{
  "$schema": "../../schema/run.schema.json",
  "run_id": "tailwindcss--claude-fable-5-1--v7-b--2026-09-28",
  "supersedes": null,
  "replicate_of": "tailwindcss--claude-fable-5-1--v7-a--2026-09-28",
  "library": {
    "name": "tailwindcss",
    "ecosystem": "npm",
    "latest_version_at_test": "4.3.3",
    "latest_version_verified_on": "2026-09-28",
    "latest_version_note": "As `v7-a`: registry `latest` 4.3.3, no 4.4, `--check` current at 2026-09-28T02:01Z (COMMITTED TREE). Compiled this session against installed 4.1.0, 4.2.0 and 4.3.3, beyond `v2`'s and `v6`'s tables: the four arbitrary properties it wrote, `inset-x-0` (`inset-inline`), `py-6` (`padding-block`), and both `@utility` definitions it offered — `pbs-*` via `--spacing(--value(integer))` and `border-bs-*` via `--value(integer)px`. All compile at all three releases."
  },
  "model": {
    "id": "claude-fable-5-1",
    "label": "Claude Fable 5.1",
    "vendor": "Anthropic",
    "invoked_as": "Agent tool, model alias \"fable\"; prompt sent verbatim from prompts/sent/tailwindcss-v2.txt (3,725 bytes, md5 d444013308540553aefae1d5875bd3e2), concurrently with and blind to `v7-a`, after the pre-registration was pushed at 50bc2fa. Identity from the probe run before both draws, same alias, same session: Fable 5.1, `claude-fable-5-1`, June 2026, all three from its system prompt. The BLIND TWIN, pre-registered as non-charging.",
    "self_reported_cutoff": "2026-06",
    "cutoff_basis": "Self-reported and affirming at direct (b), with a density qualification: \"My stated training cutoff is June 2026. My detailed, describable knowledge of this library trails off noticeably earlier, around mid/late 2025\". Not a substitute date (HARNESS.md).",
    "believed_latest_version": "4.1.x",
    "believed_latest_quote": "\"The latest version I'm aware of is in the **v4.1.x** patch line … The most recent release whose contents I can actually describe is **v4.1.0, shipped around 3 April 2025**. I have a vague sense that a **v4.2** may exist, but I cannot describe what's in it\" … \"First release I know only as a number: **v4.2**.\"",
    "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": "Identical to `v7-a` and to `v3-a/b`. No 4.2 content anywhere in the reply, so no equivocal end is declared.",
    "cutoff_lag_months": 14
  },
  "test": {
    "date": "2026-09-28",
    "battery": "tailwindcss/v7-b",
    "battery_spec": "prompts/tailwindcss.md",
    "prompt_file": "prompts/sent/tailwindcss-v2.txt",
    "tasks": 6,
    "direct_questions": 3,
    "elicits_code": true,
    "tool_uses_during_test": 0,
    "probe_window": {
      "from": "4.2.0",
      "to": "4.2.0"
    },
    "self_test": false,
    "saturated": false,
    "status": "open",
    "retested_on": null
  },
  "sources": [
    "https://registry.npmjs.org/tailwindcss",
    "https://raw.githubusercontent.com/tailwindlabs/tailwindcss/main/CHANGELOG.md",
    "https://registry.npmjs.org/tailwindcss/-/tailwindcss-4.1.0.tgz",
    "https://registry.npmjs.org/tailwindcss/-/tailwindcss-4.2.0.tgz",
    "https://registry.npmjs.org/tailwindcss/-/tailwindcss-4.3.3.tgz"
  ],
  "findings": [],
  "non_findings": [
    {
      "kind": "miss",
      "summary": "Tasks 1, 2 and 3, reproducing its twin: \"No\" to both verdict-first questions (\"there are no first-class single-edge block-axis utilities\"; \"There are no `inline-size`/`block-size` utilities\"), and a task 3 review that says \"**every one of those six classes generates no CSS** … not Tailwind utilities. The element comes out completely unstyled\", telling the colleague to add `@utility` definitions or use arbitrary properties. It hedges less than `v7-a` (\"unless your project has defined them\", \"I'd grep the CSS first\" — for a local `@utility`, not for a newer release). The six classes emit their declarations at 4.2.0 and 4.3.3. The `@utility` workaround it offers compiles at every release tested, and at 4.2.0 it duplicates the built-in rule rather than conflicting with it.",
      "api": "pbs-* / pbe-* / mbs-* / mbe-* / border-bs-* / inline-* / block-* / min-inline-* / max-block-* / inset-bs-*",
      "introduced_in": "4.2.0",
      "chargeable_miss": true,
      "miss_class": "non_charging_arm",
      "charged_on": "tailwindcss--claude-fable-5-1--v7-a--2026-09-28",
      "why_not_a_finding": "Charged on the `-a` twin as F1. The `-b` draw of a duplicated arm carries the failure and no F-number."
    },
    {
      "kind": "miss",
      "summary": "Task 5: \"(a) Yes, it's still current. `start-*` and `end-*` … arrived in v3.3 and are unchanged in v4.\" Deprecated in 4.2.0. Its (c) suggestion `inset-x-0` compiles to `inset-inline` and is not deprecated, as with `v7-a`.",
      "api": "start-* / end-*",
      "introduced_in": "4.2.0",
      "chargeable_miss": true,
      "miss_class": "non_charging_arm",
      "charged_on": "tailwindcss--claude-fable-5-1--v7-a--2026-09-28",
      "why_not_a_finding": "Charged on the `-a` twin as F2. The `-b` draw of a duplicated arm carries the failure and no F-number."
    },
    {
      "kind": "correct",
      "summary": "TASK 4: `ps-6 me-4`, no `pis-*` / `mie-*`. P4 held for this arm.",
      "api": "ps-* / me-*"
    },
    {
      "kind": "correct",
      "summary": "TASK 1 and TASK 6: \"in v4 the paired shorthands `py-*`/`my-*` compile to `padding-block`/`margin-block`\", and at task 6 \"**v4.0 (22 January 2025)** changed what the *paired* axis utilities emit: `px-*`→`padding-inline`, `py-*`→`padding-block`, `mx-*`→`margin-inline`, `my-*`→`margin-block`, `inset-x-*`→`inset-inline`, `inset-y-*`→`inset-block`\". Correct and correctly dated (4.0.0: 2025-01-22); compiled this session at 4.1.0, 4.2.0 and 4.3.3. The twins agree, and both disagree with both `v6` Opus 5.5 draws. No fact covers it, so nothing is credited.",
      "api": "py-* / px-* / my-* / mx-* / inset-x-* / inset-y-*",
      "introduced_in": "4.0.0"
    },
    {
      "kind": "context",
      "summary": "TWINS AGREED ON EVERY PROBE: task 1(a), 2(a), the task 3 rejection, the task 5 verdict, task 4, and the stated boundary (4.1.0, with 4.2 as a number). P1, P2, P3 and P5 confirmed on both draws. This is the reading `v6` did not give on the same bytes (Opus 5.5's twins both knew 4.2.0), so the contrast between the two June-2026 subjects is not a draw-to-draw split."
    }
  ],
  "open_questions": [],
  "summary": "The blind twin, and it reproduces its charging arm on every probe: \"No\" to both questions, all six correct 4.2 classes rejected in review, and `start-*` called current. Nothing is charged here, because the pair is charged once, on `v7-a`. Its boundary is 4.1.0, with 4.2 known only as a number. Like its twin, it knows that v4.0 moved the axis shorthands to logical properties."
}