Checked fact 128013 Oct 2026Safety and security

The post says preserved thinking prevents new API accounts, those created on or after 31 August 2026, from editing Claude's prior context.

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The exact words it rests on

With Claude Fable 5.1 and Claude Opus 5.5, we introduced preserved thinking, a measure that prevents new API accounts (those created on or after August 31, 2026) from editing Claude's prior context.

What the source said when we opened it, on 13 Oct 2026.

The source

Strengthening our defenses against distillation attacks
Anthropic · 2026-10-12

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Checked

Checked by the notis newsroom on 13 Oct 2026, against the source above.

In the story

Anthropic says new safeguards cut distillers' extraction of reasoning tokens 13 Oct 2026

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In a sentence

“The post says preserved thinking prevents new API accounts, those created on or after 31 August 2026, from editing Claude's prior context.” ai notis, checked 13 Oct 2026. Source: Strengthening our defenses against distillation attacks (Anthropic). https://ainotis.com/c/1280

As a reference (APA style)

ai notis. (2026, October 13). The post says preserved thinking prevents new API accounts, those created on or after 31 August 2026, from editing Claude's prior context [Checked claim 1280]. ai notis. https://ainotis.com/c/1280

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