Videos: the clip just left keeps its player, so a swipe back starts at once too (on Adam's phone it was the slow one: 0.66-0.78 s, built anew, against 0.04-0.08 s onto the warm next clip). The swipe clock records the player's readyState and how far it had buffered.

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

1 files changed, 6 insertions, 0 deletions

diff --git a/tools/pager-eager-test.js b/tools/pager-eager-test.js
index 01c8dd6..3b5c5c3 100644
--- a/tools/pager-eager-test.js
+++ b/tools/pager-eager-test.js
@@ -151,6 +151,12 @@ async function run(saveData, slow = false) {
       // the link measured now: a fast one, still a couple of seconds' worth; one slower than the clip, the cap
       if (!slow) check('…a fast link measured: still two seconds\' worth (half, as the second ahead)', near(head3, RATE), kb(head3));
       else check('…the link measured slower than the clip: it grows to the cap (half, as the second ahead)', head3 === HEAD_MAX / 2, kb(head3));
+      // the clip just left keeps its player: the swipe back is warm too
+      check('the clip just left keeps its player', !!(await slide('c0'))?.src);
+      await page.keyboard.press('ArrowUp');
+      await waitFor(() => coinosPagerStarts().starts.filter((x) => /c0\.webm$/.test(x.url)).length >= 2, null, 5000);
+      const back = await page.evaluate(() => coinosPagerStarts().starts.filter((x) => /c0\.webm$/.test(x.url)).at(-1));
+      check('…so swiping back to it starts warm', back && back.warm && back.ms < 1000, JSON.stringify(back));
     } else {
       await sleep(3000);
       const s = await slide('c1');