Merge drag-out hand-off fix: keep the drag internal while the pointer is over REAPER

src/core/ui/CLAUDE.md

@@ -88,8 +88,14 @@ L7 sub-pass, 2026-07-27):
   between evaluations. That is what makes every transition reversible and what
   makes drag speed (WM_MOUSEMOVE coalescing) unable to change an outcome. Leaving
   REAPER entirely is the one irreversible transition, because the OS hand-off goes
-  modal. A first-move class lock and a drag-lifetime "cannot hand off" latch both
-  existed here and were removed — do not reintroduce either.
+  modal — so it must be PROVEN (a window-ownership test in the shell), never inferred
+  from a hit-test token REAPER could not name; an unrecognised surface *inside* REAPER
+  refuses. That proof is necessary but NOT sufficient: a plugin bridged into
+  `reaper_host*.exe` fails the process test while still being REAPER's own UI, so the
+  hand-off additionally requires REAPER's hit-test to have named nothing — a recognised
+  token can only ever veto the hand-off, never produce one. A first-move class lock and
+  a drag-lifetime "cannot hand off" latch both existed here and were removed — do not
+  reintroduce either.
 
 ## Modules
 
@@ -97,7 +103,7 @@ L7 sub-pass, 2026-07-27):
 - `bank_grid` — REAPER-free grid layout, selection, keyboard-nav, and thumbnail-cache-key logic for the docked bank panel.
 - `tab_strip` — REAPER-free scrollable tab-strip layout + hit-test for the named-banks strip.
 - `prune_button` — pure layout/hit-test for the `bank_panel` footer Prune button.
-- `drag_out` — the pure drag-out gesture law plus path-list assembly. Owns the `ReaperSurface` vocabulary (OffReaper / TrackPanel / FxSurface / FxEmbed / Arrange / Other — `core/wire/instrument_drop` classifies REAPER's info token INTO it), `decideDropClass` (surface × single-vs-multi payload → Internal / InstrumentDrop / ArrangeInsert / Refuse / OsHandoff / None), and `cueForDropClass`. **No `DropClass` means "nothing happens"**: a surface with no defined outcome for the payload resolves to `Refuse`, which the shell shows as a cursor, so "no silent no-op release" is a property of the enumeration rather than of any call site.
+- `drag_out` — the pure drag-out gesture law plus path-list assembly. Owns the `ReaperSurface` vocabulary (TrackPanel / FxSurface / FxEmbed / Arrange / Other — `core/wire/instrument_drop` classifies REAPER's info token INTO it; there is deliberately no off-REAPER member, since no token can carry that fact), `decideDropClass` (surface × single-vs-multi payload → Internal / InstrumentDrop / ArrangeInsert / Refuse / OsHandoff / None), and `cueForDropClass`. `OsHandoff` is reachable ONLY through `DropContext::pointerOffHost` — a positive window-ownership proof the shell owes the law (`drag_out_win::pointerOverHostWindow`) — AND only where REAPER's own hit-test named nothing (`Other`, no track), gated ahead of the surface switch, so neither evidence source can give a live drag away to OLE on its own. **No `DropClass` means "nothing happens"**: a surface with no defined outcome for the payload resolves to `Refuse`, which the shell shows as a cursor, so "no silent no-op release" is a property of the enumeration rather than of any call site.
 - `theme` — pure palette module: role→color mapping, REAPER-grey neutral ladder + the pastel accent system, the keyboard strip's spectral ramp, WCAG contrast-floor helpers + `compositeOver` (the effective color of a translucent fill, so alpha overlays are testable). Only the ramp's MID stop is its own constant; lo/hi are still aliases of `accent/primary`/`accent/tertiary`, so a categorical accent move CAN still reorder the ramp — `testSpectralRampLuminanceIsMonotonic` is the build-time catch, not the structure.
 - `component_geometry` — pure button/slider/list-row geometry + hover hit-test helpers.
 - `action_bar` — pure task-grouped action-bar layout/hit-test: clusters (Capture / Placement / Maintenance / Tagging / Switching).

src/core/ui/drag_out.cpp

@@ -24,10 +24,18 @@ DropClass decideDropClass(int px, int py, const PanelClientRect& client,
     if (!ctx.drag.dragging || !ctx.drag.hasArmedSamples) return DropClass::None;
     if (insideClient(px, py, client)) return DropClass::Internal;
 
-    switch (ctx.surface) {
-        case ReaperSurface::OffReaper:
+    // The ONE route to OsHandoff, ahead of the surface switch, and it needs BOTH halves. The
+    // shell's ownership proof alone is not sufficient: REAPER runs a bridged plugin's UI in a
+    // separate process, so a window failing that test can still be REAPER's own UI. A recognised
+    // token therefore VETOES the hand-off instead of producing one — a veto can only move the
+    // answer toward staying inside REAPER, so pointerOffHost remains the only member whose true
+    // value can reach OLE. An off-host point REAPER DID name falls through to that surface's own
+    // outcome below: over a bridged FX window that is the instrument drop, as it is for a native
+    // one.
+    if (ctx.pointerOffHost && ctx.surface == ReaperSurface::Other && !ctx.haveTrack)
         return DropClass::OsHandoff;
 
+    switch (ctx.surface) {
         case ReaperSurface::TrackPanel:
         case ReaperSurface::FxSurface:
             // One instance holds one capture, so a multi payload names no instrument to build —

src/core/ui/drag_out.h

@@ -6,8 +6,9 @@
 //
 // THE LAW: the class is resolved from what is under the cursor on EVERY move; every transition
 // is reversible until release or until the pointer leaves REAPER entirely; the OS hand-off is
-// reserved for leaving REAPER, and every REAPER-internal target executes natively on release.
-// Do not reintroduce a first-move class lock or a drag-lifetime "blocked" latch.
+// reserved for leaving REAPER (DropContext::pointerOffHost owns what proves that) and every
+// REAPER-internal target executes natively on release. Do not reintroduce a first-move class
+// lock or a drag-lifetime "blocked" latch.
 //
 // Path-list assembly: turns armed sample ids into the absolute path list an OS drop carries
 // (Windows CF_HDROP / macOS file-list pasteboard) — set algebra only; the shell resolves each id
@@ -32,16 +33,16 @@ struct DragState {
 };
 
 // What REAPER reports under the pointer, reduced to the surfaces the law distinguishes.
-// Produced from GetThingFromPoint's info token by wire::classifyReaperSurface.
+// Produced from GetThingFromPoint's info token by wire::classifyReaperSurface. No off-REAPER
+// member: that fact enters through DropContext::pointerOffHost, which owns the reasoning.
 enum class ReaperSurface {
-    OffReaper,   // not over REAPER at all — the one irreversible exit
     TrackPanel,  // TCP/MCP, ANY sub-element: the WHOLE panel is the instrument hotspot
     FxSurface,   // fx_* — the FX chain and floating-FX windows
     FxEmbed,     // tcp.fxembed / mcp.fxembed — an instance already draws there
     Arrange,     // the timeline
-    Other,       // ruler, transport, spacers, docker chrome, unknown future tokens
+    Other,       // ruler, transport, spacers, docker chrome, unknown/empty future tokens
     Count,       // sentinel, NOT a real surface — tests/test_drag_out.cpp's kAllSurfaces is
-                 // pinned against this via static_assert so a 7th surface can't silently skip
+                 // pinned against this via static_assert so a 6th surface can't silently skip
                  // the exhaustiveness matrix
 };
 
