Make Design View membership edits undoable: the view_state write moves inside the block

All four actions share one body; the point turns on a model diff, so a no-op leaves history and the Undo button alone. The Save-As prompt stays outside.
2026-08-07 19:51:37 -04:00
parent 20fef2a3bf
commit d5ff476a19
7 changed files with 177 additions and 132 deletions
@@ -36,6 +36,18 @@ is owned by other directories and only skinned here.
  reclaim span is open; the mechanism and its compile-time enforcement are
  `src/shell/undo/CLAUDE.md`'s. Bank index verbs additionally stay one batched
  `UNDO_STATE_MISCCFG` point apiece, so one bank operation is one Ctrl-Z.
+- **A Design View membership edit's undo point holds its `view_state` write — so the
+  persist runs INSIDE the block, and the point turns on a MODEL DIFF, not on "REAPER
+  was written to".** All four membership actions (tag, untag / tag→Arrange, show-both,
+  the item moves) share one body, `design_view_actions`' `runMembershipEdit`.
+  Everything the reapply they drive writes is the four driven track flags, which mint
+  no undo state at all (`src/shell/view/CLAUDE.md`), so a point closed BEFORE the
+  ext-state write covered no change: the edit was not undoable and rode whatever point
+  the user's next act minted. Two consequences bind. The persist's modal Save-As half
+  is split off and runs before the block opens — a modal may not hold a block open.
+  And a no-op edit records no label, because a recorded label re-titles the Undo button
+  whether or not REAPER appends an entry. Same shape as `shell/bank_ops`'
+  `persistBankOp`, for the same reason.
 - **The prune action is the ONLY file-deletion action in the system**; it opens no
  undo point (file deletion is not REAPER-undoable). It halts on
  `blockedByTracking` and prints whichever blockers fired — the malformed ledger,
@@ -104,16 +104,13 @@ std::vector<std::string> selectedTrackGuids() {
 }

 // Reapplies the CURRENT active mode so a membership mutation takes visible effect
-// immediately (park/unpark/re-derive parents), answering whether it wrote any project
-// state — the caller's block mints only if something did. `applied` is deliberately
-// discarded: a refused reapply leaves the membership edit standing and unapplied, and
-// the user's next edit or mode switch reapplies it (a refusal writes nothing, so it
-// reports false here and the block discards). What must NOT be dropped with it is the
+// immediately (park/unpark/re-derive parents). `applied` is deliberately discarded: a
+// refused reapply leaves the membership edit standing and unapplied, and the user's
+// next edit or mode switch reapplies it. What must NOT be dropped with it is the
 // reclaimer's queue, which is why applyMode invalidates on its refusal path too
 // (view.cpp).
-bool reapplyActiveMode() {
-    return applyMode(g_session->view(), g_session->view().activeModeId(), nullptr)
-        .wroteProjectState;
+void reapplyActiveMode() {
+    applyMode(g_session->view(), g_session->view().activeModeId(), nullptr);
 }

 constexpr int kFreeModeFixedLanes = 2;  // I_FREEMODE value; mirrors the shell's constant
@@ -147,33 +144,45 @@ std::vector<RetagItem> selectedRetagItems() {
 // serialization. Every other action keeps the full save.
 enum class PersistScope { Full, ViewOnly };

-// Persists the bank + Design-View model after every state-changing action so the
-// view model is not lost across save/close/reopen. If membership is non-empty and
-// the project is unsaved, prompts Save-As first (mirrors the flow capture uses) —
-// DAW-ONLY: Main_SaveProject(proj, true) blocks until the dialog is dismissed.
-void persistViewState(PersistScope scope) {
-    if (!g_session->view().membership().empty()) {
+// The persist's MODAL half, split from the write below so a caller can run the two on
+// opposite sides of an undo block. If membership is non-empty and the project is
+// unsaved, prompts Save-As (mirrors the flow capture uses) — DAW-ONLY:
+// Main_SaveProject(proj, true) blocks until the dialog is dismissed. False means the
+// user declined and nothing may be written.
+bool ensurePersistTarget() {
+    if (g_session->view().membership().empty()) return true;
+
    ReaProject* proj = EnumProjects(-1, nullptr, 0);
-        if (proj) {
+    if (!proj) return true;  // no active project — the write below no-ops on its own
+
    auto readRppPath = [&]() -> std::string {
        std::vector<char> buf(4096, '\0');
        EnumProjects(-1, buf.data(), static_cast<int>(buf.size()));
        return std::string(buf.data());
    };

