diff --git a/CLAUDE.md b/CLAUDE.md
index c74f63e..c6ccf00 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -277,11 +277,24 @@ levels a two-field `group_by` does not have.
 `depth` is null until the first layout has been read back; the stepper shows an
 em dash rather than guessing a level.
 
-Both are **1-based**: they count the levels to show, where the imperative
-`view.set_depth()` counts the boundary below them. `server.cpp` does
-`ctx1->set_depth(row_pivot_depth - 1)` and
-`ctx2->set_depth(HEADER_COLUMN, column_pivot_depth - 1)`, so the toolbar sends
-`d + 1` and subtracts one again when reading a layout back.
+Both are **1-based counts of the levels to show**, and so is the stepper's own
+`depth` — `DepthButtons` labels `d` as `levels[d - 1]`. Same unit on both
+sides, so the value crosses unchanged in each direction. The engine agrees:
+`server.cpp` turns `group_by_depth` into `set_depth(n - 1)` and
+`t_traversal::set_depth` adds the 1 back, so `n` renders `n` levels, on both
+axes (`ctx2->set_depth(HEADER_COLUMN, column_pivot_depth - 1)` is the same
+arithmetic).
+
+The toolbar used to send `d + 1` and subtract the same 1 when reading a layout
+back. That was self-consistent — the stepper always agreed with itself — and
+off by one against the grid at every position: picking `partgroup` showed one
+level past it. The `+1` was there to dodge `depth 0`, which reaches the engine
+as `set_depth(-1)` on an unsigned `t_depth`, underflows, and clamps to *fully
+expanded*. `applyDepth` now floors the value at 1 instead, so the stepper's
+**"Total" slot still shows the first level rather than a bare total** — the
+long-standing wart, kept deliberately rather than traded for the underflow. A
+real total needs `group_rollup_mode: 'total'`, which is a field in
+`ViewConfigUpdate` but is unverified against the local WASM engine.
 
 Because a depth lives in the config, it survives every view rebuild, rides into
 the persisted and named layouts through `viewer.save()`, and needs nothing
diff --git a/ui/src/views/Forecast.jsx b/ui/src/views/Forecast.jsx
index 9147eab..ac98fa1 100644
--- a/ui/src/views/Forecast.jsx
+++ b/ui/src/views/Forecast.jsx
@@ -929,12 +929,15 @@ export default function Forecast({ sources = [], sourceId, versions = [], versio
         await viewer.restore(cfg)
         // split_full is the legacy key, from when collapsing truncated split_by
         adoptSplit(cfg.split_full?.length ? cfg.split_full : cfg.split_by,
-                   cfg.split_by_depth != null ? cfg.split_by_depth - 1 : null)
+                   cfg.split_by_depth != null ? cfg.split_by_depth : null)
         setGroupFull(cfg.group_by || [])
         // restore() has already applied group_by_depth; this only syncs the
-        // toolbar. expand_depth is the legacy key, from when depth was imperative
+        // toolbar. The config's count and the stepper's are the same unit, so
+        // it reads across as it is -- it used to subtract the 1 that applyDepth
+        // added, which kept the toolbar agreeing with itself and with nothing
+        // else. expand_depth is the legacy key, from when depth was imperative
         // and had to be stored beside the config rather than in it.
-        if (cfg.group_by_depth != null) setExpandDepth(cfg.group_by_depth - 1)
+        if (cfg.group_by_depth != null) setExpandDepth(cfg.group_by_depth)
         else if (cfg.expand_depth != null) await applyDepth(cfg.expand_depth)
       } else {
         // The default is a published layout flagged is_default. A version-scoped
@@ -970,6 +973,7 @@ export default function Forecast({ sources = [], sourceId, versions = [], versio
       // throw here would abort the rest of initViewer silently.
       try {
         await ensureRowLabelWidth()
+        await fitRowLabelsNow()
       } catch (err) {
         console.error('[pf-layout] threw', err)
       }
@@ -982,7 +986,7 @@ export default function Forecast({ sources = [], sourceId, versions = [], versio
           // collapse apart from the user rearranging the pivot.
           const live = await viewer.save()
           adoptSplit(live.split_by || [],
-                     live.split_by_depth != null ? live.split_by_depth - 1 : null)
+                     live.split_by_depth != null ? live.split_by_depth : null)
           setGroupFull(live.group_by || [])
           // the plugin element is replaced when the plugin changes, so re-assert
           hideSplitTotal()
@@ -1097,9 +1101,9 @@ export default function Forecast({ sources = [], sourceId, versions = [], versio
     if (!levels) return
     const depth = Math.max(0, Math.min(n, levels))
     try {
-      // 1-based, as with group_by_depth: server.cpp does
-      // ctx2->set_depth(HEADER_COLUMN, column_pivot_depth - 1)
-      await viewer.restore({ ...cfg, split_by_depth: depth + 1 })
+      // 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) })
       setSplitDepth(depth)
     } catch (err) {
       console.error('[applySplitDepth]', err)
@@ -1348,6 +1352,20 @@ export default function Forecast({ sources = [], sourceId, versions = [], versio
     await grid.draw({ invalid_columns: true })
   }
 
