Design-Development Parity

Keep design and development artifacts in sync, ensuring what is designed matches what is built and maintained.

A design system breaks when design and code drift apart.

Design-development parity means that design decisions and implementation represent the same system, expressed through different artifacts.

When parity is lost, teams stop trusting the system and start working around it.

Treat design and code as equal sources of truth

Neither design nor code should lead in isolation.

Align design tokens with code tokens. Manually retranslate design values into code. Keep naming consistent across Figma, documentation, and APIs. Use different terminology for the same concept.
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Documentation Exporters Importers

Encode design decisions, not screenshots

Implementation should express intent, not static visuals.

Implement components based on rules and constraints. Recreate pixel-perfect snapshots without understanding behavior. Document states, interactions, and edge cases. Rely solely on static mockups for behavior.
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Interactive documentation Addons

Share a common mental model

Designers and developers should reason about the system in the same way.

Button component anatomy

text
        Button
├─ Interaction Container
│
├─ Content
│  ├─ Icon (optional)
│  │  └─ Icon Element (mds-icon)
│  │     └─ part="icon"
│  │
│  ├─ Label (required)
│  │  └─ Text Element (mds-text)
│  │     └─ part="label"
│  │
│  └─ Notification Slot (optional)
│     └─ Slot "notification"
│        └─ Notification Component (recommended: mds-notification)
│
├─ Await / Loading Layer (conditional)
│  └─ Spinner (mds-spinner)
│
└─ Focus / Interaction Layer
      
Define component anatomy and state models. Leave structure implicit or undocumented. Review components together across disciplines. Hand off designs without discussion.
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Interactive documentation Addons Documentation

Automate parity where possible

Manual synchronization does not scale.

Use tokens and schemas as shared artifacts. Rely on human memory to maintain alignment. Validate implementations against documented specs. Accept silent divergence between design and code.
A list of tools and services related to this argument. potentially outdated
Documentation Exporters Importers

Why this principle matters

Design-development parity reduces friction, rework, and ambiguity.

When design and code speak the same language, the system becomes predictable, trustworthy, and scalable.