Error Handling Guide

Learn how to properly handle errors and implement robust error recovery in your Auth-Agent implementation.

Error Types

AuthError

All SDK methods throw AuthError objects with detailed information:

interface AuthError extends Error {
  code: string; // Error code
  description?: string; // Human-readable description
  statusCode?: number; // HTTP status code
}

Common Error Codes

token_expired

401

Access token has expired. Refresh the token or re-authenticate.

refresh_failed

401

Refresh token is invalid or expired. User must re-authenticate.

state_mismatch

400

OAuth state parameter mismatch. Possible CSRF attack.

pkce_missing

400

Code verifier not found. Must call getAuthorizationUrl() first.

forbidden

403

Insufficient permissions for the requested operation.

no_refresh_token

400

No refresh token provided for refresh operation.

no_token

400

Token required but not provided.

revoke_failed

400

Token revocation failed.

introspection_failed

400

Token introspection failed.

Basic Error Handling

Try-Catch Pattern

import type { AuthError } from "ai-auth";

try {
  const tokens = await sdk.exchangeCode(code, state, redirectUri);
  console.log("Success!", tokens);
} catch (error) {
  const authError = error as AuthError;

  console.error("Error:", authError.code);
  console.error("Description:", authError.description);
  console.error("Status:", authError.statusCode);
}

Specific Error Handling

try {
  const tokens = await sdk.exchangeCode(code, state, redirectUri);
} catch (error) {
  const authError = error as AuthError;

  switch (authError.code) {
    case "state_mismatch":
      console.error("CSRF attack detected!");
      redirectToError("Security violation detected");
      break;

    case "pkce_missing":
      console.error("Invalid OAuth flow");
      redirectToLogin();
      break;

    default:
      console.error("Unknown error:", authError.description);
      showErrorMessage(authError.description);
      break;
  }
}

Handling Specific Scenarios

Token Expiration

async function makeAuthenticatedRequest() {
  try {
    const accessToken = tokenManager.getAccessToken();
    return await sdk.getUserInfo(accessToken);
  } catch (error) {
    const authError = error as AuthError;

    if (authError.code === "token_expired" && tokenManager.refreshToken) {
      // Attempt to refresh
      try {
        await sdk.refreshAccessToken(tokenManager.refreshToken);
        // Retry the request
        const newToken = tokenManager.getAccessToken();
        return await sdk.getUserInfo(newToken);
      } catch (refreshError) {
        console.error("Refresh failed, redirecting to login");
        redirectToLogin();
      }
    }

    throw error;
  }
}

Network Errors

import { sleep } from "ai-auth";

async function retryableRequest<T>(
  fn: () => Promise<T>,
  maxRetries = 3
): Promise<T> {
  for (let i = 0; i < maxRetries; i++) {
    try {
      return await fn();
    } catch (error: any) {
      const authError = error as AuthError;

      // Don't retry on auth errors
      if (authError.statusCode === 401 || authError.statusCode === 403) {
        throw error;
      }

      // Don't retry on client errors
      if (authError.statusCode && authError.statusCode < 500) {
        throw error;
      }

      // Last attempt
      if (i === maxRetries - 1) {
        throw error;
      }

      // Network error or server error - retry with backoff
      const delay = Math.pow(2, i) * 1000;
      console.log(`Request failed, retrying in ${delay}ms...`);
      await sleep(delay);
    }
  }

  throw new Error("Max retries exceeded");
}

// Usage
const userInfo = await retryableRequest(() => sdk.getUserInfo(accessToken));

CSRF Protection

async function handleOAuthCallback(code: string, state: string) {
  // Retrieve stored state
  const storedState = await storage.getState();

  try {
    if (state !== storedState) {
      throw new Error("State mismatch - possible CSRF attack");
    }

    const tokens = await sdk.exchangeCode(code, state, redirectUri);
    return tokens;
  } catch (error) {
    const authError = error as AuthError;

    if (authError.code === "state_mismatch" || error.message.includes("CSRF")) {
      // Log security incident
      await logSecurityIncident({
        type: "csrf_attempt",
        details: { code, receivedState: state, expectedState: storedState },
      });

      // Clear potentially compromised session
      await storage.clear();

      // Redirect to safe page
      redirectToError("Security violation detected. Please try again.");
      return null;
    }

    throw error;
  } finally {
    // Always clear stored state after use
    await storage.clearState();
  }
}