-            if (readRppPath().empty()) {
+    if (!readRppPath().empty()) return true;
+
    Main_SaveProject(proj, true);
-                if (readRppPath().empty()) {  // still empty -> user cancelled
-                    ShowConsoleMsg(
-                        "ReaSampler: Design View state will not persist until "
+    if (!readRppPath().empty()) return true;  // still empty -> user cancelled
+
+    ShowConsoleMsg("ReaSampler: Design View state will not persist until "
                   "the project is saved.\n");
-                    return;
+    return false;
 }
+
+// The persist's WRITE half: the bank + Design-View model, so neither is lost across
+// save/close/reopen. Returns whether the write was ISSUED — false means no active
+// project or an unsaved one, with NOTHING written (session.h owns that contract), which
+// is the only reading a caller may turn into a discarded undo point.
+bool writePersistedState(PersistScope scope) {
+    return scope == PersistScope::ViewOnly ? g_session->saveViewStateOnly()
+                                           : g_session->saveToActiveProject();
 }
-        }
-    }
-    if (scope == PersistScope::ViewOnly) g_session->saveViewStateOnly();
-    else                                 g_session->saveToActiveProject();
+
+// The two halves as a caller holding no undo block runs them.
+void persistViewState(PersistScope scope) {
+    if (ensurePersistTarget()) writePersistedState(scope);
 }

 // The footer segment already reads disabled while the transport runs, but an action can
@@ -211,17 +220,53 @@ void doActivateMode(const std::string& modeId) {
    bankPanelInvalidate();  // repaint the footer [Arrange|Design] toggle immediately
 }

-// The block each membership-edit action below owns. The reapply they drive opens none
-// of its own — nothing it writes mints a point unaided — so a user-fired tag stays one
-// Ctrl-Z only because the ACTION spans it, and the label names the act the user
-// actually fired rather than the reapply it happened to trigger. Every one of them
-// closes the block before persistViewState, which can pop a modal Save-As.
+// The drive half of a membership edit: what runs inside the block, answering whether
+// it made a project change of its own that a point must hold even with nothing
+// persisted. The reapply alone never does — everything it writes is the four driven
+// flags, which mint no undo state (src/shell/view/CLAUDE.md).
+bool driveReapply() {
+    reapplyActiveMode();
+    return false;
+}
+
+// The item moves' drive: re-drive the same minting/apply path auto-tag uses — mint or
+// split lanes for any track whose items now span modes, then reassert active-mode lane
+// visibility. A mint moves items between lanes, which is a real project change whether
+// or not the persist below lands.
+bool driveMintLanesAndReapply() {
+    const bool minted = mintManagedLanes(g_session->view(), nullptr);
+    reapplyActiveMode();
+    return minted;
+}
+
+// The ONE body behind all four membership edits (this directory's CLAUDE.md owns the
+// rule; what follows is why the ORDER is what it is). `mutate` is a pure model edit —
+// nothing in it reaches REAPER.
 //
-// The point is recorded only where the reapply actually wrote: re-tagging tracks that
-// already sit in that mode writes nothing to the project, and the ("", 0) discard form
-// UndoBlock closes on by default is real from a hand-fired action (DAW-measured,
-// src/shell/view/CLAUDE.md). The membership move itself is never in the point either
-// way — persistViewState runs after the close.
+// The prompt sits between the edit and the block because it is pinned on both sides:
+// its condition reads the POST-edit membership (a first-ever tag on an unsaved project
+// must still prompt), and a modal may not stand inside an open block. The persist then
+// runs INSIDE, being the only thing here a point can hold; a re-tag of tracks already
+// in that mode re-writes byte-identical ext state, which is why the label turns on the
+// model diff and not on the write.
+template <class Mutate>
+void runMembershipEdit(Mutate&& mutate, bool (*drive)(), const std::string& label,
+                       int mask) {
+    const MembershipIndex before = g_session->view().membership();
+    mutate();
+    const bool changed = !(g_session->view().membership() == before);
+
+    const bool persistable = ensurePersistTarget();
+
+    UndoBlock undo(nullptr);
+    const bool structural = drive();
+    const bool persisted  = persistable && writePersistedState(PersistScope::Full);
+    if (structural || (changed && persisted))
+        undo.recordPoint(label, mask);
+    // Otherwise the block closes on its ("", 0) discard form — real from a hand-fired
+    // action (DAW-measured, src/shell/view/CLAUDE.md) — leaving history and the Undo
+    // button both untouched.
+}

