fix(ui): restore layout — same table everywhere, 50:50 split, full-height sidebar, tab styling

- Sidebar wrapper gets height:100% to fill window
- Route-scoped Exchanges uses same Dashboard table (not compact ExchangeList)
- 50:50 grid split: table on left, diagram on right when route selected
- ContentTabs gets border-bottom and surface background for visibility

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

ui/src/components/ContentTabs.module.css

@@ -1,5 +1,5 @@
 .wrapper {
-  padding: 0 1.5rem;
-  padding-top: 0.75rem;
-  padding-bottom: 0;
+  padding: 0.625rem 1.5rem 0;
+  border-bottom: 1px solid var(--border);
+  background: var(--surface);
 }

ui/src/components/LayoutShell.tsx

@@ -229,7 +229,7 @@ function LayoutContent() {
   return (
     <AppShell
       sidebar={
-        <div onClick={handleSidebarClick}>
+        <div onClick={handleSidebarClick} style={{ height: '100%' }}>
           <Sidebar apps={sidebarApps} />
         </div>
       }

ui/src/pages/Exchanges/ExchangesPage.module.css

@@ -1,10 +1,16 @@
-.threeColumn {
+.splitView {
   display: grid;
-  grid-template-columns: 280px 1fr;
+  grid-template-columns: 1fr 1fr;
   height: 100%;
   overflow: hidden;
 }
 
+.leftPanel {
+  overflow: auto;
+  height: 100%;
+  border-right: 1px solid var(--border);
+}
+
 .rightPanel {
   display: flex;
   flex-direction: column;

ui/src/pages/Exchanges/ExchangesPage.tsx

@@ -1,17 +1,15 @@
 import { useState, useMemo, useCallback } from 'react';
 import { useParams } from 'react-router';
 import { useGlobalFilters } from '@cameleer/design-system';
-import { useSearchExecutions, useExecutionDetail } from '../../api/queries/executions';
+import { useExecutionDetail } from '../../api/queries/executions';
 import { useDiagramByRoute } from '../../api/queries/diagrams';
 import { useRouteCatalog } from '../../api/queries/catalog';
-import type { ExecutionSummary } from '../../api/types';
-import { ExchangeList } from './ExchangeList';
 import { ExchangeHeader } from './ExchangeHeader';
 import { ExecutionDiagram } from '../../components/ExecutionDiagram/ExecutionDiagram';
 import { ProcessDiagram } from '../../components/ProcessDiagram';
 import styles from './ExchangesPage.module.css';
 
-// Lazy-import the full-width Dashboard for the no-route-scope view
+// The full-width Dashboard table — used at every scope level
 import Dashboard from '../Dashboard/Dashboard';
 
 export default function ExchangesPage() {
@@ -19,45 +17,44 @@ export default function ExchangesPage() {
     appId?: string; routeId?: string; exchangeId?: string;
   }>();
 
-  // If no route is scoped, render the existing full-width Dashboard table
+  // No route scoped: full-width Dashboard
   if (!routeId) {
     return <Dashboard />;
   }
 
-  // Route is scoped: render 3-column layout
+  // Route scoped: 50:50 split — Dashboard table on left, diagram on right
   return (
-    <RouteExchangeView appId={appId!} routeId={routeId} initialExchangeId={exchangeId} />
+    <div className={styles.splitView}>
+      <div className={styles.leftPanel}>
+        <Dashboard />
+      </div>
+      <div className={styles.rightPanel}>
+        <DiagramPanel appId={appId!} routeId={routeId} exchangeId={exchangeId} />
+      </div>
+    </div>
   );
 }
 
-// ─── 3-column view when route is scoped ─────────────────────────────────────
+// ─── Right panel: diagram + optional execution overlay ──────────────────────
 
-interface RouteExchangeViewProps {
+interface DiagramPanelProps {
   appId: string;
   routeId: string;
-  initialExchangeId?: string;
+  exchangeId?: string;
 }
 
-function RouteExchangeView({ appId, routeId, initialExchangeId }: RouteExchangeViewProps) {
-  const [selectedExchangeId, setSelectedExchangeId] = useState<string | undefined>(initialExchangeId);
+function DiagramPanel({ appId, routeId, exchangeId }: DiagramPanelProps) {
   const { timeRange } = useGlobalFilters();
   const timeFrom = timeRange.start.toISOString();
   const timeTo = timeRange.end.toISOString();
 
-  // Fetch exchanges for this route
-  const { data: searchResult } = useSearchExecutions(
-    { timeFrom, timeTo, routeId, application: appId, sortField: 'startTime', sortDir: 'desc', offset: 0, limit: 50 },
-    true,
-  );
-  const exchanges: ExecutionSummary[] = searchResult?.data || [];
+  // Fetch execution detail if an exchange is selected
+  const { data: detail } = useExecutionDetail(exchangeId ?? null);
 
-  // Fetch execution detail for selected exchange
-  const { data: detail } = useExecutionDetail(selectedExchangeId ?? null);
-
-  // Fetch diagram for topology-only view (when no exchange selected)
+  // Fetch diagram for topology-only view
   const diagramQuery = useDiagramByRoute(appId, routeId);
 
-  // Known route IDs for drill-down resolution
+  // Known route IDs for drill-down
   const { data: catalog } = useRouteCatalog(timeFrom, timeTo);
   const knownRouteIds = useMemo(() => {
     const ids = new Set<string>();
@@ -71,43 +68,35 @@ function RouteExchangeView({ appId, routeId, initialExchangeId }: RouteExchangeV
     return ids;
   }, [catalog]);
 
-  const handleExchangeSelect = useCallback((ex: ExecutionSummary) => {
-    setSelectedExchangeId(ex.executionId);
-  }, []);
+  // If exchange selected: show header + ExecutionDiagram
+  if (exchangeId && detail) {
+    return (
+      <>
+        <ExchangeHeader detail={detail} />
+        <ExecutionDiagram
+          executionId={exchangeId}
+          executionDetail={detail}
+          knownRouteIds={knownRouteIds}
+        />
+      </>
+    );
+  }
+
+  // No exchange: show topology-only ProcessDiagram
+  if (diagramQuery.data) {
+    return (
+      <ProcessDiagram
+        application={appId}
+        routeId={routeId}
+        diagramLayout={diagramQuery.data}
+        knownRouteIds={knownRouteIds}
+      />
+    );
+  }
 
   return (
-    <div className={styles.threeColumn}>
-      <ExchangeList
-        exchanges={exchanges}
-        selectedId={selectedExchangeId}
-        onSelect={handleExchangeSelect}
-      />
-
-      <div className={styles.rightPanel}>
-        {selectedExchangeId && detail ? (
-          <>
-            <ExchangeHeader detail={detail} />
-            <ExecutionDiagram
-              executionId={selectedExchangeId}
-              executionDetail={detail}
-              knownRouteIds={knownRouteIds}
-            />
-          </>
-        ) : (
-          diagramQuery.data ? (
-            <ProcessDiagram
-              application={appId}
-              routeId={routeId}
-              diagramLayout={diagramQuery.data}
-              knownRouteIds={knownRouteIds}
-            />
-          ) : (
-            <div className={styles.emptyRight}>
-              Select an exchange to view execution details
-            </div>
-          )
-        )}
-      </div>
+    <div className={styles.emptyRight}>
+      Loading diagram...
     </div>
   );
 }