instrument: the filter's velocity depth knob returns and multiplies the bipolar curve; the pre-v12 lift is a pure domain re-tag

tests/test_deck_groups.cpp

@@ -120,7 +120,8 @@ static void testFilterGroupCarriesItsToneControlsPlusModulation() {
     const std::vector<int> expected = {
         cell(DeckParam::kFilterMorph),  cell(DeckParam::kFilterCutoff),
         cell(DeckParam::kFilterQ),      cell(DeckParam::kFilterDrive),
-        cell(DeckParam::kFilterModAmt), cell(DeckParam::kFilterKeyTrack)};
+        cell(DeckParam::kFilterModAmt), cell(DeckParam::kFilterVel),
+        cell(DeckParam::kFilterKeyTrack)};
     CHECK(f.cellIds == expected);
     // Off by default is a state question, but reachability is a layout one: the enable
     // toggle is in the caption row and the morph law in the knob row.
@@ -237,9 +238,10 @@ static void testAmpGroupWidthSurvivesAGateTriggerFlip() {
 static void testWrappedDeckHeightAtTheEditorFloorWidth() {
     const std::vector<DeckGroupDesc> g = sampleDeckGroups(PlayMode::Gate);
     // At the floor (== default) 840 the deck takes three rows: PITCH + PITCH ENV + FILTER fill
-    // the first, FILTER ENV + AMP + VELOCITY the second, VOICE + MASTER the third. The eight
-    // groups total more than two rows can hold at this width — the VELOCITY group's three
-    // cells are ~150 px more than the FILTER group gave back when its velocity depth retired.
+    // the first (818 of the 824 available — six px of headroom, so one more FILTER cell would
+    // wrap the group and reflow everything under it), FILTER ENV + AMP + VELOCITY the second,
+    // VOICE + MASTER the third. Two rows cannot hold the eight groups in ANY order at this
+    // width: 1666 px of group plus 72 px of gaps against a 1648 px two-row capacity.
     CHECK(deckRowCount(g, kAvailAtMinWidth) == 3);
     CHECK(deckHeight(g, kAvailAtMinWidth) == 3 * kDeckGroupH + 2 * kDeckRowGap);
 
@@ -285,7 +287,7 @@ static void testHitTestResolvesTheNewFilterControls() {
         CHECK(hit.kind == DeckHitKind::Knob);
         CHECK(hit.id == c.id);
     }
-    CHECK(f.cells.size() == 6);
+    CHECK(f.cells.size() == 7);
     CHECK(f.cells[1].id == cell(DeckParam::kFilterCutoff));
 
     // The enable toggle's two segments and the morph-law row toggle's two.
@@ -333,11 +335,12 @@ static void testBipolarKnobLawRoundTripsAndIsExactAtCentre() {
 }
 
 static void testEveryDeckControlIsClassifiedLiveOrReloading() {
-    // The live set: the six filter tone/modulation knobs, plus every stage time, stage level,
+    // The live set: the seven filter tone/modulation knobs, plus every stage time, stage level,
     // hold fraction and curve exponent on all three envelopes — in BOTH mode shapes.
     const DeckParam live[] = {
         DeckParam::kFilterMorph, DeckParam::kFilterCutoff, DeckParam::kFilterQ,
-        DeckParam::kFilterDrive, DeckParam::kFilterModAmt, DeckParam::kFilterKeyTrack,
+        DeckParam::kFilterDrive, DeckParam::kFilterModAmt, DeckParam::kFilterVel,
+        DeckParam::kFilterKeyTrack,
         DeckParam::kAttack, DeckParam::kHold, DeckParam::kDecay, DeckParam::kSustain,
         DeckParam::kRelease,
         DeckParam::kTrigAttack, DeckParam::kTrigHold, DeckParam::kTrigDecay,