The contact sync streams up to MAX_CONTACTS frames back to back, but
ArduinoSerialInterface never checked whether the stream could take
them: isWriteBusy() returned false unconditionally, so MyMesh's pacing
gate had no effect, and writeFrame() called write() without looking at
availableForWrite(). On ESP32 (HWCDC, 256 byte TX ring) a host that
stalls for a moment makes the driver drop queued bytes silently, which
tears a frame in half - and since the framing is length prefixed with
no checksum and no resync marker, the client stays desynchronised for
the rest of the session. Reported as 'the app disconnects while
syncing contacts' on devices with a large contact list.
Add opt-in flow control: report busy until a whole frame fits, and
drop frames as a unit instead of tearing them. Enable it for the
companion USB interface and give HWCDC a bigger TX buffer with a short
write timeout, mirroring what kiss_modem already does.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
ArduinoSerialInterface::isConnected() always returned true, so any
companion build with a USB interface believes a client is attached from
boot onwards. Two user visible effects:
- new message notifications never fire, because MyMesh only notifies
the UI (display, buzzer) while no client is connected
- on builds that also expose BLE the home screen shows '< Connected >'
instead of the BLE pairing PIN, so a freshly flashed device cannot be
paired at all
Add an optional connection check callback and wire it up per platform:
native USB-CDC (TinyUSB on nRF52/RP2040/ESP32 with USB_MODE=0) exposes
real DTR through (bool)Serial. The ESP32 USB-Serial-JTAG peripheral has
no DTR concept - it reports 'connected' as soon as the host enumerated
the device - so fall back to frame activity there. Plain UARTs keep the
previous assume-connected behaviour.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>