{
  "$schema": "../../schema/run.schema.json",
  "run_id": "zod--claude-opus-5--v2r-b--2026-09-01",
  "markdown": "data/zod/opus-5-v2r-b.md",
  "supersedes": null,
  "replicate_of": "zod--claude-opus-5--v2--2026-08-29",
  "library": {
    "name": "zod",
    "ecosystem": "npm",
    "latest_version_at_test": "4.5.4",
    "latest_version_verified_on": "2026-09-01",
    "latest_version_note": "Re-verified against https://registry.npmjs.org/zod on the replicate date; `latest` has moved from the 4.5.2 recorded by `zod/v2` to 4.5.4, all three of 4.5.2/4.5.3/4.5.4 dated 2026-08-29 in the registry `time` map. Release dates used for scoring were read from the same response: 4.0.0 = 2025-07-09, 4.1.0 = 2025-08-23, 4.2.0 = 2025-12-15, 4.3.0 = 2025-12-31, 4.4.0 = 2026-04-29."
  },
  "model": {
    "id": "claude-opus-5",
    "label": "Claude Opus 5",
    "vendor": "Anthropic",
    "invoked_as": "Agent tool, model alias \"opus\", no tools available to the subject",
    "self_reported_cutoff": "2026-05",
    "cutoff_basis": "Self-reported: \"May 2026.\" Volunteered separately that \"today is 2026-09-01, roughly a year past that 4.1 release and past my cutoff, so npm `latest` is very likely ahead of what I can describe ... Treat my version claim as a floor, not a fact.\"",
    "believed_latest_version": "4.x, declines to name",
    "believed_latest_quote": "\"The newest Zod I can name is the 4.x line; the most recent release whose contents I can actually describe is Zod 4.1 (approximately August 2025) - the release that introduced z.codec() and the built-in codec set. I'm aware of 4.0.0 stable at approximately July 2025 ... npm `latest` is very likely ahead of what I can describe - quite possibly 4.2+ or beyond.\"",
    "knowledge_stops_at_version": "4.1.0",
    "knowledge_stops_on": "2025-08-23",
    "knowledge_gap_starts_at_version": "4.2.0",
    "knowledge_gap_starts_on": "2025-12-15",
    "cutoff_lag_months": 9
  },
  "test": {
    "date": "2026-09-01",
    "battery": "zod/v2r-b",
    "battery_spec": "prompts/zod.md",
    "prompt_file": "prompts/sent/zod-v2.txt",
    "tasks": 10,
    "direct_questions": 3,
    "tool_uses_during_test": 0,
    "probe_window": {
      "from": "4.2.0",
      "to": "4.4.0"
    },
    "self_test": true,
    "saturated": false,
    "status": "open",
    "retested_on": null
  },
  "sources": [
    "https://registry.npmjs.org/zod",
    "https://api.github.com/repos/colinhacks/zod/releases"
  ],
  "findings": [],
  "non_findings": [
    {
      "kind": "correct",
      "summary": "The measured quantity. This draw placed the last release whose contents it can describe at Zod 4.1 (approximately August 2025, actual 2025-08-23) and attributed it to `z.codec()` and the built-in codec set - correct. It agrees with its concurrent, blind twin `v2r-a` and with `zod/v2` three days earlier. Three measurements, one answer, spread 0 days, against a pre-registered prediction that this arm would spread.",
      "api": null,
      "introduced_in": null,
      "why_not_a_finding": "A boundary self-report is a belief datum, never a finding. It is what this run measures."
