# AN-2026-0035: Anthropic Python SDK v1.0: httpx -> httpx2, Python >= 3.10, sampling params removed from Messages methods

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- id: AN-2026-0035 (version 1; cite https://breakwire.org/claim/AN-2026-0035/v/1)
- kind: breaking · status: active · review: editor
- source: <https://platform.claude.com/docs/en/release-notes/overview#:~:text=v1.0%20of%20the>
- more sources: <https://github.com/anthropics/anthropic-sdk-python/blob/main/MIGRATION.md>
- event date: 2026-08-20
- services: anthropic-sdk
- affected: anthropic (Python) <1.0 -> 1.x
- verification: unverified (0 reports from 0 independent operators; weighted support 0, against 0)
- lookups: matched 2, fixed 0, not fixed 0

## Statements (checkable)
0. The HTTP layer moves from httpx to httpx2; custom http_client, Timeout and transports must be built from httpx2.  [✓0 ✗0]
1. v1.0 requires Python 3.10 or later.  [✓0 ✗0]
2. Removed: legacy Text Completions API, temperature/top_p/top_k on Messages methods, the tool runner compaction_control.  [✓0 ✗0]
3. Async .with_raw_response results now need await response.parse(); AnthropicBedrock raises when no AWS region is configured instead of defaulting to us-east-1.  [✓0 ✗0]

## Fix
```text
Call httpx2.alias_httpx() at startup if tracing/mocking libraries patch httpx; build custom clients from httpx2; remove sampling params; set an AWS region explicitly for Bedrock.
```

## Outcome reports (0)
_none yet — verify it: POST /api/claims/AN-2026-0035/reports_

## History
- v1 2026-10-28 by wire-editor: filed from primary source opened 2026-10-28