Design View: drop the undo blocks around writes that mint nothing; the membership actions own theirs

Flag writes are silent from a timer, so a block around a reapply or the reconcile
repair could only manufacture a point. The real switch's span is unchanged.

src/shell/view/view_reconcile.cpp

@@ -14,8 +14,6 @@
 #define REAPERAPI_MINIMAL
 #define REAPERAPI_WANT_EnumProjects
 #define REAPERAPI_WANT_TrackList_AdjustWindows
-#define REAPERAPI_WANT_Undo_BeginBlock2
-#define REAPERAPI_WANT_Undo_EndBlock2
 #define REAPERAPI_WANT_UpdateArrange
 #define REAPERAPI_WANT_ValidatePtr2
 #include "reaper_plugin_functions.h"
@@ -58,8 +56,11 @@ void reconcileAppliedFlags(ViewModeModel& model, ReaProject* proj) {
     readFolderEntries(project, handleByGuid);
     const TrackByGuid trackByGuid = indexHandles(handleByGuid);
 
+    // NO undo block, deliberately: this runs in the wake of a Ctrl-Z, and the flag
+    // writes below mint nothing on their own — a block could only manufacture the point
+    // that would become the thing the user's next Ctrl-Z undoes. Do not reintroduce one
+    // (see this directory's CLAUDE.md).
     bool wrote = false;
-    Undo_BeginBlock2(project);
     {
         UiRefreshHold uiHold;
         for (const TrackFlagOp& op : result.ops) {
@@ -69,7 +70,6 @@ void reconcileAppliedFlags(ViewModeModel& model, ReaProject* proj) {
                 wrote = true;
         }
     }
-    Undo_EndBlock2(project, "", 0);  // discard form — see the header
 
     if (wrote) {
         TrackList_AdjustWindows(false);  // tracks reappearing owe the full relayout