 // tag() replaces any prior single-mode membership (a leaf lives in one mode; the
 // cross-mode case is show-both).
@@ -229,13 +274,11 @@ void doTag(const std::string& modeId) {
    const std::vector<std::string> guids = selectedTrackGuids();
    if (guids.empty()) return;  // nothing selected — no act, no undo point (cf. doMoveItems)

-    {
-        UndoBlock undo(nullptr);
+    runMembershipEdit(
+        [&] {
            for (const std::string& g : guids) g_session->view().membership().tag(g, modeId);
-        if (reapplyActiveMode())
-            undo.recordPoint("ReaSampler: tag selected tracks -> " + modeId, kViewUndoMask);
-    }
-    persistViewState(PersistScope::Full);
+        },
+        &driveReapply, "ReaSampler: tag selected tracks -> " + modeId, kViewUndoMask);
 }

 // Shared body behind "Untag selected" and "Tag -> Arrange" — Arrange is the absence
@@ -244,13 +287,11 @@ void doUntag() {
    const std::vector<std::string> guids = selectedTrackGuids();
    if (guids.empty()) return;

-    {
-        UndoBlock undo(nullptr);
+    runMembershipEdit(
+        [&] {
            for (const std::string& g : guids) g_session->view().membership().untag(g);
-        if (reapplyActiveMode())
-            undo.recordPoint("ReaSampler: untag selected tracks", kViewUndoMask);
-    }
-    persistViewState(PersistScope::Full);
+        },
+        &driveReapply, "ReaSampler: untag selected tracks", kViewUndoMask);
 }

 // Flips each track's pin independently — the honest semantics of a toggle on a
@@ -259,14 +300,12 @@ void doShowBoth() {
    const std::vector<std::string> guids = selectedTrackGuids();
    if (guids.empty()) return;

-    {
-        UndoBlock undo(nullptr);
+    runMembershipEdit(
+        [&] {
            MembershipIndex& m = g_session->view().membership();
            for (const std::string& g : guids) m.setShowBoth(g, !m.isShowBoth(g));
-        if (reapplyActiveMode())
-            undo.recordPoint("ReaSampler: toggle show-both on selected tracks", kViewUndoMask);
-    }
-    persistViewState(PersistScope::Full);
+        },
+        &driveReapply, "ReaSampler: toggle show-both on selected tracks", kViewUndoMask);
 }

 // Retag the current ITEM selection to `targetMode` (empty => untag -> Arrange
@@ -281,30 +320,20 @@ void doMoveItems(const std::string& targetMode) {
    const std::vector<ItemRetagOp> ops = planItemRetag(selected, targetMode);
    if (ops.empty()) return;  // nothing selected, or every selected item was exempt/empty

