{
  "$schema": "../../schema/run.schema.json",
  "run_id": "langchain--claude-sonnet-5--v1r-a--2026-09-01",
  "markdown": "data/langchain/sonnet-5-v1r-a.md",
  "supersedes": null,
  "replicate_of": "langchain--claude-sonnet-5--v1--2026-08-31",
  "library": {
    "name": "langchain",
    "ecosystem": "pypi",
    "latest_version_at_test": "1.3.18",
    "latest_version_verified_on": "2026-08-27",
    "latest_version_note": "Carried from langchain/v1 (verified 2026-08-31 against https://pypi.org/pypi/langchain/json). No new library verification was done for a replicate: the battery is unchanged and nothing in it depends on the current release."
  },
  "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, and explicitly hedged: \"The environment/system information given to me for this session states my knowledge cutoff as January 2026. I'm reporting that because it's what I was told, not something I can independently cross-check from inside the conversation.\"",
    "believed_latest_version": "1.0.0",
    "believed_latest_quote": "\"Latest version *name* I'm aware of: LangChain 1.0 (Python), which I believe shipped roughly October 2025, alongside a corresponding LangGraph 1.0. ... Most recent release whose *contents* I can describe with any real confidence, at roughly the same date (~October 2025): the 1.0 rework itself — `langchain.agents.create_agent` becoming the primary high-level agent constructor (built on LangGraph's runtime/graph execution), the legacy `AgentExecutor`/`initialize_agent` path being deprecated, and a general slimming of the top-level `langchain` package (many integrations and legacy chains pushed out to `langchain-community`, `langchain-classic`, or provider packages like `langchain-anthropic`). Anything past that point — specific patch versions (1.0.1, 1.0.2, …), a possible 1.1, or exact changelog items — I do not have reliable, describable knowledge of.\"",
    "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": 3
  },
  "test": {
    "date": "2026-09-01",
    "battery": "langchain/v1r-a",
    "battery_spec": "prompts/langchain.md",
    "prompt_file": null,
    "tasks": 11,
    "direct_questions": 3,
    "tool_uses_during_test": 0,
    "probe_window": {
      "from": "1.0.0",
      "to": "1.2.0"
    },
    "self_test": false,
    "saturated": false,
    "status": "open",
    "retested_on": null
  },
  "sources": [
    "https://pypi.org/pypi/langchain/json",
    "https://docs.langchain.com/oss/python/releases/langchain-v1",
    "https://docs.langchain.com/oss/python/migrate/langchain-v1",
    "https://reference.langchain.com/python/langchain-classic/"
  ],
  "findings": [],
  "non_findings": [
    {
      "kind": "correct",
      "summary": "Direct question (a), the measured quantity and the reason this run exists. This draw placed its describable boundary at langchain 1.0.0 (2025-10-17) and described the contents correctly: `langchain.agents.create_agent` as the primary agent constructor, `AgentExecutor`/`initialize_agent` deprecated, the top-level package slimmed with legacy code moved to `langchain-classic`, and a matching LangGraph 1.0. Every one of those is true of 1.0.0 per the vendor's own v1 release notes and migration guide, so this is content-level knowledge rather than a recognised version string.",
      "api": null,
      "introduced_in": "1.0.0",
      "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": "context",
      "summary": "Tasks 1-11 produced code but no charged findings, per the v1r pre-registration: `langchain--claude-sonnet-5--v1--2026-08-31` already carries this subject's langchain findings and counting the same failure twice would inflate the dataset. What the code did is still evidence and is reported in the markdown. In short: despite placing its boundary at 1.0.0, this draw still wrote `from langchain import hub` (task 6) and `langgraph.prebuilt.create_react_agent` (task 10), both moved or deprecated at 1.0.0, while avoiding `create_react_agent` in tasks 2, 3 and 5, where it hand-rolled a `bind_tools` loop and used `RunnableWithMessageHistory` instead.",
      "api": null,
      "introduced_in": null,
      "why_not_a_finding": "Pre-registered: a replicate re-sends the code tasks only to hold the priming constant, and does not re-charge what the original run already charged."
    }
  ],
  "open_questions": [
    {
      "question": "This draw and `v1r-b` were given a byte-identical prompt, the same model alias, on the same day, running concurrently, and placed the boundary thirteen months apart (1.0.0 / 2025-10-17 here; 0.3.0 / 2024-09-13 there). Two draws establish that the instrument is not single-valued; they do not establish the shape of the distribution, which draw is modal, or whether the split is bimodal at all.",
      "status": "open"
    },
    {
      "question": "Every other boundary published by the Index rests on a single draw of this same instrument, including the seven that produce Opus 5's three-day intersection. None has been replicated.",
      "status": "open"
    }
  ],
  "summary": "Replicate A of `langchain/v1` against Sonnet 5, prompt unchanged. It placed its describable boundary at langchain 1.0.0 (2025-10-17) and described the 1.0 rework accurately — thirteen months later than `langchain/v1` recorded for the same model on the same battery one day earlier, and thirteen months later than its own concurrent twin `v1r-b`. Pre-registered outcome C: the two replicates disagree with each other. The instrument that produces every knowledge boundary in the Index is not single-valued under a fixed prompt. No findings are charged here; the code half is reported as prose because `langchain/v1` already carries this subject's findings. Worth noting against the alarm: the boundary self-report moved thirteen months while the generated code stayed largely stale in both draws — this draw still wrote `from langchain import hub` and `langgraph.prebuilt.create_react_agent`."
}