Event RSVP agent

import OpenAI from 'openai';
import { Mcpmailer } from '@mcpmailer/sdk';

/* ── your provider: this block is the only part that changes ── */
const client = new OpenAI({ apiKey: process.env.OPENAI_API_KEY });

const MODEL = process.env.MODEL;
if (!MODEL) throw new Error('Set MODEL to the model name your provider expects, e.g. export MODEL=gpt-4o-mini');

/** The only provider-specific code in any of these examples. */
async function ask({ system, user, schema }: {
  system: string;
  user: string;
  schema?: object;
}) {
  const res = await client.chat.completions.create({
    model: MODEL,
    messages: [
      { role: 'system', content: system },
      { role: 'user', content: user }
    ],
    // A schema turns the answer into an object instead of prose, which is what
    // the branching examples want. Without one you get the text back.
    ...(schema
      ? { response_format: { type: 'json_schema', json_schema: { name: 'out', schema, strict: true } } }
      : {})
  });

  const text = res.choices[0].message.content ?? '';
  return schema ? JSON.parse(text) : text;
}

/* ── the agent ── */

const mm = new Mcpmailer();
const ORGANISER = 'jules@acme.com';

const INVITE = `You are invited to the Acme summer dinner.

Thursday 4 September, 18:30 EEST
Kaisaniemenkatu 4, third floor, buzzer 12

Reply by Friday 29 August, and tell me if you eat anything in particular or avoid anything.`;

// One per guest. A group thread makes one reply-all everybody's problem.
for (const guest of await guestList()) {
  await mm.send({ to: [guest.email], subject: 'Acme summer dinner, 4 September', body: INVITE, style: 'plain' });
}

const RSVP = {
  type: 'object',
  properties: {
    status: { type: 'string', enum: ['confirmed', 'likely', 'declined', 'unclear'] },
    guest_name: { type: 'string' },
    dietary: { type: 'string' },
    reply: { type: 'string' }
  },
  required: ['status']
};

const counts = { confirmed: 0, likely: 0, declined: 0 };
const notes: string[] = [];

for (const reply of await mm.listMessages({ unreadOnly: true })) {
  const out = await ask({
    system: RSVP_PROMPT,
    user: reply.body ?? reply.snippet,
    schema: RSVP
  });

  // "Should be able to" is not a yes, and rounding it up is how you cater for
  // forty and seat twenty-eight.
  if (out.status !== 'unclear' && out.status in counts) counts[out.status as keyof typeof counts]++;

  if (out.dietary) {
    notes.push(`${reply.from}: ${out.dietary}`);
    await mm.forward(reply.id, [ORGANISER], { body: `Dietary: ${out.dietary}` });
  }
  if (out.reply) await mm.reply(reply.id, out.reply);
  await mm.markUnread(reply.id, false);
}

await mm.send({
  to: [ORGANISER],
  subject: `Dinner: ${counts.confirmed} confirmed, ${counts.likely} likely`,
  body: [
    `Confirmed: ${counts.confirmed}`,
    `Likely: ${counts.likely}`,
    `Declined: ${counts.declined}`,
    '',
    'Dietary and access:',
    ...notes.map((n) => `- ${n}`)
  ].join('\n'),
  style: 'plain'
});