Not by version attribution: in 5 runs, Claude Haiku 4.5 places its react-router boundary at 6.4.0 (2022-09-13), 6.15.0 (2023-08-10), 6.20.0 (2023-11-22) and 6.28.0 (2024-11-06) — below react-router 8.0.0 (2026-06-17), the first release of react-router 8. That is ~3 to ~29 months below the training cutoff the subject stated in those runs (2025-02). 2 findings are currently charged against Claude Haiku 4.5 on react-router (2x S1 breaks-build), each reproduced in a published run and checked against react-router's own release notes. Read the boundary precisely: it is the newest release whose contents the model can correctly attribute to that release, not the newest react-router feature it can use. Past it a model often writes working code with a newer API while naming the wrong release for it.
Answer class below, decided by one rule applied to every page
of this kind: every measured boundary is below the first release of the major named in the question. Every figure below is read from
the dataset at build time; nothing on this page is written by hand.
| Battery | Newest release it can place | Oldest it cannot | Lag vs stated cutoff |
|---|---|---|---|
| v1-d 2026-09-09 | 6.28.0 2024-11-06 |
7.0.0 2024-11-22 |
~3 months |
| v2-a 2026-09-10 | 6.20.0 2023-11-22 |
7.0.0 2024-11-22 |
~14 months |
| v2-b 2026-09-10 | 6.15.0 2023-08-10 |
6.21.0 2023-12-13 |
~18 months |
| v3-e 2026-09-22 | 6.20.0 2023-11-22 |
6.21.0 2023-12-13 |
~15 months |
| v4-c 2026-09-23 | 6.4.0 2022-09-13 |
6.6.0 2022-12-21 |
~29 months |
5 measurements of this pair, giving 4 different boundaries — 785 days apart, release count not covered by the stored timeline. No two of them were drawn from an identical prompt, so the spread mixes prompt differences with draw variance.
“Chargeable” means the change was published before this model’s own stated cutoff, so it had the opportunity to know it.
| Severity | Belief | Changed in | Chargeable | Proof |
|---|---|---|---|---|
| S1breaks-build | Installs and imports the whole router from react-router-dom, the package the 7.0.0 collapse folded away — which has no release on the current major at allreact-router (package exports) |
7.0.0 2024-11-22 |
yes | run · source |
| S1breaks-build | Answers "yes" to whether the current release installs on React 17 and Node 18, and states no version changes are needed — the current release refuses both halves of that environmentreact-router@7 engine and peer requirements |
7.0.0 2024-11-22 |
yes | run · source |
The react-router correction pack states what is true now for each corrected fact, with a primary-source citation, as markdown you can paste into a rules file (raw). What a correction pack measurably changed when one was tested — a pre-registered run on prisma and zod — is on the benchmark page, including where it changed nothing.
All of them at once: Which Claude model knows react-router 8 best?
Other subjects on react-router:
Claude Haiku 4.5 on the other libraries: