{
  "$schema": "../../schema/run.schema.json",
  "run_id": "next.js--claude-opus-5-5--v5--2026-09-27",
  "supersedes": null,
  "replicate_of": null,
  "library": {
    "name": "next.js",
    "ecosystem": "npm",
    "latest_version_at_test": "16.3.6",
    "latest_version_verified_on": "2026-09-27",
    "latest_version_note": "From data/next.js/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 16.3.6 the same day. Newest stable minor: 16.3.0 (2026-08-03), which is the ladder's top rung, above this subject's stated cutoff; no next.js release falls in the cutoff month. The poison rung is established from the registry document itself (3,960 versions): it lists no 15.7.x of any kind, prerelease included; 15.6.0 exists only as canaries (15.6.0-canary.0 to .61), and the `backport` dist-tag reads 15.5.26."
  },
  "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/nextjs-v5.txt (2,645 bytes, md5 c123a24f163b20a2c34ee42261ce54a4), committed and pushed at fed3643 before any subject was spawned. Identity probed BEFORE the draw through the same alias in the same session, tool-free: \"The system prompt says I am Claude Opus 5.5 (1M context), model ID `claude-opus-5-5[1m]`. On my own, I only know that I am Claude, made by Anthropic.\" and \"The system prompt gives my training cutoff as June 2026. I can't check that date against my own knowledge\". 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 stated knowledge cutoff is June 2026. My detailed knowledge of Next.js releases gets thin from about early 2026, well before that.\" A recall-density qualification, not a substitute date.",
    "believed_latest_version": "16.2, held as a number only",
    "believed_latest_quote": "\"The latest version I believe exists is 16.2. The most recent one I can actually describe is 16.1, which shipped around December 2025.\"",
    "believed_latest_quote_form": "draw",
    "knowledge_stops_at_version": "16.1.0",
    "knowledge_stops_on": "2025-12-18",
    "knowledge_stops_provenance": "stated",
    "knowledge_gap_starts_at_version": "16.2.0",
    "knowledge_gap_starts_on": "2026-03-18",
    "knowledge_gap_provenance": "stated",
    "boundary_note": "Three placements agree. The rung sort answered DESCRIBE for 15.0.0, 15.1.0, 15.2.0, 15.3.0, 15.4.0, 15.5.0, 16.0.0 and 16.1.0; NAME for 16.2.0; NO for 15.7.0 (poison) and 16.3.0. Direct (a) names 16.1 as the last describable release; direct (c) states \"The first release I know only as a version number is **16.2**\". The NAME rung carried no content (\"For 16.2 I have only a vague sense that it exists\"), so unlike valibot/v7 the stated end is not equivocal. The same reading as Claude Fable 5.1 on this library (16.1.0, from code batteries), so the comparison crosses instruments. The subject flagged lower confidence on 15.4 and 16.1 than on the others.",
    "cutoff_lag_months": 6
  },
  "test": {
    "date": "2026-09-27",
    "battery": "next.js/v5",
    "battery_spec": "prompts/nextjs.md",
    "prompt_file": "prompts/sent/nextjs-v5.txt",
    "tasks": 2,
    "direct_questions": 3,
    "tasks_declined": 0,
    "elicits_code": false,
    "tool_uses_during_test": 0,
    "probe_window": {
      "from": "15.0.0",
      "to": "16.3.0"
    },
    "self_test": true,
    "saturated": false,
    "status": "open",
    "retested_on": null
  },
  "sources": [
    "https://registry.npmjs.org/next"
  ],
  "findings": [],
  "non_findings": [
    {
      "kind": "context",
      "api": "boundary",
      "summary": "THE CELL THIS ARM WAS RUN TO FILL. Claude Opus 5.5 had never been drawn on next.js, so charge-windows.mjs printed `?` for every next.js release in its column. Stated boundary: describes 16.1.0 (2025-12-18), holds 16.2.0 (2026-03-18) as a number only, and answers NO on 16.3.0 (2026-08-03). The pre-registered prediction (boundary at 15.5.0, 16.0.0 or 16.1.0) HELD, at its upper end. It equals Claude Fable 5.1's reading on this library, which puts the Opus 5.5 ladders at two equal (zod, next.js), two one minor above (better-auth, langchain) and two one minor below (valibot, react-router). Consequence for the sweep: next.js 16.2.0 prints as live for this subject; 16.3.0 is above its stated cutoff."
    },
    {
      "kind": "correct",
      "api": "16.1.0: Turbopack dev filesystem cache on by default, bundle analyzer, next dev --inspect",
      "summary": "The one release at the boundary, described with three claims, and all three are in the shipped bytes of 16.1.0 and absent from 16.0.0 (read off the bisector's installed rungs, one release per directory): `experimental.turbopackFileSystemCacheForDev` defaults to `true` in 16.1.0's `config-shared.js` and does not appear in 16.0.0's; `dist/cli/next-analyze.js` exists in 16.1.0 and not in 16.0.0; and 16.1.0's `bin/next` handles `next dev --inspect` where 16.0.0's only prints the deprecation of the flag. Placed \"around December 2025\", right to the month (2025-12-18). NO next.js fact covers any of the three, so this is checked against shipped bytes rather than against a dated fact, and it credits nothing."
    },
    {
      "kind": "correct",
      "api": "poison rung 15.7.0, and the top rung 16.3.0",
      "summary": "BOTH ENDS HELD. Poison rung 15.7.0 answered NO, with the correct history volunteered: \"I don't believe 15.x got minors past 15.5 other than canaries\" (15.6.0 exists only as canaries; no 15.7.x exists at all). Top rung 16.3.0 (2026-08-03, above the stated cutoff) answered NO: \"I have nothing on 16.3.\""
    },
    {
      "kind": "correct",
      "api": "TASK 1: async params, notFound(), not-found.tsx, bound Server Action, revalidatePath",
      "summary": "The demonstration task, answered on the current surface: `params` typed as a `Promise` and awaited (LF13: synchronous access removed in 16.0.0); `notFound()` from `next/navigation` with a segment `not-found.tsx`; a `'use server'` action file bound with `.bind(null, projectId)`; `revalidatePath` from `next/cache` after `renameProject`. Every runtime import was resolved against next 15.0.0 and 16.3.5 installed one per directory (the bisector's ladder). Two version claims in its notes were executed and hold: `refresh` and `updateTag` are exported by `next/cache` from 16.0.0 and not by 15.5.0 (\"On Next 16 you can use `refresh()`\"), and the typegen that emits the global `PageProps` / `LayoutProps` helpers (`server/lib/router-utils/typegen.js`) first ships in 15.5.0 (\"On 15.5+\"). It also warned, correctly, that a streamed response above the lookup turns the 404 into a 200 with the not-found UI. Graded CORRECT."
    },
    {
      "kind": "context",
      "api": "release history below the boundary, partly checked",
      "summary": "Checked and right: the 16.0 list (`proxy.ts` replacing `middleware.ts`, Turbopack the default bundler, the changed `revalidateTag` signature, `next lint` removed, AMP removed, synchronous request APIs removed, Cache Components replacing the PPR flags) agrees with LF6, LF5, LF1, LF3, LF16, LF13 and LF2, and is placed \"~Oct 2025\" (16.0.0 shipped 2025-10-22). `updateTag` / `refresh` in 16.0 executed above. NOT checked, neither credited nor charged, because no next.js fact covers them: the 15.0 to 15.4 summaries (React 19, uncached fetches by default, `next/form`, `next.config.ts`; `after` stable and experimental `forbidden`/`unauthorized` in 15.1; the error overlay and streaming metadata in 15.2; `onNavigate`, `useLinkStatus` and `instrumentation-client` in 15.3; 15.4 given with low confidence), the 15.5 items other than the typegen helpers, and the 16.0 items React 19.2, React Compiler support and a DevTools MCP. 15.4.0's month was placed \"~Jul 2025\"; the registry dates it 2025-05-30. — CORRECTED 2026-09-28 (JOURNAL/323): the subject's July 2025 for 15.4 is right, and this record was wrong to call it off. The registry does date `next@15.4.0` to 2025-05-30, but that version has no GitHub release. The 15.4 line was released as v15.4.1 on 2025-07-14, and that is the release whose notes point to the Next.js 15.4 blog post (npm registry `time` map; GitHub releases API, checked 2026-09-28). The row stays `context`."
    }
  ],
  "open_questions": [],
  "summary": "A boundary ladder, not a battery: nothing charged, `elicits_code: false`, one arm, and the first next.js ladder. Claude Opus 5.5 states it describes next.js through 16.1.0 (2025-12-18), describing that release's three headline changes in terms that match its shipped bytes, and holds 16.2.0 as a number only, six months below its stated June 2026 cutoff. The pre-registered prediction (15.5.0, 16.0.0 or 16.1.0) held, and the reading equals Claude Fable 5.1's. The NAME rung carried no content, so the stated end is clean. Poison 15.7.0 and top rung 16.3.0 both NO; the demonstration task was correct on 15.0.0 and 16.3.5."
}