refactor: split sounds.ts into audio/ modules

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/game/audio/context.ts

@@ -0,0 +1,123 @@
+// Audio context, gain nodes, volume/mute management
+// This module has ZERO imports from other audio modules to prevent circular deps.
+
+let ctx: AudioContext | null = null
+let musicGain: GainNode | null = null
+let sfxGain: GainNode | null = null
+let musicPlaying = false
+let musicTimeout: number | null = null
+
+// AudioContext is ONLY created inside ensureAudioContext() (called from user gesture).
+// Before that, all SFX calls silently no-op to avoid Chrome autoplay warnings.
+let _audioUnlocked = false
+
+let masterMuted = false
+const MUSIC_VOL = 0.12
+const SFX_VOL = 0.25
+
+export function initCtx() {
+  if (ctx) return
+  ctx = new AudioContext()
+  musicGain = ctx.createGain()
+  musicGain.gain.value = masterMuted ? 0 : 0.12
+  musicGain.connect(ctx.destination)
+  sfxGain = ctx.createGain()
+  sfxGain.gain.value = masterMuted ? 0 : 0.25
+  sfxGain.connect(ctx.destination)
+}
+
+export function getCtx(): AudioContext {
+  if (!ctx) initCtx()
+  if (ctx!.state === 'suspended') {
+    ctx!.resume().catch(() => {})
+  }
+  return ctx!
+}
+
+// Get the SFX destination node (gain is 0 when muted, so audio is silent but context stays valid)
+export function getSfxDest(): AudioNode {
+  const c = getCtx()
+  return sfxGain ?? c.destination
+}
+
+export function getMusicGain(): GainNode | null {
+  return musicGain
+}
+
+export function getSfxGain(): GainNode | null {
+  return sfxGain
+}
+
+export function isMusicPlaying(): boolean {
+  return musicPlaying
+}
+
+export function setMusicPlaying(v: boolean) {
+  musicPlaying = v
+}
+
+export function getMusicTimeout(): number | null {
+  return musicTimeout
+}
+
+export function setMusicTimeout(v: number | null) {
+  musicTimeout = v
+}
+
+export function isAudioUnlocked(): boolean {
+  return _audioUnlocked
+}
+
+export function setAudioUnlocked(v: boolean) {
+  _audioUnlocked = v
+}
+
+export function isMasterMuted(): boolean {
+  return masterMuted
+}
+
+export function getMasterMuted(): boolean {
+  return masterMuted
+}
+
+export function setMusicVolume(v: number) {
+  if (musicGain) musicGain.gain.value = Math.max(0, Math.min(1, v))
+}
+
+export function setSfxVolume(v: number) {
+  if (sfxGain) sfxGain.gain.value = Math.max(0, Math.min(1, v))
+}
+
+export function setMasterMute(muted: boolean) {
+  masterMuted = muted
+  if (muted) {
+    if (musicGain) musicGain.gain.value = 0
+    if (sfxGain) sfxGain.gain.value = 0
+    // Note: kokoroStop and speechSynthesis.cancel are called from the caller
+    // to avoid circular deps — see index.ts setMasterMute wrapper
+  } else {
+    if (musicGain) musicGain.gain.value = MUSIC_VOL
+    if (sfxGain) sfxGain.gain.value = SFX_VOL
+  }
+}
+
+// Disconnect gain nodes to instantly kill all in-flight oscillators/buffers,
+// then reconnect so future sounds still work
+export function resetGainNodes() {
+  if (ctx) {
+    if (musicGain) {
+      musicGain.disconnect()
+      musicGain = ctx.createGain()
+      musicGain.gain.value = masterMuted ? 0 : MUSIC_VOL
+      musicGain.connect(ctx.destination)
+    }
+    if (sfxGain) {
+      sfxGain.disconnect()
+      sfxGain = ctx.createGain()
+      sfxGain.gain.value = masterMuted ? 0 : SFX_VOL
+      sfxGain.connect(ctx.destination)
+    }
+  }
+}
+
+export { MUSIC_VOL, SFX_VOL }