Email PDF invoices from Airtable when a record is ready

import base64
from email.mime.application import MIMEApplication
from email.mime.multipart import MIMEMultipart
from email.mime.text import MIMEText
from fpdf import FPDF
from google.oauth2.credentials import Credentials
from googleapiclient.discovery import build
from clickruntime import on_trigger, credentials, http, report_fetched
URL = "https://api.airtable.com/v0/appXXXXXXXXXXXXXX/Invoices"

@on_trigger
def run(event):
    h = {"Authorization": f"Bearer {credentials.secret('AIRTABLE_API_KEY')}"}
    recs = http.get(URL, headers=h, params={"filterByFormula": "{Status}='Ready'"}).json()["records"]
    report_fetched(len(recs))
    if not recs:
        return {"sent": 0}
    gmail = build("gmail", "v1", credentials=Credentials(credentials.connection("google", "work")), cache_discovery=False)
    for r in recs:
        f = r["fields"]
        pdf = FPDF(); pdf.add_page(); pdf.set_font("Helvetica", size=12)
        for line in (f"{f.get('Type', 'Invoice')} {f.get('Number', '')}", f"Client: {f.get('Client')}",
                     f"Items: {f.get('Items', '')}", f"Total: {f.get('Total')}", f"Due: {f.get('Due', '')}"):
            pdf.cell(0, 10, line, new_x="LMARGIN", new_y="NEXT")
        msg = MIMEMultipart(); msg["To"] = f["Client email"]; msg["Subject"] = f"{f.get('Type', 'Invoice')} {f.get('Number', '')}"
        msg.attach(MIMEText("Please find your document attached. Thank you!"))
        msg.attach(MIMEApplication(bytes(pdf.output()), Name=f"{f.get('Number', 'invoice')}.pdf"))
        gmail.users().messages().send(userId="me", body={"raw": base64.urlsafe_b64encode(msg.as_bytes()).decode()}).execute()
        http.patch(f"{URL}/{r['id']}", headers=h, json={"fields": {"Status": "Sent"}})
    return {"sent": len(recs)}