{
  "$schema": "../../schema/run.schema.json",
  "run_id": "better-auth--claude-opus-5--v5-b--2026-09-03",
  "supersedes": null,
  "replicate_of": "better-auth--claude-opus-5--v5-a--2026-09-03",
  "library": {
    "name": "better-auth",
    "ecosystem": "npm",
    "latest_version_at_test": "1.7.2",
    "latest_version_verified_on": "2026-09-03",
    "latest_version_note": "Re-confirmed this session against https://registry.npmjs.org/better-auth (`npm view better-auth version` -> 1.7.2). This battery's claim is version-independent: the phone-number plugin has no at-rest storage option at any release, so there is no probe window and nothing here depends on the current release."
  },
  "model": {
    "id": "claude-opus-5",
    "label": "Claude Opus 5",
    "vendor": "Anthropic",
    "invoked_as": "Agent tool, model override 'opus', no tools available to the subject",
    "self_reported_cutoff": "2026-05",
    "cutoff_basis": "Stated as around May 2026, with the subject's own qualification: \"I'm told my cutoff is around May 2026. My usable knowledge of this particular library is clearly much older than that - it thins out sharply after mid-2025.\" The same value and the same volunteered caveat as its twin, drawn blind from the identical stored prompt.",
    "believed_latest_version": "1.3.x",
    "believed_latest_quote": "\"The latest version I can name with any confidence is in the 1.3.x line, roughly July-September 2025. The most recent release whose contents I can actually describe is 1.3.0 (~July 2025), and even there my description is partial.\"",
    "knowledge_stops_at_version": "1.2.0",
    "knowledge_stops_on": "2025-03-01",
    "knowledge_gap_starts_at_version": "1.3.0",
    "knowledge_gap_starts_on": "2025-07-19",
    "cutoff_lag_months": 22
  },
  "test": {
    "date": "2026-09-03",
    "battery": "better-auth/v5-b",
    "battery_spec": "prompts/better-auth.md",
    "prompt_file": "prompts/sent/better-auth-v5.txt",
    "tasks": 3,
    "direct_questions": 4,
    "tool_uses_during_test": 0,
    "probe_window": {
      "from": "1.3.0",
      "to": "1.7.2"
    },
    "self_test": true,
    "saturated": false,
    "status": "open",
    "retested_on": null
  },
  "sources": [
    "https://registry.npmjs.org/better-auth",
    "https://registry.npmjs.org/better-auth/-/better-auth-1.2.12.tgz",
    "https://registry.npmjs.org/better-auth/-/better-auth-1.3.0.tgz",
    "https://registry.npmjs.org/better-auth/-/better-auth-1.5.0.tgz",
    "https://registry.npmjs.org/better-auth/-/better-auth-1.7.2.tgz"
  ],
  "findings": [],
  "non_findings": [
    {
      "kind": "miss",
      "summary": "Task 1, the probe: reproduced its twin's invention with no hedge at all. Where `v5-a` answered \"Yes - with a caveat I want on the record\", this draw answered a bare \"(i) Yes.\" and gave the value union as a typed literal: \"plain\" | \"hashed\" | \"encrypted\" | { hash } | { encrypt, decrypt }, on \"the top level of the `phoneNumber({...})` options object\". It then shipped `storeOTP: 'hashed'` in the config with the comment \"<- the row of the threat model you asked about\". Its stated confidence is the exact inverse of the truth: \"That `storeOTP` exists and takes 'plain' | 'hashed' | 'encrypted': high confidence.\" The shipped block is a TS2353 at 1.3.0, 1.5.0 and 1.7.2. Charged on its twin as F1.",
      "api": "phoneNumber({ storeOTP })",
      "introduced_in": null,
      "chargeable_miss": true,
      "miss_class": "non_charging_arm",
      "charged_on": "better-auth--claude-opus-5--v5-a--2026-09-03",
      "why_not_a_finding": "The `-b` draw of a duplicated test arm charges nothing, by the rule added in JOURNAL/028. The failure is real, it is counted, and it is carried by `v5-a`. Its value here is that it makes the belief a measurement rather than a coin: both blind draws from one stored prompt invented the same option, at the same nesting, with the same value union."
    },
    {
      "kind": "correct",
      "summary": "Task 2, the exists-control, and a clean sweep where its twin missed half: named `twoFactor({ otpOptions: { storeOTP: 'hashed' } })` at the correct nesting - \"nested inside `otpOptions`, not at the plugin's top level\" - and `oneTimeToken({ storeToken })` with the `{ type: 'custom-hasher', hash }` form. Both real, both 1.3.0, both type-check clean at 1.3.0, 1.5.0 and 1.7.2. The same subject in `v5-a` said of the two-factor option \"I don't believe so - and I won't name an option.\"",
      "api": "twoFactor otpOptions.storeOTP",
      "introduced_in": "1.3.0"
    },
    {
      "kind": "correct",
      "summary": "Named `phoneNumber({ sendPasswordResetOTP })` while flagging it as \"the weakest name in this snippet\" and offering a fallback if it did not type-check. It is real and it does type-check, at 1.3.0 through 1.7.2. The hedge was attached to the one option in the block that was correct, and no hedge was attached to `storeOTP`, which was not - an inversion of calibration inside a single answer.",
      "api": "phoneNumber sendPasswordResetOTP",
      "introduced_in": null
    },
    {
      "kind": "correct",
      "summary": "Task 3, the floor probe: passed. `customSession` plus `customSessionClient<typeof auth>()`, with the same last-in-the-array ordering constraint its twin gave.",
      "api": "customSession",
      "introduced_in": "1.0.0"
    },
    {
      "kind": "context",
      "summary": "(c) attributes SAML 2.0 in the SSO plugin, the `storeOTP`/`storeToken` hashing options and the `last-login-method` plugin all to \"1.3.x (~July 2025)\" - three features, one release, and the release is right. This is the draw that grouped them correctly, which makes `v5-d`'s split of the same two features across 1.2.x and 1.3 the more interesting reading (see P6 on that run).",
      "api": "1.3.0 release contents",
      "introduced_in": "1.3.0"
    }
  ],
  "open_questions": [],
  "summary": "The blind twin, and it turned the invention from an incident into a measurement. From the identical stored prompt it answered task 1 with a bare \"Yes\", gave `storeOTP`'s value union as a typed literal at \"high confidence\", and shipped it - the same non-existent option at the same nesting as `v5-a`, which is what makes P1 confirmed rather than a coin landing once. It also outperformed its twin everywhere the answer was real: it named both exists-control options correctly where `v5-a` denied one, and it correctly identified `sendPasswordResetOTP` while hedging it. Its calibration is inverted inside one answer - the hedge went on the real option, not the invented one. Charges nothing, by the duplicated-arm rule."
}