+    runMembershipEdit(
+        [&] {
            MembershipIndex& membership = g_session->view().membership();
-
-    {
-        UndoBlock undo(nullptr);
            for (const ItemRetagOp& op : ops) {
                if (op.untag) membership.untag(op.guid);
                else          membership.tag(op.guid, op.modeId);
            }
-        // Re-drive the same minting/apply path auto-tag uses: mint/split lanes for any
-        // track whose items now span modes, then reassert active-mode lane visibility.
-        // Either half writing is enough to mint; a retag that split no lanes and drove
-        // no flag leaves nothing for a point to hold.
-        const bool minted    = mintManagedLanes(g_session->view(), nullptr);
-        const bool reapplied = reapplyActiveMode();
-        if (minted || reapplied)
-            undo.recordPoint(targetMode.empty()
-                                 ? std::string("ReaSampler: untag selected items")
+        },
+        &driveMintLanesAndReapply,
+        targetMode.empty() ? std::string("ReaSampler: untag selected items")
                           : "ReaSampler: move selected items -> " + targetMode,
        -1);
 }

-    persistViewState(PersistScope::Full);
-}
-
 }  // namespace

 void designViewRegisterActions(reaper_plugin_info_t* rec, ReaSamplerSession* session) {
@@ -94,14 +94,18 @@ decide membership or mode rules.
  because a block there could only manufacture the point a project open or a membership
  edit must not cost. This is why the same `I_FREEMODE` write is blocked at one site and
  not the other: minting SPLITS a track, `applyLaneOps` only re-states which lane plays.
-  Second clause, binding every site that does open one: **a block that wrote nothing
-  closes on the discard form** (`Undo_EndBlock2(proj, "", 0)` — real from a hand-fired
-  action, per the measurement above), so re-tagging tracks already in that mode leaves
-  no empty point. The one exception is a REAL SWITCH, which mints written state or not:
-  it is an explicitly fired action and has to stay undoable even where the plan found
-  nothing to write. "Wrote" means a REAPER write throughout — model moves persist
-  through `persistViewState`, outside every block, so no point could carry them
-  (`ModeApplyResult`, `view.h`).
+  Second clause, binding every site that does open one: **a block with nothing REAPER
+  can hold closes on the discard form** (`Undo_EndBlock2(proj, "", 0)` — real from a
+  hand-fired action, per the measurement above), so re-tagging tracks already in that
+  mode leaves no empty point and no relabelled Undo button. The one exception is a REAL
+  SWITCH, which mints written state or not: it is an explicitly fired action and has to
+  stay undoable even where the plan found nothing to write. "Nothing REAPER can hold" is
+  NOT "no REAPER write", and reading it that way was a shipped defect: the four driven
+  flags ARE a REAPER write and mint nothing, so a site predicated on writes names points
+  REAPER then declines to append — history unchanged, Undo button relabelled. What a
+  membership edit's point holds is its `view_state` write, which is why that write is
+  INSIDE the block and the predicate is the model diff
+  (`shell/actions/design_view_actions`' `runMembershipEdit`).
 - **ONE mode switch is ONE undo point — the background FX parking included.** The
  driven flags, the lane state, AND the per-FX offline/online the reclaimer writes
  minutes-of-plugin-loads later all roll back in a single Ctrl-Z, because they share
@@ -222,8 +226,9 @@ decide membership or mode rules.
  `render_in_place`'s inner reapply. The open half is the criterion above (a reapply
  re-asserts derived state and is nobody's act); the close half is the nesting rule
  above (a reapply runs inside its driver's block, so a supersede-close from there
-  would land at depth 2->1 and hijack it). It reports what it wrote instead, and the
-  driver holding the block decides — `ModeApplyResult::wroteProjectState`.
+  would land at depth 2->1 and hijack it). It reports only whether it `applied`; a
+  driver holding a block decides its point from its OWN model diff, never from what the
+  reapply wrote, and `ModeApplyResult` no longer offers that answer to be misread.
 - **A rapid A→B→A flip moves zero plugins.** The reclaimer only starts a park's
  OFFLINE work once a track has read continuously parked for `kParkHoldMs`
  (3000ms). A flip inside that window flips the flags twice but the debounce
@@ -289,7 +294,7 @@ applies the resulting lane state to live tracks.

