The previous run showed session_started, then total silence from the
relay for the entire conversation — no events forwarded, no errors,
nothing. Two changes to disambiguate:
1. Drop the explicit audio.input.format / audio.output.format objects.
24 kHz PCM16 mono is the documented GA default for both directions
and the only thing OpenAI ever advertised; an unrecognised value
inside the format object is the most likely reason OpenAI silently
ignores incoming audio.
2. Forward 'upstream silent NxN250ms' debug envelopes every ~2 s when
ReceiveJsonAsync keeps returning null, and add a 'server_version'
field to hello_ack so the Pi journal proves which build is running.
tes
12be767325