diff --git a/services/frontend/src/components/dashboard/stat-card.tsx b/services/frontend/src/components/dashboard/stat-card.tsx
index e18f68e..37de095 100644
--- a/services/frontend/src/components/dashboard/stat-card.tsx
+++ b/services/frontend/src/components/dashboard/stat-card.tsx
@@ -3,6 +3,7 @@
 import type { LucideIcon } from "lucide-react";
 import { Area, AreaChart, ResponsiveContainer } from "recharts";
 import { GlassCard } from "@/components/glass/card";
+import { useMounted } from "@/lib/hooks/use-mounted";
 import { cn } from "@/lib/utils";
 
 interface StatCardProps {
@@ -22,6 +23,7 @@ export function StatCard({
   sparklineData,
   formatter = (v) => (typeof v === "number" ? v.toLocaleString() : v),
 }: StatCardProps) {
+  const mounted = useMounted();
   const accentColor = {
     default: "var(--color-primary)",
     danger: "var(--color-destructive)",
@@ -54,9 +56,14 @@ export function StatCard({
       </div>
 
       {/* Sparkline background */}
-      {sparklineData && sparklineData.length > 0 && (
+      {sparklineData && sparklineData.length > 0 && mounted && (
         <div className="absolute bottom-0 left-0 right-0 h-12 opacity-20">
-          <ResponsiveContainer width="100%" height="100%">
+          <ResponsiveContainer
+            width="100%"
+            height={48}
+            minWidth={0}
+            minHeight={0}
+          >
             <AreaChart data={sparklineData}>
               <defs>
                 <linearGradient
diff --git a/services/frontend/src/components/dashboard/top-channels-chart.tsx b/services/frontend/src/components/dashboard/top-channels-chart.tsx
index 2a12416..707a333 100644
--- a/services/frontend/src/components/dashboard/top-channels-chart.tsx
+++ b/services/frontend/src/components/dashboard/top-channels-chart.tsx
@@ -9,12 +9,15 @@ import {
   YAxis,
 } from "recharts";
 import { GlassCard } from "@/components/glass/card";
+import { useMounted } from "@/lib/hooks/use-mounted";
 
 interface TopChannelsChartProps {
   data?: { name: string; count: number }[];
 }
 
 export function TopChannelsChart({ data = [] }: TopChannelsChartProps) {
+  const mounted = useMounted();
+
   return (
     <GlassCard variant="base">
       <div className="flex items-center gap-2 mb-3">
@@ -23,38 +26,47 @@ export function TopChannelsChart({ data = [] }: TopChannelsChartProps) {
         </span>
       </div>
       <div className="h-48">
-        <ResponsiveContainer width="100%" height="100%">
-          <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="name"
-              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)",
-              }}
-            />
-            <Bar
-              dataKey="count"
-              fill="var(--color-primary)"
-              radius={[0, 4, 4, 0]}
-            />
-          </BarChart>
-        </ResponsiveContainer>
+        {mounted ? (
+          <ResponsiveContainer
+            width="100%"
+            height={192}
+            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="name"
+                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)",
+                }}
+              />
+              <Bar
+                dataKey="count"
+                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>
     </GlassCard>
   );
diff --git a/services/frontend/src/components/voice/activity-timeline.tsx b/services/frontend/src/components/voice/activity-timeline.tsx
index c658657..7ff2691 100644
--- a/services/frontend/src/components/voice/activity-timeline.tsx
+++ b/services/frontend/src/components/voice/activity-timeline.tsx
@@ -1,6 +1,5 @@
 "use client";
 