@@ -62,8 +63,17 @@ enum class DropClass {
 struct DropContext {
     DragState drag;
     bool singlePayload = false;  // payload holds EXACTLY one capture (arms InstrumentDrop)
-    ReaperSurface surface = ReaperSurface::OffReaper;  // only read outside the client rect
+    ReaperSurface surface = ReaperSurface::Other;  // only read outside the client rect
     bool haveTrack = false;      // GetThingFromPoint returned a non-null MediaTrack*
+    // THE ONE HOME for the hand-off's evidence rule. This is the only member whose true value
+    // can reach the irreversible OS hand-off, and it is a POSITIVE proof the shell owes the law
+    // — a window-ownership test (drag_out_win::pointerOverHostWindow), never "the hit-test named
+    // nothing I recognise", which is equally true of the transport, the toolbar and the docker
+    // chrome; reading an unnamed token as an exit is what handed live drags to OLE mid-gesture.
+    // Defaults false so an unset context stays inside REAPER: the failure mode of forgetting to
+    // resolve it must be a refusal, never a drag given away to OLE. NECESSARY but not sufficient
+    // — decideDropClass's gate carries the second half and why it needs one.
+    bool pointerOffHost = false;
 };
 
 // Resolves the class for a drag at pointer (px, py) over `client`. Position-and-context only,

src/core/wire/CLAUDE.md

@@ -81,7 +81,7 @@ This directory owns two cross-artifact contracts specifically:
 - `reasampler_uid.h` — SDK-free header owning the FOREVER-FROZEN VST3 class-UID integer macros (stable + beta pairs, `REASAMPLER_PROC_UID_*` / `REASAMPLER_PROC_UID_BETA_*`) and the `REASAMPLER_ACTIVE_UID_*` channel-selector macros. Split out of `reasampler_vst.h` so the pure extension side (`instrument_drop`) can derive the `.vstpreset` class-ID hex string without pulling in the VST3 SDK. Both `reasampler_vst.h` (runtime `FUID`) and `instrument_drop` (preset hex string) source from this single header — the binary identity and the preset-file identity cannot diverge.
 - `assignment_request` — pure ingest-assign wire: typed request record carrying the drop payload from the `ingest` shell through to the VST3 bridge.
 - `bake_wire` — the resample bake's request/outcome pair on ONE per-instance key (`rsbake_<guid>`): the instrument writes a `BakeRequest`, invokes the extension's action synchronously, and reads the extension's `BakeOutcome` back over the same key inside that one call. Not a handshake — a call and a return, and it must not grow a claim protocol. Also the ONE home of the bake action's command-id suffix and of the leading underscore `NamedCommandLookup` needs but `rec->Register("command_id", …)` does not, so both artifacts name one action. `BakeStatus` values are WIRE INTEGERS: never renumber, only append, and an unrecognized value decodes as `Failed` rather than as the numeric default `Ok`. It owns BOTH ends' reading of that key, since the key's contents are the only evidence either side gets: `classifyBakeAnswer` (instrument side — six kinds, of which `Unanswered`, the request still sitting there untouched, separates "nothing wrote an outcome over our key" from a refusal — it does NOT identify a landing that never ran, since a skipped key and a rejected answer-write look identical from here) and `classifyBakeScan` + `kMaxRequestAgeSeconds` (extension side — the per-key Land / RefuseWrongProject / ClearStale / IgnoreUnreadable / IgnoreNotARequest verdict over every open tab, stated without a REAPER type so the multi-tab matrix is unit-provable). `BakeScanTally` + `describeBakeScan` + `describeBakeKey` are that same reading counted and spoken — the rationale lives at the types. **The report's absence is NOT evidence the landing never ran**, and no sentence either artifact prints may say it is: `answered` is pass-wide and counts a QUEUED write, so a pass can answer some other key while skipping ours, or have our own answer's `SetProjExtState` rejected. The summary is therefore silent only when the pass answered somebody, left no key unanswered, and every answer was READ BACK from its own key; `describeBakeKey` prints one line per enumerated key regardless, which is the only thing that names WHICH key — the counts cannot. The read-back verdict behind `BakeWriteProof` is `ext_state_read.h`'s `extStateWriteLanded`, above. `bakeLandingAfterPersist` is the ONE route to a `Banked` landing: every `Land` verdict is assigned `Unpersisted` and passed through it, so no shell path — a dedup hit least of all, since its target may be an entry the same pass just added — can claim the word without the pass's persist having reported success. What `Banked` claims is exactly that `persisted` input — a saved project was active and the bank write was issued — and the enum comment is that claim's one home.
-- `instrument_drop` — pure FX-drop payload builder: constructs a Steinberg-format `.vstpreset` image (channel-active class ID + the instrument's own component state, capture pre-selected) the shell applies via `TrackFX_SetPreset`; owns `classifyReaperSurface`, the prefix classifier mapping a `GetThingFromPoint` (info token, track-present) pair onto `core/ui/drag_out`'s `ReaperSurface`. Classifier ordering is load-bearing: the embed strip is matched before the `tcp`/`mcp` panel family, which now claims the WHOLE track panel rather than just its FX sub-elements. All-or-nothing contract — caller rolls back via `TrackFX_Delete` on any failure.
+- `instrument_drop` — pure FX-drop payload builder: constructs a Steinberg-format `.vstpreset` image (channel-active class ID + the instrument's own component state, capture pre-selected) the shell applies via `TrackFX_SetPreset`; owns `classifyReaperSurface`, the prefix classifier mapping a `GetThingFromPoint` info token onto `core/ui/drag_out`'s `ReaperSurface`. Classifier ordering is load-bearing: the embed strip is matched before the `tcp`/`mcp` panel family, which claims the WHOLE track panel rather than just its FX sub-elements. An empty token is `Other`, never an off-REAPER verdict (`core/ui/CLAUDE.md` owns that rule). All-or-nothing contract — caller rolls back via `TrackFX_Delete` on any failure.
 - `sample_usage` — instance-usage wire: `UsageRecord`, `planUsagePublish` (fresh/heal/clean-replace/union/remint publish plan), `foldUsageRecords`/`usageHeldPaths` (liveness fold — protect-all when records exist but no instance is live; abort→protect-all on unreadable record; `counted` carries key-attributed live records), `identityMatches` (ReaSampler 9000 FX identity). REAPER-free, unit-tested. The mirror of `assignment_request` on the instrument→extension direction: the wire format and the two safety-critical decisions (what to write on publish, which records count at prune time) are pure so they are provable without a DAW. It lives here because it is a *wire format* with an instrument-side writer; the fold's output is consumed by `core/tracking`'s authority, which owns every consumer-facing decision built on it.
 
