{
  "$schema": "../../schema/run.schema.json",
  "run_id": "next.js--claude-sonnet-5--v3-a--2026-09-02",
  "supersedes": null,
  "replicate_of": null,
  "library": {
    "name": "next.js",
    "ecosystem": "npm",
    "latest_version_at_test": "16.3.4",
    "latest_version_verified_on": "2026-09-02"
  },
  "model": {
    "id": "claude-sonnet-5",
    "label": "Claude Sonnet 5",
    "vendor": "Anthropic",
    "invoked_as": "Agent tool, model alias \"sonnet\"",
    "self_reported_cutoff": "2026-01",
    "cutoff_basis": "Self-reported, accepting the environment value: \"The system context here states my knowledge cutoff as January 2026, and I'll take that as authoritative for the nominal cutoff.\" It then caveats recall depth rather than the date - \"I trust my detailed Next.js knowledge most through roughly early-to-mid 2025\" - which is a statement about confidence, not a different cutoff. Its blind twin v3-b refused the environment value outright and stated early-to-mid 2025 as the cutoff itself. Not back-filled from any other run.",
    "believed_latest_version": "15.x",
    "believed_latest_quote": "\"The most recent version name I'm aware of is somewhere in the Next.js 15.x line ... The most recent release whose actual contents I can describe with any real specificity is around Next.js 15.2-15.3 ... I'd place that roughly February-April 2025\"",
    "knowledge_stops_at_version": "15.3.0",
    "knowledge_stops_on": "2025-04-09",
    "knowledge_gap_starts_at_version": "15.4.0",
    "knowledge_gap_starts_on": "2025-05-30",
    "cutoff_lag_months": 9
  },
  "test": {
    "date": "2026-09-02",
    "battery": "next.js/v3-a",
    "battery_spec": "prompts/nextjs.md",
    "prompt_file": "prompts/sent/nextjs-v3.txt",
    "tasks": 5,
    "direct_questions": 2,
    "tool_uses_during_test": 0,
    "probe_window": {
      "from": "16.0.3",
      "to": "16.0.3"
    },
    "self_test": false,
    "saturated": false,
    "status": "open",
    "retested_on": null
  },
  "sources": [
    "https://unpkg.com/next@16.0.2/dist/server/config-shared.d.ts",
    "https://unpkg.com/next@16.0.3/dist/server/config-shared.d.ts",
    "https://unpkg.com/next@16.3.4/dist/server/config.js",
    "https://unpkg.com/next@16.3.4/dist/shared/lib/image-config.js",
    "https://nextjs.org/blog/next-16-2"
  ],
  "summary": "The charging arm of the battery written to book the miss next.js/v2 could only queue, and it books it. Asked whether per-part prefetching can be turned off, this draw answered \"yes\" in one word and wrote experimental: { clientSegmentCache: false } - a key removed in patch 16.0.3 on 2025-11-13, two months inside its own stated cutoff. Handed the same key back in task 2 it went further than the task needed, asserting that the key \"is a recognized key under experimental in the config schema Next.js validates against at build start, so no warning is printed\". It is not recognised, and the build warns. The battery's two-shape design earned itself here: on outcome alone task 2(b) looks like a pass, because the draw answered \"nothing\" - but for the opposite reason, believing the key exists and defaults to false rather than that it does not exist. Task 1 is what makes the belief legible. On the internal control it named middleware.ts, does not hold the 16.0.0 proxy.ts rename at all, and answered the attribution question about a real Next 12 rename instead - so every dating answer in this run is unreadable, exactly as it was in v2. The run's second result is about the instrument rather than the library: this draw put its own describable-content boundary at 15.2-15.3, where v1 and v2 both put it at 15.0.0, and its blind twin put it at 15.4-15.5.",
  "findings": [
    {
      "id": "F1",
      "severity": "S2",
      "severity_label": "silently-wrong",
      "title": "Answers \"yes\" and configures experimental.clientSegmentCache, a key removed in patch 16.0.3",
      "api": "experimental.clientSegmentCache",
      "change_kind": "removed",
      "introduced_in": "16.0.3",
      "introduced_on": "2025-11-13",
      "chargeable": true,
      "chargeable_note": "Removed 2025-11-13, two months before this draw's stated cutoff of January 2026, which it accepted from its environment as authoritative. Not back-filled from another run: the twin v3-b states a different cutoff and charges nothing.",
      "model_belief": "Task 1(a), one word: \"yes\". Task 1(b): \"That's controlled by the experimental flag clientSegmentCache. Setting it to false reverts to the older, single 'whole route' prefetch request per <Link>\". Task 2(a): \"It accepts the config silently. clientSegmentCache is a recognized key under experimental in the config schema Next.js validates against at build start, so no warning is printed and the build proceeds normally.\" Task 5(a): \"it has not stopped being recognized, as far as I know.\"",
      "wrong_code": "experimental: { clientSegmentCache: false }",
      "correct_code": "experimental: { prefetchInlining: true }",
      "impact": "The team asked how to cut a prefetch burst and gets a config that compiles, deploys and does nothing. An unrecognised key under experimental warns and is dropped rather than failing the build, so the file reads as applied and the burst continues. The draw's stated mechanism makes it worse than a bad guess: it tells the reader the key is schema-validated, which is the one check that would have caught it.",
      "citations": [
        {
          "url": "https://unpkg.com/next@16.0.2/dist/server/config-shared.d.ts",
          "title": "next 16.0.2 published package - the key still exists",
          "published_on": "2025-11-12",
          "quote": "clientSegmentCache?: boolean | 'client-only';"
        },
        {
          "url": "https://unpkg.com/next@16.0.3/dist/server/config-shared.d.ts",
          "title": "next 16.0.3 published package - gone one day later",
          "published_on": "2025-11-13",
          "quote": "(no occurrence of clientSegmentCache in the file)"
        },
        {
          "url": "https://unpkg.com/next@16.3.4/dist/server/config.js",
          "title": "next 16.3.4 published package - why the dead key warns instead of failing",
          "published_on": "2026-08-31",
          "quote": "if (issue.code === 'unrecognized_keys' && issue.path[0] === 'experimental') {"
        }
      ],
      "scope_note": "Re-confirmed against the published packages this session before the battery was written: two occurrences at 16.0.2, zero at 16.0.3, zero at 16.3.4."
