Found by a live boot-order test (host started before the user session's
PipeWire): PwMicSource::open returned Ok before the daemon connection was
attempted, so a PipeWire that wasn't running surfaced as an instantly-dead
instance instead of an open failure — and the pump churned
open→die→reopen at heartbeat rate (1 Hz "virtual mic ready" log spam)
instead of backing off.
- PwMicSource::open now has a bring-up handshake (mirrors the Windows
backend): ready only after connect + stream connect succeed, so a
down daemon is an open ERROR and the pump's backoff engages.
- The pump triages deaths: an instance that lived >= 5 s (a one-off
daemon restart) reopens immediately with the backoff reset; one that
died right after opening counts as a failed open and backs off
(2 s → 60 s cap). New pump test rapid_death_backs_off.
Re-validated live: host started with PipeWire stopped → throttled
"unavailable" warns, zero churn; daemon started → mic node up on the
next retry; exactly one pump + one loop thread (no leak).
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
enricobuehler
ea07ba09be