 ## Gotchas

src/core/wire/instrument_drop.cpp

@@ -87,11 +87,10 @@ DropOutcome decideDropOutcome(const DropAttempt& attempt) {
     return out;
 }
 
-ui::ReaperSurface classifyReaperSurface(const std::string& info, bool haveTrack) {
+ui::ReaperSurface classifyReaperSurface(const std::string& info) {
     // See the header contract for the prefix rule and the ordering it depends on.
     auto startsWith = [&info](const char* p) { return info.rfind(p, 0) == 0; };
 
-    if (info.empty()) return haveTrack ? ui::ReaperSurface::Other : ui::ReaperSurface::OffReaper;
     if (startsWith("tcp.fxembed") || startsWith("mcp.fxembed")) return ui::ReaperSurface::FxEmbed;
     if (startsWith("fx_")) return ui::ReaperSurface::FxSurface;
     if (startsWith("tcp") || startsWith("mcp")) return ui::ReaperSurface::TrackPanel;

src/core/wire/instrument_drop.h

@@ -55,9 +55,9 @@ std::vector<std::uint8_t> buildVstPresetBytes(const std::string& classIdHex32,
 // preset. Deterministic.
 std::vector<std::uint8_t> buildInstrumentDropPreset(const std::string& sampleId);
 
-// Pure classifier for GetThingFromPoint's (info string, track-was-returned) pair
-// into the surfaces the drag-out gesture law distinguishes. The SDK warns future
-// versions may append information, so every rule is PREFIX-based:
+// Pure classifier for GetThingFromPoint's info string into the surfaces the drag-out
+// gesture law distinguishes. The SDK warns future versions may append information, so
+// every rule is PREFIX-based:
 //   "tcp.fxembed*" / "mcp.fxembed*" -> FxEmbed. Checked FIRST: it is the surface
 //       an existing instance already draws on, and a drop must not stack a second.
 //   "fx_*"                          -> FxSurface (FX chain + floating FX windows).
@@ -66,12 +66,12 @@ std::vector<std::uint8_t> buildInstrumentDropPreset(const std::string& sampleId)
 //       still means "sampler on this track", and the old glyph-only rule is exactly
 //       why such a drop landed nowhere.
 //   "arrange*"                      -> Arrange.
-//   ""  with no track               -> OffReaper (the pointer left REAPER).
-//   anything else, incl. "" WITH a track -> Other. Over REAPER on a surface we
-//       cannot name: refuse visibly, never guess an outcome.
+//   anything else, "" INCLUDED      -> Other. A surface we cannot name: refuse
+//       visibly, never guess an outcome. An empty token is NOT evidence the pointer left
+//       REAPER — see ui::DropContext::pointerOffHost for why that rule exists.
 // The exact live token is DAW-only — confirm via
 // reaper.GetThingFromPoint(reaper.GetMousePosition()) in ReaScript if unsure.
-ui::ReaperSurface classifyReaperSurface(const std::string& info, bool haveTrack);
+ui::ReaperSurface classifyReaperSurface(const std::string& info);
 
 // The raw component-state bytes the preset carries, exposed so the round-trip
 // test can decode them back through sample_map::deserializeComponentState and

src/shell/actions/CLAUDE.md

@@ -41,8 +41,8 @@ is owned by other directories and only skinned here.
 
 - `shell/actions` (`action_registry` / `design_view_actions` / `bank_actions` / `prune_action`) — the bindable action families, all routed via the `command_id`/`gaccel`/`hookcommand` contract. `action_registry` owns the shared registration plumbing (interned channel-qualified id strings; register and mirror-unregister present the identical pointer) **and the Q-W6 registration TABLE**: `main.cpp`'s own family (capture scopes, panel toggle, insert, batch, realtime, recapture, version) is one `ActionTableRow` array — suffix, phrase, flat function-pointer handler — that registration, hookcommand dispatch, and the unload mirror-unregister all iterate, so adding an action touches the table only (OCP). Bank mutations flow through the promptless `shell/bank_ops` verbs (`bankOp*` + `persistBankOp`, taking `ReaSamplerSession&`), which the panel menus and `bank_actions` consume as thin UX skins. **Every bank index verb wraps its mutation in a batched REAPER undo point (`Undo_BeginBlock2`/`EndBlock2`, `UNDO_STATE_MISCCFG`) so one bank operation is one Ctrl-Z.** The prune action (`prune_action`, `BANK_PRUNE_FOLDER`) is **the ONLY file-deletion action in the system**; it opens no undo point (file deletion is not REAPER-undoable). `BANK_PRUNE_FOLDER` halts on `blockedByTracking` and prints each blocker that fired, with recovery instructions.
 - `package_export_action` — the "export bank as package" skin: survey and report first, confirm what is absent (and, separately, a destination being replaced), pick a destination, write. Every prompt in the flow lives here so `shell/package/export_bank` stays promptless. Read-only against the project — it holds the session by `const&`, so no ext-state write, generation bump or undo point is reachable. Registration rides `main.cpp`'s action table (`EXPORT_BANK_PACKAGE`); the panel's tab menu is the second skin over the same body.
-- `drag_out_win` — OS drag-out shell: Windows OLE `DoDragDrop`/`CF_HDROP`, copy-only (`DROPEFFECT_MOVE` not offered); macOS/Linux via `SWELL_InitiateDragDropOfFileList`.
-- `instrument_drop_win` — instrument-drop shell: `probeDropTarget` resolves a screen point to a track + a `ReaperSurface` (via the pure `wire::classifyReaperSurface`, whose token rules `core/wire/CLAUDE.md` owns), and the drop half adds a ReaSampler 9000 instance and applies the dragged capture's state via a transient `.vstpreset` + `TrackFX_SetPreset` (the former `TrackFX_SetNamedConfigParm` "vst_chunk" write was silently unappliable for VST3). Exposes `loadInstrumentOntoTrack` (inner half, no own undo block) and `performInstrumentDrop` (wraps in its own undo block). **Never captures, never writes the bank, never inserts a timeline item.**
+- `drag_out_win` — the host/OS boundary of drag-out: Windows OLE `DoDragDrop`/`CF_HDROP`, copy-only (`DROPEFFECT_MOVE` not offered); macOS/Linux via `SWELL_InitiateDragDropOfFileList`. Also owns `pointerOverHostWindow`, the window-ownership test behind `ui::DropContext::pointerOffHost` (`core/ui/CLAUDE.md` owns the hand-off rule it feeds) — process identity on Windows (`WindowFromPoint` + `GetWindowThreadProcessId`), non-null `WindowFromPoint` under SWELL, whose window list is already this-process-only. Its shipped exception: a plugin bridged into `reaper_host*.exe` reports off-host though the pointer never left REAPER.
+- `instrument_drop_win` — instrument-drop shell: `probeDropTarget` resolves a screen point to a track + a `ReaperSurface` (via the pure `wire::classifyReaperSurface`, whose token rules `core/wire/CLAUDE.md` owns) — it answers only what REAPER named, never whether the pointer is still in REAPER — and the drop half adds a ReaSampler 9000 instance and applies the dragged capture's state via a transient `.vstpreset` + `TrackFX_SetPreset` (the former `TrackFX_SetNamedConfigParm` "vst_chunk" write was silently unappliable for VST3). Exposes `loadInstrumentOntoTrack` (inner half, no own undo block) and `performInstrumentDrop` (wraps in its own undo block). **Never captures, never writes the bank, never inserts a timeline item.**
 - `arrange_drop_win` — the drag-out gesture's arrange outcome: `arrangeTimeAtScreenX` (pointer column → time via `GetSet_ArrangeView2`'s one-pixel-span reading — inferred, not SDK-documented) and `performArrangeDrop` (snap the drop time, then one `InsertMedia` per capture on the pointer's track — assumed, not confirmed, to land end-to-end via REAPER's own cursor advance — in ONE undo block, counting only InsertMedia's reported successes, with the caller's track selection and edit cursor restored). The one timeline-placing shell here, per the invariant above; it never captures and never writes the bank.
 - `package_import_action` — the bindable / bank-menu / file-drop skin over `shell/package`'s `importBankPackage`. Owns the **ledger gate**, which runs BEFORE the file picker (a refusal must not cost the user a file choice) and is keyed on the session's `LedgerStatus` alone — never on `PruneReport::blockedByTracking`, whose undecodable-`rsusage_*` arm governs deletion-time protection and would refuse an import that only writes birth records. Builds and shows every message the import produces, but the ledger-refusal body itself is `core/package::ledgerRefusalMessage` — a pure fold this TU only supplies the channel-correct namespace to — so the wording is assertable without a DAW. `doImportBankPackage`/`doImportBankPackageFile` return the minted bank id on a landed import (empty otherwise) so a caller can focus it; the verb itself is promptless.
 - `ingest` — ingest-through-the-bank shell on the EXTENSION side: three surfaces — (1) arrange capture→bank→assign (bindable action), (2) Media-Explorer import→bank→instrument on the selected track, (3) file drop onto the bank panel→bank only. Only surface (1) writes the `assignment_request` ext-state wire. **ingest NEVER inserts a timeline item.** Surface (2)'s action is the one in this directory published into a NON-main action section (Media Explorer) as well as Main — two ids, one handler, two dispatch hooks; see root `CLAUDE.md` §"REAPER extension contract" for the mechanism.

