tooltip: clamp box width to client on narrow panels; add narrow-client test

src/bank_panel.cpp

@@ -1098,6 +1098,9 @@ bool currentTooltip(int w, int h, std::string& textOut, int& ax, int& ay, int& a
 
     // The full name is stored already prefix-free, but strip defensively in case a source ever
     // carries the "ReaSampler:" display prefix (the tooltip must never show it — L5 refinement 2).
+    // Intentionally distinct sources: the tooltip reads the registered phrase (fullName) while the
+    // keybinding sub-row in drawToolbar reads the live binding via kbd_getTextFromCmd. Do not
+    // unify them — each serves a different purpose and has a different lifetime.
     textOut = stripActionPrefix(rows[static_cast<std::size_t>(hv.index)].fullName,
                                 actionDisplayPrefix());
     ax = slot->x; ay = slot->y; aw = slot->width; ah = slot->height;

src/tooltip.cpp

@@ -18,7 +18,10 @@ TooltipBox computeTooltip(int anchorX, int anchorY, int anchorW, int anchorH,
     TooltipBox box;
     if (textW <= 0 || textH <= 0 || clientW <= 0 || clientH <= 0) return box;
 
-    const int boxW = textW + 2 * spec.padX;
+    // Clamp boxW so it never exceeds the available client span; then clamp x so the (possibly
+    // reduced) box always sits within [margin, clientW - margin].
+    const int maxBoxW = clientW - 2 * spec.margin;
+    const int boxW = (textW + 2 * spec.padX < maxBoxW) ? textW + 2 * spec.padX : maxBoxW;
     const int boxH = textH + 2 * spec.padY;
 
     // Horizontal: centre on the anchor, then clamp within [margin, clientW - margin - boxW].

tests/test_tooltip.cpp

@@ -93,6 +93,20 @@ static void testBothClipClampsBottom() {
     CHECK(tb.y == 2);
 }
 
+// --- Narrow client: box width clamped ----------------------------------------
+
+// When the client is narrower than the box's natural width, the box is shrunk to fit and
+// the result satisfies x >= margin AND x + width <= clientW - margin.
+// Natural boxW = 80+12 = 92. Narrow client = 60. maxBoxW = 60-4 = 56.
+// Clamped boxW = 56. x = 2 + (108-56)/2 ... centred but clamped to [2, 60-2-56] = [2, 2].
+static void testNarrowClientBoxClamped() {
+    const TooltipSpec spec{};  // margin = 2
+    const TooltipBox tb = computeTooltip(2, 10, 108, 34, 80, 14, 60, 300, spec);
+    CHECK(!tb.empty());
+    CHECK(tb.x >= spec.margin);
+    CHECK(tb.x + tb.width <= 60 - spec.margin);
+}
+
 // --- Degenerate --------------------------------------------------------------
 
 static void testDegenerateEmpty() {
@@ -113,6 +127,7 @@ int main() {
     testClampLeft();
     testFlipAbove();
     testBothClipClampsBottom();
+    testNarrowClientBoxClamped();
     testDegenerateEmpty();
 
     if (g_fail == 0) std::printf("tooltip: all tests passed\n");