 ## Modules

- `view` — Design View shell: runs the pure planner over the live folder tree and iterates its park/restore plans, applies managed-lane and parent-visibility writes, and on a REAL SWITCH ends any prior span, raises the reclaimer's wakeup, and opens the ONE undo span all of that rides (`fx_reclaim` is what closes it; a reapply opens none and closes none). Reports what it wrote (`ModeApplyResult`) so a caller holding its own block can discard an empty point. Owns the one discriminator (`target != active`) that separates a real switch from a reapply, and with it both the playback gate (`transportBlocksModeSwitch`) and the solo cache/clear/restore seams. **Never touches master or `B_MUTE`.** FX are NOT written here — see `fx_reclaim`.
+- `view` — Design View shell: runs the pure planner over the live folder tree and iterates its park/restore plans, applies managed-lane and parent-visibility writes, and on a REAL SWITCH ends any prior span, raises the reclaimer's wakeup, and opens the ONE undo span all of that rides (`fx_reclaim` is what closes it; a reapply opens none and closes none). Reports whether it applied and nothing else (`ModeApplyResult`) — what it wrote is deliberately not an answer it gives, because none of it mints. Owns the one discriminator (`target != active`) that separates a real switch from a reapply, and with it both the playback gate (`transportBlocksModeSwitch`) and the solo cache/clear/restore seams. **Never touches master or `B_MUTE`.** FX are NOT written here — see `fx_reclaim`.
 - `view_park` — the park surface, FLAG DOMAIN ONLY. `parkTrack` captures the pre-park snapshot (flags AND the FX chain's identity-keyed offline state) when the model holds none, drives the four flags, and EXPOSEs a track that reads park-shaped with no record behind it rather than adopting it; `restoreTrack` writes the flags back from the snapshot and spends its flag half (`releaseSnapshotFlags`). Also `trackFlagParm` (the one `Flag` → REAPER-parameter mapping), `writeIfChanged` (the read-before-write every driven parameter goes through), `fxGuidString` (the one FX-identity read snapshot/reclaim both address FX through), `kViewUndoMask`, and `reportExposedTracks`/`describeExposedTracks` (named tracks, once per changed set per project).
 - `view_lanes` — managed fixed lanes: `mintManagedLanes` splits multi-mode content onto per-mode lanes, `applyLaneOps` drives `C_LANEPLAYS` for the active mode, `reconcileManagedLanes` recovers ownership from durable `P_LANENAME` on project open. Manual lanes are never minted, driven, renamed or reassigned.
 - `view_reconcile` — the repair pass for a project state REAPER reloaded under us: `noteAppliedState` records what an apply left driven; `reconcileAppliedFlags` diffs that fingerprint against the reloaded model and hands back any track the reload no longer records but still reads driven — the fix for `UNDO_STATE_TRACKCFG` not carrying `B_SHOWINTCP`/`B_SHOWINMIXER` (DAW-confirmed). It opens no undo block: it runs in the wake of a Ctrl-Z, and its writes are flags only.
@@ -339,10 +344,11 @@ applies the resulting lane state to live tracks.
  unsaved project — land inside the block after all. That is a consequence of the
  span, not a decision made here; it does not resolve the redo hypothesis below,
  which turns on capture-time semantics the SDK does not document. `[verify — DAW]`
-  that a Save-As dialog opening under an open undo block is harmless. On the reapply
-  path the write stays OUTSIDE every block, as it always did: the reapply opens none,
-  and a membership action's own `ActionUndoBlock` closes before `persistViewState` for
-  exactly this modal-Save-As reason. The UNDO direction still comes
+  that a Save-As dialog opening under an open undo block is harmless. On the MEMBERSHIP
+  path the write is now deliberately inside the action's own `UndoBlock` — it is the
+  only thing there a point can hold — and the persist is split so its modal Save-As half
+  runs BEFORE that block opens (`shell/actions/design_view_actions`, which owns the
+  reasoning). The UNDO direction still comes
  out right — the point closed over the ext state as it stood BEFORE the switch,
  which is what a Ctrl-Z should restore — but by position, not by design. The
  REDO direction is what this leaves open, and the cost is worse than the
@@ -363,9 +369,13 @@ applies the resulting lane state to live tracks.
  semantics for the state mask; (2) that a redo fires `BeginLoadProjectState`
  with `isUndo == true` so the session really does reload the stale ext state
  (asserted in `main.cpp`, never observed). If (2) is false the in-memory model
-  keeps its snapshots and the redo is consistent. `[verify — DAW]`. Do not "fix"
-  it by moving `persistViewState` inside the block — it can open a modal Save-As;
-  whether to split the persist is a separate decision.
+  keeps its snapshots and the redo is consistent. `[verify — DAW]`. Link (1) is the
+  same capture-time reading the membership path's fix now rests on, and the nearest
+  thing to evidence for it is `reaper_plugin.h:1198-1201`: REAPER serializes an
+  extension's state for a point through `SaveExtensionConfig` with `isUndo` set — i.e.
+  at point creation, not later. Settling it by moving the SWITCH path's
+  `persistViewState` is still the wrong move: that one runs with the span open, so its
+  modal would stand inside a block nothing closes until the drain converges.
 - A DIFFERENT strand entirely, which the EXPOSE report does NOT cover: an
  absent or malformed `view_state` (`loadViewModel`, `ext_state_io.cpp`) is not
  a parked-chain reading at all — it falls back to a DEFAULT model (active mode
@@ -116,7 +116,6 @@ ModeApplyResult applyModeImpl(ViewModeModel& model, const std::string& targetMod
        (targetMode ? targetMode->displayName : targetModeId) + " view";

