Who sees what
Privacy is a cursor.
Private by default. Sharing is a choice - activity by activity.
Private circle
Your coaches and you, nobody else. The activity lives in the app.
Public
The activity is published at your place, in your personal data space (your PDS) - it powers your showcase.
full track or trimmed start/end - you choose
Private is where everything starts
A session landing in your journal is visible to you and to the coaches you opened a window for. Nothing leaves on its own, ever.
Publishing is a deliberate act
Turning an activity public puts it in the space that belongs to you: it shows on your showcase and anyone with the link can read it. You also choose whether the track is whole or the start and finish are trimmed.
Sharing is something else again
The card you post to Bluesky shows only what is printed on it. It does not make the activity public, and deleting the post does not delete the session.