feat(fe): play Discord voice live + fix recording play/download

Voice page (connection tab):
- ListenControl baru: toggle Listen (Headphones) — mulai PcmPlayer dari
  user gesture, subscribe onPcm WS, volume slider, bar level per-user
  REAL dari PCM (bukan random).
- lib/audio/pcm-player.ts (baru): ScriptProcessorNode mixer — ring buffer
  2s per user (hash FNV-1a sama dengan gateway), upsampling 24k→48k
  linear, mix semua user ke mono, gain volume, cleanup ring diam 5s.
- useVoiceListen + hashUserId di hooks; auto-stop saat disconnect.

Recordings:
- recording-player: reset src+load+play() eksplisit (bukan autoPlay doang),
  tampilkan filename + error state 'playback failed' kalau file rusak.
- recording-card: tombol Download fetch blob (CORS tele open) → objectURL
  → force download dengan nama asli; fallback buka tab baru kalau fetch
  gagal; spinner saat mendownload.

Verified: FE tsc 0, next build 10/10 static pages.

services/frontend/src/app/(dashboard)/recordings/page.tsx

@@ -153,6 +153,7 @@ export default function RecordingsPage() {
 
       <RecordingPlayer
         url={currentTrack?.download_url ?? undefined}
+        filename={currentTrack?.filename ?? undefined}
         onClose={() => setPlayingId(null)}
       />
     </div>

services/frontend/src/app/(dashboard)/voice/page.tsx

@@ -4,6 +4,7 @@ import { useCallback, useEffect, useState } from "react";
 import { SubNav } from "@/components/layout/sub-nav";
 import { VoiceActivityTimeline } from "@/components/voice/activity-timeline";
 import { VoiceConnectionCard } from "@/components/voice/connection-card";
+import { ListenControl } from "@/components/voice/listen-control";
 import { MicControl } from "@/components/voice/mic-control";
 import { SpeakerWaveform } from "@/components/voice/speaker-waveform";
 import {
@@ -13,6 +14,7 @@ import {
   useVoiceChannels,
   useVoiceConnect,
   useVoiceDisconnect,
+  useVoiceListen,
   useVoiceStatus,
 } from "@/hooks";
 import { useWebSocket } from "@/lib/ws/context";
@@ -29,9 +31,11 @@ export default function VoicePage() {
   const connectMut = useVoiceConnect();
   const disconnectMut = useVoiceDisconnect();
   const micMut = useMicTransmit(ws);
+  const listen = useVoiceListen(ws);
   const [selectedChannel, setSelectedChannel] = useState("");
   const [micActive, setMicActive] = useState(false);
   const [volume, setVolume] = useState(75);
+  const [listenVolume, setListenVolume] = useState(75);
   const [tab, setTab] = useState<VoiceTab>("connection");
 
   useEffect(() => {
@@ -111,6 +115,7 @@ export default function VoicePage() {
             setMicActive(false);
             void micMut.mutateAsync(false).catch(() => {});
           }
+          if (listen.active) listen.toggle(false);
           disconnectMut.mutate(undefined);
         }}
         connecting={connectMut.isPending}
@@ -119,13 +124,27 @@ export default function VoicePage() {
       {tab === "connection" && (
         <div className="grid grid-cols-1 lg:grid-cols-2 gap-4">
           <SpeakerWaveform speakers={activeSpeakers} />
-          <MicControl
-            connected={connected}
-            active={micActive}
-            onToggle={handleMicToggle}
-            volume={volume}
-            onVolumeChange={handleVolumeChange}
-          />
+          <div className="space-y-4">
+            <ListenControl
+              connected={connected}
+              active={listen.active}
+              levels={listen.levels}
+              speakers={speakers}
+              onToggle={(on) => listen.toggle(on)}
+              volume={listenVolume}
+              onVolumeChange={(v) => {
+                setListenVolume(v);
+                listen.setVolume(v);
+              }}
+            />
+            <MicControl
+              connected={connected}
+              active={micActive}
+              onToggle={handleMicToggle}
+              volume={volume}
+              onVolumeChange={handleVolumeChange}
+            />
+          </div>
         </div>
       )}
 

services/frontend/src/components/recordings/recording-card.tsx

@@ -1,6 +1,7 @@
 "use client";
 
