Poshkan — Paper Trading

Risk-free US stock paper trading. Start with virtual cash, practice the market, track holdings and P&L — no real money on the line.

See DESIGN.md for the full product/architecture design.

Stack

• Next.js 16 (App Router) + TypeScript + Tailwind CSS v4
• Supabase — auth (with email confirmation), Postgres, Row-Level Security
• Twelve Data — live market quotes & search (proxied server-side)
• TanStack Query — live quote polling

Setup

1. Install dependencies

npm install

2. Create a Supabase project

1. Create a project at supabase.com.
2. Open the SQL Editor and run the contents of supabase/schema.sql. This creates the tables, RLS policies, the auto-profile trigger, and the trading RPC functions.
3. In Authentication → Providers → Email, keep "Confirm email" enabled.
4. In Authentication → URL Configuration, add your site URL (http://localhost:3000 for dev) to the redirect allow-list.

3. Get a Twelve Data API key

Sign up at twelvedata.com and copy your API key from the dashboard. The free tier is rate-limited (~8 requests/min) — fine for dev.

4. Configure environment

Copy .env.local.example to .env.local and fill in:

NEXT_PUBLIC_SUPABASE_URL=https://YOUR-REF.supabase.co
NEXT_PUBLIC_SUPABASE_ANON_KEY=your-anon-key
TWELVE_DATA_API_KEY=your-twelve-data-key
NEXT_PUBLIC_SITE_URL=http://localhost:3000

The Twelve Data key is server-only — never prefix it with NEXT_PUBLIC_.

5. Run

npm run dev

Open http://localhost:3000.

How it works

• Auth — email/password sign-up sends a confirmation email; the link lands on /auth/confirm which verifies the token and signs you in.
• Accounts — create multiple paper portfolios with starting cash and optional seeded holdings. Top up or reset cash anytime.
• Trading — search a symbol, then Buy / Sell / add to Watchlist. Trades fill at the live price (fetched server-side at execution) via an atomic Postgres RPC that validates cash and share balances (long-only, no margin).
• P&L — holdings show shares, avg cost, live price, day %, market value, and unrealized P&L in $ and %.

Roadmap (v2)

Crypto & Forex asset classes, limit orders, transaction-history view, account-value charts.