Orchestrate the full agentic-engineering chain on one brief — map → research → story → spec → rubric → backend lane → validator → frontend lane → final validator → PR — with three human checkpoints (story, spec+rubric, PR). Default path is in-conversation: each step runs as a forked Agent subagent so output is visible inline and per-step model selection is possible (Haiku for read-heavy steps, Sonnet/parent for writers, parent for code). Headless escape hatch: bash-invoke ${CLAUDE_SKILL_DIR}/bin/feature.sh for true AFK runs that survive terminal close. Triggers: /feature, "build this feature", "run the full chain", "orchestrate this feature end-to-end".