S4 Tier 0: the bank plays — VST3 marshals MIDI to the S3 core, reads the live bank + resolves WAV the M4 way, mono downmix, lock-free load handoff, LICE sample-pick

src/vst/editor_geometry.cpp

@@ -53,4 +53,23 @@ HitTarget hitTest(const EditorLayout& layout, int x, int y) {
     return HitTarget::kNone;
 }
 
+Rect sampleRowRect(const EditorLayout& layout, int index) {
+    if (index < 0) return Rect{};
+    const int top = layout.canvas.top + index * kSampleRowHeight;
+    return Rect{layout.canvas.left, top, layout.canvas.right, top + kSampleRowHeight};
+}
+
+int sampleRowHitTest(const EditorLayout& layout, int rowCount, int x, int y) {
+    if (rowCount <= 0) return -1;
+    // Must be within the canvas horizontally and at/below its top.
+    if (x < layout.canvas.left || x >= layout.canvas.right) return -1;
+    if (y < layout.canvas.top) return -1;
+    const int index = (y - layout.canvas.top) / kSampleRowHeight;
+    if (index < 0 || index >= rowCount) return -1;
+    // Guard the bottom edge: a click below the last row's canvas bottom is outside.
+    const Rect r = sampleRowRect(layout, index);
+    if (y >= r.bottom) return -1;
+    return index;
+}
+
 }  // namespace reasampler::vst