[FEATURE] Add AWS_REGION environment variables for all model configurations

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• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

Models can be specified via environment variables (such as ANTHROPIC_DEFAULT_OPUS_MODEL, ANTHROPIC_DEFAULT_SONNET_MODEL, etc.), but the corresponding AWS_REGION environment variables for each model are missing.

Current situation:

• ✅ ANTHROPIC_DEFAULT_OPUS_MODEL environment variable can specify the model
• ✅ ANTHROPIC_SMALL_FAST_MODEL_AWS_REGION exists
• ❌ Missing AWS_REGION environment variables for other models like ANTHROPIC_DEFAULT_OPUS_MODEL_AWS_REGION

Proposed Solution

Enable region specification via the following environment variables:

• ANTHROPIC_DEFAULT_OPUS_MODEL_AWS_REGION
• ANTHROPIC_DEFAULT_SONNET_MODEL_AWS_REGION
• ANTHROPIC_DEFAULT_HAIKU_MODEL_AWS_REGION

Alternative Solutions

Amazon Bedrock's Global cross-Region inference feature might be a workaround, but I'm not familiar with it, so I can't say for certain.

In any case, it's confusing that ANTHROPIC_SMALL_FAST_MODEL_AWS_REGION remains while ANTHROPIC_SMALL_FAST_MODEL is deprecated.

Priority

Medium - Would be very helpful

Feature Category

Configuration and settings

Use Case Example

_No response_

Additional Context

Related links:

• Settings Documentation - Environment variables
• Model Configuration - Environment Variables
• Issue #1432