Play cross-rate captures at their own pitch and length

The voice now converts the file's rate to the host's at note-on instead of assuming they match. Stage times resolve at the host rate, the filter solves at it, and the bake follows. Same-rate renders are unchanged bit for bit.

tests/test_bake_window.cpp

@@ -11,6 +11,9 @@
 #include <cmath>
 #include <cstdio>
 #include <optional>
+#include <vector>
+
+#include "tone_metrics.h"
 
 using namespace reasampler;
 using namespace reasampler::instrument::bake;
@@ -488,6 +491,54 @@ int main() {
         CHECK(hardPeak > softPeak * 2.0);
     }
 
+    // ============================ SOURCE RATE =======================================
+
+    // --- A capture at another rate bakes at its own pitch and its own wall-clock length --
+    // 441 Hz for one second of a 44.1k file, baked at 48k: the window must hold 48000 frames
+    // of sound (not the source's 44100), and the print must be 441 Hz at the render rate.
+    for (PitchEngine engine : {PitchEngine::Varispeed, PitchEngine::Preserve}) {
+        constexpr int kFileRate = 44100;
+        constexpr double kHz = 441.0;
+        SampleData s;
+        s.frames.resize(static_cast<std::size_t>(kFileRate));
+        for (std::size_t i = 0; i < s.frames.size(); ++i) {
+            s.frames[i] = static_cast<float>(
+                0.5 * std::sin(2.0 * 3.14159265358979323846 * kHz * static_cast<double>(i) /
+                               kFileRate));
+        }
+        s.sampleRate = kFileRate;
+        s.renderRate = kRate;
+        s.rootNote = 60;
+        s.play.playMode = PlayMode::Trigger;
+        s.play.pitchEngine = engine;
+        s.play.trigAhd.holdFraction = 1.0;
+
+        CHECK(derivedFrames(s) == kRate + kPad);
+        const BakeAudio audio = bakeWith(s, 0.0);
+        CHECK(peakAt(audio, kRate - 1000, kRate - 10) > 0.4);  // still sounding near 1 s
+        CHECK(lastSoundingFrame(audio) < audio.frameCount() - 1);  // and done inside the window
+
+        std::vector<double> mono(static_cast<std::size_t>(audio.frameCount()));
+        for (std::size_t f = 0; f < mono.size(); ++f) {
+            mono[f] = audio.interleaved[f * static_cast<std::size_t>(audio.channelCount)];
+        }
+        const double want = static_cast<double>(kRate) / kHz;
+        const double got = reasampler::test_support::autocorrelationPeriod(
+            mono, 10000, 8000, static_cast<std::int64_t>(want * 0.5),
+            static_cast<std::int64_t>(want * 1.7));
+        CHECK(std::fabs(got - want) < 0.005 * want);
+    }
+
+    // --- A snapshot resolved for another output rate is refused, not printed off-pitch ---
+    {
+        SampleData s = dcSample(24000);
+        s.renderRate = 44100;  // resolved for 44.1k; the plan renders at 48k
+        s.play.playMode = PlayMode::Trigger;
+        const std::optional<BakePlan> plan = planOf(derivedProgram(s, 0.0));
+        CHECK(plan.has_value());
+        if (plan) CHECK(renderBake(s, *plan, kUnity, kNoLimiter).empty());
+    }
+
     // ============================== REFUSALS ========================================
 
     // --- A legitimate dialed sound past the frame ceiling is REFUSED, and says so --------