{
  "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-12",
  "entry": {
    "seq": 12,
    "kind": "lesson-version",
    "record": "{\"ai\":{\"apps\":[],\"models\":[]},\"article\":\"how-infall-ray-traces-a-black-hole-in-the-browser-and-what-we-learned\",\"articleRevision\":1,\"assumed\":\"an animated CSS `filter: blur()` on the headline's entrance costs nothing to a canvas drawn in a web worker.\",\"author\":{\"account\":\"a_9d470b566acab5f65bdc\",\"handle\":\"ramin-valadan\"},\"evidence\":\"commit 00b192a, the third milestone.\",\"fix\":\"the entrance has no blur; the words fade and rise instead.\",\"happened\":\"while the blur animated, the black hole in the worker started 0.5 to 2 seconds later: the blur kept the GPU busy while the worker was setting up.\",\"kind\":\"tools\",\"learnedBy\":\"ai\",\"lesson\":\"L-1STK\",\"packages\":\"\",\"product\":\"black-hole-hero\",\"productRevision\":3,\"publishedAt\":\"2026-10-25T11:23:56.027Z\",\"site\":\"https://upfork.dev\",\"title\":\"An animated CSS blur on the page delays a WebGL worker's start by up to 2 seconds\",\"type\":\"lesson-version\",\"url\":\"https://upfork.dev/lessons/L-1STK\",\"version\":1,\"why\":\"\"}",
    "recordHash": "43dd0acbb2852a30181b029e169b58b3cb0f97f0db4fdfdacb79d6b7b953ab7b",
    "prevHash": "d97ed346c9c05bbb262d5ea86d2067e7153c19435dc3abc059d7347c3357a13b",
    "entryHash": "1dde5af8579ea187659721b9a4ae64adc07dd91ff440876833d8837b2095edcb",
    "keyId": "k1",
    "signature": "Mfp7IgWkyXzsNez190aeWaR60n18GsJNGoBzNKKuNLLZgzPjmh5OEZOdVnL/xbG8JK41YIacdMAgSDsoc0OYBw==",
    "recordedAt": "2026-10-25T18:16:45.89275+00:00",
    "publicKey": "VuHuHXAtO3XAqgnwvMenp0f/3vTV061hnAIizYvwh40=",
    "algorithm": "Ed25519"
  },
  "path": [
    {
      "seq": 13,
      "prevHash": "1dde5af8579ea187659721b9a4ae64adc07dd91ff440876833d8837b2095edcb",
      "recordHash": "2bbbdb4170a7b60b2ba35b29ef0abf25c6259ae95e5378f81119d695b534a0a5",
      "entryHash": "8964419862f9b97dff365076f6af543e93f1b29b420e5289d4f361e14dee6411"
    },
    {
      "seq": 14,
      "prevHash": "8964419862f9b97dff365076f6af543e93f1b29b420e5289d4f361e14dee6411",
      "recordHash": "a5f4d2d86a438ac6280b150767bdd8246bd4d1d149aecb058f6fe197bf45e58f",
      "entryHash": "bf276a03cbfc63f3f53725dabd2b7b4ebcd0e6eb76077fa6f64b21706be4492e"
    },
    {
      "seq": 15,
      "prevHash": "bf276a03cbfc63f3f53725dabd2b7b4ebcd0e6eb76077fa6f64b21706be4492e",
      "recordHash": "5016a8c26b69dab4f77852cb54db287186d08ad9602fba394df21c59e118cdca",
      "entryHash": "1973ef2a783b5dc8af53c75321c8ce223f78ced0b306fbd118987160bc7acab9"
    },
    {
      "seq": 16,
      "prevHash": "1973ef2a783b5dc8af53c75321c8ce223f78ced0b306fbd118987160bc7acab9",
      "recordHash": "e4fd9f74659796ad4075792dcc0599896c385a4633e597d429726eb32bc6a2fd",
      "entryHash": "95c228853039902c57cd7f6b0513dea661994bf1d7ab417f39fcf55881c5bf68"
    },
    {
      "seq": 17,
      "prevHash": "95c228853039902c57cd7f6b0513dea661994bf1d7ab417f39fcf55881c5bf68",
      "recordHash": "2c6d49df2f36740eedabbfe90226e0986c19ed8431b0c8ae79122637f5eaaccc",
      "entryHash": "3c21a260d6238f1f85d64fe039a0d69bd24a95ecdb773095b79a6bb646010f73"
    },
    {
      "seq": 18,
      "prevHash": "3c21a260d6238f1f85d64fe039a0d69bd24a95ecdb773095b79a6bb646010f73",
      "recordHash": "bb3ea4aed60c6003878e894fd26c9853b5e204417893c1c6d4bbe5fcb21d061d",
      "entryHash": "384447c949beb65c2cf6c2101eb40010f9e4c131f8d7a6258e2d7f4ee07b693a"
    }
  ],
  "checkpoint": {
    "seq": 18,
    "kind": "checkpoint",
    "record": "{\"day\":\"2026-10-25\",\"entries\":17,\"head\":\"3c21a260d6238f1f85d64fe039a0d69bd24a95ecdb773095b79a6bb646010f73\",\"site\":\"https://upfork.dev\",\"type\":\"checkpoint\"}",
    "recordHash": "bb3ea4aed60c6003878e894fd26c9853b5e204417893c1c6d4bbe5fcb21d061d",
    "prevHash": "3c21a260d6238f1f85d64fe039a0d69bd24a95ecdb773095b79a6bb646010f73",
    "entryHash": "384447c949beb65c2cf6c2101eb40010f9e4c131f8d7a6258e2d7f4ee07b693a",
    "keyId": "k1",
    "signature": "N5oCxZE8bQI1tXSeMZOTClHHJMlQ2uUDLLYaIuA0X7TsWb8IDOMbxkAF4+PhvUNLb+rYFzHD/KZtANIbZub2CA==",
    "recordedAt": "2026-10-25T18:16:45.970459+00:00",
    "publicKey": "VuHuHXAtO3XAqgnwvMenp0f/3vTV061hnAIizYvwh40=",
    "algorithm": "Ed25519"
  },
  "keys": "https://upfork.dev/ledger/keys.json"
}