sdd-planning

name	sdd-planning
description	Generate technical plans from specifications. Use when creating architecture documents, designing system components, or preparing for implementation.

SDD Planning Skill

Transform specifications into actionable technical plans.

When to Use

• Spec exists but plan doesn't
• Designing system architecture
• Breaking down features into components
• After research is complete

Planning Protocol

Step 1: Understand Requirements

Read spec.md, note functional/non-functional requirements, review research findings.

Step 2: Design Architecture

Identify components, define responsibilities, design interfaces, plan data flow.

Step 3: Select Technology

Evaluate against requirements, consider existing stack, document rationale.

Step 4: Plan Implementation

Break into phases (Setup → Core → Integration → Polish), identify dependencies, estimate effort.

Step 5: Assess Risks

Identify technical risks, plan mitigations, note assumptions.

Output Format

Generate plan.md with:

# Technical Plan: [Task ID]

## Overview
## Architecture (Mermaid diagram)
## Components (table: name, responsibility, dependencies)
## Technology Stack (with rationale)
## API Design
## Data Models
## Security Considerations
## Performance Targets
## Implementation Phases (Setup → Core → Integration → Polish)
## Risks (probability, impact, mitigation)
## Testing Strategy (unit, integration, E2E)
## Open Questions

References

• assets/diagram-templates.md — Architecture diagram patterns (Mermaid templates)
• references/estimation-heuristics.md — Task sizing guidelines, common pitfalls, and estimation by task type
• .sdd/templates/decision-matrix.md — When to use Brief vs Full SDD planning

Integration

• Input from: sdd-research skill, sdd-explorer subagent
• Output to: /tasks command, sdd-implementer subagent
• Use the ask question tool for architectural decisions with significant tradeoffs