Compose

The one unified composer (EC-4.5/4.7): From picker, To/Cc/Bcc (Cc/Bcc behind a toggle) with autocomplete, subject, a rich-text editor with toolbar, attachment tray, More options (Reply-To · priority · canned response), client-side signature, autosave + drafts. Switch modes (new/reply/reply all/forward) to see prefill. Keyboard behaviour and the real WebView editor are device-only; DS-1 covers geometry + state.