Execute an epic

Work an ArchDev Tasks epic one task at a time. Each task follows the same loop:

pick ready task → claim lease → start heartbeat → work → verify
      ↑                                                   ↓
 next ready task ← close ← stop heartbeat ← comment ← push + PR ← commit

Two rules matter more than anything else in this skill:

1. Never work on a task you have not leased. The claim is the only ownership gate. A ready listing is a snapshot, not ownership.
2. Never hold a lease without a running heartbeat. Leases expire (60s to 1h). Without renewal another session can claim the task while you are still editing it, and your commit then lands on work someone else owns.