fix(view): park untagged leaves in non-Arrange modes; refresh TCP/MCP on apply

planToggle now enumerates all leaves in the FolderTree instead of only tagged
membership entries, so untagged (Arrange-member) tracks park in Design and
restore in Arrange. applyMode calls TrackList_AdjustWindows + UpdateArrange so
changes render immediately. Correct the stale "tagged-only" invariant comments.

src/view.cpp

@@ -27,6 +27,8 @@
 #define REAPERAPI_WANT_TrackFX_SetOffline
 #define REAPERAPI_WANT_Undo_BeginBlock2
 #define REAPERAPI_WANT_Undo_EndBlock2
+#define REAPERAPI_WANT_TrackList_AdjustWindows
+#define REAPERAPI_WANT_UpdateArrange
 #include "reaper_plugin_functions.h"
 
 namespace reasampler {
@@ -191,6 +193,14 @@ bool applyMode(ViewModeModel& model, const std::string& targetModeId, ReaProject
 
     model.setActiveMode(targetModeId);
 
+    // Force REAPER to rebuild the TCP + MCP so visibility/park changes appear now,
+    // not on the user's next TCP interaction. TrackList_AdjustWindows(false) does the
+    // major (full) relayout required when tracks appear/disappear from the panels;
+    // UpdateArrange() repaints the arrange view. Both are documented for exactly this
+    // "you changed track-info flags, now refresh the panels" case.
+    TrackList_AdjustWindows(false);
+    UpdateArrange();
+
     Undo_EndBlock2(proj, "ReaSampler: apply Design View mode", -1);
     return true;
 }

src/view.h

@@ -15,8 +15,10 @@
 //   * Never touches the master track's visibility (SDK forbids B_SHOWINTCP/
 //     B_SHOWINMIXER on master); the master is never a node in the tree.
 //   * Never reads or writes B_MUTE / I_SOLO on any track.
-//   * Acts only on tracks the model owns (tagged leaves the planner names) plus
-//     derived parents' visibility — never an untagged track's owned flags.
+//   * Manages ALL leaves via the mode system: an untagged leaf is an Arrange member,
+//     so it is fully parked in non-Arrange modes and restored in Arrange, identically
+//     to a tagged leaf. show-both is the always-visible escape; parents are
+//     visibility-only (derived); the master is never touched.
 //   * Snapshots every to-be-parked track's prior flags BEFORE parking, storing
 //     them into the model so restore is faithful and survives a save-while-parked.
 

src/view_mode_model.cpp

@@ -204,15 +204,18 @@ std::set<std::string> ViewModeModel::visibleTracks(const FolderTree& tree,
 TogglePlan ViewModeModel::planToggle(const FolderTree& tree, const std::string& targetMode) const {
     TogglePlan plan;
 
-    // Index the tree so we can classify each tagged GUID (leaf vs parent vs stale).
-    std::map<std::string, const FolderNode*> byGuid;
-    for (const auto& node : tree.nodes) byGuid[node.guid] = &node;
-
-    for (const auto& [guid, m] : membership_.all()) {
-        auto it = byGuid.find(guid);
-        if (it == byGuid.end()) continue;        // stale GUID: prune-safe, ignore
-        if (it->second->isParent) continue;      // parents are derived, never parked
-        if (m.showBoth) continue;                // show-both leaves are never parked
+    // The mode system manages EVERY leaf, not just tagged ones. An untagged leaf is
+    // an Arrange member (leafBelongsToMode resolves that), so it must park when the
+    // target mode is not Arrange and restore when it is — the same full park/restore
+    // a tagged leaf gets. Enumerating the FolderTree (not membership_.all()) is what
+    // brings untagged leaves — which are absent from the membership index — under
+    // management. Parents are visibility-only (handled by visibleTracks + the shell's
+    // parent-visibility pass) and show-both leaves are the always-visible escape;
+    // neither is ever parked.
+    for (const auto& node : tree.nodes) {
+        if (node.isParent) continue;             // parents are derived, never parked
+        const std::string& guid = node.guid;
+        if (membership_.isShowBoth(guid)) continue;  // show-both leaves are never parked
 
