fix: match log/timeline height, DESC sort with scroll-to-top

Give logCard the same max-height and flex layout as timelineCard so
both columns are equal height. Revert .toReversed() so events stay
in DESC order (newest at top). Override EventFeed's auto-scroll-to-
bottom with a requestAnimationFrame that resets scrollTop to 0 after
mount, keeping newest entries visible at the top of both panels.

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

ui/src/pages/AgentHealth/AgentHealth.tsx

@@ -1,4 +1,4 @@
-import { useState, useMemo } from 'react';
+import { useState, useMemo, useRef, useEffect } from 'react';
 import { useParams, Link } from 'react-router';
 import {
   StatCard, StatusDot, Badge, MonoText, ProgressBar,
@@ -224,6 +224,18 @@ export default function AgentHealth() {
   const { appId } = useParams();
   const { data: agents } = useAgents(undefined, appId);
   const { data: events } = useAgentEvents(appId);
+  const timelineRef = useRef<HTMLDivElement>(null);
+
+  // Override EventFeed's auto-scroll-to-bottom so newest (DESC) events stay visible at top
+  useEffect(() => {
+    const el = timelineRef.current;
+    if (!el) return;
+    const timer = requestAnimationFrame(() => {
+      const list = el.querySelector('[aria-label="Event feed"]') as HTMLElement | null;
+      if (list) list.scrollTop = 0;
+    });
+    return () => cancelAnimationFrame(timer);
+  }, [events]);
 
   const [selectedInstance, setSelectedInstance] = useState<AgentInstance | null>(null);
   const [panelOpen, setPanelOpen] = useState(false);
@@ -256,7 +268,7 @@ export default function AgentHealth() {
                 : ('running' as const),
         message: `${e.agentId}: ${e.eventType}${e.detail ? ' \u2014 ' + e.detail : ''}`,
         timestamp: new Date(e.timestamp),
-      })).toReversed(),
+      })),
     [events],
   );
 
@@ -500,7 +512,7 @@ export default function AgentHealth() {
 
       {/* EventFeed */}
       {feedEvents.length > 0 && (
-        <div className={styles.eventCard}>
+        <div className={styles.eventCard} ref={timelineRef}>
           <div className={styles.eventCardHeader}>
             <span className={styles.sectionTitle}>Timeline</span>
             <span className={styles.sectionMeta}>{feedEvents.length} events</span>

ui/src/pages/AgentInstance/AgentInstance.module.css

@@ -132,6 +132,9 @@
   border-radius: var(--radius-lg);
   box-shadow: var(--shadow-card);
   overflow: hidden;
+  display: flex;
+  flex-direction: column;
+  max-height: 420px;
 }
 
 .logHeader {

ui/src/pages/AgentInstance/AgentInstance.tsx

@@ -1,4 +1,4 @@
-import { useMemo, useState } from 'react';
+import { useMemo, useState, useRef, useEffect } from 'react';
 import { useParams, Link } from 'react-router';
 import {
   StatCard, StatusDot, Badge, LineChart, AreaChart, BarChart,
@@ -36,10 +36,23 @@ export default function AgentInstance() {
   const timeFrom = timeRange.start.toISOString();
   const timeTo = timeRange.end.toISOString();
 
+  const timelineRef = useRef<HTMLDivElement>(null);
+
   const { data: agents, isLoading } = useAgents(undefined, appId);
   const { data: events } = useAgentEvents(appId, instanceId);
   const { data: timeseries } = useStatsTimeseries(timeFrom, timeTo, undefined, appId);
 
+  // Override EventFeed's auto-scroll-to-bottom so newest (DESC) events stay visible at top
+  useEffect(() => {
+    const el = timelineRef.current;
+    if (!el) return;
+    const timer = requestAnimationFrame(() => {
+      const list = el.querySelector('[aria-label="Event feed"]') as HTMLElement | null;
+      if (list) list.scrollTop = 0;
+    });
+    return () => cancelAnimationFrame(timer);
+  }, [events]);
+
   const agent = useMemo(
     () => (agents || []).find((a: any) => a.id === instanceId) as any,
     [agents, instanceId],
@@ -90,8 +103,7 @@ export default function AgentInstance() {
                   : ('running' as const),
           message: `${e.eventType}${e.detail ? ' \u2014 ' + e.detail : ''}`,
           timestamp: new Date(e.timestamp),
-        }))
+        })),
-        .toReversed(),
     [events, instanceId],
   );
 
@@ -436,7 +448,7 @@ export default function AgentInstance() {
           )}
         </div>
 
-        <div className={styles.timelineCard}>
+        <div className={styles.timelineCard} ref={timelineRef}>
           <div className={styles.timelineHeader}>
             <span className={styles.chartTitle}>Timeline</span>
             <span className={styles.chartMeta}>{feedEvents.length} events</span>