architecture

<skill id="architecture">

<purpose>

Architecture is about managing change over time.

Good architecture makes easy things easy and hard things possible.

AI-generated code amplifies existing patterns—good or bad.

</purpose>

<prerequisite>

Understand existing codebase structure before proposing changes.

Check for established patterns. Follow them unless explicitly changing.

</prerequisite>

<reference>

Skill-specific: skills/architecture/reference/architecture-research.md

</reference>

<core_principles>

1. FOLLOW EXISTING PATTERNS: Don't introduce new patterns without justification.
2. INTERFACE STABILITY: Changing interfaces breaks everything. Stabilize them first.
3. MODULAR BOUNDARIES: Clear separation. Each module has one reason to change.
4. DEPENDENCY DIRECTION: Depend on abstractions, not concretions. Core doesn't know about edges.
5. SMALLEST CHANGE: Prefer minimal changes that achieve the goal.

</core_principles>

<ai_code_health_nexus>

From research: 30%+ defect risk when AI applied to unhealthy code.

AI amplifies existing patterns. If code is messy, AI makes it messier.

Before adding AI to a codebase:

1. Identify health score (coupling, complexity, test coverage)
2. Fix critical health issues first
3. Establish clear interfaces
4. Then apply AI within those boundaries

</ai_code_health_nexus>

<design_heuristics>

• If you can't explain it simply, the design is too complex
• Three concrete examples before abstraction
• Composition over inheritance
• Make illegal states unrepresentable
• Parse, don't validate

</design_heuristics>

<anti_patterns>

• Premature abstraction (abstract before 3 concrete uses)
• Leaky abstractions (implementation details bleeding through)
• Circular dependencies
• God objects (one class doing everything)
• Feature envy (methods that use another class more than their own)

</anti_patterns>

<on_complete>

agentdb write-end '{"skill":"architecture","decision":"X","coupling_reduced":true,"adr":"path|none"}'

</on_complete>

</skill>