[BUG/UX] Sandbox network whitelist: No way to proactively configure domains, git operations fail without prompts

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

Git commands pre-approved in settings fail silently with exit code 128 when sandbox is enabled, due to network restrictions blocking github.com. There's no prompt to whitelist the domain, and the /sandbox command doesn't provide a way to proactively add network allowlists.

What Should Happen?

Option A (Reactive prompts):
When pre-approved git command needs network access, show prompt:
Git push requires network access to github.com
[ Deny ] [ Allow Once ] [ Update Sandbox Configuration ]

Option B (Proactive configuration):
/sandbox command should provide UI to add network whitelists:
Network allowed domains:
• code.claude.com
• github.com [Add]

[Add new domain...]

Option C (Smart defaults):
Git-related commands should auto-whitelist common git hosting domains when pre-approved:

• github.com, *.github.com
• gitlab.com, *.gitlab.com
• bitbucket.org, *.bitbucket.org

Error Messages/Logs

Error: Exit code 128
error: could not write config file .git/config: Device or resource busy
fatal: could not set 'remote.origin.url' to xxx

Steps to Reproduce

1. Enable sandbox mode in .claude/settings.local.json:

{
"permissions": {
"allow": [
"Bash(git push:*)",
"Bash(git remote set-url:*)"
]
}
}

1. Run a git command that requires network access:

git push
# or
git remote set-url origin git@github.com:user/repo.git

1. Command fails with:

Error: Exit code 128
ssh: Could not resolve hostname github.com: Temporary failure in name resolution
fatal: Could not read from remote repository.

1. Try /sandbox command to add network whitelist
2. Unable to add domains proactively

Claude Model

Sonnet (default)

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.0.37

Platform

Anthropic API

Operating System

Other Linux

Terminal/Shell

Other

Additional Information

Impact

• Broken workflow: Pre-approved git commands don't work as expected
• Poor UX: Silent failures without guidance on how to fix
• Security workaround: Users forced to disable sandbox entirely for git operations
• Documentation gap: Docs mention reactive prompts but they don't trigger