The pi route I will not try.

I don't really understand why - you get that the Pi just connects to the USB port, right? Might want to take a moment and actually check out Octoprint before ruling it out.

In any case, best of luck to ya.

Absolutely will not muck around grabbing the micro SD card from the back of the print every time I need to change something. It must be wifi or usb.

You are somewhat of a selective reader?

I said get an sd card extension cable and relocate the card to inside of the print area. Mine is just below the bed where I can easily reach it. I have to print from the card all the time due to a weird bug with my version of Repetier host that won't allow a print that goes over 20 minutes.

They do make them for micro SD, you just have to order on Ebay from China.

Just get an extension cable and route it so the card is inside the print area where you can get to it easily.

But I still would like to do sd card upload and print inititation without the xyzware crappoware.
I want the xyzware on the mac so i can
sniff its usb traffic a bit more than that previous thread did. I've got a python usb library for that.

I found on the repetier sites a mention of the fletcher-16 being the
checksum algo. heres a python impl:

def checksumByXOR(text):
  cs = 0
  for x in str(text):
     cs ^= ord(x)
  return cs

def readn(fin, n):
    s = 0
    for ti in fin.read(n):
        s = s * 256 + ord(ti)
    return s
     
def fletcher(fin, k):
    if  k not in (16, 32, 64):
        raise ValueError("Valid choices of k are 16, 32 and 64")
    nbytes = k // 16
    mod = 2 ** (8 * nbytes) - 1
    s = s2 = 0
    t = readn(fin, nbytes)
    while t:
        s += t
        s2 += s 
        t = readn(fin, nbytes)
    return s % mod + (mod + 1) * (s2 % mod)

Still having the checksum failure, suspect it is where you place the checksum in the transmission.