ToneMapEngaged

This renderer rolled HDR off to standard dynamic range to show it.

Published by the renderer that DID it, at the moment it did, and by no one else. A renderer that hands HDR to a display able to present it publishes NOTHING, which is why this is an event rather than something the engine derives from the stream's metadata: only the renderer knows which of those two happened. The engine turns the first one per open into io.github.yuroyami.kiteplayer.PlaybackWarning.HdrToneMapped and ignores the rest.

transfer is the SOURCE transfer that was rolled off, PQ or HLG, carried rather than re-derived so a mid-stream transfer change cannot be misreported.

streamIndex defaults to -1, meaning "this renderer does not track streams": it is handed frames and has no index to quote. The engine fills in the video stream it is feeding. A renderer that genuinely knows may say so, and its answer is used as given.