# HOA LedgerIQ — AI API Configuration Guide

## Overview

The **Benefit Calculator widget** currently runs entirely client-side using conservative
fixed-rate math. This guide explains how to upgrade it to call a real AI API
(Claude or OpenAI) so the recommendation text is generated dynamically by a language model.

---

## Architecture

```
Browser (app.js)
  └─► POST /api/calculate   (server.js)
        └─► Anthropic / OpenAI API
              └─► Returns AI-generated investment recommendation text
                    └─► JSON response back to browser
```

---

## Step 1 — Add your API key to `.env`

Open `.env` in the project root and add one of the following:

```env
# For Claude (Anthropic) — recommended
ANTHROPIC_API_KEY=sk-ant-...

# OR for OpenAI
OPENAI_API_KEY=sk-...
```

---

## Step 2 — Install the SDK

```bash
# Claude (Anthropic)
npm install @anthropic-ai/sdk

# OR OpenAI
npm install openai
```

---

## Step 3 — Add the `/api/calculate` endpoint to `server.js`

Add this block after the existing `/api/health` route:

### Using Claude (Anthropic)

```js
const Anthropic = require('@anthropic-ai/sdk');
const anthropic = new Anthropic({ apiKey: process.env.ANTHROPIC_API_KEY });

app.post('/api/calculate', async (req, res) => {
  const { homesites, propertyType, annualIncome, paymentFreq, reserveFunds, interest2025 } = req.body ?? {};

  if (!homesites || !annualIncome) {
    return res.status(400).json({ error: 'homesites and annualIncome are required.' });
  }

  const fmt = n => '$' + Math.round(n).toLocaleString();
  const freqLabel = { monthly: 'monthly', quarterly: 'quarterly', annually: 'annual' }[paymentFreq] || 'monthly';
  const typeLabel = { sfh: 'single-family home', townhomes: 'townhome', condos: 'condo', mixed: 'mixed-use' }[propertyType] || '';

  const prompt = `You are a conservative HOA financial advisor. Given the following community data, provide a brief (3-4 sentence) plain-English investment income recommendation. Use only conservative, realistic estimates. Do not speculate beyond what the data supports.

Community: ${homesites}-unit ${typeLabel} association
Annual dues income: ${fmt(annualIncome)} (collected ${freqLabel})
Reserve fund balance: ${fmt(reserveFunds || 0)}
Interest income earned in 2025: ${fmt(interest2025 || 0)}

Provide a recommendation focused on:
1. How much of the reserve funds could conservatively be invested and in what vehicle (e.g. CD ladder, money market, T-bills)
2. How much operating cash could earn interest between collection and expense periods
3. A realistic estimated annual interest income potential
4. A single sentence comparing that to their 2025 actual if provided

Keep the tone professional and factual. No bullet points — flowing paragraph only.`;

  try {
    const message = await anthropic.messages.create({
      model: 'claude-opus-4-6',
      max_tokens: 300,
      messages: [{ role: 'user', content: prompt }],
    });

    const text = message.content[0]?.text ?? '';
    res.json({ recommendation: text });
  } catch (err) {
    console.error('AI API error:', err.message);
    res.status(502).json({ error: 'AI service unavailable. Showing estimated result.' });
  }
});
```

### Using OpenAI (GPT-4o)

```js
const OpenAI = require('openai');
const openai = new OpenAI({ apiKey: process.env.OPENAI_API_KEY });

app.post('/api/calculate', async (req, res) => {
  const { homesites, propertyType, annualIncome, paymentFreq, reserveFunds, interest2025 } = req.body ?? {};

  // ... (same prompt construction as above) ...

  try {
    const completion = await openai.chat.completions.create({
      model: 'gpt-4o',
      max_tokens: 300,
      messages: [{ role: 'user', content: prompt }],
    });

    const text = completion.choices[0]?.message?.content ?? '';
    res.json({ recommendation: text });
  } catch (err) {
    console.error('AI API error:', err.message);
    res.status(502).json({ error: 'AI service unavailable.' });
  }
});
```

---

## Step 4 — Update `app.js` to call the API endpoint

In the `initCalculator` function, replace this line in the submitBtn handler:

```js
document.getElementById('calcAiText').textContent = ai;  // current: client-side text
```

With this:

```js
// Call the AI endpoint; fall back to client-side text if unavailable
try {
  const aiRes = await fetch('/api/calculate', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({ homesites, propertyType, annualIncome, paymentFreq, reserveFunds, interest2025 }),
  });
  if (aiRes.ok) {
    const { recommendation } = await aiRes.json();
    document.getElementById('calcAiText').textContent = recommendation;
  } else {
    document.getElementById('calcAiText').textContent = ai; // fallback
  }
} catch (_) {
  document.getElementById('calcAiText').textContent = ai; // fallback
}
```

> Note: The `submitBtn` handler must be declared `async` for the `await` above to work:
> ```js
> submitBtn?.addEventListener('click', async () => { ... });
> ```

---

## Step 5 — Restart the server

```bash
sudo systemctl restart hoaledgeriqweb

# Verify the endpoint is live
curl -X POST http://localhost:3000/api/calculate \
  -H "Content-Type: application/json" \
  -d '{"homesites":150,"propertyType":"sfh","annualIncome":300000,"paymentFreq":"monthly","reserveFunds":500000,"interest2025":4200}'
```

---

## Prompt Tuning Tips

The prompt in Step 3 is the core of the AI's behavior. You can adjust it to:

| Goal | Change |
|---|---|
| More optimistic estimates | Change "conservative" to "moderate" in the prompt |
| Shorter output | Reduce `max_tokens` to `150` |
| Include specific investment products | Add "mention specific products like Vanguard Federal Money Market or 6-month T-bills" |
| Add a disclaimer | Append "End with one sentence reminding them this is not financial advice." |

---

## Cost Estimate

| Model | Approx. cost per calculator use |
|---|---|
| Claude Opus 4.6 | ~$0.002 |
| Claude Sonnet 4.6 | ~$0.0004 |
| GPT-4o | ~$0.002 |
| GPT-4o-mini | ~$0.00005 |

For a landing page with low traffic, even Claude Opus is negligible cost. For scale,
`claude-sonnet-4-6` is the best balance of quality and price.

---

## Security Notes

- **Never expose your API key in `app.js` or any client-side code.** All AI calls must go through `server.js`.
- Rate-limit the `/api/calculate` endpoint to prevent abuse (e.g. with `express-rate-limit`):

```bash
npm install express-rate-limit
```

```js
const rateLimit = require('express-rate-limit');
const calcLimiter = rateLimit({ windowMs: 60 * 1000, max: 10 }); // 10 req/min per IP
app.use('/api/calculate', calcLimiter);
```