fix: align AgentHealth page with mock design

- DetailPanel: switch from tabs to flat children layout (fixes stale
  tab state bug), add position:fixed override, key on agent id
- Stat strip: colored status breakdown (live/stale/dead), msg/s detail
  on TPS, "requires attention" on dead count
- Scope trail: simplified to "X/Y live" label
- Event card header: rename "Event Log" to "Timeline" with count badge
- Remove unused Breadcrumb, scopeItems, groupHealth

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

ui/src/pages/AgentHealth/AgentHealth.module.css

@@ -244,3 +244,36 @@
   font-size: 12px;
   color: var(--text-muted);
 }
+
+/* Status breakdown in stat card */
+.statusBreakdown {
+  display: flex;
+  gap: 8px;
+  font-size: 11px;
+}
+
+.statusLive { color: var(--success); }
+.statusStale { color: var(--warning); }
+.statusDead { color: var(--error); }
+
+/* Scope trail */
+.scopeLabel {
+  font-size: 13px;
+  font-weight: 600;
+  color: var(--text-secondary);
+}
+
+/* DetailPanel override */
+.detailPanelOverride {
+  position: fixed;
+  top: 0;
+  right: 0;
+  height: 100vh;
+  z-index: 100;
+  box-shadow: -4px 0 24px rgba(0, 0, 0, 0.12);
+}
+
+.panelDivider {
+  border-top: 1px solid var(--border-subtle);
+  margin: 16px 0;
+}

ui/src/pages/AgentHealth/AgentHealth.tsx

@@ -2,7 +2,7 @@ import { useMemo, useState } from 'react';
 import { useParams, useNavigate } from 'react-router';
 import {
   StatCard, StatusDot, Badge, MonoText,
-  GroupCard, EventFeed, Breadcrumb, Alert,
+  GroupCard, EventFeed, Alert,
   DetailPanel, ProgressBar, LineChart,
 } from '@cameleer/design-system';
 import styles from './AgentHealth.module.css';
@@ -189,24 +189,6 @@ export default function AgentHealth() {
   const activeRoutes = (agents || []).filter((a: any) => a.status === 'LIVE').reduce((sum: number, a: any) => sum + (a.activeRoutes || 0), 0);
   const totalTps = (agents || []).filter((a: any) => a.status === 'LIVE').reduce((sum: number, a: any) => sum + (a.tps || 0), 0);
 
-  const groupHealth: 'live' | 'stale' | 'dead' = useMemo(() => {
-    if (!appId) return 'live';
-    const groupAgents = agentsByApp[appId] || [];
-    if (groupAgents.some((a: any) => a.status === 'DEAD')) return 'dead';
-    if (groupAgents.some((a: any) => a.status === 'STALE')) return 'stale';
-    return 'live';
-  }, [appId, agentsByApp]);
-
-  const scopeItems = useMemo(() => {
-    const items: { label: string; href?: string }[] = [
-      { label: 'Agent Health', href: '/agents' },
-    ];
-    if (appId) {
-      items.push({ label: appId });
-    }
-    return items;
-  }, [appId]);
-
   const feedEvents = useMemo(() =>
     (events || []).map((e: any) => ({
       id: String(e.id),
@@ -225,22 +207,25 @@ export default function AgentHealth() {
   return (
     <div>
       <div className={styles.statStrip}>
-        <StatCard label="Total Agents" value={(agents || []).length} detail={`${liveCount} live / ${staleCount} stale / ${deadCount} dead`} />
+        <StatCard
+          label="Total Agents"
+          value={(agents || []).length}
+          detail={
+            <span className={styles.statusBreakdown}>
+              <span className={styles.statusLive}>{liveCount} live</span>
+              <span className={styles.statusStale}>{staleCount} stale</span>
+              <span className={styles.statusDead}>{deadCount} dead</span>
+            </span>
+          }
+        />
         <StatCard label="Applications" value={uniqueApps} />
         <StatCard label="Active Routes" value={activeRoutes} />
-        <StatCard label="Total TPS" value={totalTps.toFixed(1)} />
-        <StatCard label="Dead" value={deadCount} accent={deadCount > 0 ? 'error' : undefined} />
+        <StatCard label="Total TPS" value={totalTps.toFixed(1)} detail="msg/s" />
+        <StatCard label="Dead" value={deadCount} accent={deadCount > 0 ? 'error' : undefined} detail={deadCount > 0 ? 'requires attention' : undefined} />
       </div>
 
       <div className={styles.scopeTrail}>
-        <Breadcrumb items={scopeItems} />
-        {!appId && <Badge label={`${liveCount} live`} variant="outlined" />}
-        {appId && (
-          <Badge
-            label={groupHealth}
-            color={groupHealth === 'live' ? 'success' : groupHealth === 'stale' ? 'warning' : 'error'}
-          />
-        )}
+        <span className={styles.scopeLabel}>{liveCount}/{(agents || []).length} live</span>
       </div>
 
       <div className={styles.groupGrid}>
@@ -349,29 +334,26 @@ export default function AgentHealth() {
 
       {feedEvents.length > 0 && (
         <div className={styles.eventCard}>
-          <div className={styles.eventCardHeader}>Event Log</div>
+          <div className={styles.eventCardHeader}>
+            <span>Timeline</span>
+            <Badge label={`${feedEvents.length} events`} variant="outlined" />
+          </div>
           <EventFeed events={feedEvents} maxItems={100} />
         </div>
       )}
 
       {selectedAgent && (
         <DetailPanel
-          open={!!selectedAgent}
+          key={selectedAgent.id}
+          open={true}
           title={selectedAgent.name ?? selectedAgent.id}
           onClose={() => setSelectedAgent(null)}
-          tabs={[
-            {
-              label: 'Overview',
-              value: 'overview',
-              content: <AgentOverviewContent agent={selectedAgent} />,
-            },
-            {
-              label: 'Performance',
-              value: 'performance',
-              content: <AgentPerformanceContent agent={selectedAgent} />,
-            },
-          ]}
-        />
+          className={styles.detailPanelOverride}
+        >
+          <AgentOverviewContent agent={selectedAgent} />
+          <div className={styles.panelDivider} />
+          <AgentPerformanceContent agent={selectedAgent} />
+        </DetailPanel>
       )}
     </div>
   );