         const bool active = leafBelongsToMode(guid, targetMode);
         if (active) {
@@ -221,10 +224,11 @@ TogglePlan ViewModeModel::planToggle(const FolderTree& tree, const std::string&
             if (const TrackSnapshot* snap = snapshot(guid))
                 plan.restore.push_back(makeRestorePlan(guid, *snap));
         } else {
-            // Inactive tagged leaf ⇒ park. fxOffline is intentionally empty here:
-            // the D2 shell expands per-FX offline writes using TrackFX_GetCount.
-            // The pure model has no access to REAPER FX counts at plan time;
-            // makeParkPlan(guid, 0) emits only the scalar flags as a result.
+            // Inactive leaf (tagged into another mode, or untagged in a non-Arrange
+            // mode) ⇒ park. fxOffline is intentionally empty here: the D2 shell
+            // expands per-FX offline writes using TrackFX_GetCount. The pure model
+            // has no access to REAPER FX counts at plan time; makeParkPlan(guid, 0)
+            // emits only the scalar flags as a result.
             plan.park.push_back(makeParkPlan(guid, /*fxCount=*/0));
         }
     }

src/view_mode_model.h

@@ -232,8 +232,9 @@ struct TrackPlan {
 // The plan for a whole toggle to a target mode: which tracks to park, and which to
 // restore from their snapshots. Parents and show-both leaves never appear here —
 // they are derived-visible and never parked (visibility is answered separately by
-// visibleTracks). Untagged tracks never appear either (the tool owns only what it
-// tagged).
+// visibleTracks). Untagged LEAVES DO appear: an untagged leaf is an Arrange member,
+// so it parks in every non-Arrange mode and restores in Arrange — the mode system
+// manages all leaves, not only tagged ones.
 struct TogglePlan {
     std::vector<TrackPlan> park;     // inactive leaves -> parked (fixed zeros)
     std::vector<TrackPlan> restore;  // active leaves returning -> snapshot values
@@ -278,11 +279,14 @@ public:
     std::set<std::string> visibleTracks(const FolderTree& tree,
                                         const std::string& modeId) const;
 
-    // Plans a toggle to `targetMode` against the current tree. Inactive tagged
-    // leaves (not show-both, not derived-visible-only) are parked with fixed zeros;
-    // leaves that become active AND have a stored snapshot are restored from it.
-    // Parents, show-both leaves, the master, and untagged tracks are never parked.
-    // Unknown/stale membership GUIDs absent from the tree are ignored (prune-safe).
+    // Plans a toggle to `targetMode` by enumerating EVERY leaf in the supplied tree.
+    // A leaf inactive in the target mode — tagged into another mode, or untagged and
+    // the target isn't Arrange — is parked with fixed zeros; a leaf that becomes
+    // active AND has a stored snapshot is restored from it. Parents (visibility-only)
+    // and show-both leaves (always visible) are never parked; the master is not in
+    // the tree. Untagged leaves ARE managed: they are Arrange members, so they park
+    // in non-Arrange modes and restore in Arrange. Tree membership is the enumeration
+    // source, so stale membership GUIDs absent from the tree are naturally ignored.
     //
     // Note: park plans emitted here have an empty fxOffline vector. The D2 shell
     // expands per-FX offline writes using TrackFX_GetCount — the pure model has no

tests/test_view_mode_model.cpp

@@ -383,6 +383,92 @@ static void testPlanToggleParkHasEmptyFxOffline() {
     CHECK(plan.park[0].flags.size() == 4);
 }
 
