Why: Simple tasks should finish as one assistant step, while complex tasks stay in leader mode, and every kernel step needs the host's tools and events.
Evidence: go test ./squad/ -count=1 passed, including direct route, leader entry, skill override, and delegation score fields.
Impact: Hosts can inject HostTools and OnEvent; a Router can choose direct or plan without changing product roles.
Refs: deliverable-quality-system B2
Co-authored-by: Cursor <cursoragent@cursor.com>