-import { Download, Play } from "lucide-react";
+import { useState } from "react";
+import { Download, Loader2, Play } from "lucide-react";
 import { GlassCard } from "@/components/glass/card";
 import type { VoiceRecording } from "@/lib/types";
 
@@ -10,10 +11,36 @@ interface RecordingCardProps {
 }
 
 export function RecordingCard({ recording, onPlay }: RecordingCardProps) {
+  const [downloading, setDownloading] = useState(false);
   const durationStr = recording.duration_bytes
     ? `${Math.floor(recording.duration_bytes / 60)}:${String(recording.duration_bytes % 60).padStart(2, "0")}`
     : "--:--";
 
+  // Fetch the file (CORS is open on the uploader) → blob → force download with
+  // the real filename. Falls back to opening the URL in a new tab.
+  const handleDownload = async (e: React.MouseEvent) => {
+    e.stopPropagation();
+    if (!recording.download_url || downloading) return;
+    setDownloading(true);
+    try {
+      const res = await fetch(recording.download_url);
+      if (!res.ok) throw new Error(`HTTP ${res.status}`);
+      const blob = await res.blob();
+      const objUrl = URL.createObjectURL(blob);
+      const a = document.createElement("a");
+      a.href = objUrl;
+      a.download = recording.filename ?? `recording-${recording.id}.mp3`;
+      document.body.appendChild(a);
+      a.click();
+      a.remove();
+      setTimeout(() => URL.revokeObjectURL(objUrl), 30_000);
+    } catch {
+      window.open(recording.download_url, "_blank", "noopener,noreferrer");
+    } finally {
+      setDownloading(false);
+    }
+  };
+
   return (
     <GlassCard variant="interactive" className="p-4" onClick={() => onPlay(recording.id)}>
       <div className="flex items-start gap-3">
@@ -50,9 +77,19 @@ export function RecordingCard({ recording, onPlay }: RecordingCardProps) {
 
         <div className="flex gap-1 shrink-0" onClick={(e) => e.stopPropagation()}>
           {recording.download_url && (
-            <a href={recording.download_url} target="_blank" rel="noopener noreferrer" className="size-7 flex items-center justify-center rounded glass hover:glass-elevated transition-all">
-              <Download className="size-3 text-text-secondary/60" />
-            </a>
+            <button
+              type="button"
+              onClick={handleDownload}
+              disabled={downloading}
+              title="Download"
+              className="size-7 flex items-center justify-center rounded glass hover:glass-elevated transition-all disabled:opacity-50"
+            >
+              {downloading ? (
+                <Loader2 className="size-3 text-text-secondary/60 animate-spin" />
+              ) : (
+                <Download className="size-3 text-text-secondary/60" />
+              )}
+            </button>
           )}
         </div>
       </div>

services/frontend/src/components/recordings/recording-player.tsx

@@ -1,31 +1,57 @@
 "use client";
 
-import { useEffect, useRef } from "react";
+import { useEffect, useRef, useState } from "react";
 import { GlassPanel } from "@/components/glass/panel";
 import { X } from "lucide-react";
 
 interface RecordingPlayerProps {
   url?: string;
+  filename?: string;
   onClose: () => void;
 }
 