src/shell/actions/drag_out_win.cpp

@@ -244,6 +244,27 @@ bool canInitiateDragOut(const std::vector<std::string>& absolutePaths) {
     return true;
 }
 
+bool pointerOverHostWindow(int screenX, int screenY) {
+    // Process identity, not window identity: REAPER's arrange, its floating FX and VST editor
+    // windows, its menus and its docker chrome are separate top-level HWNDs with no common
+    // ancestor, so no GetAncestor/GetParent walk reaches them all — but they are windows of the
+    // process this extension is loaded into, bar the bridged-plugin case the header names.
+    // Mouse capture does not affect WindowFromPoint: it hit-tests the desktop window tree, not
+    // input routing. It does skip hidden and DISABLED windows, so a REAPER window disabled behind
+    // a modal dialog raised mid-drag (a REAPER timer or another extension can raise one — capture
+    // is not a modality lock) would fall through to whatever sits beneath and read as off-host.
+    // Accepted, unverified: not reproduced, and nothing here was checked against REAPER's own
+    // dialog behavior.
+    const POINT pt{screenX, screenY};
+    const HWND hwnd = WindowFromPoint(pt);
+    // Not an unknown resolved toward hand-off: a null return is the desktop tree stating there is
+    // no window at that point at all, which is a determinate "no host window here".
+    if (!hwnd) return false;
+    DWORD pid = 0;
+    GetWindowThreadProcessId(hwnd, &pid);
+    return pid == GetCurrentProcessId();
+}
+
 }  // namespace reasampler
 
 #else  // ---- macOS / Linux (SWELL) -----------------------------------------------------
@@ -277,6 +298,15 @@ bool canInitiateDragOut(const std::vector<std::string>& absolutePaths) {
     return !absolutePaths.empty();
 }
 
+// SWELL's WindowFromPoint walks only THIS process's window list (SWELL_topwindows on
+// generic/GDK, [NSApp orderedWindows] on macOS — swell-wnd-generic.cpp / swell-wnd.mm), so a
+// non-null return already carries the process-ownership meaning Win32 needs GetWindowThread-
+// ProcessId for, and a point over any other application returns null.
+bool pointerOverHostWindow(int screenX, int screenY) {
+    POINT pt{screenX, screenY};
+    return WindowFromPoint(pt) != nullptr;
+}
+
 }  // namespace reasampler
 
 #endif

src/shell/actions/drag_out_win.h

@@ -1,7 +1,8 @@
 #pragma once
-// drag_out_win — the OS/COM initiation half of native OS drag-out: hands a resolved
-// existing-file path list to the OS's drag-drop machinery so the user can drop bank
-// samples into Explorer / another app / another DAW. The pure gesture-boundary
+// drag_out_win — the host/OS boundary of native OS drag-out: whether the pointer has
+// crossed it, whether the OS is ready to take the drag, and the hand-off itself, which
+// gives a resolved existing-file path list to the OS's drag-drop machinery so the user can
+// drop bank samples into Explorer / another app / another DAW. The pure gesture-boundary
 // decision + path-list assembly live in drag_out.*.
 //
 // COPY-ONLY is STRUCTURAL on Windows: DoDragDrop's effect mask is DROPEFFECT_COPY
@@ -32,4 +33,15 @@ bool initiateDragOut(HWND__* panelHwnd, const std::vector<std::string>& absolute
 // probe HGLOBAL immediately; SWELL exposes no probe, so macOS/Linux reduces to the non-empty check.
 bool canInitiateDragOut(const std::vector<std::string>& absolutePaths);
 
+// True iff a window belonging to the host (REAPER) process sits under the screen point — the
+// POSITIVE proof ui::DropContext::pointerOffHost is the negation of (that member owns the
+// evidence rule). Nearly every REAPER surface qualifies whether or not GetThingFromPoint can
+// name it, because the extension runs inside that process.
+// The exception, and it ships: a plugin set to "Run as separate/dedicated process" draws its
+// UI out of reaper_host32/64.exe, and WindowFromPoint descends to the deepest child — so this
+// reports false over a bridged plugin's editor although the pointer never left REAPER. The
+// law's hand-off gate absorbs that by also requiring REAPER's own hit-test to name nothing.
+// Side-effect-free; safe on every mouse-move.
+bool pointerOverHostWindow(int screenX, int screenY);
+
 } // namespace reasampler

src/shell/actions/instrument_drop_win.cpp

@@ -83,7 +83,7 @@ DropProbe probeDropTarget(int screenX, int screenY) {
     // doc-comment says so), so the track and the surface are two independent facts and both
     // are reported. The pure classifier owns every token rule.
     out.track = GetThingFromPoint(screenX, screenY, info, sizeof(info));
-    out.surface = classifyReaperSurface(info, out.track != nullptr);
+    out.surface = classifyReaperSurface(info);
     return out;
 }
 

src/shell/actions/instrument_drop_win.h

@@ -29,12 +29,14 @@ namespace reasampler {
 // (ui::decideDropClass) turns this plus the payload size into an outcome.
 struct DropProbe {
     MediaTrack* track = nullptr;  // the track under the pointer (null if none / not a track)
-    ui::ReaperSurface surface = ui::ReaperSurface::OffReaper;
+    ui::ReaperSurface surface = ui::ReaperSurface::Other;
 };
 
