At some point (hopefully in the near future) the cloud API should return an activated_at timestamp field and the quantum API should return an activatedAtactivated_at field. Those will indicate when the session last went into the active state and can be used with the active_ttl to calculate how much time is remaining in the active window for the session (assuming the session has more jobs to run and doesn't go inactive after the interactive_ttl expires).

Originally posted by @mriedem in #1119 (comment)