Form Builder

Multi-field registration form with sync + async validation, derived aggregation for form-level state.

Try it: Fill in the fields — validation runs in real-time. The email field simulates an async uniqueness check with debounce. Submit is disabled until all fields are valid.

What it demonstrates

Primitive	Module	Role
formField	patterns/formField	Per-field reactive validation (sync + async)
derived	core	Form-level allValid, anyDirty, anyValidating aggregation
useSubscribe	compat/vue	Bridge stores to Vue refs

How it works

Each field is a formField() — a self-contained reactive unit with value, error, dirty, touched, valid, and validating stores. Sync validators run immediately on value change. Async validators are debounced (300ms default) and auto-cancelled via AbortSignal.

Form-level stores (allValid, anyDirty) are derived() from all field stores — diamond resolution ensures they update exactly once per change.

All tree-shakeable. Zero framework lock-in.