Run next.js--claude-opus-5--v4-f--2026-09-05 · self-test: the subject is the operator
The bridge arm in the favourable order: ladder first, boundary question last, the position every published battery uses. D = 16.0.0, S = 16.0.0/16.1.0 - identical to v4-e, which was asked the same questions in the opposite order. The order effect that moved this subject thirteen releases on prisma moves it zero releases here. Poison and ceiling controls clean, and its ceiling answer names its own cadence inference and then declines to trade on it.
| Subject | Claude Opus 5 claude-opus-5, Anthropic |
|---|---|
| Invoked as | Agent tool, model override 'opus'; prompt sent verbatim from prompts/sent/nextjs-v4-cs.txt. An identity probe run in the same session answered "Claude Opus 5 (1M context variant)", model id `claude-opus-5[1m]`, cutoff May 2026 - the same subject as every earlier Claude Opus 5 run in the Index, so the id is recorded unchanged as `claude-opus-5`. |
| Cutoff the model states | 2026-05 |
| Newest next.js release it could place | 16.0.0 · 2025-10-22 (~7 month lag) |
| Oldest next.js release it could not place | 16.1.0 · 2025-12-18 (so this run brackets the subject’s boundary to 2025-10-22 – 2025-12-18) |
| In its own words | "The latest version I have any awareness of as a number is somewhere in the 16.x line - I have a weak sense of 16.1 and possibly 16.2 existing, roughly late 2025 into early 2026. But the most recent release whose contents I can actually describe is 16.0.0" |
| Library at test time | next.js 16.3.4 (npm), verified 2026-09-05 |
| Battery | next.js/v4-f · 0 tasks, 10 direct questions · probe window 15.1.0 to 16.3.0 |
| Tool uses during test | 0 (a run with any tool use is void — we measure training knowledge, not retrieval) |
| Tested | 2026-09-05 |
| Findings | 0, of which 0 chargeable |
None. Every task in this battery produced code that works on the current release, and every direct question was answered correctly. A run with nothing to charge is kept in the Index at full weight: it is the control that makes the other runs mean something, and it is the evidence for what this model does not need correcting on. What the subject actually said is recorded below.
Recorded so the run cannot be read as a hit list. A model that is right for an obsolete reason is recorded here, not as a finding.
| Kind | API | Note |
|---|---|---|
| correct | next 16.0.0 |
LADDER GRADE - CORRECT. Turbopack default for dev and build, Cache Components graduating dynamicIO into a cacheComponents option with use cache, cacheLife/cacheTag, updateTag/refresh beside revalidateTag, proxy.ts replacing middleware.ts, React 19.2 with Activity, the AMP and next lint removals, the Node 20.9 floor and the adapters API in alpha. Self-rated "high" on most of that list and "medium" on proxy.ts and the adapters API - both of which are correct. |
| context | next 16.1.0 |
LADDER GRADE - ABSTAIN, unambiguous. "Cannot describe. I believe a 16.1 was released (the 16.x line clearly continued past the initial release), but I cannot name a single feature, config key, or API from it with any confidence. I'd rather say nothing than guess." Existence without content, which is the definition the Index's boundary interval is built on. |
| correct | next 15.3.0 |
LADDER GRADE - CORRECT. next build --turbopack alpha, instrumentation-client.ts, onNavigate and useLinkStatus, experimental next-rspack, TypeScript language-server performance. |
| correct | next 15.1.0 |
LADDER GRADE - CORRECT. React 19 stable, after() stable with the correct import path, forbidden()/unauthorized() behind experimental.authInterrupts with forbidden.tsx/unauthorized.tsx, and the source-map and stack-trace work. |
| correct | next 15.5.0 |
LADDER GRADE - CORRECT. Turbopack production builds beta, Node.js middleware stable, typedRoutes out of experimental with route export validation, next lint deprecated with removal announced for 16, and the AMP deprecation warning. |
| correct | next 15.7.0 |
POISON RUNG. 15.7.0 has never been published in any form - zero versions of any kind match 15.7.* on the npm registry, checked this session. "Cannot describe. I have no content for this version, and I am not confident it was ever released - my knowledge of the 15.x line effectively ends at 15.5 with a possible 15.6 that I also cannot describe." P4 holds on this arm, so its CORRECT grades stand. |
| correct | next 16.3.0 |
CEILING RUNG. 16.3.0 (2026-08-03) is above this subject's stated cutoff. "Cannot describe... I would guess from release cadence that a 16.3 plausibly exists by mid-2026, but that is inference from the pattern, not knowledge, so I am not going to characterize it." Naming the inference and then refusing to trade on it is the behaviour the ceiling rung exists to check for. P5 holds on this arm. |
| context | self-placement |
"First release I know only as a version number, with no content attached: 16.1.0." Identical to its -sc counterpart v4-e and to the five prior next.js runs of this subject. The boundary this Index publishes for Claude Opus 5 on next.js is now seven runs deep and has never moved. |
Battery specification: prompts/nextjs.md in the studio repo.
Every finding above also carries its own citation.