GPAI Ledger › Claude Mythos Preview (Anthropic)
Claude Mythos Preview
Public summary of training content · Article 53(1)(d), Regulation (EU) 2024/1689
Provider: Anthropic — status: Published
Anthropic publishes a public summary of training content for Claude Mythos Preview under the EU AI Act; every version this ledger has captured is archived below with its hash and timestamp proof.
AIAL metadata: summary dated 2026-07-24, model released 2026-06-02, eval page
Anthropic publishes this model's summary inside its trust center; the document is also captured in the Anthropic trust-center bundle.
Document versions
| Capture (UTC) | Source of copy | URL | SHA-256 | Bytes | Notes |
|---|---|---|---|---|---|
| 20260811T102605Z | AIAL archived copy | aial.ie/research/gpai-training-transpare…_Mythos_Preview_2026_08_03.pdf | 038c305c4760c4d2… | 280,947 |
Watch-surface captures
Captures of the page(s) where the document is published (portals, hubs, docs pages) — monitored for change detection; not the document itself.
| Capture (UTC) | Source of copy | URL | SHA-256 | Bytes | Notes |
|---|---|---|---|---|---|
| 20260930T112625Z | provider site | trust.anthropic.com/resources | 2d0cb0f33301a748… | 258,532 | rendered page (captured with a browser); page text changed vs the previous capture of this target (16 word(s) differ in the extracted text) |
| 20260929T113847Z | provider site | trust.anthropic.com/resources | eba317748274eb6f… | 258,172 | rendered page (captured with a browser); page text changed vs the previous capture of this target (54 word(s) differ in the extracted text) |
| 20260924T103409Z | provider site | trust.anthropic.com/resources | 37b7597fdc56473c… | 251,991 | rendered page (captured with a browser); page text changed vs the previous capture of this target (30 word(s) differ in the extracted text) |
| 20260923T102032Z | provider site | trust.anthropic.com/resources | ce514a80ab7ca363… | 248,586 | rendered page (captured with a browser); page text changed vs the previous capture of this target (44 word(s) differ in the extracted text) |
| 20260918T055803Z | provider site | trust.anthropic.com/resources | 239bb4b36921aa97… | 242,509 | rendered page (captured with a browser); page text changed vs the previous capture of this target (32 word(s) differ in the extracted text) |
| 20260910T055938Z | provider site | trust.anthropic.com/resources | 704469fdc3784d7b… | 230,301 | rendered page (captured with a browser); page text changed vs the previous capture of this target (19 word(s) differ in the extracted text) |
| 20260902T060003Z | provider site | trust.anthropic.com/resources | d74e825b8c395d9e… | 227,111 | rendered page (captured with a browser); page text changed vs the previous capture of this target (56 word(s) differ in the extracted text) |
| 20260826T081049Z | provider site | trust.anthropic.com/resources | ef1cae6ce146db4f… | 220,078 | rendered page (captured with a browser); page text changed vs the previous capture of this target (57 word(s) differ in the extracted text) |
| 20260825T080700Z | provider site | trust.anthropic.com/resources | d35a4e92d16ca1ee… | 218,623 | rendered page (captured with a browser); captured with a different method than the previous capture (rendering, frame or consent handling changed): the extracted text differs, which is not evidence of a content change |
| 20260817T082339Z | provider site | trust.anthropic.com/resources | 76c2f3bf16214ed8… | 216,234 | rendered page (captured with a browser); captured with a different method than the previous capture (rendering, frame or consent handling changed): the extracted text differs, which is not evidence of a content change |
| 20260811T102534Z | provider site | trust.anthropic.com/resources | 4c3d597e28e68975… | 6,949 | page as served without JavaScript — mostly empty shell; later captures store the fully rendered page |
Third-party evaluation
The AI Accountability Lab scores published summaries against the Commission's template and publishes the result. These are captures of their assessment, archived here because they are revised over time and a score is otherwise unrecoverable once changed. It is AIAL's research judgement, not a legal determination, and not the provider's document. Their assessment is archived here but not served on this site or in the dataset: each capture below proves what was published and when, and points to AIAL for the content. Attribution: aial.ie.