    bool laneModeChanged = false;
-    bool wrote = false;  // REAPER writes only — see ModeApplyResult
    std::vector<std::string> exposedNames;  // named while handles are fresh, reported after the writes

    // ONLY A REAL SWITCH, both halves — end a prior switch's still-open span, then open
@@ -155,7 +154,6 @@ ModeApplyResult applyModeImpl(ViewModeModel& model, const std::string& targetMod
            MediaTrack* tr = resolve(trackByGuid, guid);
            if (!tr) continue;  // stale/deleted GUID — prune
            const TrackParkResult r = parkTrack(model, guid, tr, tp.flags);
-            if (r.wrote) wrote = true;
            // Named here, not after the block: TrackList_AdjustWindows below can
            // invalidate the handle.
            if (r.exposed) exposedNames.push_back(trackDisplayName(tr));
@@ -166,14 +164,13 @@ ModeApplyResult applyModeImpl(ViewModeModel& model, const std::string& targetMod
            const std::string& guid = tp.flags.front().guid;
            MediaTrack* tr = resolve(trackByGuid, guid);
            if (!tr) continue;  // stale/deleted GUID — prune
-            if (restoreTrack(model, guid, tr, tp.flags)) wrote = true;
+            restoreTrack(model, guid, tr, tp.flags);
        }

        // MANAGED LANES: the active mode's lane plays+shows, every other managed lane
        // is silenced+hidden. Empty on a D1-only project — byte-identical there.
        const LaneApplyResult lanes = applyLaneOps(trackByGuid, plan.lanes);
        laneModeChanged = lanes.freeMode;
-        if (lanes.wrote) wrote = true;

