niche

# Niche v1 — Trading Card Marketplace with Partial Deposits

A peer-to-peer trading card marketplace where users list, discover, and transact cards with partial USDC deposits on Base Sepolia. Meet in person to inspect cards before completing payment.

## Architecture

**Hosted backend** on Supabase Edge Functions. The CLI is a thin HTTP client — all heavy logic (auth, signing, escrow, on-chain transactions) runs server-side.

```
CLI (thin client)          →  Edge Functions (Supabase)
  fetch() + open()              niche-api   (REST API)
  ~/.niche/auth.json            niche-ui    (hosted HTML pages)
  @supabase/supabase-js         niche-sign  (passkey signing)
  open (browser launcher)       niche-escrow (on-chain ops)
```

**Hosted UI:** https://niche-ddq89ltdk-clement-sutjiatmas-projects.vercel.app

Anyone with the link can browse cards — no install needed.

## Why Partial Deposits + In-Person Inspection

- **Partial deposits** — Hold a card with just $10-50 deposit, not full price
- **Meet & inspect** — See the card condition in person before final payment
- **Atomic payment** — Buyer confirms + pays remaining amount in single action
- **USDC escrow** — All funds secured on-chain, released when both confirm
- **Buyer cancellation** — Get full refund before seller confirms meetup
- **Passkey signing** — Touch ID / Face ID to authorize transactions
- **Gas sponsored** — No ETH needed for transactions
- **Shareable links** — Send card URLs to anyone, no app needed

## Trading Card Flow

```
1. Seller lists "Charizard Base Set" for $50 with $10 min deposit
2. Buyer deposits $10 USDC → card is held for buyer
3. Buyer can cancel anytime before seller confirms → full $10 refund
4. Both parties meet in person to inspect card
5. Seller confirms they showed up
6. Buyer confirms AND pays $40 remaining (atomic action)
7. Backend releases total $50 to seller
```

## Commands

### Browse (no account needed)

```bash
niche search --category "Pokemon" --max-price 100
niche bro...