When a Discord voice message arrives, the adapter sets event.text to
"(The user sent a message with no text content)" since voice messages
have no text content. The transcription enrichment in
_enrich_message_with_transcription() then prepends the transcript but
leaves the placeholder intact, causing the agent to receive both:
[The user sent a voice message~ Here's what they said: "..."]
(The user sent a message with no text content)
The agent sees this as two separate user turns — one transcribed
and one empty — creating confusing duplicate messages.
Fix: when the transcription succeeds and user_text is only the empty
placeholder, return just the transcript without the redundant placeholder.
25080986a0