diff --git a/CLAUDE.md b/CLAUDE.md
index 8ec6da7..6c0fbe8 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -600,6 +600,13 @@ anyone else, gone on another machine. The one server-side layout was
 published layout with no owner. That route is gone; the column remains, migrated
 and read by nothing.
 
+**Grand totals ride in the layout under `pf_totals`** — `{ row, col }`, the
+toolbar's *Total row* / *Total column* toggles. The engine has no rollup mode
+for "subtotals but no grand total", so both are hidden in the grid's DOM rather
+than in `ViewConfig`; `captureConfig()` adds the key and `cleanLayout()` strips
+it before `restore()`. A layout without it gets the old behaviour: row shown,
+column hidden.
+
 `cleanLayout()` guards `aggregates` along with the axes — including the weight
 column of the multi-arg form — and drops the offending *entry* rather than the
 layout, since `restore()` is all-or-nothing.
diff --git a/ui/src/views/Forecast.jsx b/ui/src/views/Forecast.jsx
index 3e73393..a36904b 100644
--- a/ui/src/views/Forecast.jsx
+++ b/ui/src/views/Forecast.jsx
@@ -36,6 +36,9 @@ function cleanLayout(cfg, validCols) {
   // 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
+  // Ours, not the engine's: read off the layout with totalsOf() before this
+  // runs, and kept out of restore(), which knows nothing of it.
+  delete c[PF_TOTALS]
   // 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)) {
@@ -76,6 +79,20 @@ function cleanLayout(cfg, validCols) {
 // names a column that no longer exists.
 const DEAD_ORDER_EXPRS = ['pf_bucket_ord', 'pf_segment_ord', 'Bucket', 'Segment']
 
+// Whether the grand-total row and column are shown. Neither has a ViewConfig
+// field -- the engine's rollup modes are rollup, flat and total, none of them
+// "subtotals but no grand total" -- so both are hidden in the grid's DOM, and
+// the choice travels beside the engine's config under this key: added by
+// captureConfig, stripped by cleanLayout. A layout saved before the key existed
+// gets the defaults, which are what the grid showed then: the row, and not the
+// column.
+const PF_TOTALS = 'pf_totals'
+const DEFAULT_TOTALS = { row: true, col: false }
+const totalsOf = (cfg) => ({
+  row: cfg?.[PF_TOTALS]?.row ?? DEFAULT_TOTALS.row,
+  col: cfg?.[PF_TOTALS]?.col ?? DEFAULT_TOTALS.col,
+})
+
 export default function Forecast({ sources = [], sourceId, versions = [], versionId, refreshSources }) {
   const { dark } = useTheme()
   const { user } = useAuth()
@@ -180,15 +197,11 @@ export default function Forecast({ sources = [], sourceId, versions = [], versio
   useEffect(() => { localStorage.setItem('pf_scale_plug_v2', scalePlug) }, [scalePlug])
   useEffect(() => { localStorage.setItem('pf_panel_open', panelOpen ? 'open' : 'closed') }, [panelOpen])
 
-  // Whether the grand-total row is drawn. Per-browser, like the panel state: it
-  // is how you like to read the grid, not a property of the layout.
-  const [showTotalRow, setShowTotalRow] = useState(() => localStorage.getItem('pf_total_row') !== 'hidden')
-  const showTotalRowRef = useRef(showTotalRow)
-  useEffect(() => {
-    localStorage.setItem('pf_total_row', showTotalRow ? 'shown' : 'hidden')
-    showTotalRowRef.current = showTotalRow
-    gridRef.current?.regular_table?.draw()
-  }, [showTotalRow])
+  // Whether the grand-total row and grand-total column are drawn. Part of the
+  // layout (see PF_TOTALS), so the ref is what captureConfig reads -- it has to
+  // be current the moment a toggle persists, before React has re-rendered.
+  const [totals, setTotals] = useState(DEFAULT_TOTALS)
+  const totalsRef = useRef(DEFAULT_TOTALS)
 
