The wheel coasts over a video and on a thread, and a turn back against a coast is a gentler half push that winds up again from the next notch.

A notch with the pointer over a clip fell to the browser's single-notch scroll: video and audio were on the wheel handler's hands-off list from the first commit, though the wheel does nothing to a player itself. The thread page was outside the handler's scope altogether, so a thread scrolled plain while the feed coasted. Both coast now, like the words around them (Adam, 2026-10-16).

A reversal was a full notch the other way followed by two notches without wind-up, and felt like an overshoot. It is now half a notch's travel at half the speed, so the reader who flew past a post settles back onto it; the next notch the same way is a plain one, winding up from whatever speed the half push left, so a spin on after a reversal gets going at once. (The five-notch quarter-size hunt stays gone.)

feed-wheel-reverse-test: the half push, the wind-up from the second notch, a notch over a video / audio / a thread coasts, one in a text box or the pager does not; the fixture's target can sit inside a given element and on a thread page.

Co-Authored-By: Claude Fable 5.1 <[email protected]>
Claude-Session: https://claude.ai/code/session_01J1Kon8bxJoHRpJdSzshCkp

1 files changed, 24 insertions, 17 deletions

diff --git a/src/app.js b/src/app.js
index dae7b17..96c6af1 100644
--- a/src/app.js
+++ b/src/app.js
@@ -6617,13 +6617,17 @@ if (INTENT_URI) {
 // selection, and a drag that moved isn't a click on what it started on.
 (() => {
   if (typeof window === 'undefined' || matchMedia('(prefers-reduced-motion: reduce)').matches) return;
-  const SCOPE = '.feed-page, .notes-feed';
+  const SCOPE = '.feed-page, .notes-feed, .thread-page'; // a thread scrolls the same as a feed (Adam, 2026-10-16)
   const TAU = 325; // ms: how quickly a coast dies down (the phone's feel)
   const VMAX = 16; // px/ms
   const inScope = (t) => {
     const el = t && t.closest ? t : t && t.parentElement;
     if (!el || !el.closest(SCOPE)) return false;
-    if (el.closest('input, textarea, select, video, audio, [contenteditable], .feed-chips, .lightbox, .media-pager')) return false;
+    // (A video or an audio player is part of the feed: a notch over a clip
+    // coasts like one over the words — the wheel does nothing to a player
+    // itself, so there is nothing to leave it. Adam, 2026-10-16: "over a
+    // video it doesn't initiate a coast, just a single notch".)
+    if (el.closest('input, textarea, select, [contenteditable], .feed-chips, .lightbox, .media-pager')) return false;
     // something inside that scrolls on its own (a caption, a list) keeps its wheel
     for (let n = el; n && n !== document.body; n = n.parentElement) {
       if (n.scrollHeight > n.clientHeight + 1 && /(auto|scroll)/.test(getComputedStyle(n).overflowY)) return false;
@@ -6653,16 +6657,19 @@ if (INTENT_URI) {
     if (!raf && v) { last = performance.now(); raf = requestAnimationFrame(tick); }
   };
   // ---- the wheel
-  // A turn back against the coast catches the page at once and is a plain
-  // notch from rest — no flight the other way, since the next couple of
-  // notches after a reversal (CALM) don't wind the speed up, so a couple of
-  // correcting notches travel a couple of notches; a spin that keeps going
-  // winds up again from the third. (A spell of quarter-size "hunting"
-  // notches ramping back up was tried here and felt like a stutter and a
-  // slow patch; a 700 ms spell without wind-up after a reversal was tried
-  // too and a spin begun inside it felt slow — Adam, 2026-10-16.)
-  const CALM = 2; // notches after a reversal without wind-up
-  let calmLeft = 0; // (lastDir/lastMoveAt: the tick's, above)
+  // A turn back against the coast catches the page at once and is a gentler
+  // push the other way — half a notch's travel, at half the speed — so the
+  // reader who overshot a post settles back onto it instead of flying past
+  // it the other way. The next notch the same way is a plain one, winding
+  // up from whatever speed the half push left, so a spin on after a
+  // reversal gets going again at once. (A spell of quarter-size "hunting"
+  // notches ramping back up over five turns was tried here and felt like a
+  // stutter and a slow patch; a full notch then two without wind-up felt
+  // like an overshoot — Adam, 2026-10-16: "could the first coast in the
+  // opposite direction be smaller/slower than usual? then speed up if we
+  // scroll again in the same direction".)
+  const REVERSE = 0.5; // of a notch: the first push back against a coast
+  // (lastDir/lastMoveAt: the tick's, above)
   let smoothUntil = 0; // a trackpad's events were just seen: hands off
   window.addEventListener('wheel', (e) => {
     if (e.ctrlKey || e.shiftKey || e.defaultPrevented) return;
@@ -6680,19 +6687,19 @@ if (INTENT_URI) {
       // A reversal catches the old coast immediately. Discard its fractional
       // step and frame clock too: after a busy frame, applying the NEW velocity
       // to the OLD elapsed time made the first reverse step jump. Give the
-      // notch a small response now, then coast the rest of its travel.
+      // notch a small response now, then coast the rest of its (half) travel.
       stop();
-      calmLeft = CALM;
-      const first = dir * Math.min(16, Math.abs(px * 3 / TAU) * 16);
+      const travel = px * 3 * REVERSE;
+      const first = dir * Math.min(16, Math.abs(travel / TAU) * 16);
       window.scrollBy({ top: first, behavior: 'instant' });
       lastDir = dir; lastMoveAt = now;
-      coast((px * 3 - first) / TAU, TAU);
+      coast((travel - first) / TAU, TAU);
     } else {
       // A notch into a page already moving pushes harder: the faster it
       // goes, the more each turn adds (up to 2.5x), so keeping the wheel
       // turning winds the speed up instead of settling at a stroll. From
       // rest a notch is the same push as ever.
-      const gain = calmLeft-- > 0 ? 1 : 1 + Math.min(1.5, Math.abs(v) / 4);
+      const gain = 1 + Math.min(1.5, Math.abs(v) / 4);
       coast(v + (px * 3 * gain) / TAU, TAU);
     }
   }, { passive: false });