Show the selected range, not just the active cell, in status/formula bar

New store computed selectionRangeName: for a single cell it's identical
to activeCellName ("Umsatz::B2"), for a multi-cell selection it shows
the full primary rectangle ("Umsatz::B2:E6"), and a discontiguous
multi-selection gets a "+N" suffix for the further rectangles.
activeCellName itself is untouched (still anchor-only, since that's what
a formula/edit actually targets) -- only the formula bar's name field and
the status bar's range label switch to the new computed.

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

src/store/__tests__/document.spec.ts

@@ -138,6 +138,22 @@ describe('seed document acceptance (canvas model)', () => {
     // the active cell is the anchor -- the first cell of the selection -- not
     // wherever the selection was extended to.
     expect(s.activeCellName.value).toBe(`Umsatz::${toA1(1, 1)}`);
+    // selectionRangeName shows the full range instead (status bar / formula bar)
+    expect(s.selectionRangeName.value).toBe(`Umsatz::${toA1(1, 1)}:${toA1(1, 5)}`);
+  });
+
+  it('selectionRangeName shows a single address for a 1x1 selection and a "+N" suffix for a discontiguous multi-selection', () => {
+    const s = fresh();
+    const umsatz = tableId(s, 'Umsatz');
+    s.setSelection({ tableId: umsatz, anchor: { col: 0, row: 0 }, focus: { col: 0, row: 0 } });
+    expect(s.selectionRangeName.value).toBe(`Umsatz::${toA1(0, 0)}`);
+
+    s.addToSelection(umsatz, 3, 3);
+    s.addToSelection(umsatz, 5, 5);
+    // addToSelection() moves the primary rect to the just-clicked cell (see
+    // "Mehrfachauswahl" tests below) -- the range name follows it, plus a
+    // "+N" for the other rectangles now in the selection.
+    expect(s.selectionRangeName.value).toBe(`Umsatz::${toA1(5, 5)} +2`);
   });
 
   it('recalculation visits precedents before dependents across tables', () => {

src/store/document.ts

@@ -1412,6 +1412,28 @@ function createStore() {
     return `${t?.name ?? '—'}::${toA1(cell.col, cell.row)}`;
   });
 
+  /** Like {@link activeCellName}, but for a multi-cell selection it shows the
+   *  full range (`Umsatz::B2:E6`) instead of just the anchor -- used wherever
+   *  the UI shows "where am I" (formula bar, status bar), as opposed to
+   *  `activeCellName`/`activeCell`, which stay anchor-only because that's
+   *  what a formula/edit actually targets (see the "selection aggregate &
+   *  cell name are live" test). A discontiguous multi-selection additionally
+   *  gets a `+N` suffix for the further rectangles beyond the primary one. */
+  const selectionRangeName = computed(() => {
+    const sel = doc.selection;
+    const t = sel ? tableById(sel.tableId) : activeTable.value;
+    const tableName = t?.name ?? '—';
+    if (!sel) return `${tableName}::${toA1(0, 0)}`;
+    const rects = selectionRects(sel);
+    const [p] = rects;
+    const addr =
+      p.c0 === p.c1 && p.r0 === p.r1
+        ? toA1(p.c0, p.r0)
+        : `${toA1(p.c0, p.r0)}:${toA1(p.c1, p.r1)}`;
+    const extra = rects.length > 1 ? ` +${rects.length - 1}` : '';
+    return `${tableName}::${addr}${extra}`;
+  });
+
   const activeCellInput = computed(() => {
     const sel = doc.selection;
     return sel ? cellInput(sel.tableId, sel.anchor.col, sel.anchor.row) : '';
@@ -1606,6 +1628,7 @@ function createStore() {
     selectionRects,
     activeCell,
     activeCellName,
+    selectionRangeName,
     activeCellInput,
     selectionAggregate,
     // clipboard