Error Recovery Strategies

Graceful Degradation

class APIClient {
  async getUserProfile(): Promise<UserProfile | null> {
    try {
      const token = await this.getValidToken();
      const profile = await sdk.getAgentProfile(token);
      return profile;
    } catch (error) {
      const authError = error as AuthError;

      if (authError.code === "token_expired") {
        console.warn("Session expired, user needs to re-login");
        this.notifySessionExpired();
        return null; // Graceful degradation
      }

      if (authError.statusCode && authError.statusCode >= 500) {
        console.error("Server error, using cached profile");
        return this.getCachedProfile(); // Fallback to cache
      }

      throw error; // Re-throw unexpected errors
    }
  }
}

Automatic Recovery

class RobustAPIClient {
  private retryCount = 0;
  private maxRetries = 3;

  async makeRequest<T>(requestFn: (token: string) => Promise<T>): Promise<T> {
    while (this.retryCount < this.maxRetries) {
      try {
        const token = await this.getValidToken();
        const result = await requestFn(token);
        this.retryCount = 0; // Reset on success
        return result;
      } catch (error) {
        const authError = error as AuthError;

        if (authError.code === "token_expired") {
          // Try to refresh
          try {
            await this.refreshToken();
            this.retryCount++;
            continue; // Retry with new token
          } catch (refreshError) {
            throw new Error("Session expired, please login again");
          }
        }

        if (authError.statusCode && authError.statusCode >= 500) {
          // Server error - retry with backoff
          this.retryCount++;
          if (this.retryCount < this.maxRetries) {
            await sleep(Math.pow(2, this.retryCount) * 1000);
            continue;
          }
        }

        throw error; // Non-recoverable error
      }
    }

    throw new Error("Max retries exceeded");
  }
}

User Notification

interface ErrorNotification {
  title: string;
  message: string;
  action?: () => void;
}

function handleError(error: AuthError): ErrorNotification {
  switch (error.code) {
    case "token_expired":
    case "refresh_failed":
      return {
        title: "Session Expired",
        message: "Your session has expired. Please log in again.",
        action: () => redirectToLogin(),
      };

    case "forbidden":
      return {
        title: "Access Denied",
        message: "You don't have permission to perform this action.",
        action: () => redirectToHome(),
      };

    case "state_mismatch":
      return {
        title: "Security Error",
        message: "A security issue was detected. Please try again.",
        action: () => redirectToLogin(),
      };

    default:
      if (error.statusCode && error.statusCode >= 500) {
        return {
          title: "Server Error",
          message:
            "Our servers are experiencing issues. Please try again later.",
          action: () => retryLastAction(),
        };
      }

      return {
        title: "Error",
        message: error.description || "An unexpected error occurred.",
        action: undefined,
      };
  }
}

// Usage
try {
  await sdk.getUserInfo(accessToken);
} catch (error) {
  const notification = handleError(error as AuthError);
  showNotification(notification);
}

Logging and Monitoring

Error Logging

class ErrorLogger {
  static log(error: AuthError, context: any = {}) {
    const errorData = {
      timestamp: new Date().toISOString(),
      code: error.code,
      description: error.description,
      statusCode: error.statusCode,
      stack: error.stack,
      context,
    };

    // Log to console
    console.error("[Auth Error]", errorData);

    // Send to monitoring service
    if (typeof window !== "undefined") {
      // Client-side monitoring (e.g., Sentry)
      window.errorTracker?.captureException(error, {
        extra: errorData,
      });
    } else {
      // Server-side monitoring
      logger.error("Auth error occurred", errorData);
    }
  }
}

// Usage
try {
  await sdk.exchangeCode(code, state, redirectUri);
} catch (error) {
  ErrorLogger.log(error as AuthError, {
    operation: "oauth_code_exchange",
    userId: currentUser?.id,
  });
  throw error;
}

Metrics Collection

class ErrorMetrics {
  private static errors: Map<string, number> = new Map();

  static track(error: AuthError) {
    const key = error.code;
    const count = this.errors.get(key) || 0;
    this.errors.set(key, count + 1);
  }

  static getReport() {
    return Array.from(this.errors.entries()).map(([code, count]) => ({
      code,
      count,
    }));
  }

  static clear() {
    this.errors.clear();
  }
}

// Track errors
try {
  await sdk.getUserInfo(accessToken);
} catch (error) {
  ErrorMetrics.track(error as AuthError);
  throw error;
}

// Get report
console.log("Error Report:", ErrorMetrics.getReport());

Complete Error Handling Example

import { AgentSDK, TokenManager, sleep } from "ai-auth";
import type { AuthError } from "ai-auth";

class RobustAuthService {
  private sdk: AgentSDK;
  private tokenManager: TokenManager;
  private refreshInProgress = false;

  constructor() {
    this.tokenManager = new TokenManager();
    this.sdk = new AgentSDK({
      agentId: process.env.AGENT_ID!,
      onTokensReceived: (tokens) => this.tokenManager.setTokens(tokens),
      onTokensRefreshed: (tokens) => this.tokenManager.setTokens(tokens),
      onTokensRevoked: () => this.tokenManager.clear(),
    });
  }

  async makeRequest<T>(
    requestFn: (token: string) => Promise<T>,
    options = { retries: 3, backoff: true }
  ): Promise<T> {
    let attempts = 0;

    while (attempts < options.retries) {
      try {
        // Ensure token is valid
        await this.ensureValidToken();

