Ψ-W1-T4: resolve drop targets per move, not once — every surface gets a defined outcome, a cue, and no silent no-op

src/shell/panel/panel_state.h

@@ -71,9 +71,11 @@ using ui::CardGesture;
 using ui::CellRect;
 using ui::ClusterSpec;
 using ui::CursorCue;
-using ui::DragGesture;
 using ui::DragModifiers;
 using ui::DragState;
+using ui::DropClass;
+using ui::DropContext;
+using ui::DropCue;
 using ui::DropRegion;
 using ui::FooterBarLayout;
 using ui::FooterBarSpec;
@@ -118,9 +120,10 @@ using ui::computeSlotRectsForDrop;
 using ui::computeTabRects;
 using ui::computeTabStripLayout;
 using ui::computeTooltip;
+using ui::cueForDropClass;
 using ui::cursorForGesture;
 using ui::decideCardGesture;
-using ui::decideGesture;
+using ui::decideDropClass;
 using ui::formatBarsBeats;
 using ui::formatSecondsMs;
 using ui::hitTestActionBar;
@@ -317,14 +320,10 @@ struct PanelState {
     CardGesture cardGesture = CardGesture::None;
     int         dragTargetSlot = -1;
 
-    // While a single-capture drag is over REAPER's own UI, heading for a track's TCP FX
-    // button: on release this adds a ReaSampler 9000 preloaded with the capture. Null
-    // when the pointer is not over an FX button.
-    MediaTrack* instrumentDropTrack = nullptr;
-
-    // Latched once an OsDrag hand-off resolves "cannot hand off" for this gesture — skips
-    // re-running resolveDragPathsForOs (fs::exists per sample) each move. Cleared by resetDragState.
-    bool dragOsHandoffBlocked = false;
+    // NO out-of-client drop-target state is kept here on purpose. The drag-out class and its
+    // track are re-resolved from the live pointer on every move and again at the release point,
+    // which is what makes a class transition reversible and one unresolvable evaluation
+    // harmless to the next. Do not reintroduce a remembered target or a "blocked" latch.
 
     // Authoritative tail setting lives in ReaSamplerSession, not here; panel reads it for
     // drawing and mutates via footer click / scroll-wheel. bankPanelTailSetting is the