    }
  ],
  "non_findings": [
    {
      "kind": "miss",
      "summary": "Task 4, the internal control. Named middleware.ts exporting middleware and does not hold the 16.0.0 rename to proxy.ts at all - asked for an older name it reached back to the per-directory pages/_middleware.ts convention of Next 12. The generated middleware.ts is deprecated as of 16.0.0 and is a real miss inside the window, but it is already charged against this subject as F1 of the v1 run, and this battery asks it as the calibration control rather than as a charging probe.",
      "api": "middleware.ts / export function middleware",
      "introduced_in": "16.0.0",
      "chargeable_miss": true,
      "miss_class": "probe_class",
      "charged_on": "next.js--claude-sonnet-5--v1--2026-08-31",
      "why_not_a_finding": "The internal control exists to say whether this subject's attribution answers can be read at all. It came back untestable - the subject does not hold the change, so its dating answer measures nothing (JOURNAL/030(b)). Charging it here would also double-count v1 F1."
    },
    {
      "kind": "miss",
      "summary": "Task 3, and the reason it is not charged against this subject. Answered that no framework-level source-size limit exists - \"the request to /_next/image ends with HTTP 200, provided the Node process has enough memory\" - and in (c) made the resource story explicit: \"more RAM and disk headroom make the 200-OK success path more likely\". The truth is a fixed 50 MB cap that throws a 413 while streaming, independent of RAM. images.maximumResponseBody arrived in 16.1.5 on 2026-01-26, the same month as this subject's stated cutoff, so it sits outside the fairness window under the same-month rule and is not a chargeable miss. It did name 50 MB, but attached it to Vercel's hosted platform rather than to the framework, and used that attribution to rule the limit out for a self-hosted app.",
      "api": "images.maximumResponseBody",
      "introduced_in": "16.1.5",
      "chargeable_miss": false
    },
    {
      "kind": "context",
      "summary": "Task 2(b) is the reason this battery asked the same surface two ways. On outcome alone it passed - \"it's identical to omitting the key entirely\" - and a battery that had asked only the recognition question would have scored a pass. The mechanism is the opposite of the truth: the draw believes the key is live and defaults to false, not that it does not exist, and flagged the alternative reading at \"maybe 55/45\". BACKLOG 2b asked for the recognition shape alone; keeping the offer shape as well is what made the belief legible.",
      "api": "experimental.clientSegmentCache",
      "introduced_in": "16.0.3",
      "chargeable_miss": false
    },
    {
      "kind": "context",
      "summary": "The boundary moved between batteries for this subject, which v1 and v2 gave no sign of. v1 (2026-08-31) and v2-c (2026-09-02) both read 15.0.0 / 15.1.0. This draw reads 15.2-15.3 describable, \"roughly February-April 2025\", and its blind twin reads 15.4-15.5. JOURNAL/030(c) concluded from v1 and v2 that a different battery is not a different boundary; on this subject and this library, v3 contradicts it, and the twin pair shows the movement inside one stored prompt. Not charged - the S4 recency finding for this subject belongs to v1 F7.",
      "api": null,
      "introduced_in": null,
      "chargeable_miss": false
    },
    {
      "kind": "context",
      "summary": "The stated cutoff, recorded because it is the input to the fairness rule and because it moved. This draw accepted the environment value as authoritative and caveated only its recall depth; its blind twin v3-b explicitly refused it - \"that's the environment's clock, not evidence about my training horizon\" - and stated early-to-mid 2025 instead. Same subject, same stored prompt, same session, two different cutoffs. This is JOURNAL/031's zod/v4 result replicating in a second library, with the arms the other way round: there the charging arm disqualified itself, here the charging arm is the one that admits the release.",
      "api": null,
      "introduced_in": null,
      "chargeable_miss": false
    }
  ],
  "open_questions": [
    {
      "question": "The cutoff self-report has now split between blind twins in two libraries (zod/v4, next.js/v3). Two draws of two batteries is not a rate. The index publishes stated cutoffs as if they were a property of the subject; they are a property of the draw, and nothing on the site says so yet.",
      "status": "open"
    },
    {
      "question": "This subject's next.js boundary now has four readings across three batteries (15.0.0, 15.0.0, 15.3.0, 15.5.0). JOURNAL/030(c) read v1-vs-v2 agreement as evidence that a battery does not move a boundary. Whether v3 moved it, or whether v1 and v2 happened to agree, cannot be settled from four points.",
      "status": "open"
    }
  ]
}