fix(view): redraw arrange when inserted item lands on already-split lane

An item inserted onto an already-split folder in Design mode sat on the
correct lane but stayed invisible until a manual toggle: mintManagedLanes
returned on the idempotent no-op path before its UpdateArrange call. Force
the redraw there so the item appears immediately.

src/view.cpp

@@ -595,11 +595,25 @@ bool mintManagedLanes(ViewModeModel& model, ReaProject* proj) {
     const bool changed = applyMintPlan(model, plan, handleByGuid);
 
     if (!changed) {
-        // The plan was non-empty but every write was already satisfied (idempotent
-        // re-run: lanes exist, items already assigned, ownership already recorded). Close
-        // the block with no description so REAPER discards the empty undo point rather
-        // than flooding history with a no-change entry every detection tick.
+        // The plan was non-empty but every REAPER write was already satisfied. Close the
+        // block with no description so REAPER discards the empty undo point rather than
+        // flooding history with a no-change entry every detection tick.
         Undo_EndBlock2(proj, "", 0);
+
+        // BUT the arrange still needs a redraw. On the detect-tick caller (bankPanelRefresh)
+        // mintManagedLanes runs only when this tick just tagged new content, and a NON-EMPTY
+        // plan means that content sits on a managed-split track. The idempotent no-op path is
+        // reached when a freshly-inserted item ALREADY landed on the active mode's playing
+        // lane (REAPER places a new item on the playing lane; the active mode's lane IS the
+        // playing lane, so assignItemToLane sees I_FIXEDLANE unchanged and writes nothing).
+        // The item is correctly placed and confined, but the arrange was never told to
+        // repaint it onto the lane — so it stayed invisible until a manual mode toggle forced
+        // applyMode's refresh. Force the redraw here so the item appears immediately without a
+        // toggle. UpdateArrange() only repaints (no I_FREEMODE transition happened on this
+        // path, so UpdateTimeline is not owed); it is NOT a project mutation, so it stays
+        // outside the undo block and adds no history entry. On the action caller (doMoveItems)
+        // this is a harmless repaint immediately before its own reapplyActiveMode() refresh.
+        UpdateArrange();
         return false;
     }