# Starter Dough — Comprehensive Application Specification & Architecture

## Overview
Starter Dough is an enterprise-grade financial management tool crafted by LoafPickle Worldwide. Available at https://billing.loafpickle.com, it bridges lightweight client-side privacy with powerful PDF generation, ledger auditing, tax estimation, and optional encrypted cloud backup.

## Core Features & Functionality Breakdown

### 1. Invoices & Purchase Orders
- 100% Free Unlimited Creation: Users can build as many PDF Invoices and Purchase Orders as needed with zero limits or paywalls.
- Dynamic Form Inputs: Billed From / Billed To company info, issue date, due date, invoice number, line items with description, quantity, unit price, tax rates, and notes.
- Instant Client-Side PDF Generation: Uses html2pdf / jspdf to render vector PDF documents directly in the browser DOM. No document data is ever sent to an unencrypted backend server.

### 2. Expense & Revenue Ledger
- Track operational income and expenses categorized by client, vendor, project, or cost center.
- Summary analytics providing gross revenue, total expenses, net income, and tax reserve suggestions.
- Local storage persistence with JSON export/import capability.

### 3. Tax Estimate Calculator
- Real-time calculations for self-employed individuals and 1099 freelancers.
- Factor in standard deductions, self-employment tax rates (15.3%), and state/federal brackets to forecast quarterly payments.

### 4. Privacy & WebAuthn Passkey Security
- Local-First Architecture: Primary data resides in browser IndexedDB/LocalStorage.
- WebAuthn Passkey Encryption: Optional hardware/biometric authentication (TouchID, FaceID, Windows Hello, YubiKey) encrypts local client states.

### 5. Starter Dough Pro Upgrade
- Pricing: $29 one-time payment with promo code support (e.g. STARTER100 for 100% off).
- Payment Gateways: Integrated Stripe Checkout (`/api/create-checkout-session` & `/api/verify-checkout-session`) and direct Web3 Crypto payment options (Solana, Ethereum, Base, Polygon).
- Exclusive Pro Features:
  - Multi-device Cloud Sync backed by Supabase.
  - Custom branding presets (logos, accent colors, typography).
  - Stripe live payment links directly on exported invoices.
  - Crypto payment QR codes embedded in client invoices.
  - Advanced CSV / JSON ledger exporting for accounting software (QuickBooks, Xero).

## Technical Stack
- Frontend: React, Vite, Lucide Icons, html2canvas, jspdf.
- Hosting & Edge APIs: Vercel Serverless Functions (`/api/*`).
- Security & Database: Supabase Auth & PostgreSQL, WebAuthn API, Stripe Node SDK.

## URL Structure
- Main App: https://billing.loafpickle.com
- OpenAPI / Verification Endpoint: https://billing.loafpickle.com/api/verify-checkout-session
- LLM Overview: https://billing.loafpickle.com/llms.txt
- Sitemap: https://billing.loafpickle.com/sitemap.xml
- Robots: https://billing.loafpickle.com/robots.txt