REPL doesn't handle blocks larger than the console window on some terminals

[encukou]

Bug report

Bug description:

On Windows, if the currently edited block does not fit in the console (the lines are too long and there are too many lines), and the cursor is moved around, the REPL's state gets corrupted: lines are overwritten with parts of other lines, parts of the prompt appear in places, the cursor behaviour doesn't match the text around it.

For example, in a small console window, I pressed Up to go back in history to this piece of colorsys:

def yiq_to_rgb(y, i, q):
    # r = y + (0.27*q + 0.41*i) / (0.74*0.41 + 0.27*0.48)
    # b = y + (0.74*q - 0.48*i) / (0.74*0.41 + 0.27*0.48)
    # g = y - (0.30*(r-y) + 0.11*(b-y)) / 0.59

    r = y + 0.9468822170900693*i + 0.6235565819861433*q
    g = y - 0.27478764629897834*i - 0.6356910791873801*q
    b = y - 1.1085450346420322*i + 1.7090069284064666*q

    if r < 0.0:
        r = 0.0
    if g < 0.0:
        g = 0.0
    if b < 0.0:
        b = 0.0
    if r > 1.0:
        r = 1.0
    if g > 1.0:
        g = 1.0
    if b > 1.0:
        b = 1.0
    return (r, g, b)

and then pressed some arrow keys to get:

CPython versions tested on:

CPython main branch

Operating systems tested on:

Windows

[StanFromIreland]

This also causes weird behavior on Linux for example this happened:

If I move my cursor up on a small screen it results in:

This occurred several times when trying it.

Ptyixs on Fedora 41, cpython main branch