What
Region values read from the environment must now look like a region (/^[a-z]{2,}(?:-[a-z0-9]+){0,4}$/i); anything else is treated as unset and the default is used instead of a malformed value being sent to the endpoint.
Details
- Applies to
AWS_REGION,AWS_DEFAULT_REGION, the region resolved from the AWS config file,ANTHROPIC_SMALL_FAST_MODEL_AWS_REGIONandCLOUD_ML_REGION. CLOUD_ML_REGIONwas previously used verbatim with a plain fallback tous-east5and no check at all.
Evidence
Strings lifted out of the shipped bundle, so the claim above can be checked against them.