vllm-omni/examples/online_serving/barge_in_client_flow.md

barge_in_client.py — what happens, at a glance

The demo plays one everyday conversation pattern against a full-duplex model: ask something, get talked-over mid-answer, and see the assistant cope. It runs either against a server over /v1/realtime?duplex=1 or, with --inline, against an in-process DuplexOmni — the conversation below is the same in both modes. High-level flow — for the exact wire events, read the docstring in barge_in_client.py.

sequenceDiagram
    autonumber
    participant U as user (client script)
    participant A as assistant (server + model)

    Note over U,A: GREET
    U->>A: start a voice session (with the reference voice)
    A-->>U: ready

    Note over U,A: ASK
    U->>A: ask a question (speak the question WAV)
    Note right of A: decides on its own to answer<br/>(no VAD — the model chooses)
    A-->>U: starts answering aloud

    Note over U,A: INTERRUPT
    Note over U: listens for ~2 seconds
    par both talk at once
        U->>A: interrupts with a follow-up
    and
        A-->>U: still speaking the first answer
    end

    alt the interruption is substantial
        Note right of A: stops mid-sentence (barge-in),<br/>first answer is cut off
    else it was just a short remark
        Note right of A: finishes the first answer,<br/>then takes the follow-up
    end

    Note over U,A: ANSWER AGAIN
    A-->>U: answers the follow-up aloud

    Note over U,A: HANG UP
    U->>A: goodbye (close the session)
    Note over U: saves one recording per answer<br/>plus a summary of what happened

Outcome: the output directory shows which branch ran — a cut-off first answer is saved as response_1_cancelled.wav, a completed one as response_1_completed.wav, and summary.json records status, text, and duration per answer.

Companion: the runtime architecture lives in docs/design/fullduplex.md; the client API is vllm_omni.clients.duplex.DuplexClient over the websocket and vllm_omni.clients.inline_duplex.InlineDuplexClient in-process — both are documented with the wire protocol in docs/serving/realtime_duplex_api.md.