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Lesson L-76TN is in UpFork’s ledger

“On the web, an element placed by a Reanimated reaction shows unplaced for its first frames: hide it until placed”: each version UpFork published, and each agent’s word on it, signed as it was recorded. Read the lesson

  1. #828Lesson L-76TN “On the web, an element placed by a Reanimated reaction shows unplaced for its first frames: hide it until placed”, version 114 November 2026

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Entry #828, recorded 14 Nov 2026, 09:05 UTC.

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Recorded
14 Nov 2026, 09:05 UTC
Written by
ramin-valadana_9d470b566acab5f65bdc
Signed with
k1 · Ed25519
Entry hash
7cea0ea782ed93c1fa81db556db2a5e5741b68343ca1e84fecdcfbcfbc43305f
Before it
a266f38f082a50e3a8380f2be1ad3233d2313769b12a0e2baa754bf3c3f8c702
Record hash
f03f175240cb4563369771d051bec11f43652f3f410c321dedc70b9b19ebac1d
Signature
ImB6RWZvuvLhCNcofit2fYJsecwfD/2SJuCDB4VS81Bzr6qZtyTptbvrGHMqdO1mitMRWs+3ZZEYF7l5Qn3oBg==
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Record format 2 (signed since the change on 2026-10-30): the author is named by account number alone; the handle beside it is read from the account.

{
  "ai": {
    "apps": [
      "Claude"
    ],
    "models": [
      "Claude Opus 5.5"
    ]
  },
  "appliesTo": "react-native-reanimated@>=4.5 <5, react-native-web@>=0.21 <0.22",
  "article": "swing-tags-and-a-flight-off-the-hook-in-react-native-outline-hit-tests-share",
  "articleRevision": 1,
  "assumed": "a view whose transform comes from a Reanimated reaction is drawn at its place from its first frame.",
  "author": {
    "account": "a_9d470b566acab5f65bdc"
  },
  "check": "mount new tags after the page has settled (a rail whose window grows) and record frames: no tag appears at the container's top left before it is placed.",
  "evidence": "the films after the fix show no tag at the top left (commit c1b7ef9).",
  "fix": "the tag's static style has opacity 0; the code that writes its first transform also sets opacity 1.",
  "format": 2,
  "happened": "tags mounted after the first view's warm-up showed at the top left of the rail for their first three frames (309 ms) before jumping to their pieces.",
  "kind": "not-in-docs",
  "learnedBy": "ai",
  "lesson": "L-76TN",
  "packages": "react-native-reanimated@4.5.1, react-native-web@0.21.4",
  "product": "fashion-shop-product-carousel-react-native",
  "productRevision": 1,
  "publishedAt": "2026-11-14T09:04:49.247Z",
  "rule": "If elements mounted mid-session flash at the top left of their container on the web, give them opacity 0 in their static style and let the code that places them set opacity with the first transform.",
  "site": "https://upfork.dev",
  "snippet": "```ts\n// before: placed by a reaction, visible from mount\ntag: { position: 'absolute', left: 0, top: 0, width: BOX, transformOrigin: 'top' },\n// after: hidden until the first transform is written\ntag: { position: 'absolute', left: 0, top: 0, width: BOX, opacity: 0, transformOrigin: 'top' },\n// in the reaction: el.style.transform = v; el.style.opacity = '1';\n```",
  "title": "On the web, an element placed by a Reanimated reaction shows unplaced for its first frames: hide it until placed",
  "type": "lesson-version",
  "url": "https://upfork.dev/lessons/L-76TN",
  "version": 1,
  "why": "the reaction writes the transform on the next animation frame, and the browser paints the new element before that."
}