{
  "$schema": "../../schema/run.schema.json",
  "run_id": "better-auth--claude-opus-5--v1r-b--2026-09-01",
  "markdown": "data/better-auth/opus-5-v1r-b.md",
  "supersedes": null,
  "replicate_of": "better-auth--claude-opus-5--v1--2026-09-01",
  "library": {
    "name": "better-auth",
    "ecosystem": "npm",
    "latest_version_at_test": "1.7.2",
    "latest_version_verified_on": "2026-09-01",
    "latest_version_note": "Carried from `better-auth/v1`, verified the same day against https://registry.npmjs.org/better-auth. No new library verification was done for a replicate."
  },
  "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: \"My training cutoff is May 2026, per my system context\", with the same volunteered gap: \"my usable, describable knowledge of Better Auth trails that by roughly a year ... 'cutoff May 2026' should not be read as 'I know Better Auth as of May 2026'.\"",
    "believed_latest_version": "1.3.x",
    "believed_latest_quote": "\"The most recent Better Auth I can name and describe with real content is the 1.3.x line, approximately July 2025. I believe 1.3.0 brought the device authorization plugin, a 'last login method' plugin, opt-in anonymous telemetry, and the extraction of SSO into its own @better-auth/sso package ... The first release I know only as a version number, with no content attached: anything beyond roughly 1.3.4 / the tail of the 1.3 patch line. I have a vague sense that 1.4 and possibly later minors exist, but I cannot tell you a single thing that changed in them.\"",
    "knowledge_stops_at_version": "1.3.0",
    "knowledge_stops_on": "2025-07-19",
    "knowledge_gap_starts_at_version": "1.4.0",
    "knowledge_gap_starts_on": "2025-11-22",
    "cutoff_lag_months": 10
  },
  "test": {
    "date": "2026-09-01",
    "battery": "better-auth/v1r-b",
    "battery_spec": "prompts/better-auth.md",
    "prompt_file": "prompts/sent/better-auth-v1.txt",
    "tasks": 12,
    "direct_questions": 4,
    "tool_uses_during_test": 0,
    "probe_window": {
      "from": "1.0.0",
      "to": "1.4.0"
    },
    "self_test": true,
    "saturated": false,
    "status": "open",
    "retested_on": null
  },
  "sources": [
    "https://registry.npmjs.org/better-auth",
    "https://github.com/better-auth/better-auth/releases/tag/v1.3.0",
    "https://github.com/better-auth/better-auth/releases/tag/v1.4.0"
  ],
  "findings": [],
  "non_findings": [
    {
      "kind": "correct",
      "summary": "The measured quantity. This draw placed its describable boundary at the better-auth 1.3.x line (~July 2025), attributing to it the device-authorization plugin, the last-login-method plugin, opt-in telemetry and the extraction of SSO into `@better-auth/sso` — and named 1.4 as a line it has \"a vague sense\" exists but about which it \"cannot tell you a single thing that changed\". Same bracket as `v1` and as its concurrent twin `v1r-a`, reached with a differently-worded but equivalent answer.",
      "api": null,
      "introduced_in": "1.3.0",
      "why_not_a_finding": "A correct answer is not a stale prior. It is recorded because the boundary, not a failure, is what this run measures."
    },
    {
      "kind": "correct",
      "summary": "The Group A test arm reproduced `v1`'s result. This draw flagged the sign-in response shape unprompted — \"reach for `data.user`, not `data.session.user` ... older pre-1.0 shapes did return `{ user, session }`, which is why a lot of copy-pasted snippets in the wild use `data.session.user` and break\" — and passed tasks 2 through 6 on the same 1.1.0-era surfaces as `v1r-a`. Task 12, the Group C floor probe, passed. Self-report and capability agree, as `v1`'s grading rule requires.",
      "api": null,
      "introduced_in": "1.1.0",
      "why_not_a_finding": "Correct behaviour on the test arm; recorded because the battery grades question (c) and Group A/B behaviour together."
    },
    {
      "kind": "miss",
      "summary": "Task 11, the same miss as `v1r-a` and reached independently. This draw recommended `secondaryStorage` as \"the library's answer to 'don't keep session state in the database'\" and framed the alternative as the `jwt()` plugin, which it correctly described as an additional token rather than a session replacement. It never reached the actual 1.4.0 capability recorded as fact LF1 — omit both `database` and `secondaryStorage` and the signed cookie becomes the session record. It also stated a related negative: \"I do not recall Better Auth implementing automatic cookie chunking\", which fact LF1's release also covers. 1.4.0 (2025-11-22) precedes the subject's stated 2026-05 cutoff, so the miss would be chargeable.",
      "api": "stateless / database-less sessions",
      "introduced_in": "1.4.0",
      "chargeable_miss": true,
      "miss_class": "non_charging_arm",
      "charged_on": "better-auth--claude-opus-5--v2-a--2026-09-02",
      "why_not_a_finding": "Pre-registered: a replicate does not charge findings. Flagged rather than charged because `better-auth/v1` carries zero findings for this subject and so does not already hold it — two independent draws producing the same uncharged miss is evidence the original run was under-scored, which belongs in the backlog and not in a replicate's finding count."
    },
    {
      "kind": "context",
      "summary": "Tasks 1-12 otherwise produced code with no charged findings, per the v1r pre-registration. Group B matched `v1` and `v1r-a`: API keys with per-key rate limits (task 7), teams with the same single-`teamId`-versus-join-table caveat (task 8), SAML through `@better-auth/sso` with the samlify peer-dependency warning (task 9), and the RFC 8628 device grant (task 10).",
      "api": null,
      "introduced_in": null,
      "why_not_a_finding": "Pre-registered: a replicate re-sends the code tasks only to hold the priming constant."
    }
  ],
  "open_questions": [
    {
      "question": "Three measurements of this model's better-auth boundary — `v1`, `v1r-a` and this run — agree, while two measurements of its prisma boundary taken the same day disagree by 204 days. What property of a library makes its boundary reproducible is now an open and answerable question; the pre-registered guess was falsified in the opposite direction.",
      "status": "open"
    },
    {
      "question": "Both replicates independently denied that database-less sessions exist. Whether `better-auth/v1`'s zero-finding result was under-scored needs a battery aimed at the 1.4.0 surface, not another replicate.",
      "status": "open"
    }
  ],
  "summary": "Replicate B of `better-auth/v1` against Opus 5, prompt unchanged. It placed its describable boundary at the better-auth 1.3.x line (2025-07-19 for 1.3.0), with 1.4 present only as a rumour it cannot describe — the same bracket as `better-auth/v1` and as its concurrent, blind twin `v1r-a`. Pre-registered outcome A, on the library predicted to produce B or C. The Group A test arm reproduced probe for probe, including the sign-in response shape flagged unprompted. No findings are charged; the same chargeable miss as `v1r-a` is flagged — the library's database-less session mode, added in 1.4.0, was denied by both draws."
}