TradeSphere

Pulling live market prices from a third-party API sounds like the easy half. It is not. The provider rate limits you, goes down during exactly the hours people want to check their portfolio, and returns a stale price without saying so. The design question was never how to fetch a price, it was what the dashboard shows when the price is an hour old or missing. A portfolio screen displaying a confidently wrong valuation is worse than one admitting it does not currently know, because someone might act on the first. So every figure carries the time it was fetched, and a failed feed leaves the last known value on screen with its age visible.