Got a Clue but haven't got a clue

Hi, just got an Adafruit Clue a couple of weeks ago (first batch I think) and I'm trying to port Espruino to it (obvs).

But I'm running out of ideas how to get it going - all I want to get running at first is a Bluetooth connection to the web IDE to test that JS works OK, I don't care about pins and peripherals yet.

Hence here's my super-cut-down board file:

import pinutils;

info = {
 'name' : "Adafruit Clue",
 'link' :  [ "https://www.adafruit.com/clue" ],
 'default_console' : "EV_BLUETOOTH",
 'variables' : 2100,
 'bootloader' : 1,
 'binary_name' : 'espruino_%v_cluejs.hex',
 'build' : {
   'optimizeflags' : '-Os',
   'libraries' : [
     'BLUETOOTH',
   ],
   'makefile' : [
     'DEFINES+=-DCONFIG_GPIO_AS_PINRESET',
     'DEFINES+=-DBLUETOOTH_NAME_PREFIX=\'"Clue"\'',
     'NRF_SDK15=1'
   ]
 }
};

chip = {
  'part' : "NRF52840",
  'family' : "NRF52",
  'package' : "QFN48",
  'ram' : 256,
  'flash' : 1024,
  'speed' : 64,
  'usart' : 2,
  'spi' : 3,
  'i2c' : 2,
  'adc' : 1,
  'dac' : 0,
  'saved_code' : {
    'address' : ((270 - 10) * 4096),
    'page_size' : 4096,
    'pages' : 10,
    'flash_available' : 1024 - ((31 + 30 + 2 + 10)*4)
  },
};

devices = {
  'BTN1' : { 'pin' : 'D5', 'pinstate' : 'IN_PULLDOWN' },
};

board = {
  'left' : [],
  'right' : [],
  '_notes' : {
  }
};
board["_css"] = """
""";

def get_pins():
  pins = [
   { "name":"PD5", "sortingname":"D05", "port":"D", "num":"17", "functions":{}, "csv":{} },
  ];
  return pins

I nicked bits of it from the Nordic dongle suggestions on this forum (I did get the dongle working OK, so the SDK 15 stuff is fine for me). I set the JS code address up a bit in case that needs to be clear of stuff below, but I have to admit I don't know what to put there!

I build with:

make clean; rm *hex *.elf
BOARD=CLUEJS RELEASE=1 make

..not DFU I don't think, cos they use uf2 for the Clue - so I flash with:

[..]/uf2/utils/uf2conv.py -f 0xada52840 --convert espruino_2v04.399_cluejs.hex
cp flash.uf2 /media/duncan/FTHR840BOOT/

which is getting set into the device OK, but I can't see the Clue Bluetooth device in the IDE.

Any ideas?