Function getModelForRequest

sdk/src/impl/model-provider.ts:115–163

(
  params: ModelRequestParams,
)

 * This function is async because it may need to refresh the OAuth token.
 */
export async function getModelForRequest(
  params: ModelRequestParams,
): Promise<ModelResult> {
  const { apiKey, model, skipChatGptOAuth, costMode } = params

  // Check if we should use ChatGPT OAuth direct
  // Only attempt for allowlisted models; non-allowlisted models silently fall through to backend.
  if (
    CHATGPT_OAUTH_ENABLED &&
    !skipChatGptOAuth &&
    isOpenAIProviderModel(model) &&
    isChatGptOAuthModelAllowed(model)
  ) {
    // In free mode, rate-limited ChatGPT OAuth must not silently fall through to
    // the Codebuff backend — freebuff should only use the direct OpenAI route or fail.
    if (isChatGptOAuthRateLimited()) {
      if (isFreeMode(costMode)) {
        throw new Error(
          'ChatGPT rate limit reached. Please wait a few minutes and try again.',
        )
      }
    } else {
      const chatGptOAuthCredentials = await getValidChatGptOAuthCredentials()

      if (chatGptOAuthCredentials) {
        return {
          model: createOpenAIOAuthModel(
            model,
            chatGptOAuthCredentials.accessToken,
          ),
          isChatGptOAuth: true,
        }
      }

      // In free mode, if credentials are unavailable, don't fall through to backend.
      if (isFreeMode(costMode)) {
        throw new Error(
          'ChatGPT OAuth credentials unavailable. Please reconnect with /connect:chatgpt.',
        )
      }
    }
  }

  // Default: use Codebuff backend
  return {
    model: createCodebuffBackendModel(apiKey, model),
    isChatGptOAuth: false,
  }
}

/**
 * Create an OpenAI model that routes through the ChatGPT backend API (Codex endpoint).