Module error_category 

Unified error categorization system for consistent error classification across VT Code.

This module provides a single canonical ErrorCategory enum that unifies the previously separate classification systems in registry::error (8-variant ToolErrorType) and unified_error (16-variant UnifiedErrorKind). Both systems now map through this shared taxonomy for consistent retry decisions and error handling.

Error Categories

Errors are divided into retryable (transient) and non-retryable (permanent) categories, with sub-classifications for specific handling strategies.

Design Decisions

• String-based fallback is preserved only for anyhow::Error chains where the original type is erased. Typed From conversions are preferred.
• Policy violations are explicitly separated from OS-level permission denials.
• Rate limiting is a distinct category (not merged with network errors).
• Circuit breaker open is categorized separately for recovery flow routing.

Enums

BackoffStrategy

Backoff strategy for retryable errors.

ErrorCategory

Canonical error category used throughout VT Code for consistent retry decisions, user-facing messages, and error handling strategies.

Retryability

Describes whether and how an error can be retried.

Functions

classify_anyhow_error

Classify an anyhow::Error into a canonical ErrorCategory.

classify_error_message

Classify an error message string into an ErrorCategory.

is_retryable_llm_error_message

Check if an LLM error message is retryable (used by the LLM request retry loop).