Module graph

The dependency graph is a contract about what each layer is allowed to know. IOHIDPublic is a header-only bridging shim and knows nothing about Yamete. YameteCore knows nothing about sensors or outputs; it only knows what a Reaction is. SensorKit and ResponseKit both depend on YameteCore but never on each other; sources publish Reactions, outputs subscribe to Reactions, and the bus is the only handshake between them. YameteApp wires everyone together.

The codebase is split into four Swift Package Manager targets with a strictly unidirectional dependency graph. YameteApp sees everything. IOHIDPublic sees nothing.

      SPM dependency graph

• IOHIDPublic -- C header shim exposing private IOKit HID types Apple does not publish. Read-only; never changes.

      - `YameteCore` -- shared types, the reaction bus, signal processing, and logging. No sensor knowledge, no UI. Imported by everything.
  
      - `SensorKit` -- the entire sensor abstraction: impact sensors (accelerometer, microphone, AirPods motion), infrastructure event sources (USB, power, Bluetooth, audio peripherals, Thunderbolt, display hotplug, sleep/wake), ImpactFusion engine, and ImpactDetector per-sensor gate chain.
  
      - `ResponseKit` -- audio playback, screen overlay, LED flash, notification dispatch, face image cache. Knows about reactions and intensity; knows nothing about where they came from.
  
      - `YameteApp` -- the orchestrator. Owns the bus, wires sources and outputs, manages lifecycle. Also the SwiftUI menu bar shell.