs go, then mise looks at its own MISE_* env vars to decide which Go version to dispatch to.

When sandbox strips MISE_* (or ASDF_*, DIRENV_*) from the child's environment, the shim runs without configuration and either fails or falls back to a system tool the user did not intend to use.

Resolution

Add the variables your runtime manager needs to sandbox.env.passthrough:

sandbox:
  env:
    passthrough:
      - "MISE_*" # mise
      - "ASDF_*" # asdf
      - "DIRENV_*" # direnv

Pick the one (or two) you actually use. The wildcard is a suffix match so MISE_* covers MISE_DATA_DIR, MISE_SHIMS, __MISE_*, etc.

These variables do not, by themselves, contain credentials a supply-chain attacker would target. They configure a local tool manager. Adding them to the passthrough list does not weaken sandbox's secret-protection guarantee.

If you do not use a PATH-shim manager and this code fires, the heuristic is wrong; please file an issue with the parent PATH and the failing command.

sandbox diagnosticsLanding page for the sandbox that confines magus spells to the workspace, plus its MGS2xxx diagnostics for denied reads, writes, execs, and env leaks. magus stdlibReference for every magus stdlib module - fs, os, http, json, yaml, crypto, and the rest of the magusfile API surface. MGS2001: path read deniedFires when a spell tries to read a file outside the workspace and outside the configured sandbox allowlist, typically a credential store. MGS2002: path write deniedFires when a spell tries to write to a file outside the workspace and outside the sandbox allowlist, blocking persistence and tampering attacks.
MGS2006sandboxmiseasdfdirenvPATHshimspassthrough
Last updated (b022d75e)
Glossary

Workspace

The magus root directory that owns a set of projects and shared config; the unit magus operates over. See workspace.

Target

A named operation (build, test, ...) you invoke with magus run <target>; it may compose a spell's tool-native operations and depend on other targets. See targets.

Sandbox

The restricted filesystem and environment a target runs in, so builds stay reproducible and side-effect-free. See sandbox.

CI

An ordinary magusfile-defined target you compose yourself with magus\needs - magus does not hardcode its stages. Magus.RunCI treats it specially only in that it strips the rw charm, it is the anchor magus affected ci keys off, and a selected scope with no project declaring it is a load error rather than a silent no-op. See targets.

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