-export function RecordingPlayer({ url, onClose }: RecordingPlayerProps) {
+export function RecordingPlayer({ url, filename, onClose }: RecordingPlayerProps) {
   const audioRef = useRef<HTMLAudioElement>(null);
+  const [error, setError] = useState(false);
 
   useEffect(() => {
-    if (url && audioRef.current) {
-      audioRef.current?.play().catch(() => {});
-    }
+    const audio = audioRef.current;
+    if (!url || !audio) return;
+    setError(false);
+    // Fresh element state: reset src, load, then play (the click that opened
+    // the player counts as a user gesture, so autoplay is allowed).
+    audio.src = url;
+    audio.load();
+    const p = audio.play();
+    if (p) p.catch(() => setError(true));
   }, [url]);
 
   if (!url) return null;
 
   return (
-    <GlassPanel dense className="fixed bottom-20 left-4 z-30 w-72 flex items-center gap-3">
-      <audio ref={audioRef} src={url} controls className="flex-1 h-8 [&::-webkit-media-controls-panel]:bg-transparent" autoPlay />
-      <button type="button" onClick={onClose}>
-        <X className="size-3.5 text-text-secondary/60 hover:text-text-primary" />
-      </button>
+    <GlassPanel dense className="fixed bottom-20 left-4 z-30 w-80 flex flex-col gap-1.5">
+      <div className="flex items-center gap-3">
+        <audio
+          ref={audioRef}
+          controls
+          preload="auto"
+          className="flex-1 h-8 [&::-webkit-media-controls-panel]:bg-transparent"
+          onError={() => setError(true)}
+        />
+        <button type="button" onClick={onClose} className="shrink-0">
+          <X className="size-3.5 text-text-secondary/60 hover:text-text-primary" />
+        </button>
+      </div>
+      <div className="flex items-center justify-between px-0.5">
+        <span className="truncate text-[10px] font-mono text-text-secondary/60">
+          {filename ?? "recording"}
+        </span>
+        {error && (
+          <span className="shrink-0 text-[10px] text-red-400/90">
+            playback failed
+          </span>
+        )}
+      </div>
     </GlassPanel>
   );
 }

