instrument: fix AHD node-tracking/tie-break/live-latch defects and close staged-envelope-curve test gaps

tests/test_component_state_io.cpp

@@ -681,6 +681,26 @@ static void testNonFiniteFilterFieldsLiftToTheNeutralDefault() {
     CHECK(g.enabled);
 }
 
+// A non-finite attackSeconds/decaySeconds on a stored AHD (a corrupt blob) must lift to 0
+// seconds rather than reach resolvePlay's static_cast<std::int64_t> (sample_map.cpp) — UB on
+// NaN, and on a large-enough finite value. Mirrors
+// testNonFiniteFilterFieldsLiftToTheNeutralDefault's per-field precedent, on the v10 AHD tail.
+static void testNonFiniteAhdSecondsLiftToZero() {
+    ComponentState in;
+    in.selectionId = "pad";
+    in.params.play.trigAhd.attackSeconds = std::numeric_limits<double>::quiet_NaN();
+    in.params.play.trigAhd.decaySeconds = std::numeric_limits<double>::infinity();
+    in.params.play.filter.trigEnv.attackSeconds = -std::numeric_limits<double>::infinity();
+    in.params.play.filter.trigEnv.decaySeconds = std::numeric_limits<double>::quiet_NaN();
+
+    const ComponentState out =
+        deserializeComponentState(serializeComponentState(in), 48000.0);
+    CHECK(out.params.play.trigAhd.attackSeconds == 0.0);
+    CHECK(out.params.play.trigAhd.decaySeconds == 0.0);
+    CHECK(out.params.play.filter.trigEnv.attackSeconds == 0.0);
+    CHECK(out.params.play.filter.trigEnv.decaySeconds == 0.0);
+}
+
 // The WRITER emits the CURRENT payload version, and the marker + version sit at the head of
 // the payload — the self-describing property every legacy branch depends on. Asserted
 // against the semantic constants, not literals.
@@ -1273,6 +1293,7 @@ int main() {
     testV8RecordLiftsToTheOffNeutralFilter();
     testFilterTailRoundTripsLosslessly();
     testNonFiniteFilterFieldsLiftToTheNeutralDefault();
+    testNonFiniteAhdSecondsLiftToZero();
     if (failures == 0) {
         std::printf("component_state_io_tests: all tests passed\n");
         return 0;