diff --git a/ui/src/components/StatusBar.jsx b/ui/src/components/StatusBar.jsx
index b7440dd..284f2b7 100644
--- a/ui/src/components/StatusBar.jsx
+++ b/ui/src/components/StatusBar.jsx
@@ -11,6 +11,10 @@ export default function StatusBar({ view, sources = [], sourceId, setSourceId, v
   const [info, setInfo]     = useState(null)
   const [showInfo, setShow] = useState(false)
   const [copied, setCopied] = useState(false)
+  // Forecast.jsx mirrors the pivot's own updating state onto this event. The
+  // viewer shows the same thing as a beaker in its settings panel, which is
+  // exactly where you cannot see it once the panel is closed.
+  const [busy, setBusy]     = useState(false)
 
   const refreshInfo = useCallback(async () => {
     if (!versionId || !showVersion) { setInfo(null); return }
@@ -29,6 +33,12 @@ export default function StatusBar({ view, sources = [], sourceId, setSourceId, v
     return () => window.removeEventListener('pf-data-changed', onChange)
   }, [refreshInfo])
 
+  useEffect(() => {
+    const onBusy = (e) => setBusy(!!e.detail?.busy)
+    window.addEventListener('pf-pivot-busy', onBusy)
+    return () => window.removeEventListener('pf-pivot-busy', onBusy)
+  }, [])
+
   async function copyTable() {
     if (!info?.fc_table) return
     try {
@@ -127,6 +137,23 @@ export default function StatusBar({ view, sources = [], sourceId, setSourceId, v
         </>
       )}
 
+      {/* Left of the ml-auto block, so it sits beside the pivot's own figures
+          rather than out among the account controls. Occupies no space at all
+          when idle: a permanently reserved slot reads as a thing that is broken
+          when empty. */}
+      {busy && view === 'forecast' && (
+        <span
+          className="flex items-center gap-1.5 text-blue-600"
+          title="The pivot is rebuilding its view — sorting, filtering, or changing depth on a large grain takes a moment"
+        >
+          <svg width="12" height="12" viewBox="0 0 24 24" fill="none" stroke="currentColor"
+               strokeWidth="3" strokeLinecap="round" className="animate-spin">
+            <path d="M12 3a9 9 0 1 0 9 9" />
+          </svg>
+          Calculating…
+        </span>
+      )}
+
       <div className="ml-auto flex items-center gap-2">
         {user && (
           <>
diff --git a/ui/src/views/Forecast.jsx b/ui/src/views/Forecast.jsx
index 91e2318..0d81545 100644
--- a/ui/src/views/Forecast.jsx
+++ b/ui/src/views/Forecast.jsx
@@ -29,6 +29,13 @@ const LAYOUTS_KEY = (vid) => `pf_layouts_v${vid}`  // legacy named list, migrate
 function cleanLayout(cfg, validCols) {
   if (!cfg) return cfg
   const c = { ...cfg }
+  // The theme is the reader's own light/dark choice, not a property of the
+  // layout. viewer.save() includes it, so it ends up baked into every stored
+  // config -- and restoring one then snapped the pivot back to whatever the
+  // author had, silently undoing the toggle. Dropped on the way in, which makes
+  // the app's `dark` state the only thing that sets it, and means a published
+  // layout cannot impose its author's theme on everyone who applies it.
+  delete c.theme
   // Dead expressions go before the axis filter, not after: dropping them from
   // `expressions` is what makes `ok()` reject them everywhere else.
   if (DEAD_ORDER_EXPRS.some(n => c.expressions?.[n] !== undefined)) {
@@ -263,6 +270,9 @@ export default function Forecast({ sources = [], sourceId, versions = [], versio
   const [undoingId,     setUndoingId]     = useState(null)
 
   const viewerRef      = useRef(null)
+  // Depth, not a boolean: config updates overlap, and the first one to finish
+  // would otherwise clear the flag while the others are still rebuilding.
+  const busyRef        = useRef(0)
   const workerRef      = useRef(null)
   const tableRef       = useRef(null)
   const colMetaRef     = useRef([])
@@ -784,7 +794,11 @@ export default function Forecast({ sources = [], sourceId, versions = [], versio
   // differs on every refresh, so it is never a real difference.
   function sameConfig(a, b) {
     if (!a || !b) return false
-    const strip = ({ table, ...rest }) => JSON.stringify(rest)
+    // table is the per-load table name, different on every refresh. theme is
+    // the reader's light/dark choice and is not part of the layout (see
+    // cleanLayout) -- without it here, toggling the theme would light the dirty
+    // dot and offer to save a layout nothing had edited.
+    const strip = ({ table, theme, ...rest }) => JSON.stringify(rest)
     return strip(a) === strip(b)
   }
 
