Your backend as an AI proxy

import { AuthClient } from '@monetize.software/sdk/core';
 
const auth = new AuthClient({ paywallId: 'pw_123', apiOrigin: 'https://pay.yourapp.com' });
 
async function askAI(prompt: string) {
  const token = await auth.getAccessToken();
  if (!token) { openLogin(); return; }
 
  const res = await fetch('https://api.yourapp.com/chat', {
    method: 'POST',
    headers: {
      'Content-Type': 'application/json',
      Authorization: `Bearer ${token}`
    },
    body: JSON.stringify({ prompt })
  });
  return res.json();
}

import { usePaywall } from '@monetize.software/sdk-react';
 
function Chat() {
  const paywall = usePaywall();
 
  async function askAI(prompt: string) {
    const token = await paywall?.auth?.getAccessToken();
    if (!token) { paywall?.openAuth(); return; }
 
    const res = await fetch('https://api.yourapp.com/chat', {
      method: 'POST',
      headers: { 'Content-Type': 'application/json', Authorization: `Bearer ${token}` },
      body: JSON.stringify({ prompt })
    });
    return res.json();
  }
  // ...
}

// POST /chat  —  Express / any Node handler
import { BillingClient, PaywallError } from '@monetize.software/sdk/core';
import OpenAI from 'openai';
 
const ORIGIN = process.env.PAYWALL_ORIGIN!;
const PAYWALL_ID = process.env.PAYWALL_ID!;
const openai = new OpenAI();
 
const billing = new BillingClient({
  paywallId: PAYWALL_ID,
  apiOrigin: ORIGIN,
  apiKey: process.env.MONETIZE_API_KEY!
});
 
app.post('/chat', async (req, res) => {
  // 1. pull the Bearer the browser attached
  const token = (req.headers.authorization || '').replace(/^Bearer /, '');
  if (!token) return res.status(401).json({ error: 'no_token' });
 
  // 2. verify it & resolve the monetize user.id
  const who = await fetch(`${ORIGIN}/api/v1/paywall/${PAYWALL_ID}/user`, {
    headers: { Authorization: `Bearer ${token}` }
  });
  if (!who.ok) return res.status(401).json({ error: 'invalid_token' });
  const { user, paid } = await who.json();
  // optional: gate on subscription state too
  // if (!paid) return res.status(402).json({ error: 'no_subscription' });
 
  // 3. call the AI provider with YOUR key
  const completion = await openai.chat.completions.create({
    model: 'gpt-4',
    messages: [{ role: 'user', content: req.body.prompt }]
  });
 
  // 4. debit AFTER success, against the verified user
  try {
    billing.setIdentity({ userId: user.id });
    await billing.debitTokens({ type: 'gpt-4', amount: 1 });
  } catch (e) {
    if (e instanceof PaywallError && e.code === 'insufficient') {
      return res.status(402).json({ error: 'out_of_credits' });
    }
    throw e;
  }
 
  res.json({ answer: completion.choices[0].message.content });
});

app.post('/chat', async (req, res) => {
  const token = (req.headers.authorization || '').replace(/^Bearer /, '');
  if (!token) return res.status(401).json({ error: 'no_token' });
 
  // verify
  const who = await fetch(`${ORIGIN}/api/v1/paywall/${PAYWALL_ID}/user`, {
    headers: { Authorization: `Bearer ${token}` }
  });
  if (!who.ok) return res.status(401).json({ error: 'invalid_token' });
  const { user } = await who.json();
 
  // ... call the AI provider ...
 
  // debit with the owner key
  const debit = await fetch(`${ORIGIN}/api/v1/paywall/${PAYWALL_ID}/balances`, {
    method: 'POST',
    headers: {
      'Content-Type': 'application/json',
      'X-Api-Key': process.env.MONETIZE_API_KEY!
    },
    body: JSON.stringify({ user_id: user.id, type: 'gpt-4', amount: 1, op: 'debit' })
  });
  if (debit.status === 400) {
    const { code } = await debit.json();
    if (code === 'insufficient') return res.status(402).json({ error: 'out_of_credits' });
  }
 
  res.json({ answer: '...' });
});

# 2. verify the user's token → user.id
curl "$PAYWALL_ORIGIN/api/v1/paywall/$PAYWALL_ID/user" \
  -H "Authorization: Bearer $USER_BEARER"
# → { "user": { "id": "auth-uuid", "email": "..." }, "paid": true, "balances": [...] }
 
# 4. debit with YOUR owner key
curl -X POST "$PAYWALL_ORIGIN/api/v1/paywall/$PAYWALL_ID/balances" \
  -H "Content-Type: application/json" \
  -H "X-Api-Key: $MONETIZE_API_KEY" \
  -d '{ "user_id": "auth-uuid", "type": "gpt-4", "amount": 1, "op": "debit" }'