/**
 * Error types for the AI provider layer.
 *
 * Errors are classified so callers can react appropriately: auth failures are
 * terminal (the key is wrong), rate-limit/overloaded errors are retryable, and
 * budget violations are a client-side guard.
 *
 * See CHUNK#8.md §3.
 */

/** Base class for all provider-layer errors. */
export class ProviderError extends Error {
  constructor(message: string) {
    super(message);
    this.name = "ProviderError";
  }
}

/** The provider rejected the request due to missing/invalid credentials. */
export class ProviderAuthError extends ProviderError {
  constructor(message = "Provider authentication failed (invalid API key).") {
    super(message);
    this.name = "ProviderAuthError";
  }
}

/** The provider rate-limited or overloaded the request; safe to retry. */
export class ProviderRateLimitError extends ProviderError {
  constructor(message = "Provider rate limit exceeded; retrying.") {
    super(message);
    this.name = "ProviderRateLimitError";
  }
}

/** The request exceeded the configured token budget. */
export class BudgetExceededError extends ProviderError {
  constructor(message: string) {
    super(message);
    this.name = "BudgetExceededError";
  }
}

/** No provider adapter is registered for the given kind. */
export class UnknownProviderError extends ProviderError {
  constructor(kind: string) {
    super(`Unknown provider kind: ${kind}`);
    this.name = "UnknownProviderError";
  }
}