-// Wraps GetThingFromPoint and hands its (info string, track) pair to the pure
+// Wraps GetThingFromPoint: its track comes back as-is, its info string goes to the pure
 // wire::classifyReaperSurface. Cheap enough to run on every mouse-move, but the panel
 // evaluates it only OUTSIDE its own client rect — the internal drag never pays for it.
+// Reports only what REAPER named; no output here implies an exit (ui::DropContext::
+// pointerOffHost owns that rule).
 DropProbe probeDropTarget(int screenX, int screenY);
 
 // Adds a fresh ReaSampler 9000 instance to `track` and applies `presetBytes` as its

src/shell/panel/panel_drag.cpp

@@ -199,6 +199,10 @@ LiveDrop resolveLiveDrop(int x, int y) {
         const DropProbe probe = probeDropTarget(sp.x, sp.y);
         ctx.surface = probe.surface;
         ctx.haveTrack = probe.track != nullptr;
+        // Two probes because they answer two independent questions: what REAPER named, and
+        // whether we are still inside REAPER at all. The law's hand-off gate reads both — see
+        // ui::DropContext::pointerOffHost.
+        ctx.pointerOffHost = !pointerOverHostWindow(sp.x, sp.y);
         out.track = probe.track;
         out.screenX = sp.x;
     }
@@ -219,11 +223,12 @@ LiveDrop resolveLiveDrop(int x, int y) {
 // loop, so the internal drag must be fully wound down first, and only once the payload is known
 // to be hand-off-able. This runs on every qualifying move — do not memoize a failed attempt.
 //
-// Residual (accepted): once the pointer has left REAPER, dragging back INTO a REAPER window
+// Residual (accepted): once the pointer has genuinely left every REAPER window, dragging back IN
 // mid-modal-loop delivers a CF_HDROP to REAPER's own file-import drop target rather than to our
 // gesture law. NOT confirmed by experiment — inferred from REAPER's handling of external file
 // drops, and the inferred outcome (an item at the drop point) coincides with what our own
-// arrange path would have done.
+// arrange path would have done. This is now the ONLY way to see that import ghost mid-drag;
+// reaching it from a surface still inside REAPER was the defect pointerOffHost closed.
 void handOffToOs() {
     // Resolve BEFORE tearing anything down (the resolver reads the live drag payload), then let
     // the pure rule couple the two side effects: an unresolvable payload leaves the internal
@@ -242,6 +247,10 @@ void handOffToOs() {
     invalidatePanel();
 
     initiateDragOut(g_panel.hwnd, paths);  // COPY-ONLY; blocking on Windows
+
+    // The drag state was reset above, so the WM_LBUTTONUP that ends the modal loop takes
+    // onLBtnUp's not-dragging branch and never restores the arrow — do it here instead.
+    SetCursor(LoadCursor(nullptr, IDC_ARROW));
 }
 
 // Resolves the topmost INTERACTIVE element under client (x, y) for hover feedback,

tests/test_drag_out.cpp

@@ -2,8 +2,9 @@
 // as the sibling pure tests: assert the gesture law and the path-list assembly directly.
 //
 // Covers:
-//   * The full class matrix: every ReaperSurface x {single, multi} x {track, no track}, inside
-//     and outside the client rect, plus the half-open edge and a non-zero panel origin.
+//   * The full class matrix: every ReaperSurface x {single, multi} x {track, no track} x
+//     {over a host window, off it}, inside and outside the client rect, plus the half-open edge
+//     and a non-zero panel origin.
 //   * Reversibility and speed-independence, stated as properties: a class transition sequence
 //     resolves the same forwards and backwards, and one unresolvable evaluation cannot change
 //     any later evaluation's outcome.
@@ -28,7 +29,8 @@ static int g_fail = 0;
 
 static const PanelClientRect kPanel{0, 0, 400, 300};
 
-// A live single-card drag over `surface`, with a track resolved unless stated otherwise.
+// A live single-card drag over `surface`, still inside REAPER, with a track resolved unless
+// stated otherwise.
 static DropContext ctx(ReaperSurface surface, bool single = true, bool haveTrack = true) {
     DropContext c;
     c.drag = DragState{/*dragging=*/true, /*hasArmedSamples=*/true};
@@ -38,13 +40,23 @@ static DropContext ctx(ReaperSurface surface, bool single = true, bool haveTrack
     return c;
 }
 
+// The same drag with the shell's positive off-REAPER proof set. `surface` is whatever the SDK
+// hit-test reported at that point — it still matters: the hand-off needs REAPER to have named
+// nothing too, so the defaults here (Other, no track) are the only combination that hands off.
+static DropContext offHost(ReaperSurface surface = ReaperSurface::Other, bool single = true,
+                           bool haveTrack = false) {
+    DropContext c = ctx(surface, single, haveTrack);
+    c.pointerOffHost = true;
+    return c;
+}
+
 // Every surface the law enumerates, so the matrix tests iterate rather than list.
 static const ReaperSurface kAllSurfaces[] = {
-    ReaperSurface::OffReaper, ReaperSurface::TrackPanel, ReaperSurface::FxSurface,
-    ReaperSurface::FxEmbed,   ReaperSurface::Arrange,    ReaperSurface::Other,
+    ReaperSurface::TrackPanel, ReaperSurface::FxSurface, ReaperSurface::FxEmbed,
+    ReaperSurface::Arrange,    ReaperSurface::Other,
 };
 