        // Make request
        const token = this.tokenManager.getAccessToken();
        return await requestFn(token);
      } catch (error) {
        const authError = error as AuthError;
        attempts++;

        // Handle specific errors
        if (this.shouldRetry(authError, attempts, options.retries)) {
          if (options.backoff) {
            await sleep(Math.pow(2, attempts - 1) * 1000);
          }
          continue;
        }

        // Log and re-throw
        this.logError(authError);
        throw this.createUserFriendlyError(authError);
      }
    }

    throw new Error("Max retry attempts exceeded");
  }

  private async ensureValidToken() {
    if (this.tokenManager.isExpired()) {
      // Prevent multiple simultaneous refresh attempts
      if (this.refreshInProgress) {
        // Wait for refresh to complete
        while (this.refreshInProgress) {
          await sleep(100);
        }
        return;
      }

      if (!this.tokenManager.refreshToken) {
        throw this.createError("session_expired", "Please log in again");
      }

      try {
        this.refreshInProgress = true;
        await this.sdk.refreshAccessToken(this.tokenManager.refreshToken);
      } catch (error) {
        this.tokenManager.clear();
        throw this.createError("session_expired", "Your session has expired");
      } finally {
        this.refreshInProgress = false;
      }
    }
  }

  private shouldRetry(
    error: AuthError,
    attempts: number,
    maxRetries: number
  ): boolean {
    // Don't retry if max attempts reached
    if (attempts >= maxRetries) {
      return false;
    }

    // Don't retry auth errors
    if (error.code === "forbidden" || error.code === "state_mismatch") {
      return false;
    }

    // Don't retry client errors (except token_expired)
    if (error.statusCode && error.statusCode >= 400 && error.statusCode < 500) {
      return error.code === "token_expired";
    }

    // Retry server errors and network errors
    return !error.statusCode || error.statusCode >= 500;
  }

  private logError(error: AuthError) {
    console.error("[Auth Service Error]", {
      code: error.code,
      description: error.description,
      statusCode: error.statusCode,
      timestamp: new Date().toISOString(),
    });
  }

  private createError(code: string, message: string): AuthError {
    const error = new Error(message) as AuthError;
    error.code = code;
    error.description = message;
    return error;
  }

  private createUserFriendlyError(error: AuthError): Error {
    const userMessages: Record<string, string> = {
      token_expired: "Your session has expired. Please log in again.",
      refresh_failed: "Your session has expired. Please log in again.",
      forbidden: "You don't have permission to perform this action.",
      state_mismatch: "Security verification failed. Please try again.",
      session_expired: "Your session has expired. Please log in again.",
    };

    const message =
      userMessages[error.code] || error.description || "An error occurred";
    return new Error(message);
  }
}

export default new RobustAuthService();

Best Practices

Always catch and handle errors

Never let authentication errors crash your application. Always use try-catch blocks.

Provide user-friendly error messages

Translate technical error codes into messages users can understand and act on.

Log errors for debugging

Log all authentication errors with context to help diagnose issues in production.

Implement retry logic for transient errors

Network errors and server errors should be retried with exponential backoff.

Handle token expiration gracefully

Attempt to refresh expired tokens automatically before prompting users to re-login.

Monitor error rates

Track error frequencies to identify systemic issues early.

Next Steps

Token Refresh

Learn about token refresh strategies

AgentSDK Methods

Explore all SDK methods

Get Started

Core Concepts

Components

Guides

Advanced

Error Handling Guide

Error Handling Guide

Error Types

AuthError

Common Error Codes

Basic Error Handling

Try-Catch Pattern

Specific Error Handling

Handling Specific Scenarios

Token Expiration

Network Errors

CSRF Protection

Error Recovery Strategies

Graceful Degradation

Automatic Recovery

User Notification

Logging and Monitoring

Error Logging

Metrics Collection

Complete Error Handling Example

Best Practices

Next Steps

Token Refresh

AgentSDK Methods

​Error Handling Guide

​Error Types

​AuthError

​Common Error Codes

​Basic Error Handling

​Try-Catch Pattern

​Specific Error Handling

​Handling Specific Scenarios

​Token Expiration

​Network Errors

​CSRF Protection

​Error Recovery Strategies

​Graceful Degradation

​Automatic Recovery

​User Notification

​Logging and Monitoring

​Error Logging

​Metrics Collection

​Complete Error Handling Example

​Best Practices

​Next Steps

Token Refresh

AgentSDK Methods

Error Handling Guide

Error Types

AuthError

Common Error Codes

Basic Error Handling

Try-Catch Pattern

Specific Error Handling

Handling Specific Scenarios

Token Expiration

Network Errors

CSRF Protection

Error Recovery Strategies

Graceful Degradation

Automatic Recovery

User Notification

Logging and Monitoring

Error Logging

Metrics Collection

Complete Error Handling Example

Best Practices

Next Steps