add support for token provider

[deyaaeldeen]

• I understand that this repository is auto-generated and my pull request may not be merged

Changes being requested

This PR introduces a new tokenProvider option to the OpenAI client, enabling dynamic token retrieval for authentication scenarios where API keys need to be refreshed or obtained at runtime.

Additional context & links

Changes

New Feature: tokenProvider Option

• Added TokenProvider type definition: () => Promise<AccessToken>
• Added AccessToken interface with token: string property
• Added tokenProvider option to ClientOptions interface
• Implemented token provider logic in the _setToken() method

Key Benefits

1. Dynamic Authentication: Supports scenarios where tokens expire and need to be refreshed
2. Enhanced Security: Tokens can be retrieved just-in-time rather than stored statically
3. Enterprise Integration: Enables integration with corporate identity providers and token management systems
4. Flexible Authentication: Provides an alternative to static API keys for environments requiring dynamic credentials

Implementation Details

Client Construction:

• tokenProvider and apiKey are mutually exclusive - only one can be provided
• If neither is provided, an error is thrown requiring one of the two authentication methods
• Browser usage automatically allowed when using tokenProvider (sets dangerouslyAllowBrowser: true)

Token Management:

• _setToken() method now returns a boolean indicating if a token was successfully retrieved
• Token provider is called on every request preparation via prepareOptions()

Usage Example

const client = new OpenAI({
  tokenProvider: async () => {
    // Fetch token from your auth service
    const response = await fetch('/api/auth/token');
    const data = await response.json();
    return { token: data.access_token };
  }
});

Backward Compatibility

This change is fully backward compatible. Existing code using apiKey continues to work unchanged. The new tokenProvider option is purely additive.

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[RobertCraigie]

question: why call it tokenProvider and not apiKeyProvider? I think the former matches the existing terminology better

[deyaaeldeen]

API key auth is already supported. This feature enables short-lived token-based auth and we want to advertise it as such. Implementation-wise, it is piggybacking off the apiKey field which is just a hack to simplify the implementation.

[RobertCraigie]

nit: I think "refresh" is a better verb than "set" here?

[deyaaeldeen]

The decision to refresh is taken by the input function and not by this method, i.e. it is not guaranteed that the token will be refreshed if this method is called. However, let me know if you feel strongly about it and I can update the name.