diff --git a/ui/src/pages/Pivot.jsx b/ui/src/pages/Pivot.jsx
index 9675fde..35433d2 100644
--- a/ui/src/pages/Pivot.jsx
+++ b/ui/src/pages/Pivot.jsx
@@ -74,12 +74,15 @@ function filterRowsByConfig(allRows, filters) {
 }
 
 const LAYOUT_KEY = (source) => `psp_layout_${source}`
-const DEFAULT_PLUGIN_CONFIG = { edit_mode: 'SELECT_ROW' }
+const DEFAULT_PLUGIN_CONFIG = { edit_mode: 'SELECT_REGION' }
+
 
 export default function Pivot({ source }) {
   const viewerRef = useRef()
   const workerRef = useRef()
+  const tableRef = useRef()
   const allRowsRef = useRef([])
+  const expandDepthRef = useRef(null)
   const [status, setStatus] = useState('idle')
   const [error, setError] = useState('')
   const [inspectedRows, setInspectedRows] = useState(null)
@@ -135,8 +138,9 @@ export default function Pivot({ source }) {
         if (cancelled) { worker.terminate(); return }
         workerRef.current = worker
 
-        await worker.table(rows, { name: source })
+        const table = await worker.table(rows, { name: source })
         if (cancelled) return
+        tableRef.current = table
 
         const viewer = viewerRef.current
 
@@ -147,18 +151,42 @@ export default function Pivot({ source }) {
           const eventFilters = (detail.config || {}).filter || []
           const config = await viewer.save()
           setClickDetail({ row, config, column_names, eventFilters })
-          const matched = filterRowsByConfig(allRowsRef.current, eventFilters)
-          setInspectedRows(matched)
+
+          // Use a Perspective view with the event filters + expressions so computed
+          // columns (split_by) are evaluated and filtered correctly
+          try {
+            const view = await tableRef.current.view({
+              filter: eventFilters,
+              expressions: config.expressions || [],
+            })
+            const data = await view.to_json()
+            await view.delete()
+            // Strip expression columns — only show raw source columns
+            const exprNames = new Set(Object.keys(config.expressions || {}))
+            const cleaned = data.map(r =>
+              Object.fromEntries(Object.entries(r).filter(([k]) => !exprNames.has(k)))
+            )
+            setInspectedRows(cleaned)
+          } catch {
+            setInspectedRows(filterRowsByConfig(allRowsRef.current, eventFilters))
+          }
         })
 
         await viewer.load(worker)
 
+        const plugin = await viewer.getPlugin()
         const savedLayout = localStorage.getItem(LAYOUT_KEY(source))
         if (savedLayout) {
-          await viewer.restore(JSON.parse(savedLayout))
+          const parsed = JSON.parse(savedLayout)
+          await viewer.restore(parsed)
+          await plugin.restore(parsed.plugin_config || DEFAULT_PLUGIN_CONFIG)
+          if (parsed.expand_depth != null) await applyExpandDepth(viewer, parsed.expand_depth)
         } else {
           await viewer.restore({ table: source, settings: true, plugin_config: DEFAULT_PLUGIN_CONFIG })
+          await plugin.restore(DEFAULT_PLUGIN_CONFIG)
         }
+        await viewer.flush()
+
         setStatus('ready')
       } catch (err) {
         if (!cancelled) { setStatus('error'); setError(err.message) }
@@ -169,21 +197,58 @@ export default function Pivot({ source }) {
     return () => { cancelled = true }
   }, [source])
 
+  async function applyExpandDepth(viewer, depth) {
+    if (depth == null) return
+    const view = await viewer.getView()
+    await view.set_depth(depth)
+    const plugin = await viewer.getPlugin()
+    await plugin.draw(view)
+    expandDepthRef.current = depth
+  }
+
   async function applyLayout(layout) {
     const viewer = viewerRef.current
     if (!viewer) return
     await viewer.restore(layout.config)
+    if (layout.config.plugin_config) {
+      const plugin = await viewer.getPlugin()
+      await plugin.restore(layout.config.plugin_config)
+    }
+    await applyExpandDepth(viewer, layout.config.expand_depth ?? null)
     setActiveLayoutId(layout.id)
     // also persist to localStorage so it survives refresh
     localStorage.setItem(LAYOUT_KEY(source), JSON.stringify(layout.config))
   }
 
+  async function captureConfig() {
+    const viewer = viewerRef.current
+    if (!viewer) return null
+    const plugin = await viewer.getPlugin()
+    const [viewerConfig, pluginConfig] = await Promise.all([viewer.save(), plugin.save()])
+    return { ...viewerConfig, plugin_config: pluginConfig, expand_depth: expandDepthRef.current }
+  }
+
+  async function handleSaveOver() {
+    const layout = layouts.find(l => l.id === activeLayoutId)
+    if (!layout) return
+    const config = await captureConfig()
+    if (!config) return
+    try {
+      const saved = await api.savePivotLayout(source, layout.layout_name, config)
+      localStorage.setItem(LAYOUT_KEY(source), JSON.stringify(config))
+      await loadLayouts()
+      setActiveLayoutId(saved.id)
+      flashMsg('Saved!')
+    } catch (err) {
+      flashMsg(err.message)
+    }
+  }
+
   async function handleSaveAs() {
     const name = saveAsName.trim()
     if (!name) return
-    const viewer = viewerRef.current
-    if (!viewer) return
-    const config = await viewer.save()
+    const config = await captureConfig()
+    if (!config) return
     try {
       const saved = await api.savePivotLayout(source, name, config)
       localStorage.setItem(LAYOUT_KEY(source), JSON.stringify(config))
@@ -257,6 +322,13 @@ export default function Pivot({ source }) {
           </div>
         ))}
 
+        {activeLayoutId !== null && !showSaveAs && (
+          <button onClick={handleSaveOver}
+            className="text-xs text-blue-500 hover:text-blue-700 border border-blue-200 rounded px-2 py-0.5">
+            Save
+          </button>
+        )}
+
         {showSaveAs ? (
           <div className="flex items-center gap-1">
             <input
@@ -296,7 +368,8 @@ export default function Pivot({ source }) {
               await view.set_depth(d)
               const p = await v.getPlugin()
               await p.draw(view)
-            }} className="text-xs border border-gray-200 rounded px-1.5 py-0.5 text-gray-500 hover:border-gray-400 hover:border-gray-400">
+              expandDepthRef.current = d
+            }} className="text-xs border border-gray-200 rounded px-1.5 py-0.5 text-gray-500 hover:border-gray-400">
               {d}
             </button>
           ))}