Fix drag-handoff bugs: gate FX re-resolve on outside-panel, cache unresolvable OS-drag verdict, block double FX-add retry

tests/test_drag_out.cpp

@@ -223,39 +223,26 @@ static void testMixedTallies() {
 
 // --- OS hand-off ordering -----------------------------------------------------
 //
-// The drag-out-lands-without-audio regression: the shell used to wind its internal drag down
+// The empty-payload teardown regression: the shell used to wind its internal drag down
 // (release capture, clear drag state) BEFORE checking whether the payload had resolved to any
-// on-disk file. A payload that resolved to nothing therefore consumed the gesture — the drag
-// died half-torn-down and the user saw a drop with no audio and dragged again. The two side
-// effects are one decision; these pin that.
+// on-disk file. For an unresolvable payload, initiateDragOut is never reached — no OS drop
+// happens at all — but the teardown ran anyway, so the drag just silently stopped mid-gesture
+// with no highlight and no drop. The user has to press and start an entirely new drag; retrying
+// the SAME stale selection resolves to the same empty payload and fails identically. These pin
+// the fix: the two side effects (teardown, hand-off) are one decision.
 
 // Nothing draggable -> hand off nothing AND keep the internal drag alive.
 static void testEmptyPathsHandsOffNothingAndKeepsInternalDrag() {
     const OsHandoff h = decideOsHandoff({});
-    CHECK(!h.startOsDrag);
-    CHECK(!h.releaseInternalDrag);
+    CHECK(!h.handOffToOs);
 }
 
-// A resolvable payload -> release the internal drag, then start the OS drag.
+// A resolvable payload -> hand off (release the internal drag, then start the OS drag).
 static void testResolvablePayloadHandsOff() {
     const OsHandoff one = decideOsHandoff({"C:/proj/bank/a.wav"});
-    CHECK(one.startOsDrag);
-    CHECK(one.releaseInternalDrag);
+    CHECK(one.handOffToOs);
     const OsHandoff many = decideOsHandoff({"a.wav", "b.wav", "c.wav"});
-    CHECK(many.startOsDrag);
-    CHECK(many.releaseInternalDrag);
-}
-
-// The coupling itself: releasing without starting is the defect, so it must be unreachable
-// for every input the assembler can produce.
-static void testNeverReleasesWithoutStarting() {
-    const std::vector<std::vector<std::string>> inputs = {
-        {}, {"a.wav"}, {"a.wav", "b.wav"}, {""},
-    };
-    for (const std::vector<std::string>& in : inputs) {
-        const OsHandoff h = decideOsHandoff(in);
-        CHECK(!(h.releaseInternalDrag && !h.startOsDrag));
-    }
+    CHECK(many.handOffToOs);
 }
 
 // End to end through the assembler: a selection whose every entry is stale/unresolvable
@@ -263,8 +250,7 @@ static void testNeverReleasesWithoutStarting() {
 static void testAllSkippedSelectionKeepsInternalDrag() {
     const PathList l = assemblePathList({missing("g1.wav"), unresolved()});
     const OsHandoff h = decideOsHandoff(l.paths);
-    CHECK(!h.startOsDrag);
-    CHECK(!h.releaseInternalDrag);
+    CHECK(!h.handOffToOs);
 }
 
 int main() {
@@ -292,7 +278,6 @@ int main() {
 
     testEmptyPathsHandsOffNothingAndKeepsInternalDrag();
     testResolvablePayloadHandsOff();
-    testNeverReleasesWithoutStarting();
     testAllSkippedSelectionKeepsInternalDrag();
 
     if (g_fail == 0) std::printf("All tests passed.\n");

tests/test_instrument_drop.cpp

@@ -237,29 +237,15 @@ static void testEmbedStripIsNotHotspot() {
 // --- Drop surface parity: container vs FX button ------------------------------
 //
 // The container-drop regression (instance loads, capture does not): the two surfaces must be
-// one code path carrying one payload. The payload is a function of the capture alone, so the
-// surface cannot influence it — and both surfaces must classify as hotspots so both reach it.
-
-// Every surface a drop can land on admits the SAME capture and yields a payload that decodes
-// back to it. The payload takes the capture and nothing else, so the surface cannot influence
-// it — walking the surfaces here is what pins that the container family is not second-class.
-static void testEveryDropSurfaceCarriesTheCapture() {
-    const char* surfaces[] = {
-        "fx_chain",  // FX chain window / container list — the reported failing surface
-        "fx_0",      // floating FX window
-        "tcp.fx",    // TCP FX button — the reference path
-        "mcp.fx",    // MCP FX button
-    };
-    const std::string sampleId = "cap-7f3a";
-    for (const char* info : surfaces) {
-        CHECK(infoNamesFxHotspot(info));
-        const ParsedPreset p = parsePreset(buildInstrumentDropPreset(sampleId));
-        CHECK(p.ok);
-        CHECK(p.classId == vstClassIdHex());
-        const ComponentState cs = deserializeComponentState(p.compChunk, kRate);
-        CHECK(cs.selectionId == sampleId);
-    }
-}
+// one code path carrying one payload. buildInstrumentDropPreset takes only sampleId, so the
+// payload side of that claim is already proven once by testPresetRoundTripsThroughInstrumentReader
+// and every "fx_"/"tcp.fx"/"mcp.fx" surface classifying as a hotspot is proven by
+// testTcpMcpFxFamilyIsHotspot / testFxWindowStillHotspot. A loop that reruns both against a
+// fixed sampleId per surface string can't distinguish the surfaces (the loop body is identical
+// every iteration) — it isn't a stronger test than those two, so there is no separate test here.
+// The one thing that DOES vary by surface — the shell's TrackFX_AddByName `instantiate` value
+// picked for a container drop vs. a bare FX-button drop — lives in instrument_drop_win.cpp and
+// is untestable without a live DAW (GetThingFromPoint/TrackFX_AddByName have no pure model).
 
 // --- All-or-nothing rollback --------------------------------------------------
 
@@ -314,7 +300,6 @@ int main() {
     testNonFxSurfacesAreNotHotspot();
     testEmbedStripIsNotHotspot();
 
-    testEveryDropSurfaceCarriesTheCapture();
     testAddFailureLeavesNothingToRollBack();
     testPresetFailureRollsBackTheCreatedIndex();
     testSuccessKeepsTheInstance();