refactor: add common controller interface

src/App.tsx

@@ -1,7 +1,20 @@
 import { AppRoutes } from './app/AppRoutes'
+import { useKeyboardInput } from './input/useKeyboardInput'
+import { usePoseInput } from './input/usePoseInput'
+
+function InputControllers() {
+  useKeyboardInput()
+  usePoseInput()
+  return null
+}
 
 function App() {
-  return <AppRoutes />
+  return (
+    <>
+      <InputControllers />
+      <AppRoutes />
+    </>
+  )
 }
 
 export default App

src/features/song-select/SongSelectScreen.tsx

@@ -1,5 +1,6 @@
-import { useEffect, useMemo, useState } from 'react'
+import { useMemo, useState } from 'react'
 import type { CSSProperties } from 'react'
+import { useGameInput } from '../../input/useGameInput'
 import { ARHud } from './ARHud'
 import { SONGS } from './song-data'
 import { SongCarousel } from './SongCarousel'
@@ -14,21 +15,21 @@ function wrapIndex(index: number, length: number): number {
 export function SongSelectScreen() {
   const [currentIndex, setCurrentIndex] = useState(0)
   const activeSong = SONGS[currentIndex]
+  const handleConfirm = () => {}
 
-  useEffect(() => {
-    const onKeyDown = (event: KeyboardEvent) => {
-      if (event.key === 'ArrowLeft') {
+  useGameInput((action) => {
+    if (action === 'LEFT') {
         setCurrentIndex((prev) => wrapIndex(prev - 1, SONGS.length))
-      }
-
-      if (event.key === 'ArrowRight') {
-        setCurrentIndex((prev) => wrapIndex(prev + 1, SONGS.length))
-      }
     }
 
-    window.addEventListener('keydown', onKeyDown)
-    return () => window.removeEventListener('keydown', onKeyDown)
-  }, [])
+    if (action === 'RIGHT') {
+      setCurrentIndex((prev) => wrapIndex(prev + 1, SONGS.length))
+    }
+
+    if (action === 'BUTTON_A') {
+      handleConfirm()
+    }
+  })
 
   const cssVars = useMemo(
     () =>
@@ -60,7 +61,7 @@ export function SongSelectScreen() {
 
         <SongInfoBar
           song={activeSong}
-          onConfirm={() => {}}
+          onConfirm={handleConfirm}
         />
       </div>
     </main>

src/input/actions.ts

@@ -0,0 +1 @@
+export type GameAction = 'LEFT' | 'RIGHT' | 'UP' | 'DOWN' | 'BUTTON_A' | 'BUTTON_B'

src/input/inputBus.ts

@@ -0,0 +1,16 @@
+import type { GameAction } from './actions'
+
+type GameActionListener = (action: GameAction) => void
+
+const listeners = new Set<GameActionListener>()
+
+export function emit(action: GameAction): void {
+  listeners.forEach((listener) => listener(action))
+}
+
+export function subscribe(listener: GameActionListener): () => void {
+  listeners.add(listener)
+  return () => {
+    listeners.delete(listener)
+  }
+}

src/input/useGameInput.ts

@@ -0,0 +1,7 @@
+import { useEffect } from 'react'
+import type { GameAction } from './actions'
+import { subscribe } from './inputBus'
+
+export function useGameInput(onAction: (action: GameAction) => void): void {
+  useEffect(() => subscribe(onAction), [onAction])
+}

src/input/useKeyboardInput.ts

@@ -0,0 +1,25 @@
+import { useEffect } from 'react'
+import type { GameAction } from './actions'
+import { emit } from './inputBus'
+
+const KEY_TO_ACTION: Partial<Record<string, GameAction>> = {
+  ArrowLeft: 'LEFT',
+  ArrowRight: 'RIGHT',
+  ArrowUp: 'UP',
+  ArrowDown: 'DOWN',
+  Enter: 'BUTTON_A',
+  Escape: 'BUTTON_B',
+}
+
+export function useKeyboardInput(): void {
+  useEffect(() => {
+    const onKeyDown = (event: KeyboardEvent) => {
+      const action = KEY_TO_ACTION[event.key]
+      if (!action) return
+      emit(action)
+    }
+
+    window.addEventListener('keydown', onKeyDown)
+    return () => window.removeEventListener('keydown', onKeyDown)
+  }, [])
+}

src/input/usePoseInput.ts

@@ -0,0 +1,21 @@
+import { useEffect } from 'react'
+import { emit } from './inputBus'
+
+export function usePoseInput(): void {
+  useEffect(() => {
+    const emitAction = (action: Parameters<typeof emit>[0]) => {
+      emit(action)
+    }
+
+    // MediaPipe integration point:
+    // Convert detected pose/gesture events into GameAction values and call `emitAction(action)`.
+    // Example mapping idea: swipe-left -> 'LEFT', swipe-right -> 'RIGHT',
+    // hand-raise -> 'BUTTON_A', cancel gesture -> 'BUTTON_B'.
+    // Keep all MediaPipe-specific setup/teardown in this hook so UI components remain input-agnostic.
+    void emitAction
+
+    return () => {
+      // Cleanup MediaPipe resources/listeners here when integration is added.
+    }
+  }, [])
+}