SpawnPw() looked the desktop user up with getpwnam() — one static buffer —
from the mic thread and the playout thread at the same instant. When the
race made both lookups fail, uid stayed 0 and both pw helpers were started
with XDG_RUNTIME_DIR=/run/user/0, where no PipeWire session lives: pw-record
hit EOF at once, pw-play never connected, and a call that was up with RTP
flowing both ways was answered into static (tx_mic=0 rx_played=0 qdrop=883,
dev phone 2026-09-08 20:01, first time in years of calls — timing).
AudioUid() resolves AUDIO_USER once under std::call_once with getpwnam_r and
a private buffer, complains when the user does not exist, and logs the
session the helpers are aimed at on every call, so a field journal answers
"where did the audio go" directly.
Jorijn van der Graaf
b8d439246a