   // Esc closes the panel — the usual way out of the floating window
   useEffect(() => {
@@ -1002,9 +1015,12 @@ export default function Forecast({ sources = [], sourceId, versions = [], versio
       // localStorage and comes back when there are rows again.
       const saved = rowCount > 0 ? localStorage.getItem(LAYOUT_KEY(vid)) : null
       if (rowCount === 0) {
+        adoptTotals(DEFAULT_TOTALS)
         await viewer.restore({ settings: false, plugin_config: { edit_mode: 'SELECT_REGION' } })
       } else if (saved) {
-        const { table: _t, ...rest } = cleanLayout(JSON.parse(saved), validCols)
+        const parsed = JSON.parse(saved)
+        adoptTotals(totalsOf(parsed))
+        const { table: _t, ...rest } = cleanLayout(parsed, validCols)
         const cfg = { ...rest, plugin_config: { ...(rest.plugin_config || {}), edit_mode: 'SELECT_REGION' } }
         await viewer.restore(cfg)
         // split_full is the legacy key, from when collapsing truncated split_by
@@ -1027,6 +1043,7 @@ export default function Forecast({ sources = [], sourceId, versions = [], versio
         const defaultRow  = defaults.find(l => l.version_id != null) || defaults[0]
         const sourceDefault = defaultRow?.config
         let cfg
+        adoptTotals(totalsOf(sourceDefault))
         if (sourceDefault && Object.keys(sourceDefault).length > 0) {
           const { table: _t, ...rest } = cleanLayout(sourceDefault, validCols)
           cfg = { ...rest, plugin_config: { ...(rest.plugin_config || {}), edit_mode: 'SELECT_REGION' } }
@@ -1046,7 +1063,7 @@ export default function Forecast({ sources = [], sourceId, versions = [], versio
         // dirty dot has something to compare against. Read back rather than
         // reusing cfg: restore() normalises, so the live config is what a later
         // save() will be compared with.
-        if (defaultRow) markClean(await viewer.save(), defaultRow.id)
+        if (defaultRow) markClean(await captureConfig(), defaultRow.id)
       }
 
       // Its own try: the restore above has one, but this sits outside it, and a
@@ -1250,8 +1267,11 @@ export default function Forecast({ sources = [], sourceId, versions = [], versio
         const head = meta?.row_header
         const isTotal = meta?.y === 0 && Array.isArray(head) &&
                         String(head[0]) === 'TOTAL' && !head.slice(1).some(notBlank)
-        tr.classList.toggle('pf-total-row', isTotal && !showTotalRowRef.current)
+        tr.classList.toggle('pf-total-row', isTotal && !totalsRef.current.row)
       }
+      // The column's switch, for GRID_CSS. Re-asserted per draw because the
+      // datagrid can hand us a fresh table element.
+      table.toggleAttribute('data-pf-col-total', totalsRef.current.col)
 
       const body = table.querySelectorAll('tbody td')
       // The deepest column path is a leaf; anything shorter is an aggregate of
@@ -1271,6 +1291,15 @@ export default function Forecast({ sources = [], sourceId, versions = [], versio
         if (Array.isArray(path)) depth = Math.max(depth, path.filter(notBlank).length)
       }
 
+      // A rule only means something when a group spans several columns. A path
+      // ends with the measure, so depth counts split levels plus one: with a
+      // single split level (or the axis collapsed to one) and a single measure,
+      // every group is one column and the rule would sit on every column,
+      // separating nothing. Measures are counted, not read off the config,
+      // because two of them under one split value do make a group worth ruling.
+      const measures = new Set(metas.map(([, m]) => m?.column_header?.at?.(-1)).filter(notBlank))
+      const ruled = depth > 2 || (depth === 2 && measures.size > 1)
+
       let prevGroup = null
       for (const [td, meta] of metas) {
         td.classList.remove('pf-group-start', 'pf-subtotal')
@@ -1278,7 +1307,7 @@ export default function Forecast({ sources = [], sourceId, versions = [], versio
         if (!Array.isArray(path) || !path.length) { prevGroup = null; continue }
         const named = path.filter(notBlank)
         const group = named[0]
-        if (group !== prevGroup) { td.classList.add('pf-group-start'); prevGroup = group }
+        if (group !== prevGroup) { if (ruled) td.classList.add('pf-group-start'); prevGroup = group }
         if (named.length < depth) td.classList.add('pf-subtotal')
       }
     })
@@ -1471,8 +1500,10 @@ export default function Forecast({ sources = [], sourceId, versions = [], versio
       white-space: nowrap !important;
     }
 