services/frontend/src/components/voice/listen-control.tsx

@@ -0,0 +1,151 @@
+"use client";
+
+import { useEffect, useMemo, useState } from "react";
+import { GlassCard } from "@/components/glass/card";
+import { Button } from "@/components/ui/button";
+import { hashUserId } from "@/hooks";
+import type { ActiveSpeaker } from "@/lib/types";
+import { Headphones, HeadphoneOff } from "lucide-react";
+
+interface ListenControlProps {
+  connected: boolean;
+  active: boolean;
+  levels: Map<number, number>;
+  speakers: ActiveSpeaker[];
+  onToggle: (active: boolean) => void;
+  volume: number;
+  onVolumeChange: (v: number) => void;
+}
+
+/** Live bar for one speaker — level 0..1 from the PCM player. */
+function SpeakerLevel({
+  speaker,
+  level,
+}: {
+  speaker: ActiveSpeaker;
+  level: number;
+}) {
+  const [bars, setBars] = useState<number[]>(Array(24).fill(0.06));
+
+  useEffect(() => {
+    const id = setInterval(() => {
+      setBars((prev) => {
+        const next = [...prev];
+        for (let i = 0; i < next.length; i++) {
+          const target = level > 0.004 ? level * 0.9 + 0.08 : 0.05;
+          next[i] = next[i] + (target - next[i]) * 0.35;
+        }
+        return next;
+      });
+    }, 60);
+    return () => clearInterval(id);
+  }, [level]);
+
+  return (
+    <div className="flex items-center gap-2">
+      <span className="w-24 truncate text-[11px] text-text-secondary">
+        {speaker.username}
+      </span>
+      <div className="flex flex-1 items-end gap-[2px] h-6">
+        {bars.map((h, i) => (
+          <div
+            key={i}
+            className="flex-1 rounded-t-sm bg-primary/70 transition-[height]"
+            style={{ height: `${Math.max(6, h * 100)}%` }}
+          />
+        ))}
+      </div>
+      <span className="w-8 text-right font-mono text-[10px] text-text-secondary/50">
+        {Math.round(level * 100)}%
+      </span>
+    </div>
+  );
+}
+
+export function ListenControl({
+  connected,
+  active,
+  levels,
+  speakers,
+  onToggle,
+  volume,
+  onVolumeChange,
+}: ListenControlProps) {
+  const activeLevels = useMemo(() => {
+    const map = new Map<string, number>();
+    for (const s of speakers) {
+      const lvl = levels.get(hashUserId(s.userId)) ?? 0;
+      map.set(s.userId, lvl);
+    }
+    return map;
+  }, [speakers, levels]);
+
+  const talking = useMemo(
+    () => [...activeLevels.values()].some((l) => l > 0.004),
+    [activeLevels],
+  );
+
+  return (
+    <GlassCard variant="base">
+      <div className="flex items-center gap-3">
+        <Button
+          variant={active ? "default" : "secondary"}
+          size="sm"
+          onClick={() => onToggle(!active)}
+          disabled={!connected}
+          className="h-9"
+        >
+          {active ? (
+            <Headphones className="size-4 mr-1" />
+          ) : (
+            <HeadphoneOff className="size-4 mr-1" />
+          )}
+          {active ? "Listening" : "Listen"}
+        </Button>
+        <div className="flex-1 flex items-center gap-2">
+          <span className="text-[10px] text-text-secondary/60 font-mono">Vol</span>
+          <input
+            type="range"
+            min={0}
+            max={100}
+            value={volume}
+            onChange={(e) => onVolumeChange(Number(e.target.value))}
+            className="flex-1 h-1 appearance-none bg-glass-border rounded-full accent-primary [&::-webkit-slider-thumb]:appearance-none [&::-webkit-slider-thumb]:size-3 [&::-webkit-slider-thumb]:rounded-full [&::-webkit-slider-thumb]:bg-primary [&::-webkit-slider-thumb]:shadow-[0_0_8px] [&::-webkit-slider-thumb]:shadow-primary/60"
+          />
+          <span className="text-[10px] font-mono text-text-secondary w-8 text-right">
+            {volume}%
+          </span>
+        </div>
+      </div>
+
+      <div className="mt-3 space-y-1">
+        {active && speakers.length > 0 ? (
+          speakers.map((s) => (
+            <SpeakerLevel
+              key={s.userId}
+              speaker={s}
+              level={activeLevels.get(s.userId) ?? 0}
+            />
+          ))
+        ) : (
+          <span className="text-[11px] text-text-secondary/40">
+            {!connected
+              ? "Connect to a voice channel first."
+              : active
+                ? "Listening for Discord voice…"
+                : "Toggle Listen to hear Discord voice."}
+          </span>
+        )}
+        {active && talking && (
+          <span className="inline-flex items-center gap-1.5 text-[10px] text-primary/80">
+            <span className="relative flex size-1.5">
+              <span className="absolute inline-flex size-full rounded-full bg-primary opacity-75 live-pulse-ring" />
+              <span className="relative inline-flex size-1.5 rounded-full bg-primary" />
+            </span>
+            live
+          </span>
+        )}
+      </div>
+    </GlassCard>
+  );
+}

services/frontend/src/hooks/index.ts

@@ -34,10 +34,12 @@ export {
   useRecordingsWsSync,
 } from "./use-recordings";
 export {
+  hashUserId,
   useMicTransmit,
   useSpeakers,
   useVoiceChannels,
   useVoiceConnect,
   useVoiceDisconnect,
+  useVoiceListen,
   useVoiceStatus,
 } from "./use-voice";

services/frontend/src/hooks/use-voice.ts

@@ -1,11 +1,23 @@
-import { useCallback, useRef, useState } from "react";
+import { useCallback, useEffect, useRef, useState } from "react";
 import useSWR, { useSWRConfig } from "swr";
 import { useAction } from "@/hooks/use-action";
 import { voiceApi } from "@/lib/api";
 import { MicTransmitter } from "@/lib/audio/mic-transmit";
+import { PcmPlayer } from "@/lib/audio/pcm-player";
 import type { ActiveSpeaker, Channel, VoiceStatus } from "@/lib/types";
+import type { PcmChunk } from "@/lib/ws/types";
 import type { WsHook } from "@/lib/ws-hook";
 
