Mic passthrough silently died on real hosts. Root causes, all fixed:
- No liveness anywhere: a PipeWire restart (Linux) or any WASAPI device
error (Windows) killed the backend worker; push() fed the dead queue
for the rest of the host's life. VirtualMic now has a liveness
contract (push -> bool, alive(), discard()) and the new shared
audio::MicPump reopens with backoff, probing on an idle heartbeat so
the mic heals BETWEEN sessions too. Validated live: systemctl restart
pipewire -> node back in ~0.5 s, tone flows through the reopened
backend.
- Lazy creation: the mic device didn't exist until the first 0xCB
frame, but games bind their capture device at launch and never
re-follow. The pump opens eagerly at host start (node exists with
zero clients, elected default source).
- Windows headless dead-end: with VB-CABLE as the ONLY render endpoint
(exactly what the installer ships), the anti-echo guard rejected the
cable as the default render endpoint -> mic permanently dead. The new
wiring_plan (pure, unit-tested on every platform) assigns the mic its
endpoint FIRST (cable reserved for the mic), points the loopback at a
DIFFERENT endpoint, and the capture side now yields (explicit
endpoint or honest error) instead of the mic dying. Plan recomputed
per (re)open — endpoints churn at boot/logon/driver installs.
- Stale bursts: buffered audio from a previous session played into a
newly-attached recorder (observed live). Timestamped chunks + a
consumer-gap check in the process callback age everything past 1 s.
The Linux node mechanism stays the stream-based Audio/Source with
RT_PROCESS + priority.session: the canonical null-audio-sink adapter
recipe was tested on this box (PipeWire 1.6.2) and never gets a clock
(QUANT 0 -> pure silence), and WirePlumber reroutes a feeder targeting
it to the default sink (echo). Decision documented in the module docs.
Live-validated on this box (synthetic host + probe --mic-test,
pw-record): eager node, both attach orderings, PipeWire-restart
self-heal, post-session silence. Windows side compile/CI + on-glass
validation pending.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
enricobuehler
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