What: Fine-grained filesystem access controls using macOS sandbox-exec, allowing you to restrict which files and directories bash commands can read or write.
How to use: Configure in .claude/settings.json:
{
"sandbox": {
"filesystem": {
"read": {
"allow": ["~/projects/*", "~/data"],
"deny": ["/etc/passwd"]
},
"write": {
"allow": ["~/projects/output/*"],
"deny": ["~/projects/output/protected"]
}
}
}
}Details:
- Complements existing network sandboxing (v1.0.113 only had network restrictions)
- Read allow-list mode denies all reads except specified paths
- Write deny-list blocks specific paths while allowing essential system paths
- Automatically allows stdout/stderr, temp directories, and Claude config paths
- Supports path expansion (
~,./,../) and wildcards (/*suffix only) - Path validation prevents shell metacharacters (
&&,||,;, backticks,$) - Evidence:
QBB() at line 374281,y41() at line 353864