Design Rationale

A design rationale document captures the "why" behind design decisions.the context, constraints, alternatives considered, and reasoning that led to a particular solution. While designs themselves show what was built, rationale documents preserve institutional knowledge about why it was built that way.

When to Use

• When making significant UX decisions that affect user experience
• Before design reviews to prepare stakeholder discussions
• When multiple valid approaches exist and the choice needs justification
• To onboard new team members to existing design decisions
• When revisiting past decisions to understand original reasoning
• During design system evolution to document pattern choices

When NOT to Use

• The decision is architectural or a technology selection -> use develop-adr (Nygard format)
• You need stakeholder alignment on the overall solution direction -> use develop-solution-brief
• You are documenting exploration findings rather than a decision -> use develop-spike-summary
• The decision is trivially reversible and low-stakes: a rationale document adds ceremony; record the reasoning in the PR or ticket instead