Method categorizeError

src/node/services/streamManager.ts:3451–3615

* Categorizes errors for better error handling (used for event emission)

(error: unknown)

   * Categorizes errors for better error handling (used for event emission)
   */
  private categorizeError(error: unknown): StreamErrorType {
    if (error instanceof StreamTruncatedError) {
      return "stream_truncated";
    }

    // Use AI SDK error type guards first
    if (LoadAPIKeyError.isInstance(error)) {
      return "authentication";
    }
    if (APICallError.isInstance(error)) {
      if (error.statusCode === 401) return "authentication";
      // 402 (Payment Required) is used by mux gateway for billing/credits issues
      // (e.g. "Insufficient balance. Please add credits to continue.").
      // Treat as non-retryable quota. Some providers also encode quota failures as
      // 429, so classify 429 by payload intent instead of status code alone.
      if (error.statusCode === 402) return "quota";
      if (error.statusCode === 429) {
        return classify429Capacity({
          message: error.message,
          data: error.data,
          responseBody: error.responseBody,
        });
      }
      if (error.statusCode && error.statusCode >= 500) return "server_error";

      // Check for model_not_found errors (OpenAI and Anthropic)
      // Type guard for error data structure
      const hasErrorProperty = (
        data: unknown
      ): data is { error: { code?: string; type?: string } } => {
        return (
          typeof data === "object" &&
          data !== null &&
          "error" in data &&
          typeof data.error === "object" &&
          data.error !== null
        );
      };

      // OpenAI: 400 with error.code === 'model_not_found'
      const isOpenAIModelError =
        error.statusCode === 400 &&
        hasErrorProperty(error.data) &&
        error.data.error.code === "model_not_found";

      // Anthropic: 404 with error.type === 'not_found_error'
      const isAnthropicModelError =
        error.statusCode === 404 &&
        hasErrorProperty(error.data) &&
        error.data.error.type === "not_found_error";

      if (isOpenAIModelError || isAnthropicModelError) {
        return "model_not_found";
      }

      // Check for context exceeded errors (Anthropic + OpenAI-compatible / Copilot)
      const msgLower = error.message.toLowerCase();