## Feature 001: Start and complete a focus session

**Sources:** start-and-complete-a-focus-session
**Personas:** busy professional seeking structure, knowledge worker fighting distraction
**Stack span:** full-stack
**Tier:** v1

**Description:**

User initiates a timed Pomodoro work session, receives clear feedback as it runs, and marks it complete when finished.

**Constituent tickets:**
- ticket-001-pomodoro-timer-ui
- ticket-002-session-state-management
- ticket-003-session-lifecycle-handlers
