SKILL.make: Makefile Styled Skill File

SKILL.make introduces a Makefile-inspired specification for agent skill files, replacing prose-based SKILL.md with DAG-resolved execution graphs using Target:Dependency+Recipe syntax. Benchmarks across 14 real-world skill files show 3-52% token reduction, with git-guardrails hitting -19% and migrate-to-shoehorn an outlier at -52%. The format enforces strict execution ordering, eliminating LLM step-guessing, while supporting conditional branching via ifeq and cross-file target composition. Agent framework developers and prompt engineers managing large skill libraries should evaluate this immediately for context window cost reduction and auditability gains.