Audio overview

AgentSquadAudio is a separate Swift package product that ships two AVFoundation-backed implementations — MicCapture and AudioPlayback — built on top of two protocols declared in the core AgentSquad module.

import AgentSquad        // AudioInput, AudioOutput protocols
import AgentSquadAudio   // MicCapture, AudioPlayback

Protocols

Both protocols are declared in AgentSquad (not AgentSquadAudio), so you can write custom conformances, unit-test stubs, or file-based implementations without pulling in AVFoundation.

AudioInput

public protocol AudioInput: Sendable {
    /// Captured PCM16 chunks. Bounded drop-oldest — a slow consumer never blocks the audio thread.
    /// Finishes when capture stops.
    var frames: AsyncStream<Data> { get }

    func start() async throws
    func stop()  async
}

start() should install the capture source and begin yielding frames. stop() should halt capture and call continuation.finish() so consumers exit their for await loop cleanly.

AudioOutput

public protocol AudioOutput: Sendable {
    func start()                async throws
    func enqueue(_ pcm16: Data) async
    func flush()                async
    func stop()                 async
}

enqueue schedules one PCM16 frame without waiting for it to finish playing — implementations must not serialize to real-time playback speed. flush is the barge-in primitive: it discards all queued or in-flight audio instantly.

How they feed the voice runtime

RealtimeRuntime accepts an AudioInput and an AudioOutput at construction time:

let runtime = RealtimeRuntime(
    input:  MicCapture(),
    output: AudioPlayback(),
    // ... other config
)

The runtime drives start, stop, enqueue, and flush from its single event pump, so implementations are never called concurrently by the runtime itself.

Built-in implementations

Type	Protocol	Description
`MicCapture`	`AudioInput`	AVAudioEngine tap → PCM16 @ 24 kHz, with iOS permission gating
`AudioPlayback`	`AudioOutput`	AVAudioEngine + AVAudioPlayerNode, with barge-in flush

Custom implementations

You can replace either built-in with any conforming type — useful for tests, file-based input, or platforms where AVFoundation is unavailable.

See Custom audio for worked examples of a file-replay AudioInput and a recording AudioOutput test sink.

Voice overview — the RealtimeRuntime that consumes these protocols
OpenAI Voice agent — built-in agent wired to the voice runtime
Custom audio