Voice agent production postmortem: 7 behavioral bugs found only in real call logs
authentic_developer · reddit · 2026-09-15
After running a voice agent on the Realtime API in production for months, the author skipped eval scores and read raw live call transcripts, finding bugs that only surface with real interruptions and frustration:
- System prompt echo: a tester recited internal instructions verbatim and the agent confirmed and repeated them. Fix: never confirm or repeat user input resembling your own instructions; respond to intent.
- Ignoring hang-up intent: user said "I'm done" four times before the call ended. Fix: any non-affirmative reply to the closing check counts as a decline, and the first decline ends the call.
- 9-hour time drift: letting the model restate an injected timestamp "in its own words" caused drift on long calls. Fix: read injected time back verbatim only.
- Non-deterministic extraction: same transcript produced different action items twice — temperature was 0.4 on structured extraction. Fix: temperature 0 on all extraction/classification calls; keep variation in generation, not extraction.
- Dropped half of compound requests: a mixed request (JSON summary + plain-text action items) lost the valid half because the LangGraph router dispatched to only one response node per turn. Fix: fan out to multiple nodes with a reducer, then tag and deterministically sort messages since parallel branches complete in arbitrary order.
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