# Anthropic extends preserved thinking to all Fable 5.2 API accounts

> Original title: To help prevent distillation, preserved thinking now covers all API accounts on Fable 5.2.

- Source: ClaudeDevs
- Published: 2026-11-09T19:04:18.000Z
- Bad Influence: https://badinfluence.news/items/ux03d0u8txafpky1k9qvcfzng
- Original: https://x.com/ClaudeDevs/status/2119868703265419688

## Summary

Anthropic says preserved thinking now covers all API accounts on Fable 5.2, a change it describes as a way to help prevent distillation. Editing prior context can return a 400 error, so the company recommends compaction, context editing, or mid-conversation system messages instead. Claude Code, Managed Agents, and the Agent SDK handle this automatically.

## Post

To help prevent distillation, preserved thinking now covers all API accounts on Fable 5.2.

Editing prior context can 400. Use compaction, context editing, or mid-conversation system messages. Claude Code, Managed Agents & Agent SDK handle this for you.

https://platform.claude.com/docs/build-with-claude/preserved-thinking