Implement a feature in baguette

baguette is a CLI + WebSocket server, not a SwiftUI app. There is no ViewModel layer, no async actors in the input path — gestures are synchronous Bool-returning calls into the @Mockable Input abstraction whose only concrete adapter is IndigoHIDInput. The frontend is hand-written vanilla JS IIFEs (no bundler) that talk to the server via one WebSocket per stream.

Naming abstractions: every @Mockable protocol in this codebase is a domain noun for the role it plays — Input, Screen, Accessibility, LogStream, DeviceHost, Subprocess, Chromes, Simulators. The pattern-label suffixes "Port" / "Service" / "Manager" never appear. If you reach for XxxPort, the abstraction isn't named yet — keep going until the noun describes what the thing is in the domain.