feat: add app name filter to runtime toolbar

Text input next to view toggle filters apps by name (case-insensitive
substring match). KPI stat strip uses unfiltered counts so totals
stay accurate. Clear button on non-empty input.

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

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

@@ -379,10 +379,55 @@
   display: flex;
   align-items: center;
   justify-content: flex-start;
-  gap: 8px;
+  gap: 12px;
   margin-bottom: 12px;
 }
 
+/* App name filter */
+.appFilterWrap {
+  position: relative;
+  display: flex;
+  align-items: center;
+}
+
+.appFilterInput {
+  width: 180px;
+  height: 28px;
+  padding: 0 24px 0 8px;
+  border: 1px solid var(--border-subtle);
+  border-radius: var(--radius-sm);
+  background: transparent;
+  color: var(--text-primary);
+  font-size: 12px;
+  font-family: var(--font-body);
+  outline: none;
+  transition: border-color 150ms ease;
+}
+
+.appFilterInput::placeholder {
+  color: var(--text-muted);
+}
+
+.appFilterInput:focus {
+  border-color: var(--running);
+}
+
+.appFilterClear {
+  position: absolute;
+  right: 4px;
+  background: transparent;
+  border: none;
+  color: var(--text-muted);
+  cursor: pointer;
+  font-size: 14px;
+  line-height: 1;
+  padding: 2px;
+}
+
+.appFilterClear:hover {
+  color: var(--text-primary);
+}
+
 /* View mode toggle */
 .viewToggle {
   display: flex;

ui/src/pages/AgentHealth/AgentHealth.tsx

@@ -284,6 +284,7 @@ export default function AgentHealth() {
   const [eventRefreshTo, setEventRefreshTo] = useState<string | undefined>();
   const { data: events } = useAgentEvents(appId, undefined, 50, eventRefreshTo, selectedEnv);
 
+  const [appFilter, setAppFilter] = useState('');
   const [logSearch, setLogSearch] = useState('');
   const [logLevels, setLogLevels] = useState<Set<string>>(new Set());
   const [logSource, setLogSource] = useState<string>('');  // '' = all, 'app', 'agent'
@@ -305,7 +306,9 @@ export default function AgentHealth() {
 
   const agentList = agents ?? [];
 
-  const groups = useMemo(() => groupByApp(agentList).sort((a, b) => a.appId.localeCompare(b.appId)), [agentList]);
+  const allGroups = useMemo(() => groupByApp(agentList).sort((a, b) => a.appId.localeCompare(b.appId)), [agentList]);
+  const appFilterLower = appFilter.toLowerCase();
+  const groups = appFilterLower ? allGroups.filter((g) => g.appId.toLowerCase().includes(appFilterLower)) : allGroups;
 
   // Aggregate stats
   const totalInstances = agentList.length;
@@ -486,18 +489,18 @@ export default function AgentHealth() {
         />
         <StatCard
           label="Applications"
-          value={String(groups.length)}
+          value={String(allGroups.length)}
           accent="running"
           detail={
             <span className={styles.breakdown}>
               <span className={styles.bpLive}>
-                <StatusDot variant="live" /> {groups.filter((g) => g.deadCount === 0 && g.staleCount === 0).length} healthy
+                <StatusDot variant="live" /> {allGroups.filter((g) => g.deadCount === 0 && g.staleCount === 0).length} healthy
               </span>
               <span className={styles.bpStale}>
-                <StatusDot variant="stale" /> {groups.filter((g) => g.staleCount > 0 && g.deadCount === 0).length} degraded
+                <StatusDot variant="stale" /> {allGroups.filter((g) => g.staleCount > 0 && g.deadCount === 0).length} degraded
               </span>
               <span className={styles.bpDead}>
-                <StatusDot variant="dead" /> {groups.filter((g) => g.deadCount > 0).length} critical
+                <StatusDot variant="dead" /> {allGroups.filter((g) => g.deadCount > 0).length} critical
               </span>
             </span>
           }
@@ -666,6 +669,26 @@ export default function AgentHealth() {
               <List size={14} />
             </button>
           </div>
+          <div className={styles.appFilterWrap}>
+            <input
+              type="text"
+              className={styles.appFilterInput}
+              placeholder="Filter apps\u2026"
+              value={appFilter}
+              onChange={(e) => setAppFilter(e.target.value)}
+              aria-label="Filter applications"
+            />
+            {appFilter && (
+              <button
+                type="button"
+                className={styles.appFilterClear}
+                onClick={() => setAppFilter('')}
+                aria-label="Clear filter"
+              >
+                &times;
+              </button>
+            )}
+          </div>
         </div>
       )}