Anthropic's Python SDK v1.0 swaps httpx. Pin your SDKs.

A major version bump on a vendor SDK is the kind of thing that breaks a Friday deploy for a team that never opted into it. Anthropic released v1.0 of the Claude Python SDK on August 20, moving the HTTP layer off httpx and dropping years of deprecated surface. Nothing here is unreasonable. All of it will bite you if your requirements.txt says anthropic with no version constraint.

What actually happened

Per the Claude Platform release notes, v1.0 moves the SDK's HTTP layer from httpx to httpx2, which Anthropic describes as a maintained, API-compatible fork. Practically: build custom http_client, Timeout, and transport objects from httpx2 rather than httpx. The DefaultHttpxClient helpers are unchanged. If you use tracing or mocking libraries that monkey-patch httpx — and if you have tests, you probably do — call httpx2.alias_httpx() at startup.

The removals are the sharper edge. v1.0 requires Python 3.10 or later and drops long-deprecated surface: the legacy Text Completions API, and the temperature, top_p, and top_k parameters on Messages methods. The tool runner's client-side compaction_control is gone. On the async client, .with_raw_response results now require await response.parse(). And AnthropicBedrock raises an error when no AWS region is configured instead of quietly defaulting to us-east-1.

That last one is the good kind of breaking change. A silent region default is a bill you find out about later, in a region you did not intend to run in. Anthropic publishes a v1 migration guide with before-and-after snippets for every change.

Why SDK versioning matters for your business

Unpinned dependencies are an outage waiting for a trigger. If your container build runs pip install anthropic fresh, the next image you push picks up v1.0 whether you planned for it or not. Pin the version, upgrade on your calendar, in a branch, with tests.

The sampling-parameter removal is not just cosmetic. temperature and top_p were already rejected on the newer Claude models. Now the SDK will not even accept them. Code carrying those arguments forward from a 2024 prototype fails at the call site instead of the API — which is faster feedback, but still a failure.

Python 3.10+ is a real gate for older deployments. If you have a Lambda, an ECS task, or a customer-hosted box still on 3.9, the SDK upgrade is now a runtime upgrade. Budget accordingly, or stay on 0.x and set a date.

Wrap the client. We put every vendor SDK behind a thin internal module. When a major version lands, one file changes and the migration is a diff a reviewer can actually read — instead of forty call sites and a hope.

Sources: Claude Platform release notes, Anthropic Python SDK v1 migration guide.