Fix Wave-2 review findings: FX union on re-park, per-project reconcile memo, shared undo mask, decayed test oracle

src/shell/view/view_park.h

@@ -4,6 +4,7 @@
 // FX half is captured here (a read) but never written here; the reclaimer owns
 // every TrackFX_SetOffline, off the switch's synchronous path.
 
+#include <set>
 #include <string>
 #include <vector>
 
@@ -27,6 +28,42 @@ inline const char* trackFlagParm(Flag f) {
     return "B_SHOWINTCP";  // unreachable; keeps the compiler quiet
 }
 
+// A re-park's FX half, unioned rather than overwritten: keeps every FX identity
+// `prior` already names (the user's real pre-park state, still offline while the
+// reclaimer hasn't run) and appends whatever identity `live` sees that `prior`
+// does not — a plugin added during the restored interval, which a verbatim keep
+// of `prior` would otherwise never capture and leave stuck offline for good once
+// the reclaimer lands. Only meaningful when `prior` is Identity-keyed; a
+// Slot-keyed legacy record has no identities to union against, so parkTrack falls
+// back to trusting it verbatim instead of calling this. An empty fxGuid (REAPER
+// reported no identity) is never deduped against another empty one — it is
+// unrestorable either way, so appending it costs nothing and dedup would be a
+// coin flip.
+inline std::vector<FxOfflineState> unionFxOfflineOnRepark(
+        const std::vector<FxOfflineState>& prior, const std::vector<FxOfflineState>& live) {
+    std::vector<FxOfflineState> merged = prior;
+    std::set<std::string> named;
+    for (const FxOfflineState& fx : merged)
+        if (!fx.fxGuid.empty()) named.insert(fx.fxGuid);
+    for (const FxOfflineState& fx : live)
+        if (fx.fxGuid.empty() || named.insert(fx.fxGuid).second) merged.push_back(fx);
+    return merged;
+}
+
+// The undo-state domains both the mode-switch apply (view.cpp) and lane minting
+// (view_lanes.cpp) write: track config/routing, item lane assignment, and the
+// ext-state block (UNDO_STATE_MISCCFG covers extension state). NOT UNDO_STATE_ALL,
+// and no UNDO_STATE_FX at all — neither writer moves FX state, so carrying the
+// project's whole FX chunk on every point would cost with the plugin count for
+// nothing. One symbol, not two identically-valued constants free to diverge.
+// [verify — DAW] INFERRED, not documented: UNDO_STATE_TRACKCFG reads "track/master
+// vol/pan/routing" (reaper_plugin.h:1541) and names neither the fixed-lane
+// properties (assumed to ride UNDO_STATE_ITEMS, :1543) nor
+// B_SHOWINTCP/B_SHOWINMIXER — and for the visibility pair that inference is now
+// DISPROVEN in the DAW: REAPER's undo does not restore them, which is what
+// view_reconcile exists to repair.
+extern const int kViewUndoMask;
+
 // A track parameter written only when it is not already there. A reapply re-plans
 // every flag it already applied, so most of what it writes is a value the track
 // already holds. The read is ASSUMED cheaper than the write it elides (unmeasured);