0002 — Nacre design system

• Status: accepted
• Date: 2026-09-29

Context

The product's value is largely experiential: a calm, fast interface for a capable agent. Off-the-shelf kits (MUI, Chakra, shadcn defaults) would give Conch a common look, and frosted-glass effects cost GPU time and lower text contrast.

Decision

Build Nacre, our own component library:

• Behaviour & accessibility from Radix Primitives (radix-ui), cmdk for the command palette, sonner for toasts, shiki for code highlighting — battle-tested headless layers we style completely.
• Styling with CSS Modules + custom properties + cascade layers. No runtime CSS-in-JS; variants are data-* attributes; all values are tokens.
• OKLCH colour, derived at runtime from a few knobs (accent hue/chroma, neutral tint), so themes are one CSS variable away and always perceptually balanced.
• Lustre — an opaque, porcelain material with pointer-reactive iridescence — as the brand signature instead of glass (see docs/design/NACRE.md).
• Motion via CSS linear() springs for state transitions and motion for layout animation, all collapsing under reduced-motion preferences.

Consequences

More upfront work than adopting a kit, but full control over the details, a look of its own, and no fighting library defaults. Every component must ship with stories and axe-checked tests.