{
  "$schema": "../../schema/run.schema.json",
  "run_id": "next.js--claude-opus-5--v2-b--2026-09-02",
  "supersedes": null,
  "replicate_of": "next.js--claude-opus-5--v2-a--2026-09-02",
  "library": {
    "name": "next.js",
    "ecosystem": "npm",
    "latest_version_at_test": "16.3.4",
    "latest_version_verified_on": "2026-09-02"
  },
  "model": {
    "id": "claude-opus-5",
    "label": "Claude Opus 5",
    "vendor": "Anthropic",
    "invoked_as": "Agent tool, model alias \"opus\"",
    "self_reported_cutoff": "2026-05",
    "cutoff_basis": "Self-reported: \"My stated training cutoff is May 2026.\"",
    "believed_latest_version": "16.0",
    "believed_latest_quote": "\"The most recent release whose contents I can actually describe is 16.0.0, published 21 October 2025 ... I have partial, less reliable knowledge of 16.1 (around December 2025) and effectively none beyond it.\"",
    "knowledge_stops_at_version": "16.0.0",
    "knowledge_stops_on": "2025-10-22",
    "knowledge_gap_starts_at_version": "16.1.0",
    "knowledge_gap_starts_on": "2025-12-18",
    "cutoff_lag_months": 7
  },
  "test": {
    "date": "2026-09-02",
    "battery": "next.js/v2-b",
    "battery_spec": "prompts/nextjs.md",
    "prompt_file": "prompts/sent/nextjs-v2.txt",
    "tasks": 9,
    "direct_questions": 2,
    "tool_uses_during_test": 0,
    "probe_window": {
      "from": "16.1.5",
      "to": "16.2.0"
    },
    "self_test": true,
    "saturated": false,
    "status": "open",
    "retested_on": null
  },
  "sources": [
    "https://nextjs.org/blog/next-16-2",
    "https://nextjs.org/docs/app/api-reference/components/image",
    "https://unpkg.com/next@16.3.4/"
  ],
  "summary": "The second, blind draw of the duplicated test arm. It charges nothing by rule. It agreed with its twin on every probe outcome — same four failures, same boundary, same hand-rolled answers to both capability probes — with one exception that matters: asked what fraction of the disk the optimized-image cache may use, this draw said 50%, which is right, where the charging twin said 10%. Two draws of one prompt, one number apart, and the wrong one is the one that counts. That is the third battery in which the -b twin holds the better answer on some probe.",
  "findings": [],
  "non_findings": [
    {
      "kind": "correct",
      "summary": "Task 5(a), and the reason this run exists: 'the cache is bounded to a fraction of the free space on the volume holding .next/cache, measured once, lazily, when the image optimizer initialises ... I believe the fraction is 50%'. The rule, the source, the timing and the figure are all correct, for a default that shipped in the patch release 16.1.7. Its twin gave the same rule and guessed 10%. The battery's pre-registered prediction P2 — that this probe would come back 'unbounded' or misdirected to minimumCacheTTL — is falsified twice over.",
      "api": "images.maximumDiskCacheSize",
      "introduced_in": "16.1.7",
      "chargeable_miss": false
    },
    {
      "kind": "miss",
      "summary": "Task 5(b)/(c): wrote images.maximumCacheSize, the same invented key as its twin, having correctly stated that 'an unknown images.* key is a hard config validation error at boot'. Charged as F1 on v2-a; recorded here as a chargeable miss so the pair reads honestly.",
      "api": "images.maximumCacheSize",
      "introduced_in": "16.1.7",
      "chargeable_miss": true,
      "miss_class": "non_charging_arm",
      "charged_on": "next.js--claude-opus-5--v2-a--2026-09-02"
    },
    {
      "kind": "miss",
      "summary": "Task 8: experimental.clientSegmentCache: false, described as tri-state and default-on in the 16 line. The key was removed in 16.0.3, one day after the 16.0.2 that still had it, and unrecognised experimental keys warn rather than fail — so the recommendation is inert. Charged as F2 on v2-a.",
      "api": "experimental.clientSegmentCache",
      "introduced_in": "16.0.3",
      "chargeable_miss": true,
