Design system

A design system is a set of constraints that makes consistency the cheap path. If the system is harder to follow than to ignore, it will be ignored.

Tokens first

Define the primitives before any component. Every visual decision references a token; nothing hard-codes a value.

• Color — semantic names, not literal ones. surface, surface-raised, text-primary, text-muted, border, accent, danger. A token named blue-500 cannot be re-themed.
• Type — a scale with a stated ratio, and a line-height per step. Four to six steps. More than that and nobody can tell them apart.
• Spacing — one scale, geometric, used for every gap and inset. Arbitrary spacing is the single most common source of "it looks off but I can't say why."
• Radius, elevation, motion — small closed sets. Two or three each.

Every token needs a light and dark value defined together. Adding dark mode later means auditing every surface.

Component contracts

A component in the system carries: the states it supports (default, hover, focus, active, disabled, loading, error, empty), the props that vary it, and what it will not do. The last one matters most — a component that accepts arbitrary overrides is a styling function, not a component.

Every interactive component needs a visible focus state and a target big enough to hit. This is not a polish item; it is whether people can use it.

Growth rules

• A new component enters the system only after the same need appears three times. Before that it is local.
• Changing a token is a system-wide change — treat it like an API change, because it is.
• Never remove a token or component because it looks unused. You cannot see every consumer from inside the system. Deprecate, announce, then remove.

Tooling

Design source: Figma, and similar. Component documentation and review: Storybook.

Token pipelines: Style Dictionary, Tokens Studio, Figma variables exported to code, and similar. Visual regression: Chromatic, Percy, Playwright snapshots, and similar.

The system is the code, not the design file. When the two disagree, the code is what ships.

Never

• Add a component for a single screen. A one-use component is a snippet, not a system.
• Hard-code a value a token already covers. The exception becomes the next inconsistency.
• Redefine what an existing token means instead of adding one. Changing a semantic silently redecorates everything downstream.
• Ship a component without its states documented — empty, loading, error, disabled.

Return contract

Report tokens added or changed, components affected, anything now inconsistent with the system, and what needs migrating.