Fix Insert-as-FX review findings: id rename, selection-count drift, refusal tooltip, success msg, master-only, reserve test

Renames the permanent action id out of the placement family, makes the button's
painted state and pressed outcome share one selection count, surfaces
panel-known refusals in the tooltip, reports the target track on success,
distinguishes a master-only selection, and pins the overflow-reserve test to the
real bar spec.

tests/test_action_bar.cpp

@@ -229,6 +229,48 @@ static void testOverflowReserveHonouredAcrossWidths() {
     CHECK(sawReserveCostAButton);
 }
 
+// --- Reserve against the REAL panel spec: names the button and the exact width -----
+
+// roundSpec() above uses clusterGap=16 for hand-checkable pixel math; the panel's actual
+// bar (shell/panel/panel_state.h's kBarSpec) uses clusterGap=24. Reproduced literally here
+// because this test target is REAPER-free and cannot include that shell header -- keep
+// the two in sync by hand if either spec ever changes.
+static ActionBarSpec realBarSpec() {
+    ActionBarSpec s;
+    s.buttonWidth = 108;
+    s.buttonGap = 4;
+    s.clusterGap = 24;
+    s.sidePad = 8;
+    s.verticalInset = 3;
+    return s;
+}
+
+// At the real spec plus the real 40 px reserve (28 + 2*6, panel_state.h's kMenuBtnSpec --
+// all default-constructed here since its defaults already match), 764 is the narrowest
+// band that still shows all six buttons; one pixel narrower drops Insert as FX (flat index
+// 5, the trailing Placement button) alone into overflow, leaving its five neighbours intact.
+static void testReserveDropsInsertAsFxAtRealWidth() {
+    const auto clusters = inventory();
+    const ActionBarSpec spec = realBarSpec();
+    const MenuButtonSpec menuSpec;
+    const int reserve = menuButtonReserve(MenuBarRect{0, 0, 900, 34}, menuSpec);
+    CHECK(reserve == 40);
+
+    const int allSixWidth = 764;
+    {
+        ActionBarRect action{0, 0, allSixWidth - reserve, 34};
+        const auto slots = computeBarSlots(action, clusters, spec);
+        CHECK(slots.size() == 6);
+        CHECK(slots.back().index == 5);  // Insert as FX still visible
+    }
+    {
+        ActionBarRect action{0, 0, allSixWidth - 1 - reserve, 34};
+        const auto slots = computeBarSlots(action, clusters, spec);
+        CHECK(slots.size() == 5);        // Insert as FX alone dropped
+        CHECK(slots.back().index == 4);  // Insert Conform is now the trailing visible button
+    }
+}
+
 // --- Degenerate --------------------------------------------------------------
 
 static void testDegenerate() {
@@ -356,6 +398,7 @@ int main() {
     testOverflowDropsTrailingWhole();
     testTooNarrowForAny();
     testOverflowReserveHonouredAcrossWidths();
+    testReserveDropsInsertAsFxAtRealWidth();
     testDegenerate();
     testHitTestHitsButtons();
     testHitTestGapsAreMisses();

tests/test_insert_fx_enable.cpp

@@ -27,6 +27,18 @@ static void testEveryCombination() {
     CHECK(insertFxRefusal(3, true) == InsertFxRefusal::MultiCapture);
 }
 
+// GetSelectedTrack ignores the master track, so "only the master is selected" is a
+// distinct refusal from a plain empty selection -- both are !trackSelected, but the
+// message differs so a master-only user isn't told "select a track" when they did.
+static void testMasterOnlySelectedIsDistinctFromNoTrack() {
+    CHECK(insertFxRefusal(1, false, /*masterOnlySelected=*/true) ==
+          InsertFxRefusal::MasterOnlySelected);
+    CHECK(insertFxRefusal(1, false, /*masterOnlySelected=*/false) == InsertFxRefusal::NoTrack);
+    // The payload axis still runs first -- a bad capture count refuses on ITS reason
+    // even with the master selected.
+    CHECK(insertFxRefusal(0, false, /*masterOnlySelected=*/true) == InsertFxRefusal::NoCapture);
+}
+
 // Exactly one capture is the only count that can run; two is already too many.
 static void testOnlyASingleCaptureRuns() {
     CHECK(insertFxRefusal(2, true) == InsertFxRefusal::MultiCapture);
@@ -68,18 +80,24 @@ static void testEveryRefusalHasItsOwnSentence() {
     const std::string noCap = insertFxRefusalMessage(InsertFxRefusal::NoCapture);
     const std::string multi = insertFxRefusalMessage(InsertFxRefusal::MultiCapture);
     const std::string noTrk = insertFxRefusalMessage(InsertFxRefusal::NoTrack);
+    const std::string masterOnly = insertFxRefusalMessage(InsertFxRefusal::MasterOnlySelected);
 
     CHECK(none.empty());
     CHECK(!noCap.empty());
     CHECK(!multi.empty());
     CHECK(!noTrk.empty());
+    CHECK(!masterOnly.empty());
     CHECK(noCap != multi);
     CHECK(noCap != noTrk);
     CHECK(multi != noTrk);
+    CHECK(masterOnly != noTrk);
+    CHECK(masterOnly != noCap);
+    CHECK(masterOnly != multi);
 }
 
 int main() {
     testEveryCombination();
+    testMasterOnlySelectedIsDistinctFromNoTrack();
     testOnlyASingleCaptureRuns();
     testNegativeCountRefuses();
     testButtonBitIsThePayloadAxisOfTheFold();