Archive updates
| Date | Archive event | Why it belongs here | Source |
|---|---|---|---|
| 2026-09-19 | Second Claude Archive source pass. | Extended the timeline through Fable 5.1, logged the Opus 5 launch, the watermarking announcement, and the Sonnet 5 price permanence, and closed the Opus 4.1 retirement. | Source index |
| 2026-09-01 | Claude Fable 5.1 and Mythos 5.1 launch. | New most capable generally available model; Fable 5 becomes history. Cache reads cut to $0.25 per MTok. | Fable/Mythos 5.1 |
| 2026-09-01 | Sonnet 5 introductory rate becomes the standard rate. | The announced rise to $3/$15 did not happen, so the original launch-post framing is now a superseded plan. | Pricing docs |
| 2026-08-14 | Text watermarking announced. | Changes what can accurately be said about Claude output provenance from this date forward. | Text watermarking |
| 2026-08-05 | Claude Opus 4.1 retires. | Closes the deadline opened by the June 5, 2026 deprecation notice; requests to the ID now fail. | Model deprecations |
| 2026-07-24 | Claude Opus 5 launches. | New Opus-class model at the same $5/$25 rate as Opus 4.8; retires the claim that Opus 4.8 is the current Opus. | Opus 5 |
| 2026-07-06 | Initial Claude Archive source pass. | Created source-backed sitemap, timeline, deprecation ledger, pricing history, and system-prompt guide. | Source index |
| 2026-07-01 | Fable/Mythos access restoration appears on Anthropic pages. | Important status update for a 5-era model launch that had a temporary access interruption. | Fable/Mythos 5 |
| 2026-06-30 | Claude Sonnet 5 launches. | Latest Sonnet generation, with pricing announced as introductory through August 31, 2026. | Sonnet 5 |
| 2026-06-30 | Redeploying Fable 5 post published. | Explains suspension, export-control context, and planned return starting July 1. | Redeploying Fable 5 |
| 2026-06-05 | Opus 4.1 deprecation announced. | Created the August 5, 2026 retirement deadline. | Model deprecations |
| 2026-05-28 | Claude Opus 4.8 launches. | New Opus snapshot, effort controls, dynamic workflows, and updated fast-mode economics. | Opus 4.8 |
Weekly extension process
Future updates should scan the Anthropic newsroom, platform release notes, model deprecations page, pricing page, model overview, and system-prompt release notes. Add only changes that affect historical facts, model availability, migration, pricing, or prompt-publication records.
Do not use this page as a general Claude news digest. That belongs to Claude Weekly. This ledger is for durable archive deltas.
Entry format
Every new ledger item should answer four questions: date, event, why it matters historically, and primary source. If a claim cannot pass that format, it is probably commentary rather than archive material.
Questions this page answers
Why does Claude Archive need a release ledger?
The network brief requires a freshness surface. This ledger can be extended weekly with durable source-backed changes.
Is this a Claude news page?
No. It records archive-relevant changes and links current news coverage to Claude Weekly instead.
What changed in the September 2026 pass?
The pass added the July 24, 2026 Opus 5 launch, the August 14, 2026 watermarking announcement, the September 1, 2026 Fable 5.1 and Mythos 5.1 launch, and the September 1, 2026 Sonnet 5 price permanence, and recorded the completed August 5, 2026 Opus 4.1 retirement.