## Feature 001: Start a focus session and get notified when it ends

**Sources:** start-a-focus-session-and-receive-completion-notification
**Personas:** Marcus
**Stack span:** full-stack
**Tier:** v1

**Description:**

Tap 'Start Session,' watch the timer count down, receive notification when time's up.

**Constituent tickets:**
- 001
- 002
- 003