+/** FNV-1a 32-bit — same hash the gateway uses to tag PCM frames. */
+export function hashUserId(userId: string): number {
+  let hash = 0x811c9dc5;
+  for (let i = 0; i < userId.length; i++) {
+    hash ^= userId.charCodeAt(i);
+    hash = Math.imul(hash, 0x01000193);
+  }
+  return hash >>> 0;
+}
+
 const STATUS_KEY = ["voice-status"] as const;
 
 export function useVoiceStatus() {
@@ -90,3 +102,60 @@ export function useMicTransmit(ws: {
 
   return { ...action, setVolume };
 }
+
+/**
+ * Receive + play Discord voice in the browser.
+ *
+ * Toggling on (from a user gesture) starts a PcmPlayer, subscribes to the WS
+ * binary PCM stream, and exposes per-user activity levels for the waveform UI.
+ * `toggle(false)` tears everything down.
+ */
+export function useVoiceListen(ws: {
+  onPcm: (handler: (chunk: PcmChunk) => void) => () => void;
+}) {
+  const playerRef = useRef<PcmPlayer | null>(null);
+  const unsubRef = useRef<(() => void) | null>(null);
+  const timerRef = useRef<ReturnType<typeof setInterval> | null>(null);
+  const [active, setActive] = useState(false);
+  const [levels, setLevels] = useState<Map<number, number>>(new Map());
+
+  const stop = useCallback(() => {
+    unsubRef.current?.();
+    unsubRef.current = null;
+    if (timerRef.current) clearInterval(timerRef.current);
+    timerRef.current = null;
+    playerRef.current?.stop();
+    playerRef.current = null;
+    setActive(false);
+    setLevels(new Map());
+  }, []);
+
+  const toggle = useCallback(
+    (on: boolean) => {
+      if (on) {
+        const player = new PcmPlayer();
+        playerRef.current = player;
+        player.setVolume(0.75);
+        player.start(); // called from the click gesture
+        unsubRef.current = ws.onPcm((chunk) => {
+          player.push(chunk.userIdHash, chunk.samples);
+        });
+        timerRef.current = setInterval(() => {
+          setLevels(player.getLevels());
+        }, 100);
+        setActive(true);
+      } else {
+        stop();
+      }
+    },
+    [ws, stop],
+  );
+
+  const setVolume = useCallback((v: number) => {
+    playerRef.current?.setVolume(v / 100);
+  }, []);
+
+  useEffect(() => stop, [stop]);
+
+  return { active, levels, toggle, setVolume };
+}