| Capture (UTC) | Source of copy | URL | SHA-256 | Bytes | Notes |
|---|---|---|---|---|---|
| 20260916T072611Z | AIAL evaluation page | aial.ie/research/gpai-training-transpare…thropic-claude-mythos-preview/ | 9561a8249573bc89… | 20,873 | bytes identical to 20260831T113316Z |
| 20260916T072605Z | AIAL evaluation | raw.githubusercontent.com/AIAccountabili…pic-claude-mythos-preview.yaml | 695ae15fd187551e… | 4,976 | bytes identical to 20260829T142257Z |
| 20260831T113323Z | AIAL evaluation page | raw.githubusercontent.com/AIAccountabili…review/version-2026-08-04.html | 9561a8249573bc89… | 20,873 | the state that stood upstream from 6 Aug 2026 (fetched here on 31 Aug 2026); bytes identical to 20260831T113316Z |
| 20260831T113316Z | AIAL evaluation page | raw.githubusercontent.com/AIAccountabili…aude-mythos-preview/index.html | 9561a8249573bc89… | 20,873 | the state that stood upstream from 6 Aug 2026 (fetched here on 31 Aug 2026); bytes differ from the previous capture; the extracted text is identical, so no change is visible in the text layer (the text layer does not carry checkbox or form-field state) |
| 20260831T112041Z | AIAL evaluation page | raw.githubusercontent.com/AIAccountabili…review/version-2026-08-04.html | e4e29e6ac11459d4… | 20,546 | the state that stood upstream from 6 Aug 2026 (fetched here on 31 Aug 2026); bytes identical to 20260831T112034Z |
| 20260831T112034Z | AIAL evaluation page | raw.githubusercontent.com/AIAccountabili…aude-mythos-preview/index.html | e4e29e6ac11459d4… | 20,546 | the state that stood upstream from 6 Aug 2026 (fetched here on 31 Aug 2026); page text changed vs the previous capture of this target (1 word(s) differ in the extracted text) |
| 20260831T111132Z | AIAL evaluation page | raw.githubusercontent.com/AIAccountabili…aude-mythos-preview/index.html | 63d6a8a8e9193e46… | 20,536 | the state that stood upstream from 6 Aug 2026 (fetched here on 31 Aug 2026); bytes differ from the previous capture; the extracted text is identical, so no change is visible in the text layer (the text layer does not carry checkbox or form-field state) |
| 20260831T110401Z | AIAL evaluation page | raw.githubusercontent.com/AIAccountabili…aude-mythos-preview/index.html | 4f30bc00bc081d7a… | 20,408 | the state that stood upstream from 6 Aug 2026 (fetched here on 31 Aug 2026); page text changed vs the previous capture of this target (2 word(s) differ in the extracted text) |
| 20260831T105830Z | AIAL evaluation page | raw.githubusercontent.com/AIAccountabili…aude-mythos-preview/index.html | 0beaf020aed73d72… | 20,408 | the state that stood upstream from 5 Aug 2026 (fetched here on 31 Aug 2026); page text changed vs the previous capture of this target (4 word(s) differ in the extracted text) |
| 20260831T105312Z | AIAL evaluation page | raw.githubusercontent.com/AIAccountabili…aude-mythos-preview/index.html | 81760c3eab93c529… | 20,407 | the state that stood upstream from 5 Aug 2026 (fetched here on 31 Aug 2026); page text changed vs the previous capture of this target (27 word(s) differ in the extracted text) |
| 20260831T104823Z | AIAL evaluation page | raw.githubusercontent.com/AIAccountabili…aude-mythos-preview/index.html | a98919d3327c12ca… | 20,214 | the state that stood upstream from 4 Aug 2026 (fetched here on 31 Aug 2026); page text changed vs the previous capture of this target (108 word(s) differ in the extracted text) |
| 20260831T103639Z | AIAL evaluation page | raw.githubusercontent.com/AIAccountabili…aude-mythos-preview/index.html | 105be4af4a82a236… | 19,443 | the state that stood upstream from 3 Aug 2026 (fetched here on 31 Aug 2026); page text changed vs the previous capture of this target (421 word(s) differ in the extracted text) |
| 20260831T103125Z | AIAL evaluation page | raw.githubusercontent.com/AIAccountabili…aude-mythos-preview/index.html | cd8cf0cc7685e4b7… | 12,722 | the state that stood upstream from 3 Aug 2026 (fetched here on 31 Aug 2026) |
| 20260829T190624Z | AIAL evaluation (earlier state) | raw.githubusercontent.com/AIAccountabili…als/claude-mythos-preview.yaml | 695ae15fd187551e… | 4,976 | the state that stood upstream from 6 Aug 2026 (fetched here on 29 Aug 2026); bytes identical to 20260829T142257Z |
