Strip FX writes from the Design View mode switch; split view.cpp into park/lanes/reconcile/tracks and add the record-scoped undo repair pass

src/shell/view/view.h

@@ -1,10 +1,9 @@
 #pragma once
-// REAPER-facing shell of Design View (D2): reads the live folder tree, runs
-// ViewModeModel's pure planner, and applies the resulting flag / per-FX /
-// lane writes. The .cpp is the sole REAPER-facing TU here (CLAUDE.md contract:
-// only main.cpp defines the API pointers). See src/shell/view/CLAUDE.md for
-// the enforced invariants (never touch master/mute, solo cached per mode and
-// never lost, snapshot-based restore).
+// REAPER-facing shell of Design View: reads the live folder tree, runs
+// ViewModeModel's pure planner, and applies the resulting flag / lane / parent
+// writes under ONE undo block. See src/shell/view/CLAUDE.md for the enforced
+// invariants (never touch master/mute, solo cached per mode and never lost,
+// record-based restore).
 
 #include <string>
 
@@ -25,51 +24,41 @@ 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 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 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 and the reconcile pass use 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).
+// 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;
 }
 
-// True while an applyMode call is on the stack. applyMode fails closed when re-entered
-// (its FX writes are assumed to pump the message loop, so a timer tick or an action can
-// land inside one), and this lets a caller with no fallback test BEFORE it spends a
+// True while an applyMode call is on the stack. applyMode fails closed when
+// re-entered, and this lets a caller with no fallback test BEFORE it spends a
 // one-shot signal on a call that would be refused — see main.cpp's load glue.
 bool modeApplyInProgress();
 
-// 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 — 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, if this is a real switch
-// (target != active) while the transport is running, if it is re-entered
+// Captures each about-to-park track's prior flag values into `model`, caches/clears
+// the outgoing mode's solo state and replays the incoming mode's, runs planToggle,
+// applies the park/restore flag writes plus managed-lane and parent-visibility
+// writes, then sets the active mode. ONE switch is ONE undo point; everything it
+// moved rolls back in a single Ctrl-Z.
+//
+// FX are NOT written here. Offlining a parked chain is the reclaimer's job, off this
+// path: TrackFX_SetOffline was 1897ms of a measured 1942ms switch, against 0.02ms for
+// all the flag work below. Do not reintroduce a synchronous FX write.
+//
+// Returns false (no mutation) if `targetModeId` isn't registered, if this is a real
+// switch (target != active) while the transport is running, if it is re-entered
 // (modeApplyInProgress), or if the project does not validate. A reapply (target ==
-// active) is never gated and never touches solo. `proj` == nullptr means the
-// current project, resolved ONCE and used for every call this apply makes.
+// active) is never gated and never touches solo. `proj` == nullptr means the current
+// project, resolved ONCE and used for every call this apply makes.
 bool applyMode(ViewModeModel& model, const std::string& targetModeId, ReaProject* proj);
 
-// Splits any track visible in more than one mode while carrying its own media
-// into fixed lanes (one managed lane per involved mode), assigns items, and
-// records ownership in `model`. Never touches manual lanes. Runs planLaneMinting
-// (model + tree aware); wraps the mutation in one Undo block when non-empty.
-// Returns true if any lane was minted (repaint hint). `proj` == nullptr means
-// the current project.
-bool mintManagedLanes(ViewModeModel& model, ReaProject* proj);
-
-// Recovers managed-lane ownership from durable P_LANENAME on project open —
-// self-healing, without minting/reassigning anything and without touching
-// membership. A lane without the managed prefix is left untouched (manual).
-// `proj` == nullptr means the current project.
-void reconcileManagedLanes(ViewModeModel& model, ReaProject* proj);
-
 } // namespace reasampler