First Session
Domain: Installation & Setup
Motivation
The first session is booting a profile and actually running something through it, confirming the loop works end to end. This is where auto-initialization (for shipped profiles) plus credentials plus the model all have to line up. A developer cares because it is the real proof that install + config + auth are all correct.
Concrete Example
Boot a profile and run a job, e.g. dsh --profile headless "hi", to confirm a session actually completes.
Analogy
Like the first lap around the track to prove the new car is road-legal.