Claude Codeに頼んだらGmailの振り分け・ラベル付け・返信が全自動になった話【2026年版】

# Claude Codeが自動生成したGmail自動化スクリプト
from google.oauth2.credentials import Credentials
from google_auth_oauthlib.flow import InstalledAppFlow
from google.auth.transport.requests import Request
from googleapiclient.discovery import build
import anthropic, base64, json, pickle, os
from email.mime.text import MIMEText

SCOPES = [
    'https://www.googleapis.com/auth/gmail.readonly',
    'https://www.googleapis.com/auth/gmail.compose',
    'https://www.googleapis.com/auth/gmail.modify',
]

def get_gmail_service():
    """OAuth 2.0認証でGmailサービスを取得"""
    creds = None
    if os.path.exists('token.pickle'):
        with open('token.pickle', 'rb') as f:
            creds = pickle.load(f)
    if not creds or not creds.valid:
        if creds and creds.expired and creds.refresh_token:
            creds.refresh(Request())
        else:
            flow = InstalledAppFlow.from_client_secrets_file('credentials.json', SCOPES)
            creds = flow.run_local_server(port=0)
        with open('token.pickle', 'wb') as f:
            pickle.dump(creds, f)
    return build('gmail', 'v1', credentials=creds)


def get_unread_emails(service, max_results=20):
    """未読メールを取得して辞書リストで返す"""
    results = service.users().messages().list(
        userId='me', q='is:unread', maxResults=max_results
    ).execute()
    messages = results.get('messages', [])
    email_list = []
    for msg in messages:
        raw = service.users().messages().get(
            userId='me', id=msg['id'], format='full'
        ).execute()
        headers = {h['name']: h['value'] for h in raw['payload']['headers']}
        body = _extract_body(raw['payload'])
        email_list.append({
            'id': msg['id'],
            'from': headers.get('From', ''),
            'subject': headers.get('Subject', ''),
            'body': body[:2000],
        })
    return email_list


def analyze_email_with_claude(email_data):
    """Claudeでメールを分析し、返信下書きを生成（送信はしない）"""
    client = anthropic.Anthropic()
    prompt = f"""
以下のメールを分析してください。

差出人: {email_data['from']}
件名: {email_data['subject']}
本文: {email_data['body']}

JSON形式で回答してください（コードブロック不要）:
{{
  "priority": "high/medium/low",
  "category": "inquiry/appointment/support/newsletter/other",
  "summary": "要約（50文字以内）",
  "action_required": true/false,
  "draft_reply": "返信下書き（丁寧なビジネス日本語で200文字程度）"
}}
"""
    response = client.messages.create(
        model="claude-opus-4-5",
        max_tokens=1024,
        messages=[{"role": "user", "content": prompt}]
    )
    return json.loads(response.content[0].text)


def create_draft(service, to, subject, body):
    """Gmailに返信下書きを保存する（絶対に送信しない）"""
    message = MIMEText(body)
    message['to'] = to
    message['subject'] = f'Re: {subject}'
    raw = base64.urlsafe_b64encode(message.as_bytes()).decode('utf-8')
    draft = service.users().drafts().create(
        userId='me', body={'message': {'raw': raw}}
    ).execute()
    return draft['id']  # 下書きIDを返す（送信はしない）


def add_label(service, message_id, label_name):
    """メールにラベルを付与する"""
    # 既存ラベルを検索
    labels = service.users().labels().list(userId='me').execute().get('labels', [])
    label_id = None
    for label in labels:
        if label['name'] == label_name:
            label_id = label['id']
            break
    # ラベルがなければ新規作成
    if not label_id:
        new_label = service.users().labels().create(
            userId='me', body={'name': label_name}
        ).execute()
        label_id = new_label['id']
    # ラベルを付与
    service.users().messages().modify(
        userId='me', id=message_id,
        body={'addLabelIds': [label_id]}
    ).execute()


def main():
    """メイン処理：未読メールを一括処理する"""
    service = get_gmail_service()
    emails = get_unread_emails(service, max_results=20)
    print(f"📬 未読メール {len(emails)}件を取得しました\n")

    for i, email in enumerate(emails):
        print(f"[{i+1}/{len(emails)}] 分析中: {email['subject'][:30]}...")
        result = analyze_email_with_claude(email)

        # カテゴリラベルを付与
        label_map = {
            'inquiry': 'AI分類/問い合わせ',
            'appointment': 'AI分類/アポ依頼',
            'support': 'AI分類/サポート',
            'newsletter': 'AI分類/ニュース',
        }
        label = label_map.get(result['category'], 'AI分類/その他')
        add_label(service, email['id'], label)

        # 優先度highで対応必要なメールは下書きを作成
        if result['priority'] == 'high' and result['action_required']:
            draft_id = create_draft(service, email['from'], email['subject'], result['draft_reply'])
            print(f"  🔴 優先度HIGH → 下書き作成: {draft_id[:10]}...")
        else:
            print(f"  ⚪ 優先度{result['priority'].upper()} → ラベル付与のみ")

    print("\n✅ 全メール処理完了。Gmailの下書きを確認してください。")

if __name__ == '__main__':
    main()