Claude Code Hooks 実践

Claude がツール呼び出しを決定
      ↓
[PreToolUse フック] ← exit 2 でブロック可能
      ↓
ツール実行（Bash, Write, Edit など）
      ↓
[PostToolUse フック]
      ↓
Claude が次のアクションを決定

{
  "hooks": {
    "PreToolUse": [
      {
        "matcher": "Bash",
        "hooks": [
          {
            "type": "command",
            "command": ".claude/hooks/safety.sh"
          }
        ]
      }
    ],
    "PostToolUse": [
      {
        "matcher": "Write|Edit|MultiEdit",
        "hooks": [
          {
            "type": "command",
            "command": ".claude/hooks/format.sh"
          }
        ]
      }
    ],
    "Notification": [
      {
        "hooks": [
          {
            "type": "command",
            "command": ".claude/hooks/notify-slack.sh"
          }
        ]
      }
    ]
  }
}

#!/usr/bin/env bash
# .claude/hooks/format.sh
set -euo pipefail

if ! command -v pnpm >/dev/null 2>&1; then
  echo "[format] pnpm not found, skipping"
  exit 0
fi

if [ ! -d .git ]; then
  echo "[format] Not a git repository, skipping"
  exit 0
fi

# 変更されたファイルを取得（-z で空白ファイル名も安全に処理）
git diff -z --name-only --diff-filter=ACMRTUXB HEAD 2>/dev/null \
  | while IFS= read -r -d '' file; do
    case "$file" in
      *.js|*.jsx|*.ts|*.tsx|*.json|*.md|*.yml|*.yaml|*.mjs)
        if [ -f "$file" ]; then
          pnpm exec prettier --write "$file" || true
        fi
        ;;
    esac
  done

echo "[format] Done"

"PostToolUse": [
  {
    "matcher": "Write|Edit|MultiEdit",
    "hooks": [
      { "type": "command", "command": ".claude/hooks/format.sh" }
    ]
  }
]

#!/usr/bin/env bash
# .claude/hooks/safety.sh
set -euo pipefail

# CLAUDE_TOOL_INPUT 環境変数から実行予定コマンドを取得（公式値）
tool_input="${CLAUDE_TOOL_INPUT:-}"
if [ -z "$tool_input" ] && [ ! -t 0 ]; then
  tool_input="$(cat)"
fi

# JSON からコマンド文字列を抽出
command_str=""
if [ -n "$tool_input" ] && command -v node >/dev/null 2>&1; then
  command_str="$(printf '%s' "$tool_input" \
    | node -e 'const d=JSON.parse(require("fs").readFileSync(0,"utf8"));
               if(d&&typeof d.command==="string") process.stdout.write(d.command);'
  )"
fi

if [ -z "$command_str" ]; then
  exit 0
fi

command_lc="$(printf '%s' "$command_str" | tr 'A-Z' 'a-z')"

# ブロックするパターン一覧
danger_patterns=(
  "rm -rf"
  "rm -fr"
  "git reset --hard"
  "git clean -fd"
  "git clean -fdx"
  "kubectl delete"
  "docker system prune"
  "mkfs"
  "dd if="
  "shutdown"
  "reboot"
)

for pattern in "${danger_patterns[@]}"; do
  if [[ "$command_lc" == *"$pattern"* ]]; then
    echo "[safety] Blocked: $pattern" >&2
    echo "[safety] Command: $command_str" >&2
    exit 2  # exit 2 でツール呼び出しをキャンセル
  fi
done

exit 0

#!/usr/bin/env bash
# .claude/hooks/notify-slack.sh
set -euo pipefail

SLACK_WEBHOOK_URL="${SLACK_WEBHOOK_URL:-}"

if [ -z "$SLACK_WEBHOOK_URL" ]; then
  echo "[notify] SLACK_WEBHOOK_URL not set, skipping"
  exit 0
fi

# CLAUDE_NOTIFICATION_MESSAGE 環境変数に通知メッセージが入る（公式値）
message="${CLAUDE_NOTIFICATION_MESSAGE:-Claude Code: タスクが完了しました}"
project_dir="$(pwd | xargs basename)"

payload="{
  \"text\": \"*[${project_dir}]* ${message}\",
  \"username\": \"Claude Code\",
  \"icon_emoji\": \":robot_face:\"
}"

curl -s -X POST \
  -H 'Content-Type: application/json' \
  -d "$payload" \
  "$SLACK_WEBHOOK_URL" \
  > /dev/null

echo "[notify] Sent to Slack"

"Notification": [
  {
    "hooks": [
      { "type": "command", "command": ".claude/hooks/notify-slack.sh" }
    ]
  }
]

#!/usr/bin/env bash
# .claude/hooks/session-report.sh
set -euo pipefail

report_dir=".claude/session-reports"
mkdir -p "$report_dir"

timestamp="$(date +%Y%m%d-%H%M%S)"
report_file="${report_dir}/${timestamp}.txt"

{
  echo "=== Claude Code Session Report: $(date) ==="
  echo ""
  echo "--- Git Status ---"
  git status --short 2>/dev/null || echo "(not a git repo)"
  echo ""
  echo "--- Changed Files ---"
  git diff --name-only HEAD 2>/dev/null || true
} > "$report_file"

echo "[session-report] Saved to $report_file"

"Stop": [
  {
    "hooks": [
      { "type": "command", "command": ".claude/hooks/session-report.sh" }
    ]
  }
]

.claude/
  settings.json          # チーム共通設定（リポジトリに含める）
  hooks/
    format.sh            # 自動フォーマット
    safety.sh            # 危険コマンドガード
    notify-slack.sh      # Slack 通知
    session-report.sh    # 完了レポート

# フックを手動実行してデバッグ
CLAUDE_TOOL_INPUT='{"command": "rm -rf /tmp/test"}' bash .claude/hooks/safety.sh

# settings.json のバリデーション
python3 -m json.tool .claude/settings.json