VoxTrace-The Flight Recorder For Voice Agents

Most voice agent demos stop when the answer sounds good. Production breaks in the moments between words. A voice agent can be fluent yet cut off a thoughtful pause, repeat a side effect after a tool timeout, act on a withdrawn confirmation, or guess when a sensitive case needs a human. When it does, teams get transcripts but no evidence. VoxTrace fills this gap: a reliability lab for voice agents built on the AssemblyAI Voice Agent API that treats conversations as inspectable, replayable, testable runs. How it works. Run one of three scenarios — resilient support, consent gate, or human escalation. VoxTrace records every event with timestamp, latency, reason, and outcome: transcripts, speech boundaries, agent replies, tool calls/results, consent read-backs, retries, and escalations. Live mode connects the browser to the AssemblyAI Voice Agent WebSocket for real-time voice; the same event monitor consumes transcripts, turn boundaries, audio replies, and tool calls. At run end, export a JSON replay for QA, incident review, or CI regression testing. Guardrails are enforced, not requested. VoxTrace treats side effects as distinct from suggestions. Actions are blocked until exact read-back confirmation; repeated side effects are refused so tickets are created once; changed details invalidate prior confirmations; and sensitive cases leave the agent with evidence and a case reference instead of a guess. The system records evidence that allowed or denied each action rather than asking models to promise care. Keys never reach the browser. The server requests short-lived AssemblyAI tokens so the frontend never leaks permanent credentials. Measured, not asserted. Across three scenarios VoxTrace records 45 events, recovers 100% of injected tool failures, blocks 2 unsafe actions, escalates 1 sensitive case, and holds p95 turn latency between 660 and 820 ms. The demo runs without an API key using the live client event vocabulary, letting judges evaluate the product directly.