Drop the selection line; Post goes last

The summary printed back the cells you had just clicked in the grid --
count, total and filter, none of it news. It is a peek button now, and
the peek still carries the pivot filter and the duplicate-slice warning,
which are the parts that are not visible in the grid.

Post moves to a footer of its own, last in the flow: pick the operation,
read the ledger, name the change, post it. It sits on the same label
column as every other button, and sticks to the bottom of the dock --
a fixed-height dock with its own scrollbar would otherwise put the
primary action below the fold.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

ui/src/components/OperationPanel.jsx

@@ -166,45 +166,7 @@ function scopeText(viewScope = []) {
     .join('  ·  ')
 }
 
-// The selection, in one line you can open. What it always shows is what is not
+function SelectionList({ slices, viewScope = [], distinctSlices, currentTotals, onRemove, onClear }) {
-// visible anywhere else: how many slices, what they total, and the pivot filter
-// they sit inside -- which scopes every figure in the ledger and every row the
-// write touches, while appearing in none of the slices themselves.
-function SliceSummary({ slices, viewScope, distinctSlices, currentTotals, open, onToggle }) {
-  const scope = scopeText(viewScope)
-  const one   = slices.length === 1 ? sliceLabel(slices[0]) : null
-  const total = currentTotals
-    ? (currentTotals.total?.value || 0) + (currentTotals.excluded?.value || 0)
-    : null
-  const dupes = distinctSlices != null && distinctSlices < slices.length
-
-  return (
-    <div className="flex items-baseline gap-2 min-w-0">
-      <span className="text-gray-600 shrink-0">
-        {one ? '1 slice' : `${slices.length} slices`}
-      </span>
-      {one && <span className="font-mono text-gray-700 truncate max-w-[22rem]" title={one}>{one}</span>}
-      {total != null && (
-        <span className="font-mono tabular-nums text-gray-700 shrink-0">{fmtNum(total)}</span>
-      )}
-      {scope && (
-        <span className="text-gray-500 truncate max-w-[16rem]" title={scope}>
-          <span className="uppercase tracking-wide text-gray-400">within </span>
-          <span className="font-mono">{scope}</span>
-        </span>
-      )}
-      {dupes && (
-        <span className="shrink-0 px-1 py-0.5 rounded bg-amber-50 text-amber-700 text-[10px] uppercase tracking-wide"
-              title={`${slices.length} cells cover ${distinctSlices} distinct slices — some differ only by a column operations cannot target. The duplicates are applied once.`}>
-          {distinctSlices} distinct
-        </span>
-      )}
-      <TextButton onClick={onToggle}>{open ? '▾ hide' : '▸ peek'}</TextButton>
-    </div>
-  )
-}
-
-function SelectionList({ slices, viewScope = [], currentTotals, onRemove, onClear }) {
   const multi    = slices.length > 1
   const perSlice = currentTotals?.perSlice || []
   const valueCol = currentTotals?.valueCol
@@ -226,6 +188,15 @@ function SelectionList({ slices, viewScope = [], currentTotals, onRemove, onClea
 
   return (
     <div className="min-w-0">
+      {/* Cells that differ only by a column operations cannot filter on collapse
+          to the same slice — say so, rather than implying more reach than there is */}
+      {distinctSlices != null && distinctSlices < slices.length && (
+        <p className="text-amber-700 bg-amber-50 border border-amber-200 rounded px-2 py-1 mb-2 leading-snug">
+          {slices.length} cells cover {distinctSlices} distinct{' '}
+          {distinctSlices === 1 ? 'slice' : 'slices'} — some differ only by a column
+          operations cannot target. The duplicates are applied once.
+        </p>
+      )}
       {scopeLine && (
         <div className="mb-1 flex items-baseline gap-1.5 text-[11px]">
           <span className="text-gray-400 uppercase tracking-wide shrink-0">within</span>
@@ -1450,13 +1421,10 @@ export default function OperationPanel({
           </Field>
 
           {hasSlice && (
-            <div className="ml-auto flex items-center gap-3 pt-0.5">
+            <div className="ml-auto pt-1">
-              <SliceSummary slices={slices} viewScope={viewScope} distinctSlices={distinctSlices}
+              <TextButton onClick={() => setPeek(o => !o)}>
-                            currentTotals={currentTotals} open={peek} onToggle={() => setPeek(o => !o)} />
+                {peek ? '▾' : '▸'} {slices.length} {slices.length === 1 ? 'slice' : 'slices'}
-              {opBusy && <span className="text-gray-500">writing rows…</span>}
+              </TextButton>
-              <Submit onClick={() => submitOp(activeOp)} busy={!!opBusy}>
-                {opBusy ? POSTING : POST}
-              </Submit>
             </div>
           )}
         </div>
@@ -1476,6 +1444,7 @@ export default function OperationPanel({
           <SelectionList
             slices={slices}
             viewScope={viewScope}
+            distinctSlices={distinctSlices}
             currentTotals={currentTotals}
             onRemove={(i) => setSlices(prev => prev.filter((_, x) => x !== i))}
             onClear={() => setSlices([])}
@@ -1506,6 +1475,23 @@ export default function OperationPanel({
           <Block title="Label this change" horizontal={horizontal}>{labelZone}</Block>
         </div>
       )}
+
+      {/* Last, because it is last: pick the operation, read the ledger, name
+          the change, post it. The blank label keeps Post in the same column as
+          every other button in the panel rather than at an edge of its own.
+          Sticky, because the bottom dock is a fixed height with its own scroll
+          -- a primary action that has to be scrolled to is a primary action
+          people miss. */}
+      {hasSlice && (
+        <div className="sticky bottom-0 z-10 flex items-center gap-3 px-3 py-2 border-t border-gray-200 bg-gray-50">
+          <Field label="">
+            <Submit onClick={() => submitOp(activeOp)} busy={!!opBusy}>
+              {opBusy ? POSTING : POST}
+            </Submit>
+          </Field>
+          {opBusy && <span className="text-gray-500">writing rows — the pivot updates when it finishes</span>}
+        </div>
+      )}
     </div>
   )
 }