0009. Forms and i18n

• Status: Accepted
• Date: 2026-10-10
• Questions: D7, D8

Decision

• Forms (D7): react-hook-form 7 with @hookform/resolvers/zod. The same Zod schema validates the form and the API payload. Field primitives in shared/ui/form handle labels, errors, hints, keyboard avoidance (keyboard-controller) and next-field focus. Forms that must not submit offline use offline pattern C (input kept, submit disabled).
• i18n (D8): i18next + react-i18next with react-native-localize for the device locale and a manual override in Settings. Translation keys are typed from en.json. ICU-style plurals and Intl formatting. A lint rule flags hard-coded user-visible strings. RTL is supported (ADR 0008).

Alternatives considered

• TanStack Form: type-first, smaller ecosystem.
• Lingui: excellent extraction workflow, less common in templates.