Clear stale hover on capture-loss and Alt-delete; derive gutter test via chromeRects

CMakeLists.txt

@@ -1034,7 +1034,7 @@ target_link_libraries(capture_browser_tests PRIVATE capture_browser)
 add_test(NAME capture_browser_tests COMMAND capture_browser_tests)
 
 add_executable(keyboard_strip_tests tests/test_keyboard_strip.cpp)
-target_link_libraries(keyboard_strip_tests PRIVATE keyboard_strip sample_bands)
+target_link_libraries(keyboard_strip_tests PRIVATE keyboard_strip sample_bands sample_chrome)
 add_test(NAME keyboard_strip_tests COMMAND keyboard_strip_tests)
 
 # waveform_view (S11): the pure marker geometry + zero-crossing snap. Links waveform_view (+

src/shell/instrument/editor_input.cpp

@@ -82,7 +82,10 @@ void ReaSamplerEditor::onMouseUp(int x, int y) {
     // hover_ is deliberately not re-resolved during a drag (see resolveHover's caller), so it
     // still names wherever the drag started. Re-resolve now against the release position, for
     // every drag kind — otherwise the next paint latches a stale hover (wrong note name/tooltip,
-    // wrong control outline) until the next WM_MOUSEMOVE.
+    // wrong control outline) until the next WM_MOUSEMOVE. This resolve runs before the release
+    // branches below can delete or relocate the hovered element; a future branch that does so
+    // must clear hover_ itself afterwards (as the curve drag-off delete does below) rather than
+    // rely on this resolve, which reflects pre-mutation state.
     resolveHover(x, y);
     // A scrollbar drag is transient UI (no parameter change), and the processor-side knobs
     // (the preview-velocity -2 sentinel, voice count, master gain) are per-instance settings

src/shell/instrument/editor_input_curve.cpp

@@ -47,7 +47,10 @@ void ReaSamplerEditor::handleCurveMouseDown(const Rect& r, int x, int y) {
     // Modifier-click (Alt) deletes an interior node — a discrete, final edit committed at once
     // (deletePoint refuses the two endpoints, so an Alt-click on them is a safe no-op).
     if (idx >= 0 && (GetKeyState(VK_MENU) & 0x8000) != 0) {
-        if (params_.velocityCurve.deletePoint(static_cast<std::size_t>(idx))) commitAndReload();
+        if (params_.velocityCurve.deletePoint(static_cast<std::size_t>(idx))) {
+            hover_ = HoverTarget{};  // a stale kCurveNode index would light a shifted node
+            commitAndReload();
+        }
         return;
     }
 

src/shell/instrument/editor_platform.cpp

@@ -231,6 +231,10 @@ LRESULT CALLBACK ReaSamplerEditor::wndProc(HWND hwnd, UINT msg, WPARAM wParam,
                     self->drag_ = DragKind::kNone;
                     self->dragParamId_ = -1;
                     self->curvePointIndex_ = -1;  // curve-node drag state (peer reset)
+                    // No cursor position is available here to re-resolve hover (unlike
+                    // onMouseUp's release coordinates), so clear rather than leave it naming
+                    // wherever the drag started.
+                    self->hover_ = HoverTarget{};
                     self->invalidate();
                 }
             }

tests/test_keyboard_strip.cpp

@@ -16,9 +16,11 @@
 // unverified by this suite (see src/core/instrument/CLAUDE.md).
 
 #include "../src/core/instrument/ui/keyboard_strip.h"
-#include "../src/core/instrument/ui/sample_bands.h"  // kPad, to derive the strip width the
+#include "../src/core/instrument/ui/sample_bands.h"   // computeSampleBands, to derive the CHROME
-                                                       // shipped default window (840x620,
+                                                       // band the shipped default window (840x620,
                                                        // editor_session.cpp) hands the strip
+#include "../src/core/instrument/ui/sample_chrome.h"  // chromeRects, to derive rootStrip's width
+                                                       // the same way the shell does
 
 #include <cstdio>
 #include <string>
@@ -288,8 +290,15 @@ static void testNoteNamesFollowTheC4Convention() {
 // one pixel of resize (840->841) collapses both gutters to zero and grows every white key
 // from 10px to 11px.
 static void testGutterAtTheShippedDefaultWindowSize() {
-    constexpr int kShippedDefaultWindowW = 840;  // editor_session.cpp's ViewRect default
+    constexpr int kShippedDefaultWindowW = 840;   // editor_session.cpp's ViewRect default
-    const int stripW = kShippedDefaultWindowW - 2 * kPad;  // chromeRects insets rootStrip by kPad
+    constexpr int kShippedDefaultWindowH = 620;   // editor_session.cpp's ViewRect default
+    // Derive rootStrip's width the same way the shell does, through the real allocator +
+    // chrome layout, rather than re-deriving the inset formula — so a change to either one
+    // fails this test instead of silently moving the shipped gutter out from under it.
+    const SampleBands bands =
+        computeSampleBands(kShippedDefaultWindowW, kShippedDefaultWindowH, 0);
+    const ChromeRects chrome = chromeRects(bands.chrome, /*knobSize=*/24);
+    const int stripW = chrome.rootStrip.width;
     CHECK(stripW == 824);
 
     const StripLayout L = layoutStrip(stripW, 30);