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llm-anthropic 0.27 adds anthropic v1.0.0 support

toolsThe Glonce editorsSimon Willison🔥41Glonce rating41Impact35Novelty25Relevance65Surprise20Players40Credibility85

Simon Willison released version 0.27 of llm-anthropic, the plugin that connects his LLM command line tool to Anthropic's models. The update's main purpose is compatibility with the recently released anthropic v1.0.0 Python library, which switches its underlying HTTP client from httpx to httpx2. OpenAI made the same kind of change in its own Python library two weeks earlier, in its v3.0.0 release.

To make the upgrade, Willison worked from Anthropic's own migration guide for moving to v1.0. He prompted Fable 5 inside Claude Code with an instruction to read the guide and get the test suite passing again. That produced a pull request, which Willison links to in the post without describing its size or specific contents.

Key facts

  • llm-anthropic 0.27 mainly adds compatibility with the newly released anthropic v1.0.0 Python library.
  • anthropic v1.0.0 switches its HTTP client from httpx to httpx2.
  • OpenAI made the same httpx-to-httpx2 switch in its own Python library two weeks earlier, in v3.0.0.
  • Willison used Anthropic's official migration guide and prompted Fable 5 in Claude Code to perform the upgrade and get tests passing.
  • The resulting pull request is linked in the post.

Why it matters

It is a small but concrete example of AI coding tools being used for routine maintenance: rather than manually working through a migration guide, Willison delegated the httpx-to-httpx2 upgrade to Fable 5 inside Claude Code and linked to the resulting pull request. It also shows Anthropic and OpenAI converging on the same underlying HTTP library change in their respective Python SDKs, in v1.0.0 and v3.0.0.

Who it affects

Developers who depend on llm-anthropic, the plugin that lets Willison's LLM command line tool talk to Anthropic's Claude models, and more broadly anyone using the anthropic Python library directly who needs to move to v1.0.0.

How to use it

Update the llm-anthropic plugin to version 0.27 or later to stay compatible with anthropic v1.0.0. Anyone upgrading their own code directly, rather than through the plugin, can follow the same migration guide Anthropic publishes for moving to v1.0.

How solid is it

The account comes straight from Simon Willison describing his own plugin release, and it links to both Anthropic's official migration guide and the resulting pull request, giving a verifiable trail from the change described to the actual code.

Risks and caveats

The post does not explain what httpx2 is or why the switch from httpx was made, and it does not describe the size or scope of the linked pull request. It also does not identify what Fable 5 refers to, such as which underlying model or system the name denotes.