Introduce the thinnest complete path that benchmarks a skill's efficacy
against a no-skill baseline and renders an HTML report.
- tests/ convention: a top-level tree mirroring skills/ by full path, with
case directories holding a case.md (CASE-FORMAT.md) and an optional fixture.
- benchmark-skill: a distributed, non-model-invocable runner (/benchmark-skill
<name>) that orchestrates force-invoked new-skill and skill-absent baseline
arms plus a blind per-trial judge as in-session subagents.
- Deterministic core (Python): a pure transform over the collected run data
that sums per-arm usage, collapses each trial to WIN/TIE/LOSS, applies the
efficacy pass rule (wins >= 3, losses <= 1), and renders a self-contained
report. Parameterized over arms and comparisons; two-arm here.
- Fixture-driven no-LLM check (checks/benchmark-core.nix) wired into flake.nix.
- Real tests tree for axi-review; a live run produced its efficacy report.
