Building a service booking interface inside Telegram using Vue 3 seems straightforward until you test it on an actual mobile device or expose your API endpoint to live traffic. A naive implementation faces three critical breakages: the iOS virtual keyboard pushes your form inputs off-screen, the interface flashes default white styles for dark-mode users, and malicious users can forge client API requests claiming to be any user ID they want.

Telegram Mini Apps operate inside an embedded webview with strict platform-specific behaviors. The window.Telegram.WebApp object exposes theme preferences, viewport metrics, and authentication tokens.…