Spec-Driven Development v2

v1 assumed one agent shipping one feature in one session. v2 assumes an orchestrator (or a human) driving the agent across many sessions — possibly for days — and keeps work correct the entire time.

v2 adds:

1. Three-layer hierarchy — Project → Sprint → Task
2. Per-task state — JSON files an orchestrator can read to resume cold
3. Review round-loop — review → feedback → modify → re-review until clean
4. Worktree isolation — every task runs in a clean checkout, revertable alone
5. Context pack — the briefing a reasoning-blind subagent reviewer needs
6. Mechanical task gate — sizing/acceptance/rollback checks enforced by script
7. Governance-as-code — boundary rules live in lint/CI, not markdown
8. Artifact registry — new rules captured from reviews graduate to lint

When to use v2 over v1