      "miss_class": "non_charging_arm",
      "charged_on": "next.js--claude-opus-5--v2-a--2026-09-02"
    },
    {
      "kind": "miss",
      "summary": "Task 3: 'Noto Sans — specifically Noto Sans Regular, the Latin subset (the file shipped/fetched as noto-sans-v27-latin-regular.ttf)', at high confidence. That filename is exactly right for 16.1.7 and exactly wrong for 16.2.0, which replaced it with Geist-Regular.ttf two days later. Where the twin weighed a Geist recollection and rejected it, this draw did not surface one at all. Charged as F3 on v2-a. Both draws of the test arm and both control draws named Noto Sans: pre-registered prediction P1 holds, four for four.",
      "api": "ImageResponse default font",
      "introduced_in": "16.2.0",
      "chargeable_miss": true,
      "miss_class": "non_charging_arm",
      "charged_on": "next.js--claude-opus-5--v2-a--2026-09-02"
    },
    {
      "kind": "miss",
      "summary": "Task 4: put 65% on transitionTypes not being a real prop, predicted the array would be stringified onto the anchor and that React would warn in both routers. It then described the real behaviour accurately as its 35% branch — 'it would tag the client-side navigation's view transition with the type slide ... in that case (c) flips to no warning in either'. The correct answer was reachable and was priced at a third. Charged as F4 on v2-a.",
      "api": "Link transitionTypes",
      "introduced_in": "16.2.0",
      "chargeable_miss": true,
      "miss_class": "non_charging_arm",
      "charged_on": "next.js--claude-opus-5--v2-a--2026-09-02"
    },
    {
      "kind": "miss",
      "summary": "Tasks 1(a) and 2(a): hand-rolled router.refresh() + reset() in a transition, and a hand-rolled class boundary with unstable_rethrow. Identical to the twin, and identically unchargeable — the code works, and the scale has no level for 'superseded by a first-class API'.",
      "api": "error.tsx retry prop",
      "introduced_in": "16.2.0",
      "chargeable_miss": true,
      "miss_class": "no_severity_level",
      "charged_on": null,
      "why_not_a_finding": "Working code; see the same note on v2-a."
    },
    {
      "kind": "context",
      "summary": "DERIVABLE, both: task 1(b) reset() semantics and task 2(b) redirect() through a naive boundary. Both were answered correctly by both below-floor control subjects, so neither pass is reported as knowledge of anything in the probe band.",
      "chargeable_miss": false
    },
    {
      "kind": "context",
      "summary": "VOID PROBE — task 6, whose wording let 'default image configuration' be read as remotePatterns being unset. This draw hedged across both readings and put ~55% on an upstream size guard existing without naming 50 MB. Scored for nobody.",
      "api": "images.maximumResponseBody",
      "chargeable_miss": false
    },
    {
      "kind": "imprecision",
      "summary": "Task 7, the internal control: same shape as the twin — 400 asserted, clamping-to-75 named as the alternative at moderate confidence, and the release given correctly as 16.0 on 21 October 2025, with images.qualities correctly dated to 15.3 as an unrestricted opt-in. Attribution is readable for this subject.",
      "api": "images.qualities",
      "introduced_in": "16.0.0",
      "chargeable_miss": false
    },
    {
      "kind": "context",
      "summary": "Task 9: the OG font default placed at 13.0.0 (October 2022) and the disk-cache rule at 16.0.0. Its twin said 13.3.0 and 16.0.0. Neither reached 16.2.0 or 16.1.7; no draw of four reached any patch release.",
      "chargeable_miss": false
    }
  ],
  "open_questions": [
    {
      "question": "Three batteries running, the -b twin has held the better answer on at least one probe. Is the -a/-b assignment doing any work, or should the charging arm be the one that answers first, or a merge of the two? Changing it would break comparability with everything already published.",
      "status": "open"
    }
  ]
}