fix: final-review findings (median pass tick, R11 secondary metrics, R12 chord duration, render version, dsp resample)

Co-Authored-By: Claude Sonnet 5.5 <[email protected]>

tests/pipeline/quantize.test.ts

@@ -15,11 +15,19 @@ test("drops notes before the first downbeat", () => {
   expect(q.map((n) => n.pitch)).toEqual([62]);
 });
 
-test("merges chord notes within 35 ms, with one consistent duration", () => {
+test("merges chord notes within 35 ms, with one consistent (median) duration", () => {
+  // snapped durations: 8, 4, 8 steps -> median 8
   const q = quantize([t(0.6, 1.6, 60), t(0.625, 1.1, 64), t(0.63, 1.6, 67)], g);
   expect(new Set(q.map((n) => n.tick)).size).toBe(1);
   expect(new Set(q.map((n) => n.dur)).size).toBe(1);
   expect(q).toHaveLength(3);
+  expect(q[0]!.dur).toBe(8 * 240);
+});
+
+test("one 70 ms ghost note does not collapse a long chord (median duration)", () => {
+  const q = quantize([t(0.5, 2.5, 60), t(0.5, 2.5, 64), t(0.5, 0.57, 67)], g);
+  expect(q).toHaveLength(3);
+  for (const n of q) expect(n.dur).toBe(16 * 240);
 });
 
 test("collapses exact duplicates, enforces min duration", () => {