[BUG] OpenAIModel ignores vLLM reasoning field (delta.reasoning / message.reasoning)

[austinmw]

Checks

• I have updated to the lastest minor and patch version of Strands
• I have checked the documentation and this is not expected behavior
• I have searched ./issues and there are no duplicates of my issue

Strands Version

latest

Python Version

latest

Operating System

macos

Installation Method

pip

Steps to Reproduce

Strands 1.36.0 still checks reasoning_content, while current vLLM 0.19.1 emits delta.reasoning and message.reasoning, so reasoning is dropped for OpenAI-compatible vLLM backends.

Expected Behavior

support both old and new field names.

Actual Behavior

only supports delta.reasoning_content currently

Additional Context

No response

Possible Solution

No response

Related Issues

No response