What changed

InvestSim started as a dashboard that could show a daily AI pick. Today it became a small, deterministic paper-trading engine.

The live source is the Invest AI API on Fly.io (<INVEST_API_BASE_URL>).

The app now reads:

• GET /api/v2/signals/top for the current AI pick.
• GET /api/v1/tickers?symbols=... for delayed/normalized quote prices.

The V1 rules

The engine is intentionally simple:

1. Start with $10,000.
2. Hold at most one symbol.
3. If flat, buy the latest AI pick.
4. If holding, sell by priority:
   • STOP at -5%.
   • TIME_EXIT after 2 calendar days.
   • ROTATE if the AI pick changes.
5. Use fractional shares rounded down to 4 decimals.
6. Skip if an engine fill already exists for the New York trading day.

This is not a broker and not investment advice. It is a reproducible simulation.

Why one cron

The daily Vercel Cron route is:

/api/cron/daily-run

It does two things in order:

1. Ingest the current AI pick.
2. Apply the paper-trade rules.

One route is easier to reason about than coordinating separate ingest and trade jobs.

ADRs added

InvestSim now has its own ADR index:

docs/adr/README.md
docs/adr/0001-turso-bootstrap-runtime.md
docs/adr/0002-v1-paper-trade-engine.md

The first ADR captures why Turso schema bootstrap happens inside a protected Vercel runtime endpoint. The second locks the V1 trading rules.

What is still deliberately limited

• Prices are backend quote snapshots, not exchange executions.
• Calendar days are used for V1 hold duration; true exchange-session calendars can come later.
• Slippage is currently 0.
• There is no live brokerage connection.

That restraint is the point: a paper lab should be transparent before it tries to look sophisticated.