According to https://github.com/cc65/wiki/wiki/Direct-console-IO it is undefined what happens when the end of the sceen is reached. But it is _not_ undefined what happens when the end of the line is reached. So implement the usual thing - which was easy enough to do after all.
lda CH
cmp WNDWDTH
bcc :+
lda CH
cmp WNDWDTH
bcc :+
left: lda #$00 ; Goto left edge of screen
sta CH
: rts
left: lda #$00 ; Goto left edge of screen
sta CH
: rts