OptionalcustomCell renderer for custom columns.
The record property this column reads.
OptionalenumSelectable values, for enum columns.
OptionalfieldWhich registry entry renders and edits this column.
Column header, also used as the form label.
The slice of a column definition the field registry reads.
Structural rather than generic on purpose: the registry dispatches across twenty field types with unrelated value shapes, so a single definition cannot be parameterised over any one record type.
unknownhere is the strict choice, not a lax one - it forces every renderer to narrow before using a value, whichanywould not.