Step-by-step SKILL.md packages an AI follows for a single kind of task.
A skill is a focused playbook - instructions, examples and constraints - that makes any model reliable at one job, from SQL reporting to changelog writing. The router fills a plan's skill slot with the best match for the request.
Prove one accepted proof-sketch step with local lemmas, local derivations, cited-result assumption checks, and exact target-step assembly.
