dcg (Destructive Command Guard)

A high-performance hook for AI coding agents that blocks destructive commands before they execute, protecting your work from accidental deletion across Claude Code, Codex CLI, Gemini CLI, Copilot CLI, VS Code Copilot Chat, Cursor, Hermes Agent, Grok (xAI), Posit Assistant, Oh My Pi, Factory Droid's Execute tool, and related tools.

Supported: Claude Code, Codex CLI 0.125.0+, Gemini CLI, GitHub Copilot CLI, VS Code Copilot Chat, Cursor IDE, Hermes Agent, Posit Assistant (Positron/RStudio extension, standalone server, and pa terminal client), Grok (xAI) (native ~/.grok/hooks/ plus Claude compatibility layer), Antigravity CLI (agy) (native ~/.gemini/config/hooks.json via dcg install --agy), OpenCode (native tool.execute.before plugin via dcg install --opencode — see docs/opencode-integration.md), Oh My Pi (omp) (native tool_call extension via dcg install --omp), Crush (native hooks.PreToolUse entry in crush.json via dcg install --crush — see docs/crush-integration.md), Reasonix (native hooks.PreToolUse entry in settings.json via dcg install --reasonix — see docs/reasonix-integration.md), Muse Code (native hooks.PreToolUse matcher group in ~/.config/muse/settings.json via dcg install --muse — see docs/muse-integration.md), Amp (native tool.call plugin via dcg install --amp — see docs/amp-integration.md), Pi (via extension recipe), Aider (limited—git hooks only), Continue (detection only)

Factory Droid's Execute tool is supported through dcg install --droid; see coverage and Script-mode limitations.

Install a verified release on Linux, macOS, or WSL. The copyable recipe authenticates the pinned installer before running it and supports normal, easy-mode, and system-wide installation.

Install a verified release with PowerShell. This recipe checks the installer's pinned SHA256 and Minisign signature before execution, then requires Minisign verification of the native binary too.

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TL;DR

The Problem: AI coding agents (Claude, Codex, Gemini, Copilot, etc.) occasionally run catastrophic commands like git reset --hard, rm -rf ./src, or DROP TABLE users—destroying hours of uncommitted work in seconds.

The Solution: dcg is a high-performance hook that intercepts destructive commands before they execute, blocking them with clear explanations and safer alternatives.

Why Use dcg?

Feature	What It Does
Zero-Config Protection	Blocks dangerous git/filesystem commands out of the box
50+ Security Packs	Databases, Kubernetes, Docker, AWS/GCP/Azure, Terraform, and more
Sub-Millisecond Latency	SIMD-accelerated filtering—you won't notice it's there
Heredoc/Inline Script Scanning	Catches python -c "os.remove(...)" and embedded shell scripts
Smart Context Detection	Won't block grep "rm -rf" (data) but will block rm -rf / (execution)
Rich Terminal Output	Human-readable denial panels, rule context, and suggestions on stderr
Agent-Safe Streams	Machine-readable hook output stays on stdout while rich UI stays on stderr
Native Codex Support	Codex CLI 0.125.0+ receives a minimal stdout JSON denial that current clients enforce reliably
Graceful Degradation	Plain output for CI, pipes, dumb terminals, and no-color environments
Scan Mode for CI	Pre-commit hooks and CI integration to catch dangerous commands in code review
Bounded Failure Policy	Analysis timeouts become explicit review/block outcomes; malformed raw hook envelopes remain auditable and configurable
Explain Mode	dcg explain "command" shows exactly why something is blocked

Quick Example

# AI agent tries to run:
$ git reset --hard HEAD~5

# dcg intercepts and blocks:
════════════════════════════════════════════════════════════════
BLOCKED  dcg
────────────────────────────────────────────────────────────────
Reason:  git reset --hard destroys uncommitted changes

Command: git reset --hard HEAD~5

Tip: Consider using 'git stash' first to save your changes.
════════════════════════════════════════════════════════════════

Enable More Protection

# ~/.config/dcg/config.toml
[packs]
enabled = [
    "database.postgresql",    # Blocks DROP TABLE, TRUNCATE
    "kubernetes.kubectl",     # Blocks kubectl delete namespace
    "cloud.aws",              # Blocks aws ec2 terminate-instances
    "containers.docker",      # Blocks docker system prune
]

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