{
  "context": "This criteria evaluates how effectively an engineer uses the @azure/core-auth package, specifically the TokenCredential interface and AccessToken structure, to implement a token caching service. The focus is on proper use of token retrieval, expiration handling, and scope management.",
  "type": "weighted_checklist",
  "checklist": [
    {
      "name": "TokenCredential usage",
      "description": "Correctly uses the TokenCredential interface by calling the getToken() method to obtain tokens from the underlying credential.",
      "max_score": 20
    },
    {
      "name": "AccessToken structure",
      "description": "Properly works with the AccessToken interface, accessing the token string, expiresOnTimestamp, and refreshAfterTimestamp properties to manage cached tokens.",
      "max_score": 20
    },
    {
      "name": "Token expiration",
      "description": "Correctly implements token expiration logic by comparing current time with the expiresOnTimestamp property from AccessToken to determine if a token has expired.",
      "max_score": 15
    },
    {
      "name": "Proactive refresh",
      "description": "Implements proactive token refresh by checking the refreshAfterTimestamp property from AccessToken and obtaining fresh tokens when the refresh threshold is exceeded but token hasn't expired.",
      "max_score": 15
    },
    {
      "name": "Scope handling",
      "description": "Properly handles both single scope strings and arrays of scopes by passing them correctly to TokenCredential.getToken(), which accepts string | string[] parameter.",
      "max_score": 10
    },
    {
      "name": "Scope normalization",
      "description": "Implements proper cache key generation by normalizing scopes (e.g., sorting and joining arrays) to ensure consistent cache lookups for the same set of scopes regardless of order.",
      "max_score": 10
    },
    {
      "name": "Null handling",
      "description": "Correctly handles null return values from TokenCredential.getToken() by returning null and not caching failed token requests.",
      "max_score": 10
    }
  ]
}