Bedrock model variations for on-demand throughput

Summary

AWS Bedrock model invocation fails with a ValidationException indicating that on-demand throughput is not supported when using base model identifiers like anthropic.claude-sonnet-4 in the Braintrust playground. This occurs because base Bedrock model identifiers do not support on-demand throughput, which is required for cross-region inference profiles. The issue is resolved by selecting the model variation with the full version suffix (e.g., global.anthropic.claude-sonnet-4-5-20250929-v1:0) instead of the base model identifier.

Resolution Steps

Update model selection in playground

Step 1: Locate model variation

In the Braintrust playground model dropdown, find the model variation with the full version identifier including global prefix and version suffix.

Step 2: Select versioned model

Choose the variation format (e.g., global.anthropic.claude-sonnet-4-5-20250929-v1:0) rather than the base model name.

Verify IAM permissions

Step 1: Confirm inference profile access

Ensure your IAM policy includes inference profile resources in addition to foundation models.

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Action": [
        "bedrock:InvokeModel",
        "bedrock:InvokeModelWithResponseStream"
      ],
      "Effect": "Allow",
      "Resource": [
        "arn:aws:bedrock:*::foundation-model/*",
        "arn:aws:bedrock:*:*:inference-profile/*"
      ]
    }
  ]
}