Interruptions

This recipe shows how to script a user interrupting the agent mid-reply, and explains how the SDK handles the interrupt signal differently depending on whether the adapter supports native barge-in or falls back to VAD-driven detection.

Pattern

Two equivalent forms produce identical runtime behaviour.

Unrolled form

scenario.user("Tell me about my billing"),
scenario.agent(wait=False),          # start agent reply in background
scenario.user("Wait — I meant account support"),  # interrupt when agent begins speaking
scenario.agent(),                    # let the agent finish the recovery turn

agent(wait=False) starts the adapter's reply in the background without blocking the script. The following user() call waits until the agent begins producing audio, then fires the interrupt signal and sends the replacement user turn.

Sugar form

scenario.user("Tell me about every product feature you offer"),
scenario.interrupt("Sorry — what are your business hours?"),
scenario.agent(),

scenario.interrupt(text) is shorthand for the unrolled form above. Prefer it when you only need to express a single interrupt.

Native barge-in vs VAD-driven barge-in

When user() fires the interrupt, the SDK checks whether the adapter reports native interrupt support (the interruption column in the capability matrix).

Mode	How it works
Native barge-in	The adapter sends a provider-side cancel signal (`response.cancel` for OpenAI Realtime, `clear` for Twilio, etc.). The agent's TTS stops immediately and the user turn is queued.
VAD barge-in	No provider cancel signal is available. The user audio overlaps with the agent TTS and the SUT's Voice Activity Detection detects barge-in and stops the agent. Requires `native_vad` support on the adapter side.

Check the adapter row in the capability matrix to see which mode applies to your deployment.

Worked example

interruption_recovery.py — demonstrates both unrolled and sugar forms back-to-back in a single scenario, with a JudgeAgent verifying the agent recovered from both interruptions.

Adapter-specific variants:

random_interruptions.py — randomised interrupt timing across turns
gemini_live_interruption.py — Gemini Live adapter with native barge-in
elevenlabs_interruption.py — ElevenLabs adapter interrupt path