fix(q-w0): six audit fix-nows — linked-lag stereo SOLA, playable-span prime bound, declick dead-state, provenance cursor hardening, rate-derived gain ramp + fade ceiling

tests/test_sampler_core.cpp

@@ -2474,6 +2474,68 @@ static void testPreserveTriggerTailGapFree() {
     }
 }
 
+// --- Q-W0 T1-03: the Preserve prime is bounded by the PLAYABLE span. A Trigger zone whose
+//     play length is shorter than the OLA window must never carry source PAST the user's
+//     chosen stop into the ring — pre-fix, the prime pulled a full window bounded only by
+//     frameCount, and an up-shifted tap PLAYED the cut content (transposed) before the voice
+//     freed. The sample poisons everything past playEnd with amplitude 8: if any of it
+//     reaches the output, the peak bound fails. ---
+static void testPreservePrimeStopsAtTriggerPlayEnd() {
+    const std::size_t frames = 8000;
+    const std::size_t w = 2048;          // OLA window >> playable span
+    const std::size_t playLen = 500;     // playEnd = round(8000 * 0.0625) = 500
+    SampleData s;
+    s.frames.resize(frames);
+    const double f0 = 1.0 / 50.0;        // 10 cycles inside the playable span
+    for (std::size_t i = 0; i < frames; ++i) {
+        s.frames[i] = i < playLen
+            ? static_cast<float>(std::sin(2.0 * kPi * f0 * static_cast<double>(i)))
+            : 8.0f;                       // POISON: cut content past the play end
+    }
+    s.rootNote = 60;
+    s.play.playMode = PlayMode::Trigger;
+    s.play.pitchEngine = PitchEngine::Preserve;
+    s.play.trigger.lengthFraction = 0.0625;  // exactly 500 / 8000
+    Keymap km = Keymap::singleSampleChromatic(std::move(s));
+    VoiceEngine eng(1, km, /*preserveCap=*/0, static_cast<std::int64_t>(w));
+    eng.noteOn(72, 127);                 // +1 octave: the tap outruns the read head into
+                                         // the deepest primed history the ring holds
+    std::vector<AudioSample> out;
+    eng.render(out, playLen + 64);       // through the voice's own end (readPos >= playEnd)
+    double peak = 0.0;
+    for (const AudioSample v : out) {
+        const double a = std::fabs(static_cast<double>(v));
+        if (a > peak) peak = a;
+    }
+    CHECK(peak < 1.5);   // the 8.0 poison never sounds: nothing past playEnd entered the ring
+    CHECK(peak > 0.4);   // ...and the real span genuinely played (the bound is not vacuous)
+}
+
+// --- Q-W0 T1-03 (companion): a whole sample SHORTER than the window (Gate, no loop) must not
+//     get zero padding declared as valid ring history — pre-fix, the prime zero-filled the
+//     window remainder with filled_ = window, so splices/tap travel landed in silence:
+//     hundreds-of-frames dead runs inside a sub-window one-shot (the pre-GA2 burst/gap
+//     artifact re-entering for short material). Post-fix the prime stops at the sample end
+//     and freezes the tail immediately, so the ring recycles ONLY real content. ---
+static void testPreserveSubWindowSampleNoZeroPadInRing() {
+    const std::size_t frames = 1200;     // sample < one window
+    const std::size_t w = 2048;
+    const double f0 = 1.0 / 96.0;        // period 96: zero crossings dwell ~2 frames
+    SampleData s = tailSine(frames, f0, 60);
+    s.play.pitchEngine = PitchEngine::Preserve;
+    s.play.adsr = flatAdsr();
+    Keymap km = Keymap::singleSampleChromatic(std::move(s));
+    VoiceEngine eng(1, km, /*preserveCap=*/0, static_cast<std::int64_t>(w));
+    eng.noteOn(72, 127);                 // +1 octave up-shift (tap sweeps the whole ring)
+    std::vector<AudioSample> out;
+    eng.render(out, frames);             // voice runs to its natural end (no loop)
+    // Pre-fix: the tap crossed the declared-valid zero pad repeatedly — quiet runs of 150+
+    // frames. Post-fix every relocation stays inside the real filled span; only sine zero
+    // crossings dip below the threshold.
+    CHECK(worstQuietRun(out, 0, frames, 0.05) < 30);
+    CHECK(blockPeak(out, 0, frames) > 0.5);   // and it genuinely played at full level
+}
+
 int main() {
     testChromaticSingleRoot();
     testZonedRangesBoundaries();
@@ -2584,6 +2646,11 @@ int main() {
     testPreserveTailReleaseContinuous();
     testPreserveTriggerTailGapFree();
 
+    // Q-W0 T1-03 — the prime is bounded by the playable span (Trigger playEnd / sample end),
+    // with an immediate tail freeze on sub-window spans.
+    testPreservePrimeStopsAtTriggerPlayEnd();
+    testPreserveSubWindowSampleNoZeroPadInRing();
+
     if (g_fail == 0) {
         std::printf("all sampler_core tests passed\n");
         return 0;