        // PARENT VISIBILITY (never parked): recomputed every toggle, never recorded.
        // Only the two visibility flags — never mainSend/FX on a parent.
@@ -183,8 +180,8 @@ ModeApplyResult applyModeImpl(ViewModeModel& model, const std::string& targetMod
            MediaTrack* tr = resolve(trackByGuid, node.guid);
            if (!tr) continue;  // stale GUID — prune
            const double show = visible.count(node.guid) ? 1.0 : 0.0;
-            if (writeIfChanged(tr, "B_SHOWINTCP", show)) wrote = true;
-            if (writeIfChanged(tr, "B_SHOWINMIXER", show)) wrote = true;
+            writeIfChanged(tr, "B_SHOWINTCP", show);
+            writeIfChanged(tr, "B_SHOWINMIXER", show);
        }

        model.setActiveMode(targetModeId);
@@ -225,7 +222,7 @@ ModeApplyResult applyModeImpl(ViewModeModel& model, const std::string& targetMod
    // an undo rolling the model back underneath it. In memory, never on disk.
    noteAppliedState(project, model);

-    return ModeApplyResult{true, wrote};
+    return ModeApplyResult{true};
 }

 } // namespace
@@ -29,17 +29,16 @@ bool modeApplyInProgress();

 // What one applyMode did.
 //
-// `wroteProjectState` counts REAPER writes ONLY — a driven flag, a lane parameter,
-// a parent's visibility. Model moves (a snapshot stored, a record's flag half spent,
-// the active mode set) are deliberately excluded: they reach disk through
-// persistViewState, which every caller runs OUTSIDE its undo block, so no point can
-// carry them and counting them would only mint an empty one. It is the answer a
-// caller holding its own block needs for the discard decision (design_view_actions'
-// ActionUndoBlock); the solo pair cannot affect it, since only a real switch drives
-// solo and a real switch mints regardless.
+// Deliberately does NOT report whether it wrote project state. It once did, and a
+// caller holding its own block used that as its mint-or-discard predicate — which is
+// wrong twice over: everything a reapply writes is the four driven flags, which mint
+// no undo state at all, so the answer was true for writes REAPER will not hold and the
+// resulting label re-titled the Undo button over an entry that was never appended. What
+// a membership edit's point actually holds is its `view_state` write; the caller's own
+// model diff is what says whether there was one (design_view_actions'
+// runMembershipEdit). Do not reintroduce a wrote-project-state return here.
 struct ModeApplyResult {
    bool applied = false;
-    bool wroteProjectState = false;
 };

 // Captures each about-to-park track's prior flag values into `model`, caches/clears
@@ -15,8 +15,8 @@ class ReaProject;
 namespace reasampler {

 // `freeMode` alone decides whether UpdateTimeline is owed (SDK: required after an
-// I_FREEMODE change); `wrote` is a REAPER write, the reading ModeApplyResult
-// (view.h) carries through to the caller's undo-point decision.
+// I_FREEMODE change); `wrote` is a REAPER write and nothing more — not an undo-point
+// predicate (these writes mint no undo state), and read by nothing today.
 struct LaneApplyResult {
    bool freeMode = false;
    bool wrote    = false;
@@ -93,13 +93,11 @@ extern const int kViewUndoMask;
 // Returns whether it wrote.
 bool writeIfChanged(MediaTrack* tr, const char* parm, double value);

-// What one parkTrack call did. `wrote` is a REAPER write — a driven flag moved —
-// and nothing else: storing the snapshot is a MODEL move, and the model reaches disk
-// outside every undo block, so counting it would mint a point carrying none of it
-// (ModeApplyResult, view.h). The two readings part company on exactly one path — a
-// RE-PARK whose restore had already handed the flags back at park-shaped values, which
-// stores a fresh snapshot and writes no flag — and the REAPER reading is the one that
-// wants: nothing in the project moved, so nothing is there for a point to hold.
+// What one parkTrack call did. `wrote` is a REAPER write — a driven flag moved — and
+// nothing else; storing the snapshot is a MODEL move and does not count. It is NOT an
+// undo-point predicate and never was a sound one: the driven flags mint no undo state,
+// so no point can hold what this reports (view.h's ModeApplyResult, which used to carry
+// it up, no longer does). Nothing reads it today.
 // `exposed` is true iff this call handed the track back visible instead of parking or
 // adopting it; the caller (view.cpp) collects exposed tracks across the whole apply for
 // the one batched console report.