PM_K-1 CircuitPython: add boot.py to guarantee the USB-MIDI port appears

If the device isn't seen as a MIDI input (USB endpoint pressure from drive+serial+HID+MIDI),
boot.py disables the unused HID interface and enables usb_midi — copy it on and power-cycle.
Bundled into pm_k1_circuitpy.zip; documented in the README.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

build.sh

@@ -39,7 +39,7 @@ pathlib.Path("dist/pico-main.py").write_text(pathlib.Path("pico/main.py").read_t
 print("copied pico-main.py")
 import zipfile  # PM_K-1 CircuitPython drive bundle (download → unzip onto CIRCUITPY)
 with zipfile.ZipFile("dist/pm_k1_circuitpy.zip", "w", zipfile.ZIP_DEFLATED) as z:
-    for f in ("code.py", "programs.json", "font_s.bin", "font_m.bin", "font_l.bin", "README.md"):
+    for f in ("code.py", "boot.py", "programs.json", "font_s.bin", "font_m.bin", "font_l.bin", "README.md"):
         z.write("pico-cp/" + f, f)
     z.write("dist/editor.html", "editor.html")        # offline copy of the editor, on the drive
 print("zipped pm_k1_circuitpy.zip")

pico-cp/README.md

@@ -28,8 +28,13 @@ same program‑string language as <https://metronome.varasys.io>.
 The board also shows up as a **USB-MIDI** device and sends a note on every click (a GM drum note per
 lane, velocity by accent). Open the [editor](https://metronome.varasys.io/editor.html) in **Chrome/Edge**,
 click **🎹 Device audio**, grant MIDI access, then press play *on the device* — the editor voices the
-groove through its full synth, out your computer's speakers, locked to the device's clock. Set
-`MUTE_BUZZER = True` in `code.py` if you'd rather silence the on-board buzzer while doing this.
+groove through its full synth, out your computer's speakers, locked to the device's clock. The button
+shows the connected device's name and pulses green on each note; set `MUTE_BUZZER = True` in `code.py`
+if you'd rather silence the on-board buzzer while doing this.
+
+If the editor says **no MIDI input is connected**, copy **`boot.py`** onto `CIRCUITPY` too and
+**power-cycle** the Pico (`boot.py` only runs on a full reset). It frees a USB endpoint (drops the
+unused HID interface) so the MIDI port is guaranteed to appear alongside the drive.
 
 ## Controls (same as the MicroPython build)
 

pico-cp/boot.py

@@ -0,0 +1,10 @@
+# boot.py — runs once before USB connects (hard reset / power-cycle to apply).
+# Guarantees the device shows up as a USB-MIDI port so the web editor's "Device audio"
+# can hear it. We don't use HID, so disabling it frees a USB endpoint for MIDI on the
+# Pico (which also exposes the CIRCUITPY drive + serial at the same time).
+import usb_hid, usb_midi
+try:
+    usb_hid.disable()
+except Exception:
+    pass
+usb_midi.enable()