feat: add expand/collapse animation for compact card toggle

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

ui/src/pages/AgentHealth/AgentHealth.tsx

@@ -1,4 +1,4 @@
-import { useState, useMemo, useCallback } from 'react';
+import { useState, useMemo, useCallback, useRef, useEffect } from 'react';
 import { useParams, useNavigate } from 'react-router';
 import { ExternalLink, RefreshCw, Pencil, LayoutGrid, List, ChevronRight, ChevronDown } from 'lucide-react';
 import {
@@ -179,6 +179,57 @@ export default function AgentHealth() {
     });
   }, []);
 
+  const [animatingApps, setAnimatingApps] = useState<Map<string, 'expanding' | 'collapsing'>>(new Map());
+  const animationTimers = useRef<Map<string, ReturnType<typeof setTimeout>>>(new Map());
+
+  const animateToggle = useCallback((appIdToToggle: string) => {
+    // Clear any existing timer for this app
+    const existing = animationTimers.current.get(appIdToToggle);
+    if (existing) clearTimeout(existing);
+
+    const isCurrentlyExpanded = expandedApps.has(appIdToToggle);
+
+    if (isCurrentlyExpanded) {
+      // Collapsing: start animation, then remove from expandedApps after transition
+      setAnimatingApps((prev) => new Map(prev).set(appIdToToggle, 'collapsing'));
+      const timer = setTimeout(() => {
+        setExpandedApps((prev) => {
+          const next = new Set(prev);
+          next.delete(appIdToToggle);
+          return next;
+        });
+        setAnimatingApps((prev) => {
+          const next = new Map(prev);
+          next.delete(appIdToToggle);
+          return next;
+        });
+        animationTimers.current.delete(appIdToToggle);
+      }, 200);
+      animationTimers.current.set(appIdToToggle, timer);
+    } else {
+      // Expanding: add to expandedApps immediately, animate in
+      setExpandedApps((prev) => new Set(prev).add(appIdToToggle));
+      setAnimatingApps((prev) => new Map(prev).set(appIdToToggle, 'expanding'));
+      // Use requestAnimationFrame to ensure the collapsed state renders first
+      requestAnimationFrame(() => {
+        requestAnimationFrame(() => {
+          setAnimatingApps((prev) => {
+            const next = new Map(prev);
+            next.delete(appIdToToggle);
+            return next;
+          });
+        });
+      });
+    }
+  }, [expandedApps]);
+
+  // Cleanup timers on unmount
+  useEffect(() => {
+    return () => {
+      animationTimers.current.forEach((timer) => clearTimeout(timer));
+    };
+  }, []);
+
   const [configEditing, setConfigEditing] = useState(false);
   const [configDraft, setConfigDraft] = useState<Record<string, string | boolean>>({});
 
@@ -653,7 +704,16 @@ export default function AgentHealth() {
         <div className={styles.compactGrid}>
           {groups.map((group) =>
             expandedApps.has(group.appId) ? (
-              <div key={group.appId} className={styles.compactGridExpanded}>
+              <div
+                key={group.appId}
+                className={`${styles.compactGridExpanded} ${styles.expandWrapper} ${
+                  animatingApps.get(group.appId) === 'expanding'
+                    ? styles.expandWrapperCollapsed
+                    : animatingApps.get(group.appId) === 'collapsing'
+                      ? styles.expandWrapperCollapsed
+                      : styles.expandWrapperExpanded
+                }`}
+              >
                 <GroupCard
                   title={group.appId}
                   accent={appHealth(group)}
@@ -666,7 +726,7 @@ export default function AgentHealth() {
                       />
                       <button
                         className={styles.collapseBtn}
-                        onClick={() => toggleAppExpanded(group.appId)}
+                        onClick={() => animateToggle(group.appId)}
                         title="Collapse"
                       >
                         <ChevronDown size={14} />
@@ -717,7 +777,7 @@ export default function AgentHealth() {
               <CompactAppCard
                 key={group.appId}
                 group={group}
-                onExpand={() => toggleAppExpanded(group.appId)}
+                onExpand={() => animateToggle(group.appId)}
               />
             ),
           )}