The six shapes a real edit screen runs into, each one live (docs/form.md).
Unsaved means different from the default. Clearing and restoring the default are two different actions.
Single-field rules attach per field; cross-field rules use refine and attach to the field to fix.
Read-only can be selected and copied, disabled cannot be touched. Both still submit their value.
Nesting by path, changing rows through useFieldArray. A rule about the array attaches to the array.
A field that is not shown is not validated. The display condition and the validation condition live in one place.
Stop while in flight, and return a server failure to the field rather than to a toast.