OptionalDurationThe provider's session duration so far, in seconds (GPT-Live reports it): a running total, so adding keeps the larger value. Only a server-side session writes it; a relayed record never carries it.
OptionalInputWhat went in: tokens added up; VideoFrames and VideoSeconds the latest running totals (telemetry).
OptionalOutputWhat came out: tokens and avatar VideoSeconds added up.
A realtime run's usage by direction and modality. Each block is shaped like Core's
RealtimeUsageModalityDetail, so a writer can add fields without renaming anything.