Update Design Document

Record/update project design and implementation decisions in .claude/docs/DESIGN.md based on conversation content.

Note: This skill explicitly invokes the same workflow as the design-tracker skill. Use this when you want to force a design document update.

Workflow

1. Read existing .claude/docs/DESIGN.md
2. Extract decisions/information from the conversation
3. Update the appropriate section
4. Add entry to Changelog with today's date

Section Mapping

Topic	Section
Goals, purpose	Overview
Structure, components	Architecture
Design patterns	Implementation Plan > Patterns
Library choices	Implementation Plan > Libraries
Decision rationale	Implementation Plan > Key Decisions
Future work	TODO
Unresolved issues	Open Questions

Update Format

When updating, add to the appropriate section:

### Key Decisions

#### {Decision Title} ({Date})

**Context**: {Why this decision was needed}
**Decision**: {What was decided}
**Rationale**: {Why this option was chosen}

Changelog Entry

Always add to Changelog:

## Changelog

### {Date}
- {Brief description of what was recorded}

Language

• Document content: English (technical), Japanese OK for descriptions
• User communication: Japanese

If $ARGUMENTS provided, focus on recording that content.