+  // fitRowLabels takes the grid; this finds it, so the restore paths can call it
+  // the same way they call ensureRowLabelWidth.
+  //
+  // Deliberately not routed through the Fit widths button: that one goes via
+  // regular-table's own auto-size, which measures the leaf header's rendered box
+  // over the rows currently in the viewport. fitRowLabels measures the label
+  // text on a canvas instead, so it is not blinded by a clipped cell and does
+  // not depend on what happens to be scrolled into view.
+  async function fitRowLabelsNow() {
+    const grid = (await viewerRef.current?.getPlugin())?.regular_table
+    if (!grid?.saveColumnSizes) return
+    await fitRowLabels(grid)
+  }
+
   const GRID_CSS = `
     /* Let headers and row labels size their own column.
      *
@@ -1426,18 +1444,25 @@ export default function Forecast({ sources = [], sourceId, versions = [], versio
   async function applyDepth(d) {
     const viewer = viewerRef.current
     if (!viewer) return
-    // group_by_depth counts levels, where view.set_depth() counts the boundary
-    // below them -- server.cpp does ctx->set_depth(row_pivot_depth - 1) for both
-    // the one- and two-sided contexts. So the toolbar's 0..3, which were written
-    // against the imperative call, are one less than the config wants: depth 0
-    // (grand total only) is group_by_depth 1, and passing 0 asked the engine for
-    // set_depth(-1).
+    // group_by_depth is a count of levels to show, and so is the stepper's own
+    // d -- DepthButtons labels d as levels[d - 1]. Same unit, so d goes across
+    // unchanged. It used to be sent as d + 1, which showed one level more than
+    // was picked at every position: server.cpp turns group_by_depth into
+    // set_depth(n - 1), and t_traversal::set_depth adds the 1 back, so n levels
+    // is what n asks for.
+    //
+    // d === 0 is the stepper's "Total" slot, which has never worked: 0 reaches
+    // the engine as set_depth(-1) on an unsigned depth, underflows, and clamps
+    // to fully expanded. Sending 1 keeps it showing the first level, which is
+    // what it has always shown -- still wrong, but wrong in the small way
+    // rather than the large one. A bare total needs group_rollup_mode.
     //
     // The whole config goes back rather than a partial update, which had no
     // 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)
     const { table: _t, ...cfg } = await viewer.save()
-    await viewer.restore({ ...cfg, group_by_depth: d + 1 })
+    await viewer.restore({ ...cfg, group_by_depth: target })
 
     // Until the engine carries the patch in ui/vendor, restore() drops the depth:
     // ViewConfig::apply_update applies ten fields and neither depth is among
@@ -1452,9 +1477,11 @@ export default function Forecast({ sources = [], sourceId, versions = [], versio
     // a button, which is predictable, and it becomes durable for free once the
     // engine is rebuilt.
     const after = await viewer.save()
-    if (after.group_by_depth !== d + 1) {
+    if (after.group_by_depth !== target) {
       const view = await viewer.getView()
-      await view.set_depth(d)
+      // set_depth counts the boundary below the levels shown, so it is one
+      // less than the config's count of them.
+      await view.set_depth(target - 1)
       const plugin = await viewer.getPlugin()
       await plugin.draw(view)
     }
@@ -1545,12 +1572,13 @@ export default function Forecast({ sources = [], sourceId, versions = [], versio
     cfg.plugin_config = { ...(cfg.plugin_config || {}), edit_mode: 'SELECT_REGION' }
     await viewer.restore(cfg)
     adoptSplit(cfg.split_full?.length ? cfg.split_full : cfg.split_by,
-               cfg.split_by_depth != null ? cfg.split_by_depth - 1 : null)
+               cfg.split_by_depth != null ? cfg.split_by_depth : null)
     setGroupFull(cfg.group_by || [])
-    if (cfg.group_by_depth != null) setExpandDepth(cfg.group_by_depth - 1)
+    if (cfg.group_by_depth != null) setExpandDepth(cfg.group_by_depth)
     else if (cfg.expand_depth != null) await applyDepth(cfg.expand_depth)
 
     await ensureRowLabelWidth()
+    await fitRowLabelsNow()
 
     // The persisted copy is taken after the restore, so it carries whatever
     // cleanLayout dropped on the way in rather than the stale original -- and