TradingGoose-Market: canonical ticker identity across market data providers

This's a repost, view original article here When we started building TradingGoose, the first thing we needed was market data. Real-time quotes, historical bars, fundamentals, the raw material for any trading application. Simple enough: pick a data provider, call their API, done. Except we didn't want to depend on just one provider. We wanted connectors to Alpaca, Yahoo Finance, Alpha Vantage, Finnhub, and more, so users could choose the source that fits their needs, or combine multiple sources f