Split button: don't repeat primary
split-button-dont-repeat-primary
Split button: full phrase on the rest-state primary; don’t repeat that primary in the secondary list.
Description
A Fluent split button puts the full phrase on the rest-state primary so the default action is clear before the menu opens. The secondary list must not repeat that same primary entry. Apply when composing a split button with a primary action and overflow list. Fail an incomplete primary phrase, or the same primary duplicated inside the secondary list.
When to use
Composing a split button with a primary and secondary list.
Not when
Ordinary button groups without a split primary-plus-menu pattern.
Agent hint
Put the full primary phrase on rest-state; do not duplicate it in the list.
Rest-state primary has the full phrase; the secondary list does not repeat that primary.
Primary phrase is incomplete, or the same primary is duplicated in the list.
Citations
Fluent 2 — Button usage
https://fluent2.microsoft.design/components/web/react/core/button/usage