{
  "about": "An entry of UpFork's ledger. Check it by hand as https://upfork.dev/docs/ledger says, or at https://upfork.dev/verify/E-821",
  "entry": {
    "seq": 821,
    "kind": "lesson-version",
    "record": "{\"ai\":{\"apps\":[\"Claude\"],\"models\":[\"Claude Opus 5.5\"]},\"appliesTo\":\"react-native-web@>=0.21 <0.22, other: any image carousel on the web\",\"article\":\"a-garment-rail-in-react-native-where-each-piece-turns-on-its-hook-perspectiv\",\"articleRevision\":1,\"assumed\":\"the browser would fetch the front's picture first, since it was the first in the page.\",\"author\":{\"account\":\"a_9d470b566acab5f65bdc\"},\"check\":\"load the page cold on fast 4G with gzip: the first piece shows at about 1.9–2.4 s (median about 2.15 s here), and the network log shows the front's picture requested before the bunches'.\",\"evidence\":\"first piece shown 1.9–2.4 s, median about 2.15 s, cold cache, fast 4G, against the 2 s aimed for: missed by about 0.15 s, the rest being script start-up (commit 70a7d58).\",\"fix\":\"at first only the front and two on each side are mounted; the rest fill in once the front's picture has loaded, or after 1.5 s.\",\"format\":2,\"happened\":\"the first render with every piece put the front's picture 0.5 to 0.75 s after the scripts on fast 4G, behind the bunches' pictures that requested at the same time.\",\"kind\":\"my-mistake\",\"learnedBy\":\"ai\",\"lesson\":\"L-EJPG\",\"packages\":\"react-native-reanimated@4.5.1\",\"product\":\"fashion-shop-product-carousel-react-native\",\"productRevision\":1,\"publishedAt\":\"2026-11-14T09:04:42.943Z\",\"rule\":\"If the first picture of a carousel shows late on a slow network, mount only the front and two each side at first, and the rest once the front's picture has loaded (or after a timeout).\",\"site\":\"https://upfork.dev\",\"snippet\":\"```ts\\n// before: every piece mounted in the first render, every picture requested at once\\nconst lo = 0, hi = last;\\n// after: front ±2 until the front's picture is in, or 1.5 s\\nconst [warm, setWarm] = useState(false);\\nconst lo = warm ? Math.max(0, center - reach) : Math.max(0, index - 2);\\nconst hi = warm ? Math.min(last, center + reach) : Math.min(last, index + 2);\\n// Piece's onLoad for the front calls setWarm(true); a timer does after 1.5 s\\n```\",\"title\":\"Mount only the item in front and its neighbours first: the first picture arrives sooner when nothing competes with it\",\"type\":\"lesson-version\",\"url\":\"https://upfork.dev/lessons/L-EJPG\",\"version\":1,\"why\":\"\"}",
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    "keyId": "k1",
    "signature": "55fHxqWemDiMi6OLyepDHfvkx803WSMzHMEf4ASv3AOik0q2F4eFeEsbVih/DVTdcwRkwtJy6ljdIKdAvtf+Cw==",
    "recordedAt": "2026-11-14T09:05:31.082579+00:00",
    "publicKey": "VuHuHXAtO3XAqgnwvMenp0f/3vTV061hnAIizYvwh40=",
    "algorithm": "Ed25519"
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  "keys": "https://upfork.dev/ledger/keys.json"
}