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Runtime Layer

The Runtime Layer resolves final field and group capabilities from reducer state. It is the policy boundary between stored meta and UI behavior.

Why Runtime Exists​

Visibility, submission, disabled state, readonly state, and validation are related decisions. If each component computes them independently, behavior diverges. Runtime centralizes those policies in one resolution step.

The current flow is:

FormState
  -> resolveRuntimeState()
  -> RuntimeState
      -> rendering
      -> submit validation
      -> changed-field validation
      -> field participation

Field Capabilities​

Each field resolves to rendered, submitable, disabled, readonly, editable, and validatable.

rendered is affected by field and group visibility. submitable currently follows rendered. validatable currently means rendered and not disabled. Readonly fields still validate.

Group Capabilities​

Each group resolves to rendered. Group visibility affects child field rendering and submit participation.

Meta Input​

Runtime reads behavior meta through getFieldBehaviorMeta and getGroupBehaviorMeta. This keeps compatibility with legacy flat meta keys while centering new logic on meta.behavior.

Consumers​

FormContent computes one runtime snapshot with useRuntimeState(state) and passes it to useFormRuntimeEvents, useFieldParticipation, and default field rendering.

Validation Policy​

Changed-field validation and submit validation both filter fields through runtimeState.fields[fieldId]?.validatable === true. Avoid direct validation against changed keys because it ignores hidden, group-hidden, disabled, and future runtime policies.

Hidden Field Participation​

useFieldParticipation clears a field value when it leaves submit participation unless preserveValueOnHide is true. If restoreValueOnShow is not false, the old value is cached and restored when the field becomes submitable again.

Extension Guidance​

Add behavior state to meta only if Runtime should decide with it. Keep render-only props in formItemProps or componentProps. Update runtime resolvers instead of duplicating policy inside components. Keep Ant Design Form as the owner of values and validation runtime state.