{
  "$schema": "../../schema/run.schema.json",
  "run_id": "langchain--claude-opus-5--v6-b--2026-09-06",
  "supersedes": null,
  "replicate_of": null,
  "library": {
    "name": "langchain",
    "ecosystem": "pypi",
    "latest_version_at_test": "1.4.0",
    "latest_version_verified_on": "2026-09-06",
    "latest_version_note": "Same verification as the `v6-a` sibling: four langchain-core wheels (0.3.22, 1.1.3, 1.2.0, 1.6.2) and langchain-anthropic 1.7.1, downloaded and unpacked before the battery was written. `extras` is absent at 1.1.3 and present at 1.2.0 (2025-12-12), undeprecated at 1.6.2."
  },
  "model": {
    "id": "claude-opus-5",
    "label": "Claude Opus 5",
    "vendor": "Anthropic",
    "invoked_as": "Agent tool, model alias \"opus\"; prompt sent verbatim from prompts/sent/langchain-v6.txt, concurrently with and blind to `v6-a`, no tools used by the subject. Identity probed through the same alias in the same session (JOURNAL/054).",
    "self_reported_cutoff": "2026-05",
    "cutoff_basis": "\"My training cutoff is May 2026. Note the asymmetry that matters for this exercise: knowledge thins out well before the cutoff — I can describe October 2025 confidently and the following six months only in outline.\" A density qualification, not a substitute cutoff. Identical month to the `-a` twin, so the cutoff self-report is stable across this pair.",
    "believed_latest_version": "1.0.x, with 1.1 held as a number only",
    "believed_latest_quote": "\"The latest I'm confident about is the 1.0 line (`langchain` 1.0.x / `langchain-core` 1.0.x). I have a weak sense that 1.x continued past that — I'd guess 1.1 or later exists by now — but I can't describe its contents and won't invent them.\"",
    "knowledge_stops_at_version": "1.0.0",
    "knowledge_stops_on": "2025-10-17",
    "knowledge_gap_starts_at_version": "1.1.0",
    "knowledge_gap_starts_on": "2025-11-24",
    "cutoff_lag_months": 7
  },
  "test": {
    "date": "2026-09-06",
    "battery": "langchain/v6-b",
    "battery_spec": "prompts/langchain.md",
    "prompt_file": "prompts/sent/langchain-v6.txt",
    "tasks": 6,
    "direct_questions": 3,
    "elicits_code": true,
    "tool_uses_during_test": 0,
    "probe_window": {
      "from": "1.2.0",
      "to": "1.4.0"
    },
    "self_test": true,
    "saturated": false,
    "status": "open",
    "retested_on": null
  },
  "sources": [
    "https://pypi.org/pypi/langchain/json",
    "https://pypi.org/pypi/langchain-core/json",
    "https://docs.langchain.com/oss/python/releases/changelog",
    "https://files.pythonhosted.org/packages/58/41/6db768d4b208a33b4f09d5415e617d489f68167bb5dd27f87c7a49d13caf/langchain_core-1.1.3-py3-none-any.whl",
    "https://files.pythonhosted.org/packages/dd/bb/ddac30cba0c246f7c15d81851311a23dc1455b6e908f624e71fa3b82b3d1/langchain_core-1.2.0-py3-none-any.whl",
    "https://files.pythonhosted.org/packages/a8/62/d3fb7c215cb2f237c3fe84880bf347a38deafef6033b6d5f1339ba8ca401/langchain_core-1.6.2-py3-none-any.whl",
    "https://files.pythonhosted.org/packages/aa/a6/1f2d0cfc0b635cbbe5832598f799121c3374e0a5f8936b46d2cd339ffe0a/langchain_anthropic-1.7.1-py3-none-any.whl"
  ],
  "findings": [],
  "non_findings": [
    {
      "kind": "miss",
      "api": "@tool(extras={...})",
      "introduced_in": "1.2.0",
      "chargeable_miss": true,
      "miss_class": "non_charging_arm",
      "charged_on": "langchain--claude-opus-5--v6-a--2026-09-06",
      "why_not_a_finding": "The `-b` arm of a born-duplicated pair charges nothing (JOURNAL/028). The identical failure is charged as F1 on the `-a` sibling.",
