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+- Added `ClientConnectedFrame`, a new `SystemFrame` pushed by all transports (Daily, LiveKit, FastAPI WebSocket, WebSocket Server, SmallWebRTC, HeyGen, Tavus) when a client connects. Enables observers to track transport readiness timing.
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-- Added `StartupTimingObserver` for measuring how long each processor's `start()` method takes during pipeline startup. Useful for diagnosing cold start slowness and identifying initialization bottlenecks.
+- Added `StartupTimingObserver` for measuring how long each processor's `start()` method takes during pipeline startup. Also measures transport readiness — the time from `StartFrame` to first client connection — via the `on_transport_readiness_measured` event. Useful for diagnosing cold start slowness and identifying initialization bottlenecks.