-// Pins kAllSurfaces against ReaperSurface::Count so a 7th surface added to the enum without a
+// Pins kAllSurfaces against ReaperSurface::Count so a 6th surface added to the enum without a
 // matching entry here fails the BUILD, not just a silently-incomplete matrix — the compiler
 // alone does not enforce this (no -Wswitch/-Wall or /W4 anywhere in the build; see
 // panel_drag.cpp's onLBtnUp for the same caveat on DropClass).
@@ -66,6 +78,10 @@ static void testInsideClientIsAlwaysInternal() {
             CHECK(decideDropClass(200, 150, kPanel, ctx(s, single)) == DropClass::Internal);
             CHECK(decideDropClass(0, 0, kPanel, ctx(s, single)) == DropClass::Internal);
             CHECK(decideDropClass(399, 299, kPanel, ctx(s, single)) == DropClass::Internal);
+            // Even a stale off-host proof cannot reinterpret a point inside our own client rect:
+            // the inside-client answer is resolved ahead of the hand-off gate, so re-entering the
+            // panel always resumes the bank-to-bank gesture.
+            CHECK(decideDropClass(200, 150, kPanel, offHost(s, single)) == DropClass::Internal);
         }
     }
 }
@@ -73,7 +89,7 @@ static void testInsideClientIsAlwaysInternal() {
 // The half-open boundary: x+width and y+height are OUTSIDE, the pixel just inside is Internal —
 // matches the panel's other hit-tests so the edge is claimed consistently.
 static void testBoundaryHalfOpen() {
-    const DropContext off = ctx(ReaperSurface::OffReaper);
+    const DropContext off = offHost();
     CHECK(decideDropClass(399, 150, kPanel, off) == DropClass::Internal);
     CHECK(decideDropClass(400, 150, kPanel, off) == DropClass::OsHandoff);
     CHECK(decideDropClass(200, 299, kPanel, off) == DropClass::Internal);
@@ -83,7 +99,7 @@ static void testBoundaryHalfOpen() {
 // A non-zero panel origin — the boundary tracks the rect, not the absolute axes.
 static void testOffsetPanelRect() {
     const PanelClientRect p{50, 20, 100, 80};  // spans x[50,150) y[20,100)
-    const DropContext off = ctx(ReaperSurface::OffReaper);
+    const DropContext off = offHost();
     CHECK(decideDropClass(100, 60, p, off) == DropClass::Internal);
     CHECK(decideDropClass(49, 60, p, off) == DropClass::OsHandoff);
     CHECK(decideDropClass(150, 60, p, off) == DropClass::OsHandoff);
@@ -129,9 +145,8 @@ static void testSingleOverOtherReaperUiRefuses() {
 }
 
 // Off REAPER entirely -> the OS drag-out, the one irreversible transition.
-static void testSingleOffReaperIsOsHandoff() {
-    CHECK(decideDropClass(kOutX, kOutY, kPanel, ctx(ReaperSurface::OffReaper)) ==
-          DropClass::OsHandoff);
+static void testSingleOffHostIsOsHandoff() {
+    CHECK(decideDropClass(kOutX, kOutY, kPanel, offHost()) == DropClass::OsHandoff);
 }
 
 // --- Matrix: outside the client, multi card ------------------------------------
@@ -154,8 +169,8 @@ static void testMultiOverArrangeIsArrangeInsert() {
 }
 
 // Multi off REAPER is the classic multi-file drag-out, unchanged.
-static void testMultiOffReaperIsOsHandoff() {
-    CHECK(decideDropClass(kOutX, kOutY, kPanel, ctx(ReaperSurface::OffReaper, false)) ==
+static void testMultiOffHostIsOsHandoff() {
+    CHECK(decideDropClass(kOutX, kOutY, kPanel, offHost(ReaperSurface::Other, false)) ==
           DropClass::OsHandoff);
 }
 
@@ -180,11 +195,73 @@ static void testNullTrackWithSurfaceRefuses() {
     }
 }
 
-// A track under the pointer never turns OffReaper into a REAPER-internal outcome: OffReaper is
-// the shell's "the info string was empty and there was no track" verdict, and the law trusts it.
-static void testOffReaperIgnoresTrackFlag() {
+// --- The hand-off gate ---------------------------------------------------------
+
+// THE REGRESSION FLOOR. No reading of REAPER's hit-test can reach the modal OLE loop while the
+// pointer is over a host window — asserted over EVERY surface the probe can report, both payload
+// sizes and both track verdicts, not just the toolbar/transport cell that was reported. The
+// defect was structural (an unnamed token read as "the user left REAPER"), so the guarantee has
+// to be structural too.
+static void testNoInReaperCombinationCanHandOff() {
+    for (ReaperSurface s : kAllSurfaces) {
+        for (bool single : {true, false}) {
+            for (bool haveTrack : {true, false}) {
+                CHECK(decideDropClass(kOutX, kOutY, kPanel, ctx(s, single, haveTrack)) !=
+                      DropClass::OsHandoff);
+            }
+        }
+    }
+}
+
+// The converse, stated as the gate's exact shape: with the ownership proof set, the hand-off
+// happens EXACTLY on the cells where REAPER's hit-test also named nothing — no surface, no track.
+// Both directions in one loop, so neither half can be weakened without a failure: a gate that
+// dropped the token condition fails on the named cells, one that over-tightened fails on Other.
+static void testOffHostHandsOffOnlyWhereReaperNamedNothing() {
+    for (ReaperSurface s : kAllSurfaces) {
+        for (bool single : {true, false}) {
+            for (bool haveTrack : {true, false}) {
+                const bool namedNothing = (s == ReaperSurface::Other) && !haveTrack;
+                const DropClass c =
+                    decideDropClass(kOutX, kOutY, kPanel, offHost(s, single, haveTrack));
+                CHECK((c == DropClass::OsHandoff) == namedNothing);
+            }
+        }
+    }
+}
+
+// The shipped exception the token condition exists for: REAPER runs a bridged plugin's UI in
+// reaper_host*.exe, so the window-ownership test reports off-host over a floating bridged FX
+// editor even though the pointer never left REAPER. There the recognised token vetoes the
+// hand-off and the surface's own REAPER-internal outcome stands — identical to the native case.
+static void testOffHostOverANamedSurfaceKeepsTheReaperOutcome() {
+    CHECK(decideDropClass(kOutX, kOutY, kPanel, offHost(ReaperSurface::FxSurface, true, true)) ==
+          DropClass::InstrumentDrop);
+    CHECK(decideDropClass(kOutX, kOutY, kPanel, offHost(ReaperSurface::TrackPanel, true, true)) ==
+          DropClass::InstrumentDrop);
+    CHECK(decideDropClass(kOutX, kOutY, kPanel, offHost(ReaperSurface::Arrange, true, true)) ==
+          DropClass::ArrangeInsert);
+    CHECK(decideDropClass(kOutX, kOutY, kPanel, offHost(ReaperSurface::FxEmbed, true, true)) ==
+          DropClass::Refuse);
+
+    // And not just for those four spot values: over every named cell the ownership proof changes
+    // nothing at all, which is what "a veto can only move the answer toward staying in REAPER"
+    // means operationally.
+    for (ReaperSurface s : kAllSurfaces) {
+        if (s == ReaperSurface::Other) continue;  // the one surface the gate can hand off from
+        for (bool single : {true, false}) {
+            for (bool haveTrack : {true, false}) {
+                CHECK(decideDropClass(kOutX, kOutY, kPanel, offHost(s, single, haveTrack)) ==
+                      decideDropClass(kOutX, kOutY, kPanel, ctx(s, single, haveTrack)));
+            }
+        }
+    }
+    // Same equality on the remaining named cell: Other WITH a track is a surface REAPER did
+    // attribute, so it refuses off-host exactly as it does on-host.
+    for (bool single : {true, false}) {
         CHECK(decideDropClass(kOutX, kOutY, kPanel,
-                          ctx(ReaperSurface::OffReaper, true, false)) == DropClass::OsHandoff);
+                              offHost(ReaperSurface::Other, single, true)) == DropClass::Refuse);
+    }
 }
 
