chore: complete clean Agent Desk source snapshot

web/lib/sound-alert.ts

@@ -0,0 +1,91 @@
+let sharedAudioContext: AudioContext | null = null
+
+/**
+ * Resets the cached AudioContext instance (used for testing).
+ */
+export function resetAudioContextForTesting(): void {
+  sharedAudioContext = null
+}
+
+function getOrCreateAudioContext(): AudioContext | null {
+  if (typeof window === "undefined") {
+    return null
+  }
+
+  const AudioContextClass =
+    window.AudioContext ||
+    (window as unknown as { webkitAudioContext?: typeof AudioContext }).webkitAudioContext
+
+  if (!AudioContextClass) {
+    return null
+  }
+
+  if (!sharedAudioContext || sharedAudioContext.state === "closed") {
+    try {
+      sharedAudioContext = new AudioContextClass()
+    } catch {
+      return null
+    }
+  }
+
+  return sharedAudioContext
+}
+
+function scheduleTone(
+  ctx: AudioContext,
+  freq: number,
+  startTime: number,
+  duration: number,
+  peakGain = 0.15
+): void {
+  const osc = ctx.createOscillator()
+  const gain = ctx.createGain()
+
+  osc.type = "sine"
+  osc.frequency.setValueAtTime(freq, startTime)
+
+  gain.gain.setValueAtTime(peakGain, startTime)
+  gain.gain.exponentialRampToValueAtTime(0.001, startTime + duration)
+
+  osc.connect(gain)
+  gain.connect(ctx.destination)
+
+  osc.start(startTime)
+  osc.stop(startTime + duration)
+}
+
+/**
+ * Plays a gentle dual-tone chime (587.33 Hz D5 -> 880.00 Hz A5) using the Web Audio API.
+ * Safely handles SSR/Node environments, unsupported browsers, suspended contexts, and
+ * browser autoplay policy rejections without throwing errors.
+ *
+ * @returns boolean indicating whether the sound playback was successfully initiated.
+ */
+export function playIncomingMessageSound(): boolean {
+  try {
+    const ctx = getOrCreateAudioContext()
+    if (!ctx) {
+      return false
+    }
+
+    if (ctx.state === "suspended") {
+      ctx.resume().catch(() => {
+        // Traps browser autoplay rejection without crashing
+      })
+    }
+
+    const now = ctx.currentTime
+    const note1Duration = 0.08
+    const note2Duration = 0.16
+
+    // Note 1: 587.33 Hz (D5) for 0.08s
+    scheduleTone(ctx, 587.33, now, note1Duration)
+
+    // Note 2: 880.00 Hz (A5) for 0.16s
+    scheduleTone(ctx, 880.00, now + note1Duration, note2Duration)
+
+    return true
+  } catch {
+    return false
+  }
+}