MGS2001: path read denied by sandbox

A spell tried to read a file outside the workspace and outside the configured allowlist.

[MGS2001] fs read denied: /home/user/.aws/credentials

Why

The sandbox confines magus's subprocesses and in-process spells to the workspace plus a curated allowlist of toolchain, cache and system paths. Reads of dotfile-style credential stores in $HOME are exactly what compromised supply-chain packages target, so they are denied by default.

Resolution

1. If this is a malicious spell (the path is a credential file you never asked the spell to touch): do not lift the restriction. This is the system working as intended. Uninstall the spell and report it.

2. If this is a legitimate spell that needs to read an external path (e.g. it reads ~/.terraform.d/plugins to discover providers): add the path to your workspace's magus.yaml:

   sandbox:
     allow:
       - path: ~/.terraform.d/plugins
         mode: ro
   

   mode is ro, rw, rx or rwx. Use the narrowest mode that lets the workflow succeed.

3. If you want to turn the sandbox off for one invocation while you investigate:

   magus --sandbox=off run build
   

   The flag, not MAGUS_SANDBOX: the variable is a floor that magus.yaml can raise and never lower.

   Do not set sandbox.mode: off in magus.yaml to silence a real denial.