services/frontend/src/lib/audio/pcm-player.ts

@@ -0,0 +1,147 @@
+/**
+ * Receive Discord voice PCM over the WebSocket and play it through the
+ * browser audio stack.
+ *
+ * Binary frame format (from the gateway, via backend WS):
+ *   Byte 0–3:  FNV-1a 32-bit userId hash (UInt32LE)
+ *   Byte 4+:   PCM audio (24kHz mono Int16LE)
+ *
+ * The player keeps one ring buffer per user (2s @ 24kHz), upsamples
+ * 24k → 48k with linear interpolation inside the audio callback, and mixes
+ * every active user into a single mono output. A ScriptProcessorNode is used
+ * because it runs on the main thread — ring buffers need no SharedArrayBuffer
+ * and work without COOP/COEP headers. `start()` must be called from a user
+ * gesture (audio autoplay policy).
+ */
+
+const INPUT_RATE = 24000;
+const OUTPUT_RATE = 48000;
+const RING_SECONDS = 2;
+const RING_LEN = INPUT_RATE * RING_SECONDS;
+
+interface UserRing {
+  data: Float32Array;
+  /** absolute write position (monotonic) */
+  write: number;
+  /** absolute read position as float — advances at 0.5× per output sample */
+  readPos: number;
+  /** last tick where this user produced audio (for stale-ring cleanup) */
+  lastActive: number;
+}
+
+export class PcmPlayer {
+  private ctx: AudioContext | null = null;
+  private processor: ScriptProcessorNode | null = null;
+  private master: GainNode | null = null;
+  private rings = new Map<number, UserRing>();
+  private levels = new Map<number, number>();
+  private volume = 0.75;
+  private started = false;
+
+  get isStarted(): boolean {
+    return this.started;
+  }
+
+  /** Create the AudioContext + processor. MUST be called from a user gesture. */
+  start(): void {
+    if (this.started) return;
+    const Ctor =
+      window.AudioContext ??
+      (window as unknown as { webkitAudioContext?: typeof AudioContext })
+        .webkitAudioContext;
+    if (!Ctor) return;
+    this.ctx = new Ctor({ sampleRate: OUTPUT_RATE });
+    this.master = this.ctx.createGain();
+    this.master.gain.value = this.volume;
+    this.master.connect(this.ctx.destination);
+
+    this.processor = this.ctx.createScriptProcessor(4096, 0, 1);
+    this.processor.onaudioprocess = (e) => this.tick(e);
+    this.processor.connect(this.master);
+    this.started = true;
+  }
+
+  /** Push one PCM chunk (s16 mono @24kHz) for a user. */
+  push(userIdHash: number, samples: Int16Array): void {
+    if (!this.started || samples.length === 0) return;
+    let ring = this.rings.get(userIdHash);
+    if (!ring) {
+      ring = { data: new Float32Array(RING_LEN), write: 0, readPos: 0, lastActive: Date.now() };
+      this.rings.set(userIdHash, ring);
+    }
+    ring.lastActive = Date.now();
+    for (let i = 0; i < samples.length; i++) {
+      ring.data[ring.write % RING_LEN] = samples[i] / 32768;
+      ring.write++;
+    }
+    // Overflow guard: never let the ring lag more than RING_LEN behind.
+    const lag = ring.write - ring.readPos;
+    if (lag > RING_LEN - 4096) {
+      ring.readPos = ring.write - RING_LEN + 4096;
+    }
+  }
+
+  setVolume(v: number): void {
+    this.volume = v;
+    if (this.master) this.master.gain.value = v;
+  }
+
+  /** Peak |sample| per user since the last call (drives the UI waveform). */
+  getLevels(): Map<number, number> {
+    return new Map(this.levels);
+  }
+
+  stop(): void {
+    if (this.processor) {
+      this.processor.disconnect();
+      this.processor.onaudioprocess = null;
+    }
+    if (this.ctx) {
+      void this.ctx.close().catch(() => {});
+    }
+    this.processor = null;
+    this.ctx = null;
+    this.master = null;
+    this.rings.clear();
+    this.levels.clear();
+    this.started = false;
+  }
+
+  private tick(e: AudioProcessingEvent): void {
+    const out = e.outputBuffer.getChannelData(0);
+    out.fill(0);
+    const n = out.length;
+    const step = INPUT_RATE / OUTPUT_RATE; // 0.5
+    const nextLevels = new Map<number, number>();
+
+    for (const [hash, ring] of this.rings) {
+      let level = 0;
+      for (let i = 0; i < n; i++) {
+        const pos = ring.readPos + i * step;
+        if (pos + 1 >= ring.write) break;
+        const i0 = Math.floor(pos);
+        const frac = pos - i0;
+        const a = ring.data[i0 % RING_LEN];
+        const b = ring.data[(i0 + 1) % RING_LEN];
+        const v = a + (b - a) * frac;
+        out[i] += v;
+        const av = Math.abs(v);
+        if (av > level) level = av;
+      }
+      ring.readPos += n * step;
+      if (ring.readPos > ring.write) ring.readPos = ring.write;
+      if (level > 0.001) {
+        ring.lastActive = Date.now();
+        nextLevels.set(hash, level);
+      }
+    }
+
+    // Drop users silent for >5s so the ring map doesn't grow unbounded.
+    const now = Date.now();
+    for (const [hash, ring] of this.rings) {
+      if (now - ring.lastActive > 5000) this.rings.delete(hash);
+    }
+
+    this.levels = nextLevels;
+  }
+}