Change one thing at a time when a session is live

A live session has several moving parts at once: the model, the region it runs in, and the tools it calls. Changing all of them together means a failure cannot be traced to any one of them.

Move, then observe, then move again

Make one change, watch the session for a full turn, and only then make the next. The observation window is what turns a guess into a fact.

Keep the way back open

Before a change, know what it would take to return to the previous state. A change with no way back turns a bad decision into an outage.

def can_revert(change):
    return change.previous is not None

Let the session finish its turn

A change applied mid turn leaves the session holding a fragment. Wait for the turn to end, apply the change, and confirm the next turn completes before the old path is retired.