| 20260829T190158Z | AIAL evaluation (earlier state) | raw.githubusercontent.com/AIAccountabili…als/claude-mythos-preview.yaml | 449ca659017331bb… | 4,966 | the state that stood upstream from 6 Aug 2026 (fetched here on 29 Aug 2026); page text changed vs the previous capture of this target (2 word(s) differ in the extracted text) |
| 20260829T185752Z | AIAL evaluation (earlier state) | raw.githubusercontent.com/AIAccountabili…als/claude-mythos-preview.yaml | 162d8142b7a49304… | 4,966 | the state that stood upstream from 5 Aug 2026 (fetched here on 29 Aug 2026); page text changed vs the previous capture of this target (1 word(s) differ in the extracted text) |
| 20260829T185445Z | AIAL evaluation (earlier state) | raw.githubusercontent.com/AIAccountabili…als/claude-mythos-preview.yaml | 5d97e2fc76b2a842… | 4,967 | the state that stood upstream from 5 Aug 2026 (fetched here on 29 Aug 2026); page text changed vs the previous capture of this target (5 word(s) differ in the extracted text) |
| 20260829T185147Z | AIAL evaluation (earlier state) | raw.githubusercontent.com/AIAccountabili…als/claude-mythos-preview.yaml | 3058db85172bd8e4… | 4,963 | the state that stood upstream from 4 Aug 2026 (fetched here on 29 Aug 2026); page text changed vs the previous capture of this target (132 word(s) differ in the extracted text) |
| 20260829T184913Z | AIAL evaluation (earlier state) | raw.githubusercontent.com/AIAccountabili…als/claude-mythos-preview.yaml | 6c03d73526e62b3f… | 4,091 | the state that stood upstream from 3 Aug 2026 (fetched here on 29 Aug 2026); page text changed vs the previous capture of this target (1 word(s) differ in the extracted text) |
| 20260829T184825Z | AIAL evaluation (earlier state) | raw.githubusercontent.com/AIAccountabili…als/claude-mythos-preview.yaml | 28d343ead36b45c4… | 4,091 | the state that stood upstream from 3 Aug 2026 (fetched here on 29 Aug 2026); page text changed vs the previous capture of this target (97 word(s) differ in the extracted text) |
| 20260829T184536Z | AIAL evaluation (earlier state) | raw.githubusercontent.com/AIAccountabili…als/claude-mythos-preview.yaml | ec2ebb9f030a2f74… | 3,925 | the state that stood upstream from 3 Aug 2026 (fetched here on 29 Aug 2026); page text changed vs the previous capture of this target (1 word(s) differ in the extracted text) |
| 20260829T184254Z | AIAL evaluation (earlier state) | raw.githubusercontent.com/AIAccountabili…als/claude-mythos-preview.yaml | a2a7d40794aa5301… | 3,915 | the state that stood upstream from 3 Aug 2026 (fetched here on 29 Aug 2026) |
Captures of superseded target URLs
Locations this ledger previously tracked for this source (per-row notes give the reason each was superseded) — kept as faithful records of what those URLs served at capture time.
| Capture (UTC) | Source of copy | URL | SHA-256 | Bytes | Notes |
|---|---|---|---|---|---|
| 20260831T115935Z | AIAL evaluation page | aial.ie/research/gpai-training-transparency/evals/claude-mythos-preview/ | 9561a8249573bc89… | 20,873 | bytes identical to 20260831T113316Z; superseded 16 Sep 2026: AIAL's 14 Sep 2026 rename moved this evaluation's page to https://aial.ie/research/gpai-training-transparency/evals/anthropic-claude-mythos-preview/, which the ledger now tracks. The pre-rename path is a leftover directory in their repository: their site writes one directory per evaluation file, and no file carries the old name any more. |
| 20260829T142257Z | AIAL evaluation | raw.githubusercontent.com/AIAccountabili…als/claude-mythos-preview.yaml | 695ae15fd187551e… | 4,976 | superseded 16 Sep 2026: AIAL's 14 Sep 2026 'name consistency check' renamed this evaluation file to anthropic-claude-mythos-preview.yaml, which the ledger now tracks; this address has answered 404 since that rename (recorded by the 14 and 15 Sep 2026 sweeps). |
Last checked: 2026-10-05 (re-checked on the daily schedule — see Methodology). Seen a summary we missed? See the contact details.