A prompt input is a form field with delusions of grandeur — it needs a label, keyboard rules, disabled states, and an answer to 'what happens when I press Enter'.
Beginner1 min read (computed · recorded 3)updated 2026-09-14aiformscomposera11ycourse
by Motif Editors
revised 2026-09-14 — First publication in the bank-4 AI-interface curriculum.
— The composer needs the same care as any form: a label, visible focus, and a stated submit gesture.
— Enter sends, Shift+Enter inserts a newline — state the convention and make it work everywhere.
— A disabled send button needs a reason the user can read.
The same anatomy as a login form
A composer has everything a form has: an input with a label (even a placeholder is a weak label), a submit affordance with enabled and disabled states, and keyboard behaviour that matches the user's expectation. The one twist is the newline: Enter sends, Shift+Enter writes a newline — and the convention must hold across desktop and mobile, where mobile keyboards may hide the modifier.
Disabled means 'why'
A send button that is greyed out with no explanation is a riddle. The honest composer either keeps the button active and explains the error on press, or prints the reason next to the disabled state — 'enter a prompt first', 'waiting for the previous answer'. The reason is the accessibility of the disabled state.