KiteTrace

The trace seam: a timeline of what the player did, for a profiler to draw.

Process wide, like KiteLog, and silent until an application installs a Sink. With no sink, every place in the engine that could trace costs one volatile read and does nothing else. ChromeTraceFormat turns what a sink receives into lines that Chrome's trace viewer and Perfetto open.

What the engine traces:

• Spans: session/open, the phases of a seek (seek/keyframe, seek/refine, seek/precise), and track/switch.

• Spans per frame, only when installed with perFrame: video/decode and video/present, each with the frame's timestamp in microseconds as pts.

• Instants: audio/underrun, when the engine sees the underrun count rise, and video/drop, when the schedule drops a late frame.

Times are nanoseconds on the engine's monotonic clock. Values are strings, and a URI arrives only as its basename, so a trace cannot leak a token from a query string.