Stocks

Package: opt-in. createStocksPackage({ fetchQuote }) is not among the built-ins createEngine() registers; you construct it with your own fetching function and add it to the engine’s packages (see choosing packages).

The engine holds no market-data key. Prices come from a function you supply, so the provider, and whatever key it needs, stays yours.

import { createStocksPackage } from "solve-engine/packages";

const stocks = createStocksPackage({
  fetchQuote: async (ticker, signal) => {
    const res = await fetch(`https://example.com/quote/${ticker}`, { signal });
    return res.json();
  },
});

With that in place, a ticker in a stock(...) call resolves to its price:

Expression	Result
stock(AAPL)	the current price
stock(AAPL) * 100	the price of a hundred shares
stock(AAPL) on April 12, 2005	the closing price on that day
stock(AAPL) close on 2005-04-12	the same, with the field named
stock(AAPL) volume on 2005-04-12	the volume traded that day

A dated lookup reads from a second function, fetchHistoricalQuote, supplied the same way. The stock(TICKER) call is the form the engine recognises; reading a bare ticker (AAPL on its own) is a further opt-in, off by default, so an ordinary word is never mistaken for a symbol.

Without a fetchQuote, stock(AAPL) returns a clearly named STOCKS_NOT_CONFIGURED error rather than a fabricated or zero price. A live price reaches the network, so its first result is a pending value and the real answer arrives once the request returns. A quote left on screen can also refresh on its own, without a keystroke: pass refetchIntervalMs and enable background refresh. See async and live data for how a host waits on the result and drives that schedule.

Each price records the provider it came from and when it was fetched (a dated close is recorded as the figure for its day), and every line computed from it carries that record; pass provider with your service’s name so the record can name it. To keep a price from moving, end the line with frozen; see frozen answers.

The results depend on the live provider, so they are shown here rather than asserted.