What
- The style validator for Box/View-style layout elements now accepts a
positionproperty (relativeorabsolute), along withtop,left,right, andbottomoffsets. This was previously unsupported. - When a rendered component tree uses one of these absolute/
position-styled elements (and the view isn't fullscreen, or is a static frame), the render node now automatically getsoverflow: "hidden"set on it, clipping content that would otherwise spill outside its bounds.
Why This lets components be positioned precisely, such as an overlay or badge placed at a specific offset, without its content spilling outside where it's meant to appear.
Names in the bundleposition
The entry above is what we published on the day. These lines were added later, as Anthropic's own pages caught up, and they sit beside the original rather than replacing it.
Added since
A small documentation edit on Request 2 caches its request content (not the response) touched a line naming position after this was published.
| **Dropped thinking blocks** | ✓ | ✓ | ✘ | When the API drops a Claude Fable 5.1, Claude Mythos 5.1, or Claude Opus 5.5 thinking block that isn't [preserved](https://platform.claude.com/docs/en/build-with-claude/thinking#preserved-thinkin…build-with-claude/prompt-caching see the edit
Confirmed since
Anthropic's documentation has since written up position, on preserved-thinking.
* [Compaction at a token threshold](https://platform.claude.com/docs/en/build-with-claude/compaction-threshold) summarizes older turns into a compaction block when the context approaches a threshold you set, and the checked prefix restarts…build-with-claude/preserved-thinking see the edit
One source agreesOne thing we can check says the same as this entry.
Anthropic's documentation agrees
Anthropic's documentation has since written up position, on preserved-thinking.