feat(ios): style SwiftUI controls instead of wrapping CDS views

[adrienzheng-cb]

What changed? Why?

iOS should not re-implement system controls as CDS views. This PR reshapes the experimental (internal) iOS components so SwiftUI owns the primitive and CDS owns the look, and adds agent guidance so future migrations follow the same pattern.

SwiftUI Style / modifier instead of CDS wrapper views

• Button → SwiftUI Button + .buttonStyle(.cds) and CDSButtonLabel for icon spacing
• Switch → SwiftUI Toggle + .toggleStyle(.cds)
• Text → SwiftUI Text + .cdsText
• ProgressCircle → SwiftUI ProgressView + .progressViewStyle(.cds)

SlideButton stays a CDS view — there is no SwiftUI primitive to restyle. The gallery demos each pattern as its own section. Components remain internal.

swiftui-best-practices skill + AGENTS guidance

• New .claude/skills/swiftui-best-practices skill (rewrite patterns, "why not a wrapper", RN → iOS map); root AGENTS.md loads it for SwiftUI / RN → iOS work.
• packages/cds-ios/AGENTS.md links the CDS SwiftUI Best Practices doc and adds:
  • Visual spec is RN, not HIG. Match the React Native component; HIG wins only for OS chrome or where iOS physically can't match.
  • Overlays are CDS views. Components like Alert, Accordion, and Tooltip become CDS views matching RN. The OS .alert shown in the gallery is for contrast only; the CDS Alert will be a CDS view matching the RN modal (doc comments and gallery copy updated accordingly).
  • Whole-app CDS is environment inheritance, not wrapper views. CDSThemeProvider sets environment defaults so plain SwiftUI controls pick up CDS styling.

UI changes

Gallery-only. No product screenshot matrix; exercise on iOS Simulator via yarn nx run ios-gallery:launch.

Testing

How has it been tested?

• Unit tests
• Interaction tests
• Pseudo State tests
• Manual - Web
• Manual - Android (Emulator / Device)
• Manual - iOS (Emulator / Device)

Testing instructions

1. yarn nx run cds-ios:test
2. yarn nx run ios-gallery:launch
3. Scroll to Text, Components, Toggle, Alert, ProgressView
4. Confirm toggles flip, Show system alert presents a system dialog (contrast reference only), and progress rings spin (plus a determinate ring)

Change management

type=routine
risk=low
impact=sev5

automerge=false

Made with Cursor

[cb-heimdall]

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