Capsule driver (the super-orchestrator seat)

Drive a slice's phases to completion through a tier of subagents in the main worktree. You hold the human's attention; everything below you is disposable context.

Announce at start: "Using the capsule-driver skill to drive SL-NNN through capsule orchestrators."

Why this exists

A slice's implementation costs far more context than one agent should hold. The tiering exists so that no single context exceeds ~250k tokens, where both cost and output quality degrade:

you (interactive, human attached)
  └── capsule-orchestrator     charters 2-4 phases, verifies, commits
        ├── capsule-phase-planner   one phase → runtime sheet
        └── capsule-worker          one phase → source delta