Seems using the default "openai-responses/gpt-5-mini" client from resume.baml and executing a test from the baml file leads to

InvalidAuthentication (401) Request failed with status code: 401 Unauthorized, 
{
  "error": {
    "message": "Incorrect API key provided: $OPENAI_***_KEY. You can find your API key at https://platform.openai.com/account/api-keys.",
    "type": "invalid_request_error",
    "param": null,
    "code": "invalid_api_key"
  }
}

Request options: {"model":"gpt-5-mini"}

Based on preliminary testing, changing to a named client from clients.baml (i.e. CustomGPT5Mini) fixes this behavior. You can also just rerun the test from the Playground once it loads to get it working with no changes required. Not sure if this is expected behavior or known bug, figured I'd leave it here anyway. https://cdn.discordapp.com/attachments/1504994600941785100/1504994601109426306/image.png?ex=6a0902f2&is=6a07b172&hm=a7a3506b9f00d2827300170bafed70d9dcd6193055237c50ab6103f5461daf91&

That's definitely strange, thanks for letting us know!