 // --- Not-a-drag ----------------------------------------------------------------
@@ -192,7 +269,8 @@ static void testOffReaperIgnoresTrackFlag() {
 // No armed samples, or not dragging -> None regardless of position or surface.
 static void testNoDragOrNoSamplesIsNone() {
     for (ReaperSurface s : kAllSurfaces) {
-        DropContext c = ctx(s);
+        for (bool off : {false, true}) {
+            DropContext c = off ? offHost(s) : ctx(s);
             c.drag = DragState{/*dragging=*/true, /*hasArmedSamples=*/false};
             CHECK(decideDropClass(kOutX, kOutY, kPanel, c) == DropClass::None);
             CHECK(decideDropClass(200, 150, kPanel, c) == DropClass::None);
@@ -201,6 +279,7 @@ static void testNoDragOrNoSamplesIsNone() {
             CHECK(decideDropClass(kOutX, kOutY, kPanel, c) == DropClass::None);
             CHECK(decideDropClass(200, 150, kPanel, c) == DropClass::None);
         }
+    }
 }
 
 // --- Reversibility, speed-independence, exhaustiveness -------------------------
@@ -219,6 +298,13 @@ static void testClassTransitionsAreReversible() {
     CHECK(decideDropClass(kOutX, kOutY, kPanel, fx) == DropClass::InstrumentDrop);
     CHECK(decideDropClass(kOutX, kOutY, kPanel, arrange) == DropClass::ArrangeInsert);
     CHECK(decideDropClass(200, 150, kPanel, inside) == DropClass::Internal);
+
+    // The hand-off leg is irreversible only because the SHELL goes modal on it. The law itself
+    // stays stateless across it: evaluating an off-host context leaves the next in-REAPER
+    // evaluation exactly where it was.
+    CHECK(decideDropClass(kOutX, kOutY, kPanel, offHost()) == DropClass::OsHandoff);
+    CHECK(decideDropClass(kOutX, kOutY, kPanel, arrange) == DropClass::ArrangeInsert);
+    CHECK(decideDropClass(200, 150, kPanel, inside) == DropClass::Internal);
 }
 
 // One unresolvable evaluation (a surface with no track, which refuses) followed by a resolvable
@@ -245,9 +331,10 @@ static void testDragSpeedCannotChangeTheOutcome() {
     const DropContext destination = ctx(ReaperSurface::TrackPanel);
     const DropClass flick = decideDropClass(kOutX, kOutY, kPanel, destination);
 
-    // The slow path crosses everything else first.
+    // The slow path crosses everything else first, off-host legs included.
     for (ReaperSurface s : kAllSurfaces) {
         (void)decideDropClass(kOutX - 10, kOutY, kPanel, ctx(s));
+        (void)decideDropClass(kOutX - 10, kOutY, kPanel, offHost(s));
         (void)decideDropClass(200, 150, kPanel, ctx(s));  // and back through the client
     }
     CHECK(decideDropClass(kOutX, kOutY, kPanel, destination) == flick);
@@ -262,12 +349,16 @@ static void testNoLiveOutsideCombinationResolvesToNone() {
     for (ReaperSurface s : kAllSurfaces) {
         for (bool single : {true, false}) {
             for (bool haveTrack : {true, false}) {
-                const DropClass c = decideDropClass(kOutX, kOutY, kPanel, ctx(s, single, haveTrack));
+                for (bool off : {false, true}) {
+                    const DropClass c = decideDropClass(
+                        kOutX, kOutY, kPanel,
+                        off ? offHost(s, single, haveTrack) : ctx(s, single, haveTrack));
                     CHECK(c != DropClass::None);
                     CHECK(c != DropClass::Internal);
                 }
             }
         }
+    }
 }
 
 // Every class carries a cue, and only the two the shell deliberately does not draw map to a
@@ -409,15 +500,17 @@ int main() {
     testSingleOverFxEmbedRefuses();
     testSingleOverArrangeIsArrangeInsert();
     testSingleOverOtherReaperUiRefuses();
-    testSingleOffReaperIsOsHandoff();
+    testSingleOffHostIsOsHandoff();
 
     testMultiOverInstrumentSurfacesRefuses();
     testMultiOverArrangeIsArrangeInsert();
-    testMultiOffReaperIsOsHandoff();
+    testMultiOffHostIsOsHandoff();
     testMultiOverOtherReaperUiRefuses();
 
     testNullTrackWithSurfaceRefuses();
-    testOffReaperIgnoresTrackFlag();
+    testNoInReaperCombinationCanHandOff();
+    testOffHostHandsOffOnlyWhereReaperNamedNothing();
+    testOffHostOverANamedSurfaceKeepsTheReaperOutcome();
     testNoDragOrNoSamplesIsNone();
 
     testClassTransitionsAreReversible();

tests/test_instrument_drop.cpp

@@ -186,39 +186,39 @@ static void testBadClassIdRejected() {
 
 using ui::ReaperSurface;
 
-static ReaperSurface onTrack(const std::string& info) {
-    return classifyReaperSurface(info, /*haveTrack=*/true);
+static ReaperSurface surfaceFor(const std::string& info) {
+    return classifyReaperSurface(info);
 }
 
 // The FX chain / floating-FX windows.
 static void testFxWindowIsFxSurface() {
-    CHECK(onTrack("fx_chain") == ReaperSurface::FxSurface);
-    CHECK(onTrack("fx_0") == ReaperSurface::FxSurface);
-    CHECK(onTrack("fx_12") == ReaperSurface::FxSurface);
+    CHECK(surfaceFor("fx_chain") == ReaperSurface::FxSurface);
+    CHECK(surfaceFor("fx_0") == ReaperSurface::FxSurface);
+    CHECK(surfaceFor("fx_12") == ReaperSurface::FxSurface);
 }
 
 // The FX-button family within the TCP/MCP — the surface the glyph-only rule used to be limited
 // to, still an instrument surface (as TrackPanel, which resolves identically).
 static void testTcpMcpFxFamilyIsTrackPanel() {
-    CHECK(onTrack("tcp.fx") == ReaperSurface::TrackPanel);
-    CHECK(onTrack("mcp.fx") == ReaperSurface::TrackPanel);
-    CHECK(onTrack("tcp.fxbyp") == ReaperSurface::TrackPanel);
-    CHECK(onTrack("tcp.fxparm") == ReaperSurface::TrackPanel);
-    CHECK(onTrack("mcp.fxlist") == ReaperSurface::TrackPanel);
-    CHECK(onTrack("tcp.fx.1") == ReaperSurface::TrackPanel);      // appended info
-    CHECK(onTrack("tcp.fx extra") == ReaperSurface::TrackPanel);  // appended info, arbitrary form
+    CHECK(surfaceFor("tcp.fx") == ReaperSurface::TrackPanel);
+    CHECK(surfaceFor("mcp.fx") == ReaperSurface::TrackPanel);
+    CHECK(surfaceFor("tcp.fxbyp") == ReaperSurface::TrackPanel);
+    CHECK(surfaceFor("tcp.fxparm") == ReaperSurface::TrackPanel);
+    CHECK(surfaceFor("mcp.fxlist") == ReaperSurface::TrackPanel);
+    CHECK(surfaceFor("tcp.fx.1") == ReaperSurface::TrackPanel);      // appended info
+    CHECK(surfaceFor("tcp.fx extra") == ReaperSurface::TrackPanel);  // appended info, arbitrary form
 }
 
