The pager's counter runs through the posts as a flight passes them, instead of jumping on landing.

Adam, 2026-10-17: "the counter should animate as we fly, right now the current position only updates when we land". While a flight is under way (a flung finger or a spin of the wheel), each scroll counts the post under the middle of the screen (a binary search over the posts' tops); the landing sets the post landed on, as before.

tools/pager-swipe-fly-test.js: a flick from post 2 shows 2, 3, 4 … 9 on the way. pager-wheel, pager-ready-gate, profile-pager and thread-pager pass.

Co-Authored-By: Claude Opus 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_013ZDf1cyCQLkfjftYhymZAg

2 files changed, 16 insertions, 3 deletions

diff --git a/src/features/messages.js b/src/features/messages.js
index 76330a4..cf6e2c7 100644
--- a/src/features/messages.js
+++ b/src/features/messages.js
@@ -13172,7 +13172,7 @@ export function messagesFeature(ctx) {
     if (land) slideFrame(land, -1);
     pagerGlide(pager.scroller, 'y', dest, vel, {
       ms: screens > 1.05 ? Math.min(most, 100 + pace * screens) : 0,
-      onDone: () => { if (!pager) return; pager.flying = false; const s = pagerHere(); if (s && s !== pager.cur) pagerArrive(s); },
+      onDone: () => { if (!pager) return; pager.flying = false; const s = pagerHere(); if (s && s !== pager.cur) pagerArrive(s); pagerPosition(); },
     });
   }
   const pagerArrive = (slide) => { if (pager && pager.arrive) pager.arrive(slide); };
@@ -13201,13 +13201,24 @@ export function messagesFeature(ctx) {
     if (!pager) return;
     const groups = pagerGroups();
     const slide = pager.cur || pager.anchor;
-    const index = groups.indexOf(slide && slide.closest('.mp-group'));
-    pager.el.querySelector('.mp-position').textContent = (index < 0 ? 0 : index + 1) + ' / ' + groups.length;
+    let index = groups.indexOf(slide && slide.closest('.mp-group'));
+    // in a flight, the post passing under the reader: the count runs with
+    // the slides rather than jumping on landing (Adam, 2026-10-17: "the
+    // counter should animate as we fly")
+    if (pager.flying && groups.length) {
+      const y = pager.scroller.scrollTop + pager.scroller.clientHeight / 2;
+      let lo = 0, hi = groups.length - 1; // the last post whose top is above the middle of the screen
+      while (lo < hi) { const m = (lo + hi + 1) >> 1; if (groups[m].offsetTop <= y) lo = m; else hi = m - 1; }
+      index = lo;
+    }
+    const text = (index < 0 ? 0 : index + 1) + ' / ' + groups.length, el = pager.el.querySelector('.mp-position');
+    if (el.textContent !== text) el.textContent = text;
   }
 
   function buildPager(want) {
     const video = want.kind === 'videos';
     const scroller = h('div', { class: 'mp-scroll' });
+    scroller.addEventListener('scroll', () => { if (pager && pager.flying) pagerPosition(); }, { passive: true });
     const el = h('div', { class: 'media-pager' + (video ? ' videos' : '') + (pagerLoud ? '' : ' quiet'), role: 'dialog', 'aria-modal': 'true' },
       scroller,
       h('div', { class: 'mp-position', role: 'status' }, '0 / 0'),
diff --git a/tools/pager-swipe-fly-test.js b/tools/pager-swipe-fly-test.js
index cae3536..418b8e4 100644
--- a/tools/pager-swipe-fly-test.js
+++ b/tools/pager-swipe-fly-test.js
@@ -108,11 +108,13 @@ try {
 
   console.log('\n[a fast flick: several posts, landing snapped]');
   const trace = async (sw) => { await page.evaluate(() => { const sc = document.querySelector('.mp-scroll'); window.__tr = []; const t0 = performance.now(); const rec = () => { window.__tr.push(sc.scrollTop); if (performance.now() - t0 < 1500) requestAnimationFrame(rec); }; requestAnimationFrame(rec); }); await sw(); await sleep(1600); return page.evaluate(() => window.__tr); };
+  await page.evaluate(() => { const el = document.querySelector('.mp-position'); window.__counts = [el.textContent]; new MutationObserver(() => { if (window.__counts.at(-1) !== el.textContent) window.__counts.push(el.textContent); }).observe(el, { childList: true, characterData: true, subtree: true }); });
   const tr = await trace(() => swipe(600, 80, 3)); await settled(); // three big moves: 3–6 px/ms as their handling takes, a long coast's worth (past the nine loaded, maybe)
   const landed = await at();
   check('a 600px flick in a few frames flies several posts on', landed !== 'between' && landed >= 5, String(landed));
   check('…landing square on a post', landed !== 'between');
   check('…in a glide, never back', tr.every((x, i) => !i || x >= tr[i - 1] - 0.5), tr.slice(0, 12).map((x) => Math.round(x)).join(' '));
+  check('the counter ran through the posts on the way, not jumping on landing', (await page.evaluate(() => window.__counts)).length >= 4, (await page.evaluate(() => window.__counts)).join(' → '));
   const seen = await page.evaluate(() => document.querySelector('.mp-position').textContent);
   check('the counter says where it landed', seen === landed + ' / ' + N, seen);