@@ -1099,16 +1113,18 @@ export default function Forecast({ sources = [], sourceId, versions = [], versio
     const levels = (cfg.split_by || []).length
     if (!levels) return
     const depth = Math.max(0, Math.min(n, levels))
+    pivotBusy(true)
     try {
       // A count of levels to show, exactly as group_by_depth is -- the engine
       // treats both axes identically. See applyDepth for why 0 is floored to 1.
       await viewer.restore({ ...cfg, split_by_depth: Math.max(1, depth) })
+      await viewer.flush()
       setSplitDepth(depth)
     } catch (err) {
       console.error('[applySplitDepth]', err)
       flash(err.message || String(err), 'error')
       return
-    }
+    } finally { pivotBusy(false) }
     try {
       const cfg2 = await captureConfig()
       if (cfg2) await persistLayout(versionId, cfg2)
@@ -1441,6 +1457,35 @@ export default function Forecast({ sources = [], sourceId, versions = [], versio
     }
   `
 
+  // Tell the app's status bar whether the pivot is rebuilding, so the wait is
+  // visible with the settings panel closed.
+  //
+  // Perspective shows this as the beaker in its own status bar, which is the
+  // honest signal -- it is driven by the session's update_count. It cannot be
+  // read from here, though: that bar lives in the viewer's shadow root, and the
+  // component carrying it is only *rendered* while settings are open once the
+  // table has loaded, so with the panel closed there is no element to watch. An
+  // earlier attempt did exactly that and only ever lit up when the panel was
+  // open, which is precisely when you do not need it.
+  //
+  // So it is raised by the callers that *start* a rebuild, and lowered once
+  // viewer.flush() says everything pending has rendered.
+  //
+  // Not from `perspective-config-update`, which was the obvious hook and is the
+  // wrong one: it is dispatched *after* the rebuild it describes. Measured on a
+  // depth change over a large grain, the event arrived seconds late and the
+  // flush that followed resolved in 6ms -- so the flag went up and down well
+  // after the wait it was meant to cover.
+  //
+  // Consequence: this covers what the toolbar drives -- depth on both axes, and
+  // applying a layout. Sorting or filtering from the viewer's own chrome still
+  // shows nothing, because the app never learns those have begun.
+  function pivotBusy(on) {
+    busyRef.current = Math.max(0, busyRef.current + (on ? 1 : -1))
+    window.dispatchEvent(
+      new CustomEvent('pf-pivot-busy', { detail: { busy: busyRef.current > 0 } }))
+  }
+
   // Find the grid wherever it is. Guessing the nesting was wrong once already --
   // the plugin element's own shadow root is not where the cells live -- so locate
   // regular-table by walking through shadow roots, then inject into whatever root
@@ -1506,6 +1551,8 @@ export default function Forecast({ sources = [], sourceId, versions = [], versio
     // effect on its own. table is dropped: it is loaded by reference, and a stale
     // name in a restored config fails the lookup.
     const target = Math.max(1, d)
+    pivotBusy(true)
+    try {
     const { table: _t, ...cfg } = await viewer.save()
     await viewer.restore({ ...cfg, group_by_depth: target })
 
@@ -1530,7 +1577,9 @@ export default function Forecast({ sources = [], sourceId, versions = [], versio
       const plugin = await viewer.getPlugin()
       await plugin.draw(view)
     }
+    await viewer.flush()
     setExpandDepth(d)
+    } finally { pivotBusy(false) }
   }
 
   async function captureConfig() {
@@ -1615,7 +1664,10 @@ export default function Forecast({ sources = [], sourceId, versions = [], versio
     const validCols = new Set(tableRef.current ? Object.keys(await tableRef.current.schema()) : [])
     const cfg = cleanLayout(layout.config, validCols)
     cfg.plugin_config = { ...(cfg.plugin_config || {}), edit_mode: 'SELECT_REGION' }
+    pivotBusy(true)
+    try {
     await viewer.restore(cfg)
+    await viewer.flush()
     adoptSplit(cfg.split_full?.length ? cfg.split_full : cfg.split_by,
                cfg.split_by_depth != null ? cfg.split_by_depth : null)
     setGroupFull(cfg.group_by || [])
@@ -1631,6 +1683,7 @@ export default function Forecast({ sources = [], sourceId, versions = [], versio
     const merged = await captureConfig()
     markClean(merged || cfg, layout.id)
     await persistLayout(versionId, merged || cfg)
+    } finally { pivotBusy(false) }
   }
 
   async function deleteLayout(layout) {