Slack bot with channel memory

import os
from datetime import datetime, timezone
from slack_bolt import App
from slack_bolt.adapter.socket_mode import SocketModeHandler
from tex import Tex

tex = Tex(api_key=os.environ["TEX_API_KEY"], base_url=os.environ["TEX_BASE_URL"])
app = App(token=os.environ["SLACK_BOT_TOKEN"])

def now_iso() -> str:
    return datetime.now(timezone.utc).isoformat().replace("+00:00", "Z")

def session_for(channel: str) -> str:
    return f"slack-{channel}"

@app.event("message")
def remember_message(event, say):
    if event.get("subtype") or event.get("bot_id"):
        return
    tex.conversations.remember(
        session_id=session_for(event["channel"]),
        turns=[{
            "role": "user",
            "text": f"<@{event['user']}>: {event['text']}",
            "timestamp": now_iso(),
        }],
    )

@app.event("app_mention")
def answer(event, say):
    query = event["text"].split(">", 1)[-1].strip()
    if not query:
        say("Ask me something and I'll search this channel's memory.")
        return

    hits = tex.recall(q=query, session_id=session_for(event["channel"]), top_k=5)

    if not hits.hits.turns or hits.confidence < 0.2:
        say(f"<@{event['user']}> I don't have anything relevant in memory yet.")
        return

    body = "\n".join(f"• {h.text}" for h in hits.hits.turns[:3])
    say(f"<@{event['user']}> here's what I remember:\n{body}")

if __name__ == "__main__":
    SocketModeHandler(app, os.environ["SLACK_APP_TOKEN"]).start()