New builtin fetch alpha

[RobertCraigie]

We've been working on an alpha version of the SDK that alongside many other cleanups, migrates from node-fetch to builtin fetch.

You can try it out by installing the 0.34.0-alpha.0 version:

pnpm add @anthropic-ai/sdk@alpha

The core happy path of the SDK remains the same, your existing method calls should just work! However you may run into typing issues as we now expect that fetch is defined as a global.

There are many other small breaking changes which you may run into, we'll share a full migration guide as soon as possible.

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Please share feedback on anything you think could be improved or if you run into any issues! Hope this is a nice early present for you all :)

Important

Unfortunately we cannot guarantee support over the holiday break (December 20th - January 6th inclusive) but we will go through every comment as soon as possible.