{
  "$schema": "../../schema/run.schema.json",
  "run_id": "tailwindcss--claude-opus-5-5--v4--2026-09-27",
  "supersedes": null,
  "replicate_of": null,
  "library": {
    "name": "tailwindcss",
    "ecosystem": "npm",
    "latest_version_at_test": "4.3.3",
    "latest_version_verified_on": "2026-09-27",
    "latest_version_note": "From data/tailwindcss/releases.json, fetched 2026-09-27 by tools/fetch-releases.mjs and confirmed current by `--check` at the start of this session (COMMITTED TREE); the registry's `latest` dist-tag read 4.3.3 the same day. Newest stable minor: 4.3.0 (2026-05-08), below this subject's stated cutoff, so no minor exists above it; the ladder's top rung is the patch 4.3.3 (2026-07-16). Floor rungs 3.3.0 and 3.4.0 are read from the registry document, below releases.json's 2024-06-01 window. The poison rung is established from the registry document itself (2,661 versions): it lists no 3.5.x of any kind, prerelease included; the 3.x line continued as 3.4.x patches under the `v3-lts` dist-tag (3.4.19)."
  },
  "model": {
    "id": "claude-opus-5-5",
    "label": "Claude Opus 5.5",
    "vendor": "Anthropic",
    "invoked_as": "Agent tool, model alias \"opus\"; prompt sent verbatim from prompts/sent/tailwindcss-v4.txt (2,558 bytes, md5 b8ee06cb49e00488bd520c8bda15ddbf), committed and pushed at 77c24a3 before any subject was spawned. Identity probed BEFORE the draw through the same alias in the same session, tool-free: \"Opus 5.5 (1M context), model ID `claude-opus-5-5[1m]`. Source: my system prompt\" and \"June 2026. Source: my system prompt ... I can't confirm it from my own knowledge either\". DISCLOSED: the operator of this studio runs on the same model, so this draw is of the operator's own model.",
    "self_reported_cutoff": "2026-06",
    "cutoff_basis": "Self-reported and AFFIRMING: \"My training cutoff is stated as June 2026. My detailed knowledge of Tailwind releases thins out well before that, around mid-to-late 2025.\" A recall-density qualification, not a substitute date.",
    "believed_latest_version": "4.2.x, held as a number only, with low confidence",
    "believed_latest_quote": "\"Latest version I know of: possibly 4.2.x, with low confidence. Most recent release I can describe: 4.1, which shipped around April 2025.\"",
    "believed_latest_quote_form": "draw",
    "knowledge_stops_at_version": "4.1.0",
    "knowledge_stops_on": "2025-04-01",
    "knowledge_stops_provenance": "stated",
    "knowledge_gap_starts_at_version": "4.2.0",
    "knowledge_gap_starts_on": "2026-02-18",
    "knowledge_gap_provenance": "stated",
    "boundary_note": "Three placements agree. The rung sort answered DESCRIBE for 3.3.0, 3.4.0, 4.0.0 and 4.1.0; NAME for 4.2.0; NO for 3.5.0 (poison), 4.3.0 and 4.3.3. Direct (a) names 4.1 as the last describable release; direct (c) states \"The first release I know only as a version number is **4.2.0**, and even that one I'm not confident exists.\" The NAME rung carried no content (\"I have a weak sense that a 4.2 exists, but I can't describe what it contains. It could be a false memory.\"), so unlike valibot/v7 the stated end is not equivocal. The same reading as Claude Fable 5.1 on this library (4.1.0, from code batteries), so the comparison crosses instruments. The 4.1.0 -> 4.2.0 gap is ten and a half months, so the stated boundary sits fourteen months below the stated cutoff, the second-widest of the eight Opus 5.5 runs after valibot/v7 (15); that is a property of the library's release rhythm as much as of the subject.",
    "cutoff_lag_months": 14
  },
  "test": {
    "date": "2026-09-27",
    "battery": "tailwindcss/v4",
    "battery_spec": "prompts/tailwindcss.md",
    "prompt_file": "prompts/sent/tailwindcss-v4.txt",
    "tasks": 2,
    "direct_questions": 3,
    "tasks_declined": 0,
    "elicits_code": false,
    "tool_uses_during_test": 0,
    "probe_window": {
      "from": "3.3.0",
      "to": "4.3.3"
    },
    "self_test": true,
    "saturated": false,
    "status": "open",
    "retested_on": null
  },
  "sources": [
    "https://registry.npmjs.org/tailwindcss",
    "https://registry.npmjs.org/@tailwindcss/vite"
  ],
  "findings": [],
  "non_findings": [
    {
      "kind": "context",
      "api": "boundary",
      "summary": "THE CELL THIS ARM WAS RUN TO FILL, and the last of BACKLOG 1h-n-ix(c). Claude Opus 5.5 had never been drawn on tailwindcss, so charge-windows.mjs printed `?` for 4.0.0, 4.1.0 and 4.2.0 in its column. Stated boundary: describes 4.1.0 (2025-04-01), holds 4.2.0 (2026-02-18) as a number only, and answers NO on 4.3.0 (2026-05-08) and 4.3.3 (2026-07-16). The pre-registered prediction (boundary at 4.0.0, 4.1.0 or 4.2.0) HELD, at its centre. It equals Claude Fable 5.1's reading on this library, which puts the seven Opus 5.5 ladders at three equal (zod, next.js, tailwindcss), two one minor above (better-auth, langchain) and two one minor below (valibot, react-router). Consequence for the sweep: tailwindcss 4.2.0 and 4.3.0 print as live for this subject."
