fix: hide empty attributes column, standardize status labels, truncate agent names

- Attributes column is now hidden when no exchanges in the current view
  have attributes; shown conditionally via hasAttributes check on rows
- Status labels already standardized via statusLabel() in ExchangeHeader
- Agent names truncated to last two hyphen-separated segments via
  shortAgentName(); full name preserved as tooltip title

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

ui/src/pages/Dashboard/Dashboard.tsx

@@ -54,9 +54,15 @@ function durationClass(ms: number, status: string): string {
   return styles.durBreach
 }
 
-// ─── Table columns (base, without inspect action) ────────────────────────────
+function shortAgentName(name: string): string {
+  const parts = name.split('-')
+  if (parts.length >= 3) return parts.slice(-2).join('-')
+  return name
+}
 
-function buildBaseColumns(): Column<Row>[] {
+// ─── Table columns ────────────────────────────────────────────────────────────
+
+function buildColumns(hasAttributes: boolean): Column<Row>[] {
   return [
     {
       key: 'status',
@@ -87,10 +93,10 @@ function buildBaseColumns(): Column<Row>[] {
         <span className={styles.appName}>{row.applicationId ?? ''}</span>
       ),
     },
-    {
+    ...(hasAttributes ? [{
-      key: 'attributes',
+      key: 'attributes' as const,
       header: 'Attributes',
-      render: (_, row) => {
+      render: (_: unknown, row: Row) => {
         const attrs = row.attributes;
         if (!attrs || Object.keys(attrs).length === 0) return <span className={styles.muted}>—</span>;
         const entries = Object.entries(attrs);
@@ -107,7 +113,7 @@ function buildBaseColumns(): Column<Row>[] {
           </div>
         );
       },
-    },
+    }] : []),
     {
       key: 'executionId',
       header: 'Exchange ID',
@@ -150,7 +156,7 @@ function buildBaseColumns(): Column<Row>[] {
       render: (_: unknown, row: Row) => (
         <span className={styles.agentBadge}>
           <span className={styles.agentDot} />
-          {row.instanceId}
+          <span title={row.instanceId}>{shortAgentName(row.instanceId)}</span>
         </span>
       ),
     },
@@ -223,7 +229,8 @@ export default function Dashboard({ onExchangeSelect, activeExchangeId }: Dashbo
   )
 
   // ─── Table columns ──────────────────────────────────────────────────────
-  const columns: Column<Row>[] = useMemo(() => buildBaseColumns(), [])
+  const hasAttributes = rows.some(r => r.attributes && Object.keys(r.attributes).length > 0)
+  const columns: Column<Row>[] = useMemo(() => buildColumns(hasAttributes), [hasAttributes])
 
   // ─── Row click → navigate to diagram view ────────────────────────────────