fix(card_drag): extend drop rects one trailing row so beyond-extent drops land

computeSlotRectsForDrop adds cols slots past maxSlot; classifyCardDrag and
drawCardDropTarget use it instead of the render rects. doReorderDrop already
accepts any non-negative slot. New tests cover beyond-extent resolves,
empty-bank trailing row, gap pixels still miss, empty-cell within-extent works.

src/bank_panel.cpp

@@ -1411,7 +1411,13 @@ void drawCardDropTarget(LICE_IBitmap* bmp, const RECT& region, bool isBanks, Reg
 
     const RECT grid = regionGridRect(region, isBanks);
     const RegionDisplay disp = regionDisplay(region, isBanks, reg);
-    for (const SlotCellRect& r : disp.slotRects) {
+    // Use the drop rects (includes the trailing row past maxSlot) so a beyond-extent
+    // target slot gets a visible highlight cue, not silence.
+    const int gridW = grid.right - grid.left;
+    const int maxSlot = disp.bank ? disp.bank->slots.maxSlot() : -1;
+    std::vector<SlotCellRect> dropRects = computeSlotRectsForDrop(maxSlot, gridW, kGrid);
+    for (SlotCellRect& r : dropRects) { r.x += grid.left; r.y += grid.top; }
+    for (const SlotCellRect& r : dropRects) {
         if (r.slot != g_panel.dragTargetSlot) continue;
         if (r.y >= grid.bottom) return;  // below the viewport (no scroll)
         const LICE_pixel hot = toLice(roleColor(Role::AccentHot));
@@ -2738,11 +2744,21 @@ void classifyCardDrag(int x, int y) {
     if (!destBank.empty() && destBank == g_panel.dragSourceBankId) {
         // Same-bank grid: a reorder/replace target. Resolve the slot the pointer sits over
         // in the SOURCE bank's own region display + whether it is occupied.
+        // Uses computeSlotRectsForDrop (one trailing row past maxSlot) so a drop beyond
+        // the last occupied card resolves to a valid trailing slot, not a -1 miss.
         mods.region = DropRegion::SameBankGrid;
         const bool isBanks = g_panel.dragSourceRegion == Region::Banks;
         const RECT region = isBanks ? banksRegionRect(w, h) : poolRegionRect(w, h);
         const RegionDisplay disp = regionDisplay(region, isBanks, g_panel.dragSourceRegion);
-        const int slot = hitTestSlot(x, y, disp.slotRects);
+        const RECT grid = regionGridRect(region, isBanks);
+        const int gridW = grid.right - grid.left;
+        const std::vector<SlotCellRect> dropRects =
+            computeSlotRectsForDrop(disp.bank ? disp.bank->slots.maxSlot() : -1,
+                                    gridW, kGrid);
+        // Translate the drop rects to client space (matching regionDisplay's translation).
+        std::vector<SlotCellRect> dropRectsClient = dropRects;
+        for (SlotCellRect& r : dropRectsClient) { r.x += grid.left; r.y += grid.top; }
+        const int slot = hitTestSlot(x, y, dropRectsClient);
         mods.targetSlot   = slot;
         mods.slotOccupied = slot >= 0 && !disp.idAtSlot(slot).empty();
         g_panel.dragTargetSlot = slot;

src/card_drag.cpp

@@ -73,6 +73,16 @@ std::vector<SlotCellRect> computeSlotRects(int maxSlot, int panelWidth,
     return rects;
 }
 
+std::vector<SlotCellRect> computeSlotRectsForDrop(int maxSlot, int panelWidth,
+                                                   const GridSpec& spec) {
+    const int cols = columnsForWidth(panelWidth, spec);
+    // One trailing row of slots past the last occupied slot — the drop-target extension.
+    // When maxSlot < 0 (empty bank) the trailing row begins at slot 0.
+    const int firstTrailing = maxSlot + 1;
+    const int newMax = firstTrailing + cols - 1;  // fills one full trailing row
+    return computeSlotRects(newMax, panelWidth, spec);
+}
+
 int hitTestSlot(int px, int py, const std::vector<SlotCellRect>& rects) {
     for (const SlotCellRect& r : rects) {
         // Half-open bounds so adjacent rects never both claim a pixel.

src/card_drag.h

@@ -128,6 +128,16 @@ struct SlotCellRect {
 std::vector<SlotCellRect> computeSlotRects(int maxSlot, int panelWidth,
                                            const GridSpec& spec);
 
+// Like computeSlotRects but extends one full trailing row of slots beyond maxSlot so a
+// drop pointer past the last occupied card still resolves to a valid target slot. The
+// trailing slots (maxSlot+1 .. maxSlot+cols) are empty — a drop on any of them calls
+// reorderSample with that slot index, which places the card there directly (no shift,
+// because the slot is empty). Used ONLY for drop hit-testing; the draw path uses
+// computeSlotRects (no trailing ghost row in the visual).
+// When maxSlot < 0 the trailing row starts at slot 0 (same as a fresh bank with no cards).
+std::vector<SlotCellRect> computeSlotRectsForDrop(int maxSlot, int panelWidth,
+                                                   const GridSpec& spec);
+
 // Hit-tests a point against slot rects (half-open bounds, matching hitTestCell). Returns
 // the SLOT index (rect.slot) of the first rect containing the point, or -1 on a miss (gap,
 // margin, below the last row). NOTE the return is the slot index, NOT the vector index —