+// -- 7b. Untagged leaves are managed by the mode system ----------------------
+//
+// The core semantic fix: an untagged leaf is an Arrange member. planToggle must
+// enumerate EVERY leaf in the tree (not just membership_.all()), so an untagged
+// leaf — absent from the membership index — parks in every non-Arrange mode and
+// restores in Arrange, identically to a tagged leaf. Parents and show-both leaves
+// remain never-parked. Tagged-leaf behavior is unchanged.
+
+static void testUntaggedLeavesManagedByModeSystem() {
+    ViewModeModel vm;
+
+    // A tree of leaves NONE of which are in the membership index (all untagged),
+    // plus a parent folder and a show-both leaf to prove they stay untouched.
+    FolderTree tree;
+    tree.nodes.push_back(FolderNode{"{P}", "", /*isParent=*/true});
+    tree.nodes.push_back(FolderNode{"{U1}", "{P}", false});  // untagged leaf
+    tree.nodes.push_back(FolderNode{"{U2}", "{P}", false});  // untagged leaf
+    tree.nodes.push_back(FolderNode{"{SB}", "", false});     // show-both leaf
+    vm.membership().setShowBoth("{SB}", true);
+
+    // (iii) Enumeration covers leaves absent from the membership index: {U1}/{U2}
+    // are NOT in membership_.all(), yet the planner reaches them.
+    CHECK(vm.membership().query("{U1}") == nullptr);
+    CHECK(vm.membership().query("{U2}") == nullptr);
+
+    // (i) Toggling to Design (non-Arrange): every untagged leaf is parked.
+    auto toDesign = vm.planToggle(tree, kDesignModeId);
+    CHECK(parkTargets(toDesign, "{U1}"));
+    CHECK(parkTargets(toDesign, "{U2}"));
+
+    // (iv) The parent and the show-both leaf are NEVER parked, in either mode.
+    CHECK(!parkTargets(toDesign, "{P}"));
+    CHECK(!parkTargets(toDesign, "{SB}"));
+
+    // (ii) Toggling to Arrange: the untagged leaves are Arrange members ⇒ active and
+    // NOT parked. (No snapshot stored yet ⇒ no restore op either; just not parked.)
+    auto toArrange = vm.planToggle(tree, kArrangeModeId);
+    CHECK(!parkTargets(toArrange, "{U1}"));
+    CHECK(!parkTargets(toArrange, "{U2}"));
+    CHECK(restoreFor(toArrange, "{U1}") == nullptr);
+    CHECK(!parkTargets(toArrange, "{P}"));
+    CHECK(!parkTargets(toArrange, "{SB}"));
+
+    // (vi) Restore-from-snapshot fidelity for a previously-parked UNTAGGED leaf:
+    // an untagged leaf parked while in Design carries a snapshot; toggling back to
+    // Arrange restores it from that snapshot verbatim, never a hardcoded default.
+    TrackSnapshot snap;
+    snap.showInTcp = 1; snap.showInMixer = 1; snap.mainSend = 0; snap.fxEnable = 1;
+    snap.fxOffline = {0, 1};
+    vm.storeSnapshot("{U1}", snap);  // as the shell would, before parking it in Design
+    auto backToArrange = vm.planToggle(tree, kArrangeModeId);
+    const TrackPlan* r = restoreFor(backToArrange, "{U1}");
+    CHECK(r != nullptr);
+    if (r) {
+        CHECK(flagValue(*r, Flag::ShowInTcp) == 1);
+        CHECK(flagValue(*r, Flag::ShowInMixer) == 1);
+        CHECK(flagValue(*r, Flag::MainSend) == 0);   // captured 0 comes back 0
+        CHECK(flagValue(*r, Flag::FxEnable) == 1);
+        CHECK(r->fxOffline.size() == 2);
+        CHECK(r->fxOffline[0].offline == false);
+        CHECK(r->fxOffline[1].offline == true);
+    }
+}
+
+// (v) Tagged-leaf park/restore behavior is unchanged after the untagged fix: a leaf
+// tagged Design parks in Arrange and is active (not parked) in Design, and a mix of
+// tagged + untagged leaves each land on the correct side of the toggle.
+
+static void testTaggedLeafBehaviorUnchangedWithUntagged() {
+    ViewModeModel vm;
+    FolderTree tree;
+    tree.nodes.push_back(FolderNode{"{DES}", "", false});  // tagged into Design
+    tree.nodes.push_back(FolderNode{"{UNT}", "", false});  // untagged ⇒ Arrange
+    vm.membership().tag("{DES}", kDesignModeId);
+
+    // In Design: {DES} active (not parked); {UNT} inactive ⇒ parked.
+    auto design = vm.planToggle(tree, kDesignModeId);
+    CHECK(!parkTargets(design, "{DES}"));
+    CHECK(parkTargets(design, "{UNT}"));
+
+    // In Arrange: {DES} inactive ⇒ parked; {UNT} active (not parked).
+    auto arrange = vm.planToggle(tree, kArrangeModeId);
+    CHECK(parkTargets(arrange, "{DES}"));
+    CHECK(!parkTargets(arrange, "{UNT}"));
+}
+
 // -- 8. nextModeId cycle (D4 toggle helper) ----------------------------------
 
 static void testNextModeIdCycles() {
@@ -417,6 +503,8 @@ int main() {
     testEmptyModelRoundTrip();
     testMalformedJson();
     testPlanToggleParkHasEmptyFxOffline();
+    testUntaggedLeavesManagedByModeSystem();
+    testTaggedLeafBehaviorUnchangedWithUntagged();
     testNextModeIdCycles();
 
     if (g_fail == 0) std::printf("All tests passed.\n");