Media pager: up and down go from post to post, left and right along a post's pictures. Adam: swipes and arrows up/down should go to the next post's media, left/right to the next within a post. The pager is now posts stacked top to bottom, each a row of its pictures or clips side by side — a quoted post's join the post that quotes it — with dots along the top when a post has more than one, saying how many and which. Up and down (swipe, arrows, j/k, Page) move a post at a time and land on a post where its row was left; left and right (swipe, arrows, h/l) move within the post and stop at its ends. A post's pictures all load as it comes near (those along its row too); a clip's head start goes to the next post's (where its row rests), the next along this one, and the post after next, at half; the look-ahead (the feed paging on, the media crawl) counts posts. Pictures pan sideways as well as up and down at 1×. Tests find the slide on screen by where it sits (the pager's children are posts now); feed-picture-pager walks right within a post, down past one with none, back up to where a post was left, left to its first, and a sideways swipe next to a swipe up; quote-pager walks the quoting post's row (its own picture, then the quote's).

Co-Authored-By: Claude Opus 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01KPw21NEpWeTGu6swVASmBt

1 files changed, 81 insertions, 23 deletions

diff --git a/src/features/messages.js b/src/features/messages.js
index a3c7cd5..6548e99 100644
--- a/src/features/messages.js
+++ b/src/features/messages.js
@@ -12225,8 +12225,33 @@ export function messagesFeature(ctx) {
     };
     return bar;
   }
-  // the pager's slides, without the loading one at the end
-  const pagerSlides = () => (pager ? [...pager.scroller.children].filter((x) => !x._tail) : []);
+  // The pager is posts stacked top to bottom (up and down go from post to
+  // post), each a row of its pictures or clips — its quotes' too — side by
+  // side (left and right go within it). Its slides, in reading order:
+  const pagerSlides = () => (pager ? [...pager.scroller.querySelectorAll('.mp-slide')] : []);
+  const pagerGroups = () => (pager ? [...pager.scroller.querySelectorAll(':scope > .mp-group')] : []);
+  // the slide a post's row rests on
+  const rowSlide = (g) => { const row = g && g._row; if (!row || !row.children.length) return null; return row.children[Math.min(row.children.length - 1, Math.round(row.scrollLeft / (row.clientWidth || 1)))]; };
+  // bring a slide to the screen: its post, and within it, the slide
+  function pagerShow(slide) {
+    const g = slide && slide.closest('.mp-group');
+    if (!g) return;
+    pager.scroller.scrollTop = g.offsetTop;
+    g._row.scrollLeft = slide.offsetLeft;
+  }
+  // what's next from a slide: down (the next post, where its row rests),
+  // along (the next in this post), and the post after next
+  function pagerAhead(slide) {
+    const out = [];
+    const nextGroup = (g) => { let n = g && g.nextElementSibling; while (n && !n.classList.contains('mp-group')) n = n.nextElementSibling; return n; };
+    const g1 = nextGroup(slide.closest('.mp-group')), g2 = nextGroup(g1);
+    const down = g1 && rowSlide(g1);
+    if (down) out.push(down);
+    if (slide.nextElementSibling) out.push(slide.nextElementSibling);
+    const down2 = g2 && rowSlide(g2);
+    if (down2) out.push(down2);
+    return out;
+  }
   function pagerAttach(slide) {
     const m = slide.querySelector('.mp-media');
     if (m && !m.getAttribute('src')) m.setAttribute('src', m.tagName === 'VIDEO' ? playSrc(m.getAttribute('data-src')) : m.getAttribute('data-src'));
@@ -12252,19 +12277,21 @@ export function messagesFeature(ctx) {
     const slides = pagerSlides();
     const i = slides.indexOf(slide);
     const eager = !frugalData();
+    const ahead = pagerAhead(slide);
     slides.forEach((s, j) => {
-      if (Math.abs(j - i) <= 2) slidePoster(s);
+      const k = ahead.indexOf(s);
+      if (Math.abs(j - i) <= 2 || k >= 0) slidePoster(s);
       if (j === i) return;
       const v = s.querySelector('video.mp-media');
-      if (eager && (j === i + 1 || j === i + 2)) {
+      if (eager && k >= 0) {
         pagerRelease(s);
-        headStart(playSrc(v.getAttribute('data-src')), j === i + 1 ? 1 : 0.5);
+        headStart(playSrc(v.getAttribute('data-src')), k === 0 ? 1 : 0.5);
         return;
       }
-      if (j === i + 1) {
+      if (k === 0) {
         const url = v.getAttribute('data-src');
         probeVideo(url).then(() => {
