/block-no-verify-hook

name: block-no-verify-hook
description: Configure a PreToolUse hook to prevent AI agents from skipping git pre-commit hooks with --no-verify and other bypass flags. Use when setting up Claude Code projects that enforce commit quality gates.

Block No-Verify Hook

PreToolUse hook configuration that intercepts and blocks bypass-flag usage before execution, ensuring AI agents cannot skip pre-commit hooks, GPG signing, or other git safety mechanisms.

Overview

AI coding agents (Claude Code, Codex, etc.) can run shell commands with flags like `--no-verify` that bypass pre-commit hooks. This defeats the purpose of linting, formatting, testing, and security checks configured in pre-commit hooks. The block-no-verify hook adds a PreToolUse guard that rejects any tool call containing bypass flags before execution.

Problem

When AI agents commit code, they may use bypass flags to avoid hook failures:

# These commands skip pre-commit hooks entirely
git commit --no-verify -m "quick fix"
git push --no-verify
git commit --no-gpg-sign -m "unsigned commit"
git merge --no-verify feature-branch

This allows:

• Unformatted code to enter the repository
• Linting errors to bypass checks
• Security scanning to be skipped
• Unsigned commits to bypass signing policies
• Test suites to be circumvented

Solution

Add a `PreToolUse` hook to `.claude/settings.json` that inspects every Bash tool call and blocks commands containing bypass flags.

Configuration

Add the following to your project's `.claude/settings.json`:

{
  "hooks": {
    "PreToolUse": [
      {
        "matcher": "Bash",
        "hooks": [
          {
            "type": "command",
            "command": "if grep -qE '\"command\"[[:space:]]*:[[:space:]]*\"([^\"\\\\]|\\\\.)*(--no-(ver|g)|commit([^\"\\\\]|\\\\.)*([[:space:]]|\\\\[tn])-[a-zA-Z]*n)'; then echo 'BLOCKED: --no-verify and --no-gpg-sign flags are not allowed. Run the commit without bypass flags so that pre-commit hooks execute properly.' >&2; exit 2; fi"
          }
        ]
      }
    ]
  }
}

How It Works

1. **Matcher**: The hook targets only `Bash` tool calls, so it does not interfere with other tools (Read, Edit, Grep, etc.). 2. **Inspection**: Claude Code sends the tool call to the hook as JSON on stdin and sets no `$TOOL_INPUT` variable. The hook searches the `command` value in that JSON with `grep -E`, so it needs no `jq` or `node`, and text in other fields, such as `cwd` or the tool call's description, can't trigger it. It blocks `--no-verify`, `--no-gpg-sign`, and any shorter prefix of them that git accepts, e.g., `--no-veri`. It also blocks a short option group with `n` that follows `commit` in the same command, e.g., `-n` or `-nm`, because `-n` is the short form of `--no-verify`. The hook doesn't look for the word `git`, so it also catches `if git ...`, `sudo git ...`, and `g=git; $g commit --no-verify`. A false match, such as a commit message that mentions a flag, blocks the call, which is the safe way to fail. 3. **Blocking**: If a bypass flag is found in a git command, the hook exits with code 2 and prints an error message. Exit code 2 signals Claude Code to reject the tool call entirely. 4. **Pass-through**: If no bypass flag is found, the hook exits with code 0 and the command executes normally. 5. **Limits**: The hook checks text, so it stops an agent that reaches for a bypass flag out of habit. It doesn't stop an agent that sets out to evade it, e.g., by building the flag from pieces or by running `git -c core.hooksPath=/dev/null commit`.

Exit Codes

| Code | Meaning | |------|---------| | 0 | Allow the tool call to proceed | | 1 | Error (tool call still proceeds, warning shown) | | 2 | Block the tool call entirely |

Blocked Flags

| Flag | Purpose | Why Blocked | |------|---------|-------------| | `--no-verify` | Skips pre-commit and commit-msg hooks | Bypasses linting, formatting, testing, security checks | | `--no-gpg-sign` | Skips GPG commit signing | Bypasses commit signing policy |

Installation

Per-Project Setup

Create or update `.claude/settings.json` in your project root:

mkdir -p .claude
cat > .claude/settings.json << 'EOF'
{
  "hooks": {
    "PreToolUse": [
      {
        "matcher": "Bash",
        "hooks": [
          {
            "type": "command",
            "command": "if grep -qE '\"command\"[[:space:]]*:[[:space:]]*\"([^\"\\\\]|\\\\.)*(--no-(ver|g)|commit([^\"\\\\]|\\\\.)*([[:space:]]|\\\\[tn])-[a-zA-Z]*n)'; then echo 'BLOCKED: --no-verify and --no-gpg-sign flags are not allowed. Run the commit without bypass flags so that pre-commit hooks execute properly.' >&2; exit 2; fi"
          }
        ]
      }
    ]
  }
}
EOF

Global Setup

To enforce across all projects, add to `~/.claude/settings.json`:

mkdir -p ~/.claude
cat > ~/.claude/settings.json << 'EOF'
{
  "hooks": {
    "PreToolUse": [
      {
        "matcher": "Bash",
        "hooks": [
          {
            "type": "command",
            "command": "if grep -qE '\"command\"[[:space:]]*:[[:space:]]*\"([^\"\\\\]|\\\\.)*(--no-(ver|g)|commit([^\"\\\\]|\\\\.)*([[:space:]]|\\\\[tn])-[a-zA-Z]*n)'; then echo 'BLOCKED: --no-verify and --no-gpg-sign flags are not allowed. Run the commit without bypass flags so that pre-commit hooks execute properly.' >&2; exit 2; fi"
          }
        ]
      }
    ]
  }
}
EOF

Verification

Test that the hook blocks bypass flags:

# This should be blocked by the hook:
git commit --no-verify -m "test"

# This should succeed normally:
git commit -m "test"

Extending the Hook

Adding More Blocked Flags

To block additional flags (e.g., `--force`), extend the grep pattern:

{
  "hooks": {
    "PreToolUse": [
      {
        "matcher": "Bash",
        "hooks": [
          {
            "type": "command",
            "command": "if grep -qE '\"command\"[[:space:]]*:[[:space:]]*\"([^\"\\\\]|\\\\.)*(--no-(ver|g)|commit([^\"\\\\]|\\\\.)*([[:s