feat(realtime): connection pre-warming via startMuted + mute/unmute#3
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Establish an authenticated, idle session up front and hold it unbilled, then go live with no startup latency. Adds ConnectOptions::startMuted (publishes the input track muted) and RealtimeSession::mute()/unmute(). An idle WebRTC track emits keepalive frames, so we mute the LiveKit local track before publishing — muting, not withholding captureFrame, is what keeps the warmed session free. Includes the realtime_warmup example, README docs, and thread-safe access to the published track. Verified live: a session alive 18.4s billed only 5s (the post-unmute generation window); the muted warmup window billed zero.
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What
Adds connection pre-warming for realtime sessions, so apps can make the "Start" moment feel instant.
Why
Normally, when a user starts a realtime session there's a noticeable wait while the connection authenticates and the media path is established. Pre-warming lets you do all of that ahead of time and hold the session idle — at no cost — so the instant the user hits Start, generation begins with no startup latency. Billing tracks active generation, so a warmed-but-idle session is free; if the user never starts or cancels, you just disconnect and aren't charged.
What's new (public API)
ConnectOptions::startMuted— connect and authenticate now, transmit nothing yet.RealtimeSession::mute()/unmute()— pause/resume transmission at runtime.decart::ConnectOptions options; options.model = model; options.initialState.prompt = decart::Prompt{"A watercolor painting", /*enhance=*/true}; options.startMuted = true; // warm + authenticate, but stay idle (unbilled) auto session = client.realtime().connect(source, options); // When the user clicks Start: session->unmute(); source->captureFrame(frame); // generation begins here // Pause without disconnecting — stops generation (and billing), keeps the session warm: session->mute(); // Resume instantly later: session->unmute(); // If they cancel entirely: session->disconnect(); // no chargeAlso ships a runnable
realtime_warmupexample and a README section.Verified end-to-end: a warmed, idle session incurs no billing, and billing begins only once the session goes live.