`safe-chains`

A command safety checker that auto-allows safe, read-only bash commands without prompting. Works as a Claude Code pre-hook, a CLI tool, or an OpenCode plugin.

When an agentic tool wants to run a bash command, safe-chains checks if every segment of the command is safe. If so, the command runs without asking for permission. If any segment is unsafe, the normal permission flow takes over. Commands in piped chains, &&, and ; sequences are each validated independently.

See COMMANDS.md for the full list of supported commands.

Install

Requires Rust.

From crates.io

cargo install safe-chains

From source

git clone git@github.com:michaeldhopkins/safe-chains.git
cd safe-chains
cargo install --path .

Both methods build the safe-chains binary and place it in ~/.cargo/bin/.

What about install.sh?

The repo includes an install.sh convenience script. All it does is run cargo install --path . and then check whether your ~/.claude/settings.json already has the hook configured. If not, it prints the JSON snippet you need to add. It does not modify any files.

Configure

Claude Code

Add this to ~/.claude/settings.json:

"hooks": {
  "PreToolUse": [
    {
      "matcher": "Bash",
      "hooks": [
        {
          "type": "command",
          "command": "safe-chains"
        }
      ]
    }
  ]
}

Restart your Claude Code sessions to activate the hook. Once configured, updating the safe-chains binary takes effect immediately.

OpenCode

Copy opencode-plugin.js from this repo to .opencode/plugins/ in your project. Requires safe-chains in PATH.

Usage

Claude Code (hook mode)

With the hook configured above, safe-chains reads JSON from stdin and responds with a permission decision. No arguments needed.

CLI mode

Pass a command as a positional argument. Exit code 0 means safe, exit code 1 means unsafe.

safe-chains "ls -la | head -5"    # exit 0 = safe
safe-chains "rm -rf /"            # exit 1 = unsafe

Developing

cargo test
cargo clippy -- -D warnings

Adding a new command:

Add constants and handler function in the appropriate src/handlers/ module
Register it in the dispatch match in src/handlers/mod.rs
Add #[cfg(test)] tests in the handler module covering both allow and deny cases
Run cargo test and cargo clippy -- -D warnings
Run ./generate-docs.sh to regenerate COMMANDS.md
Run cargo install --path . to update the installed binary

safe-chains 0.13.1

safe-chains