Hooks

Where it lives

• hooks/pre-tool-use.shGitHub ↗
  Read the script

  #!/usr/bin/env bash
  # bigpowers — pre-tool-use.sh
  # Harness-agnostic Git Safety Hook for Claude Code, Cursor, and Gemini CLI.
  # Enforces:
  # 1. Block dangerous commands (force push, reset --hard, etc.)
  # 2. Enforce Conventional Commits for 'git commit'
  # 3. Block direct commits/pushes to protected branches (main, master)
  #    unless GIT_BIGPOWERS_LAND=1 (scripts/land-branch.sh only)
  
  set -euo pipefail
  
  # Configuration
  PROTECTED_BRANCHES=("main" "master")
  DANGEROUS_PATTERNS=(
    "git reset --hard"
    "git clean -fd"
    "git clean -f"
    "git branch -D"
    "git checkout \\."
    "git restore \\."
    "push --force"
    "push -f"
    "reset --hard"
  )
  CONVENTIONAL_COMMITS_REGEX='^(feat|fix|docs|style|refactor|perf|test|build|ci|chore|revert)(\(.+\))?!?:[[:space:]].+'
  LAND_MODE="${GIT_BIGPOWERS_LAND:-}"
  
  # Detect mode from environment (for Gemini/Claude/Cursor parity)
  # GIT_GUARDRAILS_MODE: claude (default) | cursor | gemini
  MODE="${GIT_GUARDRAILS_MODE:-claude}"
  
  deny() {
    local reason="$1"
    if [ "$MODE" = "gemini" ]; then
      jq -nc --arg reason "$reason" '{decision: "deny", reason: $reason}'
    else
      echo "$reason" >&2
      exit 2
    fi
  }
  
  # Read input from stdin
  INPUT=$(cat)
  
  # Extract command using jq (standard in bigpowers)
  COMMAND=$(echo "$INPUT" | jq -r '.command // .tool_input.command // empty')
  
  if [ -z "$COMMAND" ]; then
    [ "$MODE" = "gemini" ] && echo '{"decision":"allow"}'
    exit 0
  fi
  
  # 1. Check for dangerous patterns (git push is NOT blanket-blocked)
  for p in "${DANGEROUS_PATTERNS[@]}"; do
    if echo "$COMMAND" | grep -qE "$p"; then
      deny "BLOCKED: '$COMMAND' matches dangerous pattern '$p'. Use a safer approach or ask the user."
    fi
  done
  
  # 2. Check for git commit / git push
  if [[ "$COMMAND" =~ git[[:space:]]+commit ]] || [[ "$COMMAND" =~ git[[:space:]]+push ]]; then
    CURRENT_BRANCH=$(git rev-parse --abbrev-ref HEAD 2>/dev/null || echo "unknown")
  
    # Push to protected branches
    if [[ "$COMMAND" =~ git[[:space:]]+push ]]; then
      PUSH_TARGETS_PROTECTED=false
      for b in "${PROTECTED_BRANCHES[@]}"; do
        if [[ "$COMMAND" =~ [[:space:]]+$b([[:space:]]|$) ]] \
          || [[ "$COMMAND" =~ :$b([[:space:]]|$) ]] \
          || [[ "$COMMAND" =~ refs/heads/$b ]]; then
          PUSH_TARGETS_PROTECTED=true
          break
        fi
      done
      # Bare `git push` / `git push origin` with no ref (uses upstream from protected HEAD)
      if [ "$PUSH_TARGETS_PROTECTED" = false ]; then
        for b in "${PROTECTED_BRANCHES[@]}"; do
          if [[ "$CURRENT_BRANCH" == "$b" ]] && {
            [[ "$COMMAND" =~ ^git[[:space:]]+push$ ]] \
            || [[ "$COMMAND" =~ ^git[[:space:]]+push[[:space:]]+origin$ ]];
          }; then
            PUSH_TARGETS_PROTECTED=true
            break
          fi
        done
      fi
      if [ "$PUSH_TARGETS_PROTECTED" = true ] && [ "$LAND_MODE" != "1" ]; then
        deny "BLOCKED: Direct push to protected branch is forbidden. Use kickoff-branch + release-branch (solo-local: scripts/land-branch.sh) or team-pr via gh."
      fi
    fi
  
    # Conventional Commits for 'git commit'
    if [[ "$COMMAND" =~ git[[:space:]]+commit ]]; then
      MSG=""
      if [[ "$COMMAND" =~ -m[[:space:]]+\"([^\"]+)\" ]]; then
        MSG="${BASH_REMATCH[1]}"
      elif [[ "$COMMAND" =~ -m[[:space:]]+\'([^\']+)\' ]]; then
        MSG="${BASH_REMATCH[1]}"
      fi
  
      if [ -n "$MSG" ]; then
        SUBJECT=$(echo "$MSG" | head -n 1)
        if [[ ! "$SUBJECT" =~ $CONVENTIONAL_COMMITS_REGEX ]]; then
          deny "BLOCKED: Commit message must follow Conventional Commits: <type>(<scope>): <subject>. Valid types: feat, fix, docs, style, refactor, perf, test, build, ci, chore."
        fi
  
        if [ ${#SUBJECT} -gt 72 ]; then
          deny "BLOCKED: Commit subject line must be 72 characters or less."
        fi
  
        # Block AI agent attribution (P1 — NEVER Co-authored-by:)
        if echo "$MSG" | grep -qiE '^co[- ]authored[- ]by:' || echo "$MSG" | grep -qiE '\nco[- ]authored[- ]by:'; then
          deny "BLOCKED: Commit must not include Co-authored-by: footer. All commits must appear as if authored solely by the human user (CONVENTIONS.md § Git Attribution)."
        fi
      fi
  
      # Block direct commits to main unless land script is active
      for b in "${PROTECTED_BRANCHES[@]}"; do
        if [[ "$CURRENT_BRANCH" == "$b" ]]; then
          if [ "$LAND_MODE" != "1" ]; then
            deny "BLOCKED: Direct commits to protected branch '$b' are forbidden. Use kickoff-branch to start a feature branch, or scripts/land-branch.sh to integrate."
          fi
        fi
      done
    fi
  fi
  
  # Allow everything else
  if [ "$MODE" = "gemini" ]; then
    echo '{"decision":"allow"}'
  fi
  exit 0
  

Read the script before you install anything that runs on your machine. This is the one part of a plugin that acts without being asked.