      "summary": "THE SAME DENIAL AS THE SIBLING, IN ALL THREE PLACES, AND WITH THE SHARPEST ARTEFACT IN THE BATTERY. Task 1: \"no\". Task 6: \"To my knowledge, no release has done so\" — followed by an explicit enumeration of what it believes `BaseTool`'s fields to be: \"`name`, `description`, `args_schema`, `return_direct`, `response_format`, `metadata`, `tags`, `callbacks`, `handle_tool_error`/`handle_validation_error` — `metadata` and `tags` are callback/tracing metadata and are not serialized into the tool definition sent to any provider. Provider-specific tool-definition fields have always had to be smuggled in as a raw dict through `bind_tools`.\" That list is the pre-1.2.0 field set with `extras` the only omission, which is the same shape as `v5-c`'s seven-parameter enumeration of `@tool`. Task 4's MECHANISM line: \"bind_tools (raw provider-format dict passed through, not a tool attribute)\", and the code is the same hand-rebuilt Anthropic dict as the sibling's, verified to deliver both fields. Like the sibling it hedged accurately — \"This is the answer I'm least confident in... something like a `provider_extras` / `extra_body`-style per-tool field could plausibly have landed after my cutoff. Verify against the current `BaseTool` API reference before relying on my 'no.'\" Both draws of this pair reached the same wrong verdict by the same route and flagged the same doubt about it."
    },
    {
      "kind": "correct",
      "api": "a provider-schema-format parameter on @tool (the sibling that does not exist)",
      "summary": "Task 2(a): \"no\" — correct. Reached for both nearby true things by name, `convert_to_openai_tool` in `langchain_core.utils.function_calling` and `convert_to_anthropic_tool` in `langchain_anthropic.chat_models`, and stated the mechanism correctly: \"There is no `@tool(format=\\\"anthropic\\\")` knob; the provider is chosen by which chat model you bind to.\" Both converters verified present. No charge from this task in either direction."
    },
    {
      "kind": "correct",
      "api": "create_agent (the floor probe, langchain 1.0.0)",
      "summary": "Task 3: passed. `from langchain.agents import create_agent`, `system_prompt=`, and it volunteered both the plain-callable acceptance and the historical parameter names it replaced (`prompt` / `state_modifier` on `langgraph.prebuilt.create_react_agent`), plus the fact that the legacy path now lives in `langchain-classic`."
    },
    {
      "kind": "correct",
      "api": "@tool(response_format=\"content_and_artifact\") — the supplied-name control half",
      "summary": "Task 5(b): \"yes\" available, \"no\" never deprecated — both correct. Dated to langchain-core 0.2.x, mid-2024, alongside `ToolMessage.artifact`; verified present at 0.3.22 and unchanged at 1.6.2. Flagged the same-name collision with the chat-model `response_format` unprompted."
    },
    {
      "kind": "context",
      "api": "the fabricated-deprecation probe (BACKLOG 11k-i, rebuilt)",
      "summary": "Task 5(a), on the self-produced name `bind_tools`: \"yes\" available, \"no\" never deprecated, with a correct and unprompted distinction — \"its *predecessors* — `bind_functions`, `ChatOpenAI(functions=...)` — were deprecated, but that's a different name.\" No fabrication. Consistent with P3."
    }
  ],
  "open_questions": [],
  "summary": "The blind twin of `v6-a`, and it agreed with it on every graded quantity: the same \"no\" verdict on task 1, the same hand-rebuilt Anthropic dict in task 4, the same \"no release has done so\" on task 6, the same four correct verdicts on task 5, the same floor pass and the same correct denial of the sibling. It stated the same May 2026 cutoff and the same 1.0.0 boundary. Its distinctive contribution is the artefact: an explicit enumeration of `BaseTool`'s fields that is exactly the pre-1.2.0 set with `extras` the only omission. Charges nothing; the failure is charged as F1 on `v6-a`."
}