Label new emails automatically

from google.oauth2.credentials import Credentials
from googleapiclient.discovery import build
from clickruntime import on_trigger, report_fetched, credentials, state, ai

LABELS = ["Inquiry", "Invoice", "Newsletter", "Notification", "Action needed"]

@on_trigger
def run(event):
    gmail = build("gmail", "v1", credentials=Credentials(credentials.connection("google", "work")), cache_discovery=False)
    after = state.get("after") or "1d"
    q = f"in:inbox after:{after}" if after.isdigit() else "in:inbox newer_than:1d"
    msgs = gmail.users().messages().list(userId="me", q=q, maxResults=50).execute().get("messages", [])
    done = set(state.get("done") or [])
    new = [m for m in msgs if m["id"] not in done]
    report_fetched(len(new))
    if not new:
        return {"summary": "Nothing new"}
    existing = {l["name"]: l["id"] for l in gmail.users().labels().list(userId="me").execute()["labels"]}
    for m in new:
        meta = gmail.users().messages().get(userId="me", id=m["id"], format="metadata",
                                            metadataHeaders=["From", "Subject"]).execute()
        heads = {h["name"]: h["value"] for h in meta["payload"]["headers"]}
        label = ai.generate(f"Pick one of {LABELS} for this email. Reply with the label only.\n"
                            f"From: {heads.get('From')}\nSubject: {heads.get('Subject')}\n{meta['snippet']}",
                            max_output_tokens=10).text.strip()
        label = label if label in LABELS else "Action needed"
        if label not in existing:
            existing[label] = gmail.users().labels().create(userId="me", body={"name": label}).execute()["id"]
        gmail.users().messages().modify(userId="me", id=m["id"], body={"addLabelIds": [existing[label]]}).execute()
        done.add(m["id"])
    state.set("done", sorted(done)[-1000:])
    return {"labelled": len(new)}