Collapse a Design View mode switch to ONE undo point: FX writes run inline in applyMode's block, deferred park queue deleted

src/shell/view/view.h

@@ -23,13 +23,32 @@ namespace reasampler {
 // `nullptr` meaning the current project here is inferred by analogy, not confirmed.
 bool transportBlocksModeSwitch(ReaProject* proj);
 
+// Does one applyMode leave an undo point behind?
+//
+// A REAPPLY that wrote nothing must not: the load-tick reapply over a project
+// saved fully parked re-plans a park for every inactive leaf and finds every
+// flag and every FX already where it wants them, so a point there would mean
+// opening a project costs an undo step. `Undo_EndBlock2(proj, "", 0)` is the
+// discard form (mintManagedLanes' no-op path uses the same idiom).
+//
+// A real switch mints regardless, fail-safe: it is an explicitly fired action
+// and has to stay undoable even in the degenerate case where the plan found
+// nothing to write. Note what applyMode CANNOT see when it decides — the
+// `view_state` ext-state write lands in persistViewState, after this block has
+// closed (src/shell/view/CLAUDE.md's Gotchas).
+inline bool applyMintsUndoPoint(bool realSwitch, bool wroteAnything) {
+    return realSwitch || wroteAnything;
+}
+
 // Snapshots each about-to-park track's flags into `model`, caches/clears the
 // outgoing mode's solo state and replays the incoming mode's, runs planToggle,
-// applies park/restore writes plus parent visibility flags, then sets the active
-// mode. Wrapped in one Undo block. Returns false (no mutation) if `targetModeId`
-// isn't registered, or if this is a real switch (target != active) while the
-// transport is running. A reapply (target == active) is never gated and never
-// touches solo. `proj` == nullptr means the current project.
+// applies park/restore writes — flags AND per-FX offline, synchronously — plus
+// parent visibility flags, then sets the active mode. ONE switch is ONE undo
+// point; everything it moved rolls back in a single Ctrl-Z. Returns false (no
+// mutation) if `targetModeId` isn't registered, or if this is a real switch
+// (target != active) while the transport is running. A reapply (target ==
+// active) is never gated and never touches solo. `proj` == nullptr means the
+// current project.
 bool applyMode(ViewModeModel& model, const std::string& targetModeId, ReaProject* proj);
 
 // Splits any track visible in more than one mode while carrying its own media