1 files changed, 22 insertions, 3 deletions
diff --git a/tools/feed-wheel-reverse-test.js b/tools/feed-wheel-reverse-test.js
index d8cc44a..8a00b11 100644
--- a/tools/feed-wheel-reverse-test.js
+++ b/tools/feed-wheel-reverse-test.js
@@ -28,6 +28,7 @@ function fixture() {
     frame(stamp = now) { const callbacks = [...frames.values()]; frames.clear(); for (const fn of callbacks) fn(stamp); },
   };
 }
+const settle = (f, n = 70) => { for (let i = 0; i < n; i++) { f.advance(17); f.frame(); } };
 for (const dir of [1, -1]) {
   const f = fixture();
   f.wheel(dir); f.advance(17); f.frame();
@@ -44,7 +45,25 @@ for (const dir of [1, -1]) {
   f.advance(17); f.frame();
   assert((f.y - reversed) * dir < 0, 'next frame continues in the new direction');
   assert(Math.abs(f.y - reversed) < 20, 'new velocity is not applied to the old frame delay');
-  for (let i = 0; i < 100; i++) { f.advance(17); f.frame(); }
-  assert(Math.abs(f.y - before) > 280 && Math.abs(f.y - before) < 330, 'one notch retains its coast distance');
+  settle(f);
+  // The turn back is a hunt: a quarter of a notch's travel, not a flight the other way.
+  const back = (before - f.y) * dir;
+  assert(back > 65 && back < 90, 'a reverse notch against a coast is a short step: ' + back);
+  // Each notch on grows the step back towards a full one; the sixth is a plain notch again.
+  const steps = [];
+  for (let i = 0; i < 5; i++) { f.advance(200); const y = f.y; f.wheel(-dir); settle(f); steps.push((y - f.y) * dir); }
+  assert(steps.every((s, i) => i === 0 || s > steps[i - 1] * 1.08), 'hunting steps grow notch by notch: ' + steps.map(Math.round));
+  assert(steps[0] > 95 && steps[0] < 125 && steps[3] > 240 && steps[3] < 285 && steps[4] > 280 && steps[4] < 330, 'from about a third of a notch to a full one: ' + steps.map(Math.round));
+  { f.advance(200); const y = f.y; f.wheel(-dir); settle(f); const s = (y - f.y) * dir; assert(s > 280 && s < 330, 'a few flicks on, the wheel flies again: ' + s); }
+  // A turn back while hunting starts the small steps over.
+  f.wheel(-dir); f.advance(17); f.frame(); f.advance(17); f.frame();
+  { const y = f.y; f.wheel(dir); settle(f); const s = (f.y - y) * dir; assert(s > 65 && s < 90, 'a reversal while hunting is a short step again: ' + s); }
+  { f.advance(300); const y = f.y; f.wheel(dir); settle(f); const s = (f.y - y) * dir; assert(s > 95 && s < 120, 'and the next grows from there: ' + s); }
+  // A pause ends the hunt: the next notch is the plain push from rest.
+  { f.advance(2200); const y = f.y; f.wheel(dir); settle(f); const s = (f.y - y) * dir; assert(s > 280 && s < 330, 'after a pause a notch is a full push: ' + s); }
+  // A turn back against a coast that only just died hunts too.
+  { f.wheel(dir); settle(f); f.advance(200); const y = f.y; f.wheel(-dir); settle(f); const s = (y - f.y) * dir; assert(s > 65 && s < 90, 'reversing right after the coast dies is a short step: ' + s); }
+  // ...but a notch from rest the other way, well after, is a full one.
+  { f.advance(2500); const y = f.y; f.wheel(dir); settle(f); const s = (f.y - y) * dir; assert(s > 280 && s < 330, 'from rest a notch either way is a full push: ' + s); }
 }
-console.log('✓ immediate reversal both ways, stale frame timestamps, busy frame recovery, and coast distance');
+console.log('✓ immediate reversal both ways, stale frame timestamps, busy frame recovery, precision hunt after a reversal (short steps that grow, restart on another turn back, end on a pause)');