Design View: no undo block may open over the reclaim span, and a reapply closes none

Every opener ends the span first, so a tag fired mid-drain no longer hijacks the
switch's point. One stated criterion governs both lane sites; no-op actions discard.

src/shell/capture/render_in_place.cpp

@@ -21,6 +21,7 @@
 #include "shell/capture/track_guid.h"            // guidString
 #include "shell/panel/panel_input.h"             // bankPanelTailSetting
 #include "shell/persist/session.h"
+#include "shell/view/fx_reclaim.h"               // fxReclaimEndUndoSpan
 #include "shell/view/view.h"                     // applyMode
 #include "shell/view/view_lanes.h"               // mintManagedLanes
 
@@ -133,6 +134,11 @@ void RunRenderTrackInPlace(ReaSamplerSession& session) {
     // visible — never to choose a tag. Both tags below are absolute.
     const std::string activeMode = session.view().activeModeId();
 
+    // A mode switch fired seconds ago has left the FX reclaimer's undo span open, and
+    // no block may open over it — mechanism in src/shell/view/CLAUDE.md. Ending it here
+    // mints the switch's point, whole, before this block exists; idempotent otherwise.
+    fxReclaimEndUndoSpan();
+
     Undo_BeginBlock2(nullptr);
 
     // flags = 0, never 1: flags&1 adds default envelopes/FX, and a default chain