Report: Claude Code 2.1.237 sent the 'high' effort setting as the old 'low' value

A MarsBit report on KuCoin says a developer found Claude Code 2.1.237 mapped the 'high' reasoning level to the value 10, previously used for 'low', as part of an undisclosed A/B test, and that an Anthropic engineer confirmed the issue but said it did not affect model performance.

Who is affected:

Claude Code users on version 2.1.237 who selected high effort.

What to do:

Update Claude Code and confirm the effort level with /effort.