Architecture Planning Skill

Purpose

Produce consistent, thorough architecture documentation for system design.

When to Use

• Planning significant feature implementations
• Making technology or pattern decisions
• Designing new modules or services
• Before major refactoring efforts
• System integration planning

Templates

Main Templates

• templates/architecture-doc.md - Full architecture document
• templates/decision-record.md - ADR (Architecture Decision Record) format
• templates/risk-assessment.md - Risk matrix template

Pattern Library

Reference established architectural patterns:

• patterns/microservices.md - Microservices architecture
• patterns/monolith.md - Monolithic architecture
• patterns/serverless.md - Serverless architecture

Decision Framework

When to Create an ADR

Create a formal Architecture Decision Record when:

• Choosing between technologies (database, framework, library)
• Selecting architectural patterns (monolith vs microservice)
• Defining integration approaches (sync vs async)
• Making security model changes
• Decisions that are hard to reverse

ADR Format (Lightweight)

# ADR-[N]: [Title]
**Status:** Proposed | Accepted | Deprecated | Superseded
**Date:** [YYYY-MM-DD]

## Context
[Why is this decision needed? What's the situation?]

## Decision
[What was decided?]

## Consequences
[What follows from this decision?]

Risk Assessment Matrix

Use this matrix to categorize risks:

Probability ↓ / Impact →	Low	Medium	High
High	Medium	High	Critical
Medium	Low	Medium	High
Low	Low	Low	Medium

Risk Categories

• Technical: Technology limitations, complexity, performance
• Timeline: Schedule impacts, dependencies
• Integration: External system dependencies, API changes
• Security: Vulnerabilities, compliance requirements
• Operational: Deployment, monitoring, maintenance

Architecture Document Sections

Required Sections

1. Overview - High-level description
2. Design Decisions - Key choices with rationale
3. Component Design - Responsibilities and interfaces
4. Risk Assessment - Identified risks and mitigations

Optional Sections (as needed)

• Data Flow diagrams
• Integration Points
• Security Considerations
• Performance Requirements
• Migration Strategy

Quality Checklist

Before finalizing an architecture document:

• All major decisions documented with options considered
• Rationale provided for each decision
• Trade-offs explicitly stated
• Risks identified with mitigation strategies
• Aligns with existing codebase patterns (from research)
• Integration points clearly defined
• Component responsibilities are clear and non-overlapping
• Security implications considered
• Performance requirements addressed

Output Location

Save architecture documents to:

docs/plans/architecture-{session}.md

Save ADRs to:

docs/plans/adr-{number}-{title}.md

Integration with Workflow

1. Research phase provides codebase context and patterns
2. Questioning phase provides validated requirements
3. Architecture planning creates design documents (this skill)
4. Task breakdown converts architecture to executable tasks
5. Implementation follows the approved plan