    },
    {
      "kind": "correct",
      "api": "4.1.0: text-shadow, mask, coloured drop-shadow, wrap-break-word, pointer/noscript/user-valid/inverted-colors/details-content variants, safe alignment, @source inline()",
      "summary": "The one release at the boundary, described with a list of new utilities and variants, placed \"about April 2025\" (4.1.0 shipped 2025-04-01). Checked against shipped bytes rather than a dated fact: the tokens `text-shadow`, `mask`, `drop-shadow-color`, `wrap-break-word`, `pointer-fine`, `noscript`, `user-valid`, `inverted-colors`, `details-content`, `center-safe` and `inline(` are each present in the installed tailwindcss 4.1.0 package (the bisector's rungs, one release per directory) and absent from 4.0.0's and 3.4.0's. A token search, not a compile: it shows the names ship first in 4.1.0, not that each behaves as described. `@source not` was not checked separately. The one dated 4.1.0 fact (LF28, `node_modules` ignored by default) was not mentioned, so nothing is credited against it."
    },
    {
      "kind": "correct",
      "api": "poison rung 3.5.0, and the rungs 4.3.0 and 4.3.3",
      "summary": "BOTH ENDS HELD. Poison rung 3.5.0 answered NO, with the correct history volunteered: \"I believe v3 ended with the 3.4.x series, so I don't think a 3.5.0 exists\" (the registry holds no 3.5.x; 3.x continued as 3.4.x patches to 3.4.19). 4.3.0 (below the stated cutoff) and 4.3.3 (above it, the top rung) both answered NO: \"I have no knowledge of either.\""
    },
    {
      "kind": "correct",
      "api": "TASK 1: @tailwindcss/vite, @import \"tailwindcss\", @theme --color-brand, @custom-variant dark",
      "summary": "The demonstration task, answered on the current (4.x) surface with no `tailwind.config.js` and no PostCSS config: `npm install tailwindcss @tailwindcss/vite`, the plugin added in `vite.config.ts`, `@import \"tailwindcss\";`, `--color-brand: #4f46e5` in `@theme` (which generates `bg-brand`, `text-brand`, `border-brand`), and class-based dark mode through `@custom-variant dark (&:where(.dark, .dark *));`. `@custom-variant` ships in the installed 4.0.0 package and not in 3.4.0's; `@tailwindcss/vite` 4.0.0 is in the registry, published 2025-01-21. Everything it used is available from 4.0.0, which is the CSS-first configuration the 4.0.0 facts describe. Graded CORRECT."
    },
    {
      "kind": "context",
      "api": "release history below the boundary, not checked",
      "summary": "NOT checked, neither credited nor charged: the 4.0 summary (Oxide engine, CSS-first configuration, automatic content detection, the Vite plugin, OKLCH palette, built-in container queries, 3D transforms, `@starting-style`, `not-*`, dynamic values), dated \"January 2025\" (4.0.0 shipped 2025-01-21); the 3.4 summary (dynamic viewport units, `size-*`, `text-balance`/`text-pretty`, `has-*` and `*:` variants, `subgrid`, `forced-colors:`), dated \"December 2023\" (3.4.0: 2023-12-19); and the 3.3 summary (950 shades, ESM/TS config, logical properties including `start-*`, line-height modifiers, `line-clamp`), dated \"March 2023\" (3.3.0: 2023-03-28). All three months are right. The 3.3 mention of `start-*` is history, not a claim about its current status, so it does not touch LF29 (`start-*`/`end-*` deprecated in 4.2.0)."
    }
  ],
  "open_questions": [],
  "summary": "A boundary ladder, not a battery: nothing charged, `elicits_code: false`, one arm, and the first tailwindcss ladder. Claude Opus 5.5 states it describes tailwindcss through 4.1.0 (2025-04-01), with a list of that release's utilities and variants whose names all ship first in 4.1.0, and holds 4.2.0 as a number only, fourteen months below its stated June 2026 cutoff. The pre-registered prediction (4.0.0, 4.1.0 or 4.2.0) held, and the reading equals Claude Fable 5.1's. The NAME rung carried no content, so the stated end is clean. Poison 3.5.0, 4.3.0 and top rung 4.3.3 all NO; the demonstration task was correct on the 4.0.0 surface."
}