Implement a feature in baguette

baguette is a CLI + WebSocket server, not a SwiftUI app. There is no ViewModel layer, no Repository pattern, no async actors in the input path — gestures are synchronous Bool-returning calls into a @Mockable Input port 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.

Read CLAUDE.md before proceeding — the architecture section there is authoritative; this skill describes the process of adding features that fit it.

Workflow

┌──────────────────────────────────────────────────────────────┐
│  0. ARCHITECTURE DESIGN (user approval required)             │
│     wire shape · domain types · which layers change · risks  │