Summary

Add the current session's elapsed time (duration) to the 🧵 Session: line in the status footer.

Current Behaviour

🧵 Session: agent:fraser:slack:channel:c0asptb5dmj • updated 1m ago

The status footer shows when the session was last updated but not how long the session has been active.

Requested Behaviour

🧵 Session: agent:fraser:slack:channel:c0asptb5dmj • duration 2h 14m • updated 1m ago

Include the elapsed time since the session was created, so operators can see at a glance how long a session has been running.

Implementation Notes

• The session transcript already records a type: "session" entry with a timestamp field at session creation — this could serve as the createdAt source.
• Alternatively, persist a createdAt field on the sessionEntry in sessions.json when a session is first initialised.
• The display would use the existing formatTimeAgo helper or a similar duration formatter.
• Relevant code: buildStatusMessage() in status-BIycj26I.js, specifically the sessionLine construction at line ~308.

Context

Requested by an operator managing multi-agent deployments who wants visibility into session health and longevity at a glance.