This site describes solve-engine as it is on main: 2.43.0, which npm does not have yet. npm installs 2.40.0, so a page may show an answer that version does not give yet.
COINGECKO_PROVIDER
const COINGECKO_PROVIDER: "CoinGecko" = "CoinGecko";Defined in: packages/engine/src/uom/CurrencyExchange.ts:18
The provider name the engine records for crypto prices it fetched itself from CoinGecko.