-          if (!pager || pager.cur === s || videoHeavy(url) || slides.indexOf(pager.cur) !== i) return;
+          if (!pager || pager.cur === s || videoHeavy(url) || pager.cur !== slide) return;
           v.preload = 'metadata';
           pagerAttach(s);
         });
@@ -12468,7 +12495,10 @@ export function messagesFeature(ctx) {
       for (const e of entries) {
         if (!e.isIntersecting) continue;
         watchZaps([e.target._ev.id]);
-        if (pager.kind === 'images') pagerAttach(e.target); // pictures are cheap; clips are pagerNeighbours' call
+        // pictures are cheap — a post's all at once, the ones along its row
+        // too (out of sight sideways, they'd load only on arrival); clips
+        // are pagerNeighbours' call
+        if (pager.kind === 'images') for (const x of e.target.closest('.mp-group').querySelectorAll('.mp-slide')) pagerAttach(x);
       }
     }, { root: scroller, rootMargin: '150% 0px' });
     pager.io = new IntersectionObserver((entries) => {
@@ -12489,14 +12519,14 @@ export function messagesFeature(ctx) {
         pagerCounts(e.target);
         // near the end: ask the feed for more, the pager picks them up
         if (pager.fromFeed) pagerFeedAhead();
-        else { const slides = pagerSlides(); if (slides.indexOf(e.target) >= slides.length - 3) crawlMedia().catch(() => {}); }
+        else { const gs = pagerGroups(); if (gs.indexOf(e.target.closest('.mp-group')) >= gs.length - 3) crawlMedia().catch(() => {}); }
       }
     }, { root: scroller, threshold: [0.6] });
     growPager();
     document.body.append(el);
     document.documentElement.classList.add('no-scroll');
-    const first = pagerSlides().find((s) => s.getAttribute('data-k') === want.start) || scroller.firstChild;
-    if (first) scroller.scrollTop = first.offsetTop;
+    const first = pagerSlides().find((s) => s.getAttribute('data-k') === want.start) || pagerSlides()[0];
+    if (first) pagerShow(first);
     // the clip on screen's seek bar, every frame (timeupdate comes a few times a second)
     if (video) {
       const p = pager;
@@ -12504,18 +12534,18 @@ export function messagesFeature(ctx) {
       p.raf = requestAnimationFrame(frame);
     }
     // turned on its side (or back), the slides change height: stay on this one
-    pager.onResize = () => { if (pager && pager.cur) pager.scroller.scrollTop = pager.cur.offsetTop; };
+    pager.onResize = () => { if (pager && pager.cur) pagerShow(pager.cur); };
     window.addEventListener('resize', pager.onResize);
     // new posts land in the feed while the pager is open; counts move
     pager.tick = setInterval(() => { if (pager) { growPager(); pagerFeedAhead(); if (el.classList.contains('show')) pagerCounts(pager.cur); } }, 1500);
   }
   // A pager opened from the feed walks the feed's own posts, which page in
   // ten at a time as the feed is scrolled. Swiping is the scrolling here:
-  // with only a few slides left past the one on screen (PAGER_AHEAD), the feed pages on
+  // with only a few posts left below the one on screen (PAGER_AHEAD), the feed pages on
   // (the posts it holds, then older ones from the relays) until there are
   // more — several pages if those posts carry none. A page that brings
   // nothing (the feed busy, or at its end) stops it; the tick tries again.
-  // how many slides ahead to keep: clips are fewer and further between
+  // how many posts ahead to keep: clips are fewer and further between
   // (more pages to find the next) and each is watched a while, so further
   const PAGER_AHEAD = { images: 4, videos: 6 };
   let pagerFeeding = false;
@@ -12525,8 +12555,8 @@ export function messagesFeature(ctx) {
     try {
       const c = feedNow();
       for (let pages = 0; pages < 8 && pager && pager.fromFeed; pages++) {
-        const slides = pagerSlides();
-        if (slides.length - 1 - slides.indexOf(pager.cur) > (PAGER_AHEAD[pager.kind] || 4)) break;
+        const gs = pagerGroups();
+        if (gs.length - 1 - gs.indexOf(pager.cur && pager.cur.closest('.mp-group')) > (PAGER_AHEAD[pager.kind] || 4)) break;
         const shown = c.shown, held = c.notes.length;
         await loadOlderFeed();
         growPager();
@@ -12534,27 +12564,53 @@ export function messagesFeature(ctx) {
       }
     } catch {} finally { pagerFeeding = false; }
   }
-  // Slides for feed items the pager doesn't have yet, appended (never
+  // Slides for feed items the pager doesn't have yet: into their post's row
+  // (a quote fetched late joins its post), a new post appended below (never
   // inserted above the one on screen).
