The Hidden Cost of Invisible Server Function Context

Server functions promise elegant abstraction by letting developers call server code as if it were local, but this conceals a critical truth: the same function behaves fundamentally differently depending on whether it executes in the browser, on the server, within a route loader, or after user interaction. Understanding these distinctions—as TanStack Start explicitly designs for—is crucial for avoiding performance pitfalls and unpredictable behavior in production applications.