Fix: Robust Sonnet 4.5 detection incl. Bedrock dotted vendor prefixes; avoid reasoning_effort for Sonnet 4.5

[enyst]

fix #11248

Summary

• Normalize Bedrock-style region.vendor prefixes (e.g., us.anthropic.*) so Sonnet 4.5 is recognized as a reasoning model
• Add pattern for dot variant (claude-sonnet-4.5*) in addition to dash variant
• Avoid sending reasoning_effort to Claude Sonnet 4.5 (both - and . variants)
• As a result, temperature/top_p are now correctly suppressed for Sonnet 4.5 reasoning models to prevent Bedrock 400 errors

Details

• openhands/llm/model_features.py
  • normalize_model_name: strips dotted prefixes up to the first known vendor (anthropic, meta, cohere, mistral, ai21, amazon); handles cases like bedrock/us.anthropic.claude-sonnet-4-5-20250929-v1:0 -> claude-sonnet-4-5-20250929-v1
  • REASONING_EFFORT_PATTERNS: added claude-sonnet-4.5*
• openhands/llm/llm.py
  • For reasoning models: as before, pop temperature and top_p
  • Special-case extended to also drop reasoning_effort for claude-sonnet-4.5

Verification

• Verified that normalization maps Bedrock model IDs to canonical basenames used by matching
• Verified that Sonnet 4.5 (dash or dot variants) triggers reasoning behavior and does not receive reasoning_effort

No dependency changes.

Co-authored-by: openhands [email protected]

@enyst can click here to continue refining the PR

---

To run this PR locally, use the following command:

GUI with Docker:

docker run -it --rm   -p 3000:3000   -v /var/run/docker.sock:/var/run/docker.sock   --add-host host.docker.internal:host-gateway   -e SANDBOX_RUNTIME_CONTAINER_IMAGE=docker.all-hands.dev/all-hands-ai/runtime:668e271-nikolaik   --name openhands-app-668e271   docker.all-hands.dev/all-hands-ai/openhands:668e271

CLI with uvx:

uvx --python 3.12 --from git+https://github.com/All-Hands-AI/OpenHands@fix/sonnet-4-5-bedrock-normalization#subdirectory=openhands-cli openhands

[openhands-ai]

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@OpenHands please fix the failing actions on PR #11259 at branch `fix/sonnet-4-5-bedrock-normalization`

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