-import { GlassCard } from "@/components/glass/card";
 import {
   Bar,
   BarChart,
@@ -9,12 +8,16 @@ import {
   XAxis,
   YAxis,
 } from "recharts";
+import { GlassCard } from "@/components/glass/card";
+import { useMounted } from "@/lib/hooks/use-mounted";
 
 interface ActivityTimelineProps {
   data?: { user: string; duration: number }[];
 }
 
 export function VoiceActivityTimeline({ data = [] }: ActivityTimelineProps) {
+  const mounted = useMounted();
+
   return (
     <GlassCard variant="base">
       <div className="flex items-center gap-2 mb-3">
@@ -23,39 +26,51 @@ export function VoiceActivityTimeline({ data = [] }: ActivityTimelineProps) {
         </span>
       </div>
       <div className="h-40">
-        <ResponsiveContainer width="100%" height="100%">
-          <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) => [`${(Number(value) / 60).toFixed(1)}m`, "Duration"]}
-            />
-            <Bar
-              dataKey="duration"
-              fill="var(--color-primary)"
-              radius={[0, 4, 4, 0]}
-            />
-          </BarChart>
-        </ResponsiveContainer>
+        {mounted ? (
+          <ResponsiveContainer
+            width="100%"
+            height={160}
+            minWidth={0}
+            minHeight={0}
+          >
+            <BarChart data={data} layout="vertical">
+              <XAxis
+                type="number"
+                axisLine={false}
+                tickLine={false}
+                tick={{ fill: "oklch(0.55 0.02 245)", fontSize: 10 }}
+              />
+              <YAxis
+                type="category"
+                dataKey="user"
+                axisLine={false}
+                tickLine={false}
+                tick={{ fill: "oklch(0.55 0.02 245)", fontSize: 10 }}
+                width={80}
+              />
+              <Tooltip
+                contentStyle={{
+                  background: "oklch(0.11 0.02 245 / 0.9)",
+                  border: "1px solid oklch(1 0 0 / 0.08)",
+                  borderRadius: 8,
+                  fontSize: 12,
+                  color: "oklch(0.93 0.01 245)",
+                }}
+                formatter={(value) => [
+                  `${(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>
     </GlassCard>
   );
diff --git a/services/frontend/src/hooks/use-messages.ts b/services/frontend/src/hooks/use-messages.ts
index 4d22794..ecdbe89 100644
--- a/services/frontend/src/hooks/use-messages.ts
+++ b/services/frontend/src/hooks/use-messages.ts
@@ -126,14 +126,17 @@ export function useReview(channelId?: string) {
 
 export function useMessageDetail(id: string | null) {
   const detail = useSWR<MessageRecord>(id ? msgKeys.detail(id) : null, () =>
-    messagesApi.getDetail(id!),
+    messagesApi.getDetail(id ?? ""),
   );
+  const channelId = id ? detail.data?.channel_id : undefined;
   const attachments = useSWR<AttachmentRecord[]>(
-    id && detail.data?.channel_id
-      ? [...msgKeys.detail(id), "attachments"]
-      : null,
+    channelId ? [...msgKeys.detail(id ?? ""), "attachments"] : null,
     async () => {
-      const res = await messagesApi.getAttachments(detail.data!.channel_id, 10);
+      // Guard: only fetch when we actually have a channel id — a revalidate
+      // can race the detail load and see detail.data === undefined.
+      const cid = detail.data?.channel_id;
+      if (!cid) return [];
+      const res = await messagesApi.getAttachments(cid, 10);
       return res.data;
     },
   );
diff --git a/services/frontend/src/lib/hooks/use-mounted.ts b/services/frontend/src/lib/hooks/use-mounted.ts
new file mode 100644
index 0000000..80d4373
--- /dev/null
+++ b/services/frontend/src/lib/hooks/use-mounted.ts
@@ -0,0 +1,16 @@
+import { useEffect, useState } from "react";
+
+/**
+ * Returns true once the component has mounted on the client. Charts wrapped
+ * in ResponsiveContainer measure their parent during the first layout — if
+ * the container has no size yet (hydration/flex/grid), Recharts logs
+ * "width(-1) and height(-1)" warnings. Deferring the chart render until after
+ * mount guarantees the container has real dimensions.
+ */
+export function useMounted(): boolean {
+  const [mounted, setMounted] = useState(false);
+  useEffect(() => {
+    setMounted(true);
+  }, []);
+  return mounted;
+}