Graceful Degradation

Skill Profile

(Select at least one profile to enable specific modules)

• DevOps
• Backend
• Frontend
• AI-RAG
• Security Critical

Overview

Graceful Degradation is the practice of designing systems to maintain partial functionality during failures or outages. Instead of complete failure, the system operates in a degraded mode that provides essential features while non-critical features are disabled or simplified.

Core Principle: "Better partial service than no service at all."

Why This Matters

• User Experience: Users can still access critical functionality during outages
• Business Continuity: Core operations continue even when secondary systems fail
• Reduced Support Load: Fewer users affected by complete outages
• Better Resource Utilization: Focus limited resources on critical paths
• Controlled Failure: Predictable behavior under stress

Core Concepts & Rules

1. Core Principles

• Follow established patterns and conventions
• Maintain consistency across codebase
• Document decisions and trade-offs

2. Implementation Guidelines

• Start with the simplest viable solution
• Iterate based on feedback and requirements
• Test thoroughly before deployment

Inputs / Outputs / Contracts

• Inputs:
  • Feature categorization and priority levels
  • System health metrics and thresholds
  • Fallback data and responses
• Entry Conditions:
  • Feature flags system is implemented
  • Health checks are configured for all dependencies
  • Fallback data is available and up-to-date
• Outputs:
  • Degradation configuration and thresholds
  • Monitoring dashboards for degraded state
  • Runbooks for activating/deactivating degradation modes
• Artifacts Required (Deliverables):
  • Feature flag configuration
  • Fallback response data
  • Degradation runbooks
• Acceptance Evidence:
  • Load test showing degraded state handling
  • Monitoring screenshots of graceful degradation
  • Fallback verification test results
• Success Criteria:
  • Critical features remain available during degradation
  • Non-critical features gracefully disabled
  • System recovers to full functionality when conditions improve

Skill Composition

• Depends on: Circuit Breaker, Monitoring & Observability
• Compatible with: Bulkhead Patterns, Retry Strategies
• Conflicts with: Systems that cannot function in degraded state
• Related Skills:
  • 40-system-resilience/bulkhead-patterns - Resource isolation for critical paths
  • 40-system-resilience/retry-timeout-strategies - Handling failures gracefully
  • 40-system-resilience/chaos-engineering - Testing degradation

Quick Start / Implementation Example

1. Review requirements and constraints
2. Set up development environment
3. Implement core functionality following patterns
4. Write tests for critical paths
5. Run tests and fix issues
6. Document any deviations or decisions

# Example implementation following best practices
def example_function():
    # Your implementation here
    pass

Assumptions / Constraints / Non-goals

• Assumptions:
  • Development environment is properly configured
  • Required dependencies are available
  • Team has basic understanding of domain
• Constraints:
  • Must follow existing codebase conventions
  • Time and resource limitations
  • Compatibility requirements
• Non-goals:
  • This skill does not cover edge cases outside scope
  • Not a replacement for formal training

Compatibility & Prerequisites

• Supported Versions:
  • Python 3.8+
  • Node.js 16+
  • Modern browsers (Chrome, Firefox, Safari, Edge)
• Required AI Tools:
  • Code editor (VS Code recommended)
  • Testing framework appropriate for language
  • Version control (Git)
• Dependencies:
  • Language-specific package manager
  • Build tools
  • Testing libraries
• Environment Setup:
  • .env.example keys: API_KEY, DATABASE_URL (no values)

Test Scenario Matrix (QA Strategy)

Technical Guardrails & Security Threat Model

1. Security & Privacy (Threat Model)

• Top Threats: Injection attacks, authentication bypass, data exposure

• Data Handling: Sanitize all user inputs to prevent Injection attacks. Never log raw PII
• Secrets Management: No hardcoded API keys. Use Env Vars/Secrets Manager
• Authorization: Validate user permissions before state changes

2. Performance & Resources

• Execution Efficiency: Consider time complexity for algorithms
• Memory Management: Use streams/pagination for large data
• Resource Cleanup: Close DB connections/file handlers in finally blocks

3. Architecture & Scalability

• Design Pattern: Follow SOLID principles, use Dependency Injection
• Modularity: Decouple logic from UI/Frameworks

4. Observability & Reliability

• Logging Standards: Structured JSON, include trace IDs request_id
• Metrics: Track error_rate, latency, queue_depth
• Error Handling: Standardized error codes, no bare except
• Observability Artifacts:
  • Log Fields: timestamp, level, message, request_id
  • Metrics: request_count, error_count, response_time
  • Dashboards/Alerts: High Error Rate > 5%

Agent Directives & Error Recovery

(ข้อกำหนดสำหรับ AI Agent ในการคิดและแก้ปัญหาเมื่อเกิดข้อผิดพลาด)

• Thinking Process: Analyze root cause before fixing. Do not brute-force.
• Fallback Strategy: Stop after 3 failed test attempts. Output root cause and ask for human intervention/clarification.
• Self-Review: Check against Guardrails & Anti-patterns before finalizing.
• Output Constraints: Output ONLY the modified code block. Do not explain unless asked.

Definition of Done (DoD) Checklist

• Tests passed + coverage met
• Lint/Typecheck passed
• Logging/Metrics/Trace implemented
• Security checks passed
• Documentation/Changelog updated
• Accessibility/Performance requirements met (if frontend)

Anti-patterns / Pitfalls

• ⛔ Don't: Log PII, catch-all exception, N+1 queries
• ⚠️ Watch out for: Common symptoms and quick fixes
• 💡 Instead: Use proper error handling, pagination, and logging

Reference Links & Examples

• Internal documentation and examples
• Official documentation and best practices
• Community resources and discussions

Versioning & Changelog

• Version: 1.0.0
• Changelog:
  • 2026-02-22: Initial version with complete template structure