Merge pS-w1-t5-drop: fix drop-to-FX hotspot classifier, narrowed to tcp.fx/mcp.fx (S-VIEW-BUG-1)

tests/test_instrument_drop.cpp

@@ -105,6 +105,50 @@ static void testBase64DecodeRejectsMalformed() {
     CHECK(decodeBase64("Zg==Zg==").empty()); // interior padding (pad before the final quad)
 }
 
+// --- FX-hotspot classification (S-VIEW-BUG-1) ---------------------------------
+//
+// THE BUG: dropping a capture onto a track's FX button (in the TCP) never armed the
+// instrument drop, because the old predicate matched only "fx_" — which the SDK reserves for
+// the FX CHAIN / FLOATING-FX windows. A track-panel FX-button hit reports "tcp.fx"/"mcp.fx"
+// (SDK §GetThingFromPoint: "string will begin with 'tcp' or 'mcp' or 'tcp.mute' etc").
+//
+// THE FIX: narrow to two documented FX-bearing surfaces:
+//   * "tcp.fx" / "mcp.fx"  — the TCP/MCP FX button (exact token, NOT bare tcp/mcp)
+//   * "fx_*"               — the FX-chain / floating-FX windows (prefix, as before)
+// Bare "tcp"/"mcp" and any other "tcp.*"/"mcp.*" sub-element (e.g. "tcp.mute", "tcp.vol")
+// are non-FX track-panel regions — an instrument drop must NOT fire there.
+
+// The TCP/MCP FX button specifically — the surface that arms an instrument drop (S-VIEW-BUG-1
+// fix). Under the old "fx_"-only predicate these returned false — the exact miss that produced
+// the "drops as audio to arrange" symptom on the FX button.
+static void testTcpMcpFxButtonIsHotspot() {
+    CHECK(infoNamesFxHotspot("tcp.fx"));    // TCP FX button (SDK token)
+    CHECK(infoNamesFxHotspot("mcp.fx"));    // MCP FX area (SDK token)
+}
+
+// The FX chain / floating-FX windows (the surfaces the ORIGINAL predicate matched) still
+// classify as hotspots — the fix does not regress the "fx_" surface.
+static void testFxWindowStillHotspot() {
+    CHECK(infoNamesFxHotspot("fx_chain"));  // FX chain window
+    CHECK(infoNamesFxHotspot("fx_0"));      // first FX, floating
+    CHECK(infoNamesFxHotspot("fx_12"));     // arbitrary floating-FX index
+}
+
+// Non-FX surfaces are NOT hotspots — a drop here is not an instrument drop (it would fall
+// through to the OS drag / no-op). This includes the bare TCP/MCP tokens and all non-FX
+// "tcp.*"/"mcp.*" sub-elements (e.g. mute button, volume fader, track name, meter).
+static void testNonFxSurfacesAreNotHotspot() {
+    CHECK(!infoNamesFxHotspot("tcp"));       // bare track control panel — NOT an FX hotspot
+    CHECK(!infoNamesFxHotspot("mcp"));       // bare mixer control panel — NOT an FX hotspot
+    CHECK(!infoNamesFxHotspot("tcp.mute"));  // mute button — track panel, not FX
+    CHECK(!infoNamesFxHotspot("tcp.vol"));   // volume fader — track panel, not FX
+    CHECK(!infoNamesFxHotspot("arrange"));
+    CHECK(!infoNamesFxHotspot("spacer_0"));
+    CHECK(!infoNamesFxHotspot(""));          // pointer over nothing REAPER classifies
+    CHECK(!infoNamesFxHotspot("trans"));     // transport
+    CHECK(!infoNamesFxHotspot("envcp"));     // envelope control panel — a track thing, not FX
+}
+
 int main() {
     testBlobRoundTripsThroughInstrumentReader();
     testGuidLikeIdRoundTrips();
@@ -114,6 +158,10 @@ int main() {
     testBase64RoundTripAllBytes();
     testBase64DecodeRejectsMalformed();
 
+    testTcpMcpFxButtonIsHotspot();
+    testFxWindowStillHotspot();
+    testNonFxSurfacesAreNotHotspot();
+
     if (g_fail == 0) std::printf("All tests passed.\n");
     return g_fail ? 1 : 0;
 }