Okay, I'll try that out at some point. For now I can manually make the connection with aconnect while I test.
Today's (bigger) problem is: when I send two noteOn messages to the Bela in quick succession (about 5ms spacing between them), the Bela MIDI api drops the second note. I've used aseqdump to confirm that both MIDI notes are received by the OS on the virtual midi device, but midi.getParser()->numAvailableMessages() always returns 1 (instead of 2, as it should).
I'm using the second method from the Bela MIDI example -- with the midi parser, but without the callback.
Have you seen that problem before?