-    th.psp-split-total:not(.psp-split-subtotal),
-    td.psp-split-total:not(.psp-split-subtotal) {
+    /* The grand-total column, hidden unless the layout asks for it
+     * (data-pf-col-total, set by adoptTotals and the style listener). */
+    regular-table:not([data-pf-col-total]) th.psp-split-total:not(.psp-split-subtotal),
+    regular-table:not([data-pf-col-total]) td.psp-split-total:not(.psp-split-subtotal) {
       visibility: hidden !important;
       width: 0 !important;
       min-width: 0 !important;
@@ -1613,10 +1644,40 @@ export default function Forecast({ sources = [], sourceId, versions = [], versio
     const viewer = viewerRef.current
     if (!viewer) return null
     const cfg = await viewer.save()
-    // Both depths are already in cfg, straight from save(). Nothing of ours needs
-    // to travel beside it any more -- split_full existed only because collapsing
-    // truncated split_by and the discarded levels had to be remembered.
-    return cfg
+    // Both depths are already in cfg, straight from save(). The one thing of
+    // ours that travels beside it is the totals choice, which the engine has no
+    // field for (see PF_TOTALS). split_full used to as well, only because
+    // collapsing truncated split_by and the discarded levels had to be
+    // remembered.
+    return { ...cfg, [PF_TOTALS]: { ...totalsRef.current } }
+  }
+
+  // Show or hide the grand totals. Both are DOM-side, so this is a redraw, not
+  // a rebuild: the row is tagged in the style listener, the column hidden by
+  // GRID_CSS unless the table carries data-pf-col-total. The attribute is set
+  // here as well as per draw so the draw that follows already sizes the column.
+  function adoptTotals(t) {
+    totalsRef.current = t
+    setTotals(t)
+    const table = gridRef.current?.regular_table
+    if (!table) return
+    table.toggleAttribute('data-pf-col-total', t.col)
+    table.draw()
+  }
+
+  // A toolbar toggle. It changes the layout without touching the engine, so no
+  // perspective-config-update follows -- the persist and the dirty dot that
+  // handler would have done are done here.
+  async function toggleTotal(axis, on) {
+    adoptTotals({ ...totalsRef.current, [axis]: on })
+    try {
+      const cfg = await captureConfig()
+      if (!cfg) return
+      await persistLayout(versionId, cfg)
+      setLayoutDirty(!!activeConfigRef.current && !sameConfig(cfg, activeConfigRef.current))
+    } catch (err) {
+      console.error('[toggleTotal]', err)
+    }
   }
 
   async function persistLayout(vid, cfg) {
@@ -1693,6 +1754,7 @@ export default function Forecast({ sources = [], sourceId, versions = [], versio
     cfg.plugin_config = { ...(cfg.plugin_config || {}), edit_mode: 'SELECT_REGION' }
     pivotBusy(true)
     try {
+    adoptTotals(totalsOf(layout.config))
     await viewer.restore(cfg)
     await viewer.flush()
     adoptSplit(cfg.split_full?.length ? cfg.split_full : cfg.split_by,
@@ -1726,6 +1788,7 @@ export default function Forecast({ sources = [], sourceId, versions = [], versio
   function resetLayout() {
     localStorage.removeItem(LAYOUT_KEY(versionId))
     markClean(null, null)
+    adoptTotals(DEFAULT_TOTALS)
     const viewer = viewerRef.current
     if (viewer) viewer.restore({ settings: true })
   }
@@ -2151,8 +2214,8 @@ export default function Forecast({ sources = [], sourceId, versions = [], versio
                 onPick={applyDepth} totalLabel="Total" />
               <label className="flex items-center gap-1 text-gray-600 cursor-pointer select-none"
                 title="Show the grand-total row at the top of the pivot">
-                <input type="checkbox" checked={showTotalRow}
-                  onChange={e => setShowTotalRow(e.target.checked)} />
+                <input type="checkbox" checked={totals.row}
+                  onChange={e => toggleTotal('row', e.target.checked)} />
                 Total row
               </label>
             </>
@@ -2163,6 +2226,12 @@ export default function Forecast({ sources = [], sourceId, versions = [], versio
               <div className="pf-group-rule" />
               <DepthButtons label="Columns" levels={splitFull} depth={splitDepth}
                 onPick={applySplitDepth} totalLabel="Total" />
+              <label className="flex items-center gap-1 text-gray-600 cursor-pointer select-none"
+                title="Show the grand-total column across every column group">
+                <input type="checkbox" checked={totals.col}
+                  onChange={e => toggleTotal('col', e.target.checked)} />
+                Total column
+              </label>
             </>
           )}