instrument: snap live params onto a fresh voice, roll a live drag back on capture loss, serialize the seqlock's two writers

tests/test_deck_groups.cpp

@@ -2,8 +2,9 @@
 // framework. knob_deck's own tests pin how a descriptor list LAYS OUT; these pin WHICH
 // descriptors the Sample face carries: the signal-flow group order (pitch -> filter -> amp),
 // the Filter group's contents, the wrapped deck height at the editor's floor width and its fit
-// inside the floor window, the hit-test reaching the new filter controls, and the bipolar knob
-// law's inverse pair.
+// inside the floor window, the hit-test reaching the new filter controls, the bipolar knob
+// law's inverse pair, and the commit-tier routing — which controls are live, and which drags
+// take the live tier.
 
 #include "../src/core/instrument/ui/deck_groups.h"
 #include "../src/core/instrument/ui/sample_bands.h"
@@ -186,7 +187,7 @@ static void testBipolarKnobLawRoundTripsAndIsExactAtCentre() {
     CHECK(deckNormFromBipolar(3.0) == 1.0);
 }
 
-static void testLiveRoutingCoversEveryContinuousPlaybackControl() {
+static void testEveryDeckControlIsClassifiedLiveOrReloading() {
     // The live set: the six filter tone/modulation knobs, plus every stage time and stage
     // level on all three envelopes.
     const DeckParam live[] = {
@@ -200,9 +201,8 @@ static void testLiveRoutingCoversEveryContinuousPlaybackControl() {
     };
     for (DeckParam p : live) CHECK(isLiveDeckParam(p));
 
-    // Everything else reloads or rebuilds. kFilterVel and kKeyTrack are the two that look
-    // continuous but feed values a voice latches at note-on (the velocity-curve result and
-    // the pitch ratio) — making them live would re-gain or retune a note already struck.
+    // Everything else reloads or rebuilds; deck_groups.h is the home for why each exclusion
+    // is excluded.
     const DeckParam reloads[] = {
         DeckParam::kPlayMode, DeckParam::kPitchEngine, DeckParam::kPitchEnvEnable,
         DeckParam::kFilterEnable, DeckParam::kFilterLaw, DeckParam::kFilterVel,
@@ -212,14 +212,49 @@ static void testLiveRoutingCoversEveryContinuousPlaybackControl() {
     };
     for (DeckParam p : reloads) CHECK(!isLiveDeckParam(p));
 
-    // Every id in the space is classified by one of the two lists above, so a control added
-    // later cannot slip through unclassified.
-    const std::size_t classified = (sizeof(live) + sizeof(reloads)) / sizeof(DeckParam);
-    CHECK(classified == static_cast<std::size_t>(DeckParam::kCount));
+    // COVERAGE, not cardinality: every id appears in EXACTLY ONE of the two lists. A sum check
+    // would stay green if an edit duplicated one id and dropped another, leaving that one
+    // unclassified.
+    for (int i = 0; i < static_cast<int>(DeckParam::kCount); ++i) {
+        const DeckParam p = static_cast<DeckParam>(i);
+        int seen = 0;
+        for (DeckParam q : live) if (q == p) ++seen;
+        for (DeckParam q : reloads) if (q == p) ++seen;
+        if (seen != 1) std::printf("  (deck id %d classified %d times)\n", i, seen);
+        CHECK(seen == 1);
+    }
+}
+
+static void testOnlyALiveControlsDragTakesTheLiveTier() {
+    // isLiveDeckParam alone is not what a user experiences — liveCommitFor is, at the editor's
+    // commit site. Inverting it has to FAIL a test rather than merely read wrong.
+    CHECK(liveCommitFor(LiveDragKind::kDeckKnob, static_cast<int>(DeckParam::kFilterCutoff),
+                        PlayMode::Gate));
+    // A knob's routing is the knob's, not the play mode's.
+    CHECK(liveCommitFor(LiveDragKind::kDeckKnob, static_cast<int>(DeckParam::kAttack),
+                        PlayMode::Trigger));
+    CHECK(!liveCommitFor(LiveDragKind::kDeckKnob, static_cast<int>(DeckParam::kTrigFadeIn),
+                         PlayMode::Trigger));
+    CHECK(!liveCommitFor(LiveDragKind::kDeckKnob, static_cast<int>(DeckParam::kMasterGain),
+                         PlayMode::Gate));
+    // The shell's processor-side sentinels (preview velocity is -2) and any out-of-range id
+    // are not parameter-set controls, so they must never reach the enum.
+    CHECK(!liveCommitFor(LiveDragKind::kDeckKnob, -2, PlayMode::Gate));
+    CHECK(!liveCommitFor(LiveDragKind::kDeckKnob, -1, PlayMode::Gate));
+    CHECK(!liveCommitFor(LiveDragKind::kDeckKnob, static_cast<int>(DeckParam::kCount),
+                         PlayMode::Gate));
+    // An envelope-node drag edits the AHDSR in Gate; the same drag in Trigger rewrites the
+    // play span, which is not a live control.
+    CHECK(liveCommitFor(LiveDragKind::kEnvNode, -1, PlayMode::Gate));
+    CHECK(!liveCommitFor(LiveDragKind::kEnvNode, -1, PlayMode::Trigger));
+    // Every other drag (markers, scrollbar, curve nodes) commits through a reload.
+    CHECK(!liveCommitFor(LiveDragKind::kOther, static_cast<int>(DeckParam::kFilterCutoff),
+                         PlayMode::Gate));
 }
 
 int main() {
-    testLiveRoutingCoversEveryContinuousPlaybackControl();
+    testEveryDeckControlIsClassifiedLiveOrReloading();
+    testOnlyALiveControlsDragTakesTheLiveTier();
     testDeckReadsPitchThenFilterThenAmpLeftToRight();
     testFilterGroupCarriesItsFiveToneControlsPlusModulation();
     testAmpGroupWidthSurvivesAGateTriggerFlip();