 // THE ROOT-CAUSE FIX: the bare panel token and every non-FX sub-element are now the instrument
 // hotspot too. A TCP too narrow to draw the FX button reports "tcp", which under the old
 // glyph-only rule produced a cue-less no-op.
 static void testWholeTrackPanelIsTheHotspot() {
-    CHECK(onTrack("tcp") == ReaperSurface::TrackPanel);       // bare track control panel
-    CHECK(onTrack("mcp") == ReaperSurface::TrackPanel);       // bare mixer control panel
-    CHECK(onTrack("tcp.mute") == ReaperSurface::TrackPanel);  // mute button
-    CHECK(onTrack("tcp.vol") == ReaperSurface::TrackPanel);   // volume fader
-    CHECK(onTrack("tcp.meter") == ReaperSurface::TrackPanel); // meter
-    CHECK(onTrack("tcp.f") == ReaperSurface::TrackPanel);     // truncated token — still the panel
+    CHECK(surfaceFor("tcp") == ReaperSurface::TrackPanel);       // bare track control panel
+    CHECK(surfaceFor("mcp") == ReaperSurface::TrackPanel);       // bare mixer control panel
+    CHECK(surfaceFor("tcp.mute") == ReaperSurface::TrackPanel);  // mute button
+    CHECK(surfaceFor("tcp.vol") == ReaperSurface::TrackPanel);   // volume fader
+    CHECK(surfaceFor("tcp.meter") == ReaperSurface::TrackPanel); // meter
+    CHECK(surfaceFor("tcp.f") == ReaperSurface::TrackPanel);     // truncated token — still the panel
 }
 
 // The embed strip is where a ReaSampler 9000 instance already draws inline via
@@ -226,44 +226,37 @@ static void testWholeTrackPanelIsTheHotspot() {
 // instance on the first. Matched before the "tcp"/"mcp" rule, so widening the panel hotspot
 // cannot swallow it; do not reorder these two checks in the classifier.
 static void testEmbedStripIsItsOwnSurface() {
-    CHECK(onTrack("tcp.fxembed") == ReaperSurface::FxEmbed);
-    CHECK(onTrack("mcp.fxembed") == ReaperSurface::FxEmbed);
-    CHECK(onTrack("tcp.fxembed.1") == ReaperSurface::FxEmbed);
-    CHECK(onTrack("mcp.fxembed extra") == ReaperSurface::FxEmbed);
+    CHECK(surfaceFor("tcp.fxembed") == ReaperSurface::FxEmbed);
+    CHECK(surfaceFor("mcp.fxembed") == ReaperSurface::FxEmbed);
+    CHECK(surfaceFor("tcp.fxembed.1") == ReaperSurface::FxEmbed);
+    CHECK(surfaceFor("mcp.fxembed extra") == ReaperSurface::FxEmbed);
 }
 
 // The arrange, including a token with appended information.
 static void testArrangeIsArrange() {
-    CHECK(onTrack("arrange") == ReaperSurface::Arrange);
-    CHECK(onTrack("arrange extra") == ReaperSurface::Arrange);
+    CHECK(surfaceFor("arrange") == ReaperSurface::Arrange);
+    CHECK(surfaceFor("arrange extra") == ReaperSurface::Arrange);
 }
 
 // Anything else REAPER names is Other — a defined refusal, never a guessed outcome. Includes
 // tokens REAPER may add in future versions.
 static void testUnnamedReaperSurfacesAreOther() {
-    CHECK(onTrack("spacer_0") == ReaperSurface::Other);
-    CHECK(onTrack("trans") == ReaperSurface::Other);
-    CHECK(onTrack("envcp") == ReaperSurface::Other);
-    CHECK(onTrack("ruler") == ReaperSurface::Other);
-    CHECK(onTrack("something_reaper_adds_in_2030") == ReaperSurface::Other);
+    CHECK(surfaceFor("spacer_0") == ReaperSurface::Other);
+    CHECK(surfaceFor("trans") == ReaperSurface::Other);
+    CHECK(surfaceFor("envcp") == ReaperSurface::Other);
+    CHECK(surfaceFor("ruler") == ReaperSurface::Other);
+    CHECK(surfaceFor("something_reaper_adds_in_2030") == ReaperSurface::Other);
 }
 
-// The empty info string splits on whether a track came back with it. No track means the pointer
-// has left REAPER (the OS hand-off's trigger); a track with no info means we are over REAPER on
-// a surface we cannot name, which must refuse rather than be treated as off-REAPER.
-static void testEmptyInfoSplitsOnTrackPresence() {
-    CHECK(classifyReaperSurface("", /*haveTrack=*/false) == ReaperSurface::OffReaper);
-    CHECK(classifyReaperSurface("", /*haveTrack=*/true) == ReaperSurface::Other);
+// An empty info string is Other, NOT an off-REAPER verdict — ui::DropContext::pointerOffHost
+// owns why.
+static void testEmptyInfoIsOtherNotOffReaper() {
+    CHECK(surfaceFor("") == ReaperSurface::Other);
 }
 
-// The SDK's documented null-track-with-valid-info case: the surface is read from the string
-// alone, so the classifier reports it faithfully and the gesture law decides what a missing
-// track means for that surface.
-static void testNullTrackStillClassifiesTheSurface() {
-    CHECK(classifyReaperSurface("arrange", false) == ReaperSurface::Arrange);
-    CHECK(classifyReaperSurface("tcp", false) == ReaperSurface::TrackPanel);
-    CHECK(classifyReaperSurface("fx_chain", false) == ReaperSurface::FxSurface);
-}
+// There is deliberately no second empty-info case: track presence is not an input to the
+// classifier, and "no classifier output alone can trigger a hand-off" is structural (no such
+// member exists) rather than something a per-token loop could falsify.
 
 // Do not reintroduce a per-surface "capture carries" loop test: buildInstrumentDropPreset takes
 // only sampleId (proven by testPresetRoundTripsThroughInstrumentReader), and per-surface
@@ -324,8 +317,7 @@ int main() {
     testEmbedStripIsItsOwnSurface();
     testArrangeIsArrange();
     testUnnamedReaperSurfacesAreOther();
-    testEmptyInfoSplitsOnTrackPresence();
-    testNullTrackStillClassifiesTheSurface();
+    testEmptyInfoIsOtherNotOffReaper();
 
     testAddFailureLeavesNothingToRollBack();
     testPresetFailureRollsBackTheCreatedIndex();