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Sweep 28 Aug 2026 ยท 00:00Z Build v2.1.250 478 read Stable v2.1.236 Latest v2.1.250 Next v2.1.250 Feeds RSS JSON llms.txt

DisclaimerUnofficial, and not affiliated with Anthropic. Nearly all of this is read straight out of what ships: npm bundles, captured prompts, published docs. Anthropic's own notes go in verbatim, marked as theirs. The rest is my reading, and every entry carries the strings behind it. If one looks wrong, vote it down and say why.

One change

whats-new-opus-5

models/opus-5/whats-new-opus-5

first seen The page's own history The capture it came from

Nearest release: v2.1.246, published 3 hours after this site recorded the change. Shown because the two are within 24 hours of each other. Nothing here says the release caused the edit.

models/opus-5/whats-new-opus-5 Changed · +1 / -1 lines

from line 316
   ```
 </CodeGroup>
 
-Then review the two [behavior changes](https://platform.claude.com/docs/en/models/opus-5/whats-new-opus-5#behavior-changes): thinking is on by default, and disabling thinking with effort `xhigh` or `max` returns a 400 error. See the [migration guide](https://platform.claude.com/docs/en/about-claude/models/migration-guide#migrating-from-claude-opus-4-8-to-claude-opus-5) for step-by-step instructions.
+Then review the two [behavior changes](https://platform.claude.com/docs/en/models/opus-5/whats-new-opus-5#behavior-changes): thinking is on by default, and disabling thinking with effort `xhigh` or `max` returns a 400 error. See the [migration guide](https://platform.claude.com/docs/en/models/opus-5/migration-guide#migrating-from-claude-opus-4-8-to-claude-opus-5) for step-by-step instructions.
 
 ## Next steps