Nm Leyline Error Patterns

Standardized error handling patterns with classification, recovery, and logging strategies. error handling, error recovery, graceful degradation, resilience.

Security Scan

Instruction-only error-handling patterns library that is internally consistent with its stated purpose, requests no secrets, and has no install steps — review logging/alert destinations and any file I/O it references before use.

Purpose & Capability

The name/description (error handling, recovery, logging, resilience) align with the actual content: classification, recovery strategies, agent-level escalation, and logging patterns. The single declared config requirement (night-market.usage-logging) is relevant to logging behavior. Examples referencing services (gemini, Qwen) are illustrative and reasonable for a cross-service error-patterns library.

Instruction Scope

SKILL.md is instruction-only and stays within error-classification and recovery guidance. It includes patterns that mention writing summaries to files, logging full context, and calling send_alert(log_entry) — these are reasonable for a logging/recovery library but imply file I/O and external alerting. The docs also reference user config paths (e.g. ~/.claude/leyline/) which are outside the declared night-market.usage-logging config and should be reviewed for scope.

Install Mechanism

No install spec and no code files — lowest-risk distribution model. Nothing is downloaded or written to disk by the skill itself beyond the guidance in the text.

Credentials

No environment variables or credentials are requested. The declared config path (night-market.usage-logging) is proportionate to a logging/alerting skill. No unrelated secrets or broad credential access are required.

Persistence & Privilege

always is false and the skill is user-invocable; it does not request persistent or elevated platform presence. The guidance includes writing to files or checkpoints as recovery patterns, which is normal for a resilience library but not a platform-level privilege escalation.

Assessment

This skill is a documentation-only set of error-handling patterns and appears coherent with its purpose. Before installing or enabling it, check: (1) where logs/alerts will be sent (the snippets call send_alert and log full context but don't specify destinations), (2) what the night-market.usage-logging config controls and who can read it, and (3) any filesystem paths referenced in your deployments (e.g. ~/.claude/leyline/ or checkpoint files) to ensure you’re comfortable with the skill's suggested file I/O. No credentials or installs are required, and there are no code files — the main risk is accidental logging of sensitive context if you wire up alerts/logging without review.

Night Market Skill — ported from claude-night-market/leyline. For the full experience with agents, hooks, and commands, install the Claude Code plugin.

Table of Contents

• Overview
• When to Use
• Error Classification
• By Severity
• By Recoverability
• Quick Start
• Standard Error Handler
• Error Result
• Common Patterns
• Authentication Errors (401/403)
• Rate Limit Errors (429)
• Timeout Errors
• Context Too Large (400)
• Integration Pattern
• Detailed Resources
• Exit Criteria

Error Patterns

Overview

Standardized error handling patterns for consistent, production-grade behavior across plugins. Provides error classification, recovery strategies, and debugging workflows.

When To Use

• Building resilient integrations
• Need consistent error handling
• Want graceful degradation
• Debugging production issues

When NOT To Use

• Project doesn't use the leyline infrastructure patterns
• Simple scripts without service architecture needs

Error Classification

By Severity

Level	Action	Example
Critical	Halt, alert	Auth failure, service down
Error	Retry or secondary strategy	Rate limit, timeout
Warning	Log, continue	Partial results, deprecation
Info	Log only	Non-blocking issues

By Recoverability

class ErrorCategory(Enum):
    TRANSIENT = "transient"      # Retry likely to succeed
    PERMANENT = "permanent"       # Retry won't help
    CONFIGURATION = "config"      # User action needed
    RESOURCE = "resource"         # Quota/limit issue

Verification: Run the command with --help flag to verify availability.

Quick Start

Standard Error Handler

from leyline.error_patterns import handle_error, ErrorCategory

try:
    result = service.execute(prompt)
except RateLimitError as e:
    return handle_error(e, ErrorCategory.RESOURCE, {
        "retry_after": e.retry_after,
        "service": "gemini"
    })
except AuthError as e:
    return handle_error(e, ErrorCategory.CONFIGURATION, {
        "action": "Run 'gemini auth login'"
    })

Verification: Run the command with --help flag to verify availability.

Error Result

@dataclass
class ErrorResult:
    category: ErrorCategory
    message: str
    recoverable: bool
    suggested_action: str
    metadata: dict

Verification: Run the command with --help flag to verify availability.

Common Patterns

Authentication Errors (401/403)

• Verify credentials exist
• Check token expiration
• Validate permissions/scopes
• Suggest re-authentication

Rate Limit Errors (429)

• Extract retry-after header
• Log for quota tracking
• Implement backoff
• Consider alternative service

Timeout Errors

• Increase timeout for retries
• Break into smaller requests
• Use async patterns
• Consider different model

Context Too Large (400)

• Estimate tokens before request
• Split into multiple requests
• Reduce input content
• Use larger context model

Integration Pattern

# In your skill's frontmatter
dependencies: [leyline:error-patterns]

Verification: Run the command with --help flag to verify availability.

Detailed Resources

• Classification: See modules/classification.md for error taxonomy
• Recovery: See modules/recovery-strategies.md for handling patterns
• Agent Damage Control: See modules/agent-damage-control.md for multi-agent error recovery and escalation

Exit Criteria

• Error classified correctly
• Appropriate recovery attempted
• User-actionable message provided
• Error logged for debugging

Troubleshooting

Common Issues

Command not found Ensure all dependencies are installed and in PATH

Permission errors Check file permissions and run with appropriate privileges

Unexpected behavior Enable verbose logging with --verbose flag