Emit native token outputs for iOS (Swift) and Android (Kotlin): colours, type scale, spacing, radii

[thomasdigby]

Context

The native iOS app (currently in App Store review) renders its native chrome — login screen, splash, error screens, toasts — with hardcoded colour, font-size, and radius values that drift from the design system. An Android app will follow. We want the theme package to be the single source of truth for those values, the same way it already is for web via the CSS/JS/Tailwind outputs.

Requirement

The build should emit tokens in native-consumable form alongside the existing outputs in lib/:

• Swift (lib/theme-*.swift): a ThemeTokens enum of SwiftUI Color(red:green:blue:opacity:) and CGFloat constants
• Kotlin (lib/theme-*.kt): the equivalent Compose Color(0xAARRGGBB) / Dp/TextUnit constants (needed when the Android app goes into development — can land later than Swift)

Token coverage

Group	Emit as	Conversion
color.*	Color	hsl()/hex → sRGB components at build time (SwiftUI has no HSL initialiser)
size.font.*	CGFloat (pt)	rem × 16 — e.g. sm 0.875 → 14pt
size.radii.*	CGFloat (pt)	rem × 16 — e.g. md 0.5 → 8pt
size.space.*	CGFloat (pt)	rem × 16
size.leading.*	CGFloat	unitless line-height multipliers, emitted as-is

Excluded, deliberately:

• font.families.* — web font stacks (system-ui, -apple-system, …); the native apps bind their own bundled font by name
• size.breakpoint.* — windowed-web concern, meaningless full-screen
• effects.* — CSS box-shadow strings don't translate mechanically to native shadow parameters

Details

• Flat camelCase names from the token path, e.g. color.blue.800 → blue800, color.subject.gcse-maths → subjectGcseMaths, size.font.sm → fontSm. These names become the native apps' API — renames are breaking.
• Alpha tokens (color.alpha.*) carry their opacity component.
• Per-theme variants like the other formatters (theme-base.swift, theme-atom.swift, …).
• No new packaging. The files ship inside the existing npm tarball (files: ["lib"]); the native repos vendor the file for a pinned version (fetched from unpkg in their build). No Swift Package / Maven artifact needed.
• Tests: generated files contain no unconverted hsl()/hex/rem values and no duplicate constant names.

Status

A working Swift formatter + vitest coverage already exists as a spike for the colour half (built from a local branch; the iOS repo currently vendors its output). Happy to open it as a PR to seed this — sizes are a small extension of the same formatter, and Kotlin follows the same pattern.

🤖 Generated with Claude Code

[thomasdigby]

The generated Swift export is now vendored into the iOS app and compiles clean — thanks! One small thing before it publishes: the leading* constants are untyped, so leading2xl = 1.08 infers Double while leading4xl = 1 infers Int — a different type from its siblings, which bites the first time someone multiplies a font size by it. Wrapping them like the font/radii constants (CGFloat(1.08)) makes the whole scale uniform.

🤖 Generated with Claude Code