The interactive prompt used a single-line buffer (multiline=False), so
there was no way to compose a multi-line message before submitting.
Switch to a multiline-capable buffer with custom key bindings: Enter still
submits (unchanged feel), Alt+Enter always inserts a newline, and
Shift+Enter inserts a newline on terminals that emit a distinguishable
CSI-u sequence for it (kitty, iTerm2 with the fixterms protocol) by mapping
those sequences onto the otherwise-unused ControlJ key.
wangjunweiandXubin Ren
18a230de75