{
  "context": "This criteria evaluates how well the engineer uses the AWS SDK for JavaScript v3 credential provider system to implement custom credential providers and credential provider chains. The focus is on proper usage of the AwsCredentialIdentityProvider interface, implementing fallback logic, and integrating with AWS SDK clients.",
  "type": "weighted_checklist",
  "checklist": [
    {
      "name": "AwsCredentialIdentityProvider usage",
      "description": "The custom credential provider function returns an AwsCredentialIdentityProvider (a function that returns a Promise<AwsCredentialIdentity>) rather than directly returning credentials.",
      "max_score": 20
    },
    {
      "name": "AwsCredentialIdentity structure",
      "description": "The returned credentials object correctly implements the AwsCredentialIdentity interface with required properties: accessKeyId, secretAccessKey, and optional sessionToken and expiration.",
      "max_score": 15
    },
    {
      "name": "Custom provider implementation",
      "description": "The customEnvCredentialProvider function correctly reads from custom environment variables (CUSTOM_AWS_KEY_ID, CUSTOM_AWS_SECRET_KEY) and returns a provider function.",
      "max_score": 15
    },
    {
      "name": "Provider error handling",
      "description": "The custom provider properly throws errors when required environment variables are missing, following AWS SDK error handling patterns.",
      "max_score": 10
    },
    {
      "name": "Chain fallback logic",
      "description": "The createCredentialChain function implements proper fallback logic by attempting each provider in sequence and returning credentials from the first successful provider.",
      "max_score": 20
    },
    {
      "name": "Chain error aggregation",
      "description": "The credential chain properly handles errors from individual providers and only throws an error when all providers fail, potentially aggregating error information.",
      "max_score": 10
    },
    {
      "name": "S3Client integration",
      "description": "The custom credential provider chain is properly integrated with an S3Client using the credentials configuration option, demonstrating correct usage of the AWS SDK client configuration.",
      "max_score": 10
    }
  ]
}