refactor: enhance error handling and normalization across AI engines

This update introduces a centralized error handling mechanism for various AI engines, improving the consistency and clarity of error messages. The new `normalizeEngineError` function standardizes error responses, allowing for better user feedback and recovery suggestions. Additionally, specific error classes for insufficient credits, rate limits, and service availability have been implemented, along with user-friendly formatting for error messages. This refactor aims to enhance the overall user experience when interacting with the AI services.

src/utils/engineErrorHandler.ts

@@ -0,0 +1,205 @@
+import axios from 'axios';
+import {
+  AuthenticationError,
+  InsufficientCreditsError,
+  ModelNotFoundError,
+  RateLimitError,
+  ServiceUnavailableError
+} from './errors';
+
+/**
+ * Extracts HTTP status code from various error types
+ */
+function getStatusCode(error: unknown): number | null {
+  // Direct status property (common in API SDKs)
+  if (typeof (error as any)?.status === 'number') {
+    return (error as any).status;
+  }
+
+  // Axios-style errors
+  if (axios.isAxiosError(error)) {
+    return error.response?.status ?? null;
+  }
+
+  // Response object with status
+  if (typeof (error as any)?.response?.status === 'number') {
+    return (error as any).response.status;
+  }
+
+  return null;
+}
+
+/**
+ * Extracts retry-after value from error headers (for rate limiting)
+ */
+function getRetryAfter(error: unknown): number | undefined {
+  const headers = (error as any)?.response?.headers;
+  if (headers) {
+    const retryAfter = headers['retry-after'] || headers['Retry-After'];
+    if (retryAfter) {
+      const seconds = parseInt(retryAfter, 10);
+      if (!isNaN(seconds)) {
+        return seconds;
+      }
+    }
+  }
+  return undefined;
+}
+
+/**
+ * Extracts the error message from various error structures
+ */
+function extractErrorMessage(error: unknown): string {
+  if (error instanceof Error) {
+    return error.message;
+  }
+
+  // API error response structures
+  const apiError = (error as any)?.response?.data?.error;
+  if (apiError) {
+    if (typeof apiError === 'string') {
+      return apiError;
+    }
+    if (apiError.message) {
+      return apiError.message;
+    }
+  }
+
+  // Direct error data
+  const errorData = (error as any)?.error;
+  if (errorData) {
+    if (typeof errorData === 'string') {
+      return errorData;
+    }
+    if (errorData.message) {
+      return errorData.message;
+    }
+  }
+
+  // Fallback
+  if (typeof error === 'string') {
+    return error;
+  }
+
+  return 'An unknown error occurred';
+}
+
+/**
+ * Checks if the error message indicates a model not found error
+ */
+function isModelNotFoundMessage(message: string): boolean {
+  const lowerMessage = message.toLowerCase();
+  return (
+    (lowerMessage.includes('model') &&
+      (lowerMessage.includes('not found') ||
+        lowerMessage.includes('does not exist') ||
+        lowerMessage.includes('invalid') ||
+        lowerMessage.includes('pull'))) ||
+    lowerMessage.includes('does_not_exist')
+  );
+}
+
+/**
+ * Checks if the error message indicates insufficient credits
+ */
+function isInsufficientCreditsMessage(message: string): boolean {
+  const lowerMessage = message.toLowerCase();
+  return (
+    lowerMessage.includes('insufficient') ||
+    lowerMessage.includes('credit') ||
+    lowerMessage.includes('quota') ||
+    lowerMessage.includes('balance too low') ||
+    lowerMessage.includes('billing') ||
+    lowerMessage.includes('payment required') ||
+    lowerMessage.includes('exceeded')
+  );
+}
+
+/**
+ * Normalizes raw API errors into typed error classes.
+ * This provides consistent error handling across all engine implementations.
+ *
+ * @param error - The raw error from the API call
+ * @param provider - The AI provider name (e.g., 'openai', 'anthropic')
+ * @param model - The model being used
+ * @returns A typed Error instance
+ */
+export function normalizeEngineError(
+  error: unknown,
+  provider: string,
+  model: string
+): Error {
+  // If it's already one of our custom errors, return as-is
+  if (
+    error instanceof ModelNotFoundError ||
+    error instanceof AuthenticationError ||
+    error instanceof InsufficientCreditsError ||
+    error instanceof RateLimitError ||
+    error instanceof ServiceUnavailableError
+  ) {
+    return error;
+  }
+
+  const statusCode = getStatusCode(error);
+  const message = extractErrorMessage(error);
+
+  // Handle based on HTTP status codes
+  switch (statusCode) {
+    case 401:
+      return new AuthenticationError(provider, message);
+
+    case 402:
+      return new InsufficientCreditsError(provider, message);
+
+    case 404:
+      // Could be model not found or endpoint not found
+      if (isModelNotFoundMessage(message)) {
+        return new ModelNotFoundError(model, provider, 404);
+      }
+      // Return generic error for other 404s
+      return error instanceof Error ? error : new Error(message);
+
+    case 429:
+      const retryAfter = getRetryAfter(error);
+      return new RateLimitError(provider, retryAfter, message);
+
+    case 500:
+    case 502:
+    case 503:
+    case 504:
+      return new ServiceUnavailableError(provider, statusCode, message);
+  }
+
+  // Handle based on error message content
+  if (isModelNotFoundMessage(message)) {
+    return new ModelNotFoundError(model, provider, 404);
+  }
+
+  if (isInsufficientCreditsMessage(message)) {
+    return new InsufficientCreditsError(provider, message);
+  }
+
+  // Check for rate limit patterns in message
+  const lowerMessage = message.toLowerCase();
+  if (
+    lowerMessage.includes('rate limit') ||
+    lowerMessage.includes('rate_limit') ||
+    lowerMessage.includes('too many requests')
+  ) {
+    return new RateLimitError(provider, undefined, message);
+  }
+
+  // Check for auth patterns in message
+  if (
+    lowerMessage.includes('unauthorized') ||
+    lowerMessage.includes('api key') ||
+    lowerMessage.includes('apikey') ||
+    lowerMessage.includes('authentication') ||
+    lowerMessage.includes('invalid_api_key')
+  ) {
+    return new AuthenticationError(provider, message);
+  }
+
+  // Return original error or wrap in Error if needed
+  return error instanceof Error ? error : new Error(message);
+}