Flash the Sweep

About 5 minutes. One half at a time, left first. Nothing here can brick it: the original firmware is backed up and goes back on the same way.

1. Plug in the left half

   YouUSB-C from the Mac to the left half, the one with Q W E R T.

   ClaudeStarts flash-uf2.sh cradio_left.uf2 nicenano and says “ready”. It only writes to a drive that reports itself as a nice!nano.

2. Double-tap reset

   YouDouble-tap the reset button quickly, the same button you used for the backup. One slow tap only restarts it; it has to be two quick taps.

   You'll seeThe keyboard stops typing. A drive called NICENANO appears in Finder.

3. Wait. Claude copies the firmware

   YouNothing. Don't eject or open the drive.

   ClaudeChecks the drive says nRF52840-nicenano, copies cradio_left.uf2, then waits for the drive to vanish.

   You'll seeThe drive disappears by itself after a few seconds (the half reboots). macOS may say “disk not ejected properly”: ignore it.

4. Same again for the right half

   YouUnplug the left half, plug in the right half (Y U I O P), wait for Claude's “ready”, then double-tap its reset button.

   ClaudeRuns the script with cradio_right.uf2. The two halves get different files, so the order matters.

5. Test it

   YouPlug the left half back in. In a text field: type on both halves, then hold K and press C to copy. Hold Space + J/K/L/I for arrows.

   ClaudeChecks the USB device and that ZMK Studio answers. Studio unlock is now hold Tab + press ;.

6. Test live layers

   YouIn Chrome, open keys.qingbo.us, click Connect keyboard, pick sweep split kbd and press Connect. Then hold Space: the map should switch to NAV before you press anything else.

   You'll see“Streaming from sweep split kbd” above the map, and each key lighting up while you hold it, thumbs included. Works over USB first; over Bluetooth it may need the re-pair below.

7. Only if Bluetooth won't connect

   YouSystem Settings → Bluetooth → “sweep split kbd” → ⓘ → Forget This Device. Then hold Tab + press , (that's BT1 on the FUN layer) and pair it again.

   WhyUSB always works. Bluetooth may keep the old pairing, which is usually fine, but the new layer-streaming channel only shows up over Bluetooth after a fresh pairing.