   function growPager() {
     if (!pager) return;
     const c = feedNow();
     const waiting = pager.onTail;
     let first = null;
+    pager.groups ||= new Map();
     for (const it of (pager.fromFeed ? feedMediaItems(c, pager.kind) : mediaItems(c, pager.kind))) {
       const k = mediaKey(it);
       if (pager.keys.has(k)) continue;
       pager.keys.add(k);
       const s = pagerSlide(it);
-      pager.scroller.insertBefore(s, pager.tail || null);
-      first ||= s;
+      const gk = it.row ? it.row.id : it.ev.id;
+      let g = pager.groups.get(gk);
+      if (!g) {
+        g = pagerGroup();
+        pager.groups.set(gk, g);
+        pager.scroller.insertBefore(g, pager.tail || null);
+        first ||= s;
+      }
+      g._row.append(s);
+      pagerDots(g);
       pager.near.observe(s);
       pager.io.observe(s);
     }
     // the reader was waiting at the end: onto the first that came
-    if (waiting && first) { pager.onTail = false; pager.scroller.scrollTop = first.offsetTop; }
+    if (waiting && first) { pager.onTail = false; pagerShow(first); }
     pagerTailState();
   }
+  // A post in the pager: its row of slides, side by side, and — with more
+  // than one — dots saying how many and which.
+  function pagerGroup() {
+    const row = h('div', { class: 'mp-row' });
+    const dots = h('div', { class: 'mp-dots', 'aria-hidden': 'true' });
+    const g = h('div', { class: 'mp-group' }, row, dots);
+    g._row = row; g._dots = dots;
+    row.addEventListener('scroll', () => pagerDots(g), { passive: true });
+    return g;
+  }
+  function pagerDots(g) {
+    const n = g._row.children.length;
+    if (g._dots.children.length !== (n > 1 ? n : 0)) g._dots.replaceChildren(...(n > 1 ? Array.from({ length: n }, () => h('i')) : []));
+    const at = rowSlide(g);
+    [...g._dots.children].forEach((d, i) => d.classList.toggle('on', g._row.children[i] === at));
+  }
   // the end says "more coming", or — the feed (or the media index) has no
   // more to give — that this is everything
   function pagerTailState() {
@@ -12569,9 +12625,11 @@ export function messagesFeature(ctx) {
     window.addEventListener('keydown', (e) => {
       if (!pager || e.defaultPrevented) return;
       if (e.key === 'Escape') { e.preventDefault(); dismissPager(); return; }
-      // the arrows, any of the four: next (down, right) or previous (up, left)
-      const step = ['ArrowDown', 'ArrowRight', 'j', 'PageDown'].includes(e.key) ? 1 : ['ArrowUp', 'ArrowLeft', 'k', 'PageUp'].includes(e.key) ? -1 : 0;
-      if (step) { e.preventDefault(); pager.scroller.scrollBy({ top: step * pager.scroller.clientHeight, behavior: 'smooth' }); return; }
+      // up and down: the next post, or the one before; left and right: along this post's row
+      const v = ['ArrowDown', 'j', 'PageDown'].includes(e.key) ? 1 : ['ArrowUp', 'k', 'PageUp'].includes(e.key) ? -1 : 0;
+      const hz = ['ArrowRight', 'l'].includes(e.key) ? 1 : ['ArrowLeft', 'h'].includes(e.key) ? -1 : 0;
+      if (v) { e.preventDefault(); pager.scroller.scrollBy({ top: v * pager.scroller.clientHeight, behavior: 'smooth' }); return; }
+      if (hz) { e.preventDefault(); const row = pager.onTail ? null : pager.cur && pager.cur.parentElement; if (row) row.scrollBy({ left: hz * row.clientWidth, behavior: 'smooth' }); return; }
       if (e.key === ' ' && pager.cur) {
         const v = pager.cur.querySelector('video.mp-media');
         if (v) { e.preventDefault(); if (v.paused) v.play().catch(() => {}); else v.pause(); }