    },
    {
      "kind": "miss",
      "summary": "Task 9, and the reason this run matters beyond the boundary count. Asked what `z.tuple([z.string(), z.number().default(0)]).parse([\"a\"])` returns, this draw answered that it throws a `too_small` array issue, reasoning that \"the tuple's length check runs before any element is parsed, and `.default()` does not mark a position as optional for length purposes\". Zod 4.4.0 (2026-04-29) made tuple defaults materialize, so on any current version the parse returns `[\"a\", 0]`. 4.4.0 precedes this subject's stated 2026-05 cutoff and is therefore chargeable. `zod/v2` answered this task correctly and consequently carries no finding for it, and so did this draw's own twin `v2r-a`. This is a chargeable failure the original run does not carry - a scoring gap surfaced by a replicate, not a double-count.",
      "api": "z.tuple() defaults",
      "introduced_in": "4.4.0",
      "chargeable_miss": true,
      "miss_class": "non_charging_arm",
      "charged_on": null,
      "why_not_a_finding": "Pre-registered: a replicate does not charge findings. Charging it belongs to a real battery aimed at the 4.4.0 behavioural surface, queued in BACKLOG.md, not smuggled into the run that exposed it."
    },
    {
      "kind": "context",
      "summary": "The finding inside the finding, and the second time the Index has seen it. This draw and `v2r-a` reported byte-identical boundaries from byte-identical prompts, and then gave opposite answers about what the library actually does at runtime on task 9 - one correct on 4.4.0, one not. JOURNAL/024 recorded the same dissociation on prisma in the other direction: two draws whose self-reports differed by 204 days both wrote the same stale code. Together they say the self-report and the code are not two views of one quantity. A developer is served by the correction pack, which does not move; the boundary date is the number that does.",
      "api": null,
      "introduced_in": null,
      "why_not_a_finding": "An observation about the instrument, not about zod."
    },
    {
      "kind": "context",
      "summary": "Reproduced without charge, because `zod/v2` already carries all of them: F3 - task 5 states Zod cannot consume a JSON Schema document and routes to Ajv, where 4.2.0 ships `z.fromJSONSchema()`. F4 - task 4 hand-rolls exclusive-or without `z.xor()` (4.2.0). F5 - task 8 states that `\"https:/example.com\"` parses successfully, which 4.4.0 reversed. F6 - task 7 writes a raw-input presence guard and asserts that a union with `z.undefined()` makes the key effectively optional, which 4.4.0 reversed. F1/F2 - direct question (c) states \"the hard block was removed\" in Zod 4, where 4.3.0 and 4.4.0 make `.pick()`/`.omit()`/overwriting `.extend()` throw on refined schemas. Task 6 hand-rolls slugify rather than using `z.slugify()` (4.3.0).",
      "api": null,
      "introduced_in": null,
      "why_not_a_finding": "Already carried by the run this replicates; re-charging would double-count."
    },
    {
      "kind": "context",
      "summary": "Belief data, not scored, but the twins disagree here too and in the opposite direction to task 9. This draw dated Zod 4.0 stable to \"around July 2025\", which the registry `time` map confirms as 2025-07-09; `v2r-a` said May 2025 and is wrong by nine weeks. So on the same day, from the same prompt, one twin has the better runtime model of 4.4.0 and the other has the better calendar for 4.0.0. Neither difference shows up in the boundary, which is identical.",
      "api": null,
      "introduced_in": "4.0.0",
      "why_not_a_finding": "Direct-question belief data, scored separately from the code tasks by the battery's own rule."
    }
  ],
  "open_questions": [
    {
      "question": "This draw raised `z.interface()` and said it could not recall whether it survived into stable Zod 4 - \"I have conflicting recollections\" - and declined to build task 7 on it. The Index has never verified what became of `z.interface()`. It is cheap archaeology from the 4.0.0 release notes and it would let a future battery score the question rather than watch a subject hedge past it.",
      "status": "open"
    }
  ],
  "summary": "Replicate B of `zod/v2` against Opus 5, prompt unchanged. It placed its describable boundary at Zod 4.1 (2025-08-23), identical to its blind twin `v2r-a` and to `zod/v2` - three measurements, one answer, spread 0 days, against a pre-registration that predicted a spread. No findings charged. It differs from both other measurements on task 9, asserting that a defaulted tuple element does not fill a missing slot, which 4.4.0 reversed: a chargeable failure the original run does not carry, flagged and queued."
}