[BUG] Strands should not default to us-west-2

[zastrowm]

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

0.1.6

Python Version

3.13

Operating System

macOS 15.3.2

Installation Method

pip

Steps to Reproduce

• Run strands
• Notice that we default to us-west-2 even if the aws default config specifies a different region

Expected Behavior

Strands should use AWS_REGION, or default to the value defined aws config, and not fallback to us-west-2.

Actual Behavior

We default to us-west-2 where no region is detected.

Additional Context

#183 is another case where we default to us-west-2 which has been confusing customers

Possible Solution

Instead of defaulting to us-west-2, default to the aws config default

Related Issues

#183

[zastrowm]

Team discussed - we think ultimately we should follow Boto behavior here and not default to us-west-2.

#254 created to emit a warning, then in a follow-up we can change the behavior to follow boto3 default behavior