fix(voice): activity tab rendered a permanently empty chart

VoiceActivityTimeline was never given a data prop — the Activity tab always
showed an empty Recharts bar chart while the connection tab already had live
speaker state. Replace the dead chart with a live speaker/activity list fed
from the same WebSocket data, so the tab reflects real state instead of
misleading empty bars.

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

@@ -148,7 +148,7 @@ export default function VoicePage() {
         </div>
       )}
 
-      {tab === "activity" && <VoiceActivityTimeline />}
+      {tab === "activity" && <VoiceActivityTimeline data={speakers} />}
     </div>
   );
 }

services/frontend/src/components/voice/activity-timeline.tsx

@@ -1,22 +1,30 @@
 "use client";
 
-import {
-  Bar,
-  BarChart,
-  ResponsiveContainer,
-  Tooltip,
-  XAxis,
-  YAxis,
-} from "recharts";
+import { Mic, MicOff } from "lucide-react";
 import { GlassCard } from "@/components/glass/card";
-import { useMounted } from "@/lib/hooks/use-mounted";
+import type { ActiveSpeaker } from "@/lib/types";
 
 interface ActivityTimelineProps {
-  data?: { user: string; duration: number }[];
+  data?: ActiveSpeaker[];
 }
 
+/**
+ * Voice Activity — live view of everyone currently in the monitored voice
+ * channel and whether they are speaking right now.
+ *
+ * Previously this rendered a Recharts bar chart fed from a `{user, duration}`
+ * prop that NO caller ever supplied, so the Activity tab always showed an
+ * empty, misleading chart. It now renders real live speaker state from the
+ * WebSocket (same source as the Connection tab's waveform).
+ */
 export function VoiceActivityTimeline({ data = [] }: ActivityTimelineProps) {
-  const mounted = useMounted();
+  const sorted = [...data].sort((a, b) =>
+    a.speaking === b.speaking
+      ? String(a.username).localeCompare(b.username)
+      : a.speaking
+        ? -1
+        : 1,
+  );
 
   return (
     <GlassCard variant="base">
@@ -24,54 +32,53 @@ export function VoiceActivityTimeline({ data = [] }: ActivityTimelineProps) {
         <span className="text-xs font-semibold tracking-wide uppercase text-text-secondary">
           Voice Activity
         </span>
+        <span className="text-[10px] text-text-secondary/50 ml-auto">
+          {sorted.length} speaker{sorted.length !== 1 ? "s" : ""} · live
+        </span>
       </div>
-      <div className="h-40">
-        {mounted ? (
-          <ResponsiveContainer
-            width="100%"
-            height={160}
-            minWidth={0}
-            minHeight={0}
-          >
-            <BarChart data={data} layout="vertical">
-              <XAxis
-                type="number"
-                axisLine={false}
-                tickLine={false}
-                tick={{ fill: "oklch(0.55 0.02 245)", fontSize: 10 }}
-              />
-              <YAxis
-                type="category"
-                dataKey="user"
-                axisLine={false}
-                tickLine={false}
-                tick={{ fill: "oklch(0.55 0.02 245)", fontSize: 10 }}
-                width={80}
-              />
-              <Tooltip
-                contentStyle={{
-                  background: "oklch(0.11 0.02 245 / 0.9)",
-                  border: "1px solid oklch(1 0 0 / 0.08)",
-                  borderRadius: 8,
-                  fontSize: 12,
-                  color: "oklch(0.93 0.01 245)",
-                }}
-                formatter={(value) => [
-                  `${(Number(value) / 60).toFixed(1)}m`,
-                  "Duration",
-                ]}
-              />
-              <Bar
-                dataKey="duration"
-                fill="var(--color-primary)"
-                radius={[0, 4, 4, 0]}
-              />
-            </BarChart>
-          </ResponsiveContainer>
-        ) : (
-          <div className="h-full w-full animate-pulse rounded-md bg-card/40" />
-        )}
-      </div>
+
+      {sorted.length === 0 ? (
+        <div className="flex flex-col items-center justify-center py-12 text-center">
+          <MicOff className="size-8 text-text-secondary/30 mb-2" />
+          <p className="text-xs text-text-secondary/60">
+            No speakers in the monitored voice channel.
+          </p>
+          <p className="mt-1 text-[10px] text-text-secondary/40">
+            Connect to a voice channel to see live activity here.
+          </p>
+        </div>
+      ) : (
+        <div className="space-y-1.5">
+          {sorted.map((s) => (
+            <div
+              key={s.userId}
+              className="flex items-center gap-2 rounded-lg border border-border/40 bg-card/40 px-3 py-2"
+            >
+              {s.speaking ? (
+                <Mic className="size-3.5 text-primary shrink-0" />
+              ) : (
+                <MicOff className="size-3.5 text-text-secondary/40 shrink-0" />
+              )}
+              <span
+                className={`truncate text-sm ${
+                  s.speaking
+                    ? "text-text-primary font-medium"
+                    : "text-text-secondary/70"
+                }`}
+              >
+                {s.username}
+              </span>
+              <span
+                className={`ml-auto shrink-0 text-[9px] font-semibold uppercase tracking-widest ${
+                  s.speaking ? "text-primary" : "text-text-secondary/40"
+                }`}
+              >
+                {s.speaking ? "Speaking" : "Listening"}
+              </span>
+            </div>
+          ))}
+        </div>
+      )}
     </GlassCard>
   );
 }