skill: make the peltier skill consumable across agent harnesses

The SKILL.md Agent Skills standard (agentskills.io) is now read natively by
Codex, Copilot, VS Code, Cursor, Gemini CLI, opencode, Goose, Amp, Zed,
Factory, and ZeroClaw — so the portable move is not per-harness adapter
files (forked content that drifts) but one canonical skill placed where
each harness actually looks.

- Spec-compliant frontmatter: license, compatibility (the Linux-only
  measurement story, stated up front), version/author/tags top-level
  (ZeroClaw's runtime reads those; the spec ignores unknown fields).
  reference/ renamed to references/ per the spec's conventional layout.
- .agents/skills/peltier/ mirror: the cross-tool convergence path (Codex,
  Zed, Cursor, Gemini CLI, Copilot, opencode, Goose, Amp). Byte-identical
  to the .claude canonical, enforced by CI — drift between the two copies
  is a red build, not a footnote.
- AGENTS.md at the repo root for the ~20 harnesses that read it (Claude
  Code does not; CLAUDE.md remains its file). Deliberately thin: it points
  at CLAUDE.md and the skill instead of restating rules.
- scripts/install-skill.sh: stamps a consumer repo at both discovery paths
  (--layout claude|agents|both), or emits a script-less --zeroclaw-variant.
  ZeroClaw's skill security policy blocks script files by default
  (skills.allow_scripts off) — its audit rejected the full skill and passes
  the variant, verified against the real zeroclaw binary. The variant loses
  nothing: preflight.sh still exists exactly once, in the peltier checkout
  the skill already requires, and SKILL.md now documents running it from
  there. Re-implementing preflight inline is named as a refusal condition.
- CI (skill-preflight): frontmatter upgraded to a full Agent Skills spec
  conformance check on BOTH copies (name rules, dir match, description and
  body limits, metadata string-map), plus mirror equality and a functional
  installer test (both layouts identical to canonical, variant carries no
  scripts/, nonexistent target refused).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

CLAUDE.md

@@ -29,7 +29,7 @@ Full engineering spec: `SPEC.md`. Read it before starting any phase.
 - `targets/` — vendored OSS targets for case studies (permissive licenses only)
 - `playbook/` — optimization classes, ordered, with preconditions and known risks
 - `results/` — generated reports and flamegraphs
-- `.claude/skills/peltier/` — the trust layer packaged as a consumable Claude Code skill: `verify` mode (equivalence → A/A calibration → interleaved A/B + bootstrap CI) works in any repo against any two shell commands; `attempt` mode drives the full in-repo loop. Drives the real `bench-runner` binary and refuses on unsupported hosts rather than falling back to a second, forkable copy of the statistics. Preflight refusal is asserted in CI (`skill-preflight`).
+- `.claude/skills/peltier/` — the trust layer packaged as a consumable **Agent Skill** (agentskills.io SKILL.md standard, spec-compliant frontmatter): `verify` mode (equivalence → A/A calibration → interleaved A/B + bootstrap CI) works in any repo against any two shell commands; `attempt` mode drives the full in-repo loop. Drives the real `bench-runner` binary and refuses on unsupported hosts rather than falling back to a second, forkable copy of the statistics. Cross-harness: mirrored byte-identically at `.agents/skills/peltier/` (the Codex/Zed/Cursor/Gemini/Copilot convergence path — CI enforces the mirror), `AGENTS.md` at the repo root points non-Claude harnesses here, and `scripