LLM Providers

private createAdapter(provider: LLMProvider): LLMAdapter {
  switch (provider.name) {
    case "openai":
      return new OpenAIAdapter(provider);
    case "google":
      return new GoogleAdapter(provider);
    case "anthropic":
      return new AnthropicAdapter(provider);
    case "openrouter":
      return new OpenRouterAdapter(provider);
    default:
      throw new Error(`Unsupported provider: ${provider.name}`);
  }
}

async createChatCompletion(request: LLMRequest): Promise<LLMResponse> {
  const startTime = Date.now();

  try {
    // Try with retries on primary provider
    const result = await withRetry(
      () => this.adapter.createChatCompletion(request),
      this.providerName
    );

    const duration = Date.now() - startTime;
    this.trackTokenUsage(result, request, duration);
    return result;
  } catch (error: any) {
    // Check if we need to try fallback provider
    if (error.requiresFallback) {
      return this.attemptFallbackCompletion(request, startTime, error);
    }
    throw error;
  }
}

private static readonly NORMAL_FINISH_REASONS = new Set([
  "stop",        // OpenAI, OpenRouter
  "end_turn",    // Anthropic
  "STOP",        // Google
]);

private checkFinishReason(result: LLMResponse, request: LLMRequest): void {
  if (!result.finishReason) return;

  const isNormal = LLM.NORMAL_FINISH_REASONS.has(result.finishReason);
  if (!isNormal) {
    logger.warn(
      {
        finishReason: result.finishReason,
        provider: this.providerName,
        model: request.model,
        maxTokens: request.maxTokens,
      },
      "llm_response_truncated_or_abnormal_finish"
    );
  }
}

private trackTokenUsage(
  result: LLMResponse,
  request: LLMRequest,
  duration: number,
  providerOverride?: string
): void {
  if (
    result.usage &&
    request.usageType &&
    (request.messageId || request.paperId)
  ) {
    createTokenUsage({
      message_id: request.messageId,
      paper_id: request.paperId,
      type: request.usageType,
      provider: providerOverride || this.providerName,
      model: request.model,
      prompt_tokens: result.usage.promptTokens,
      completion_tokens: result.usage.completionTokens,
      total_tokens: result.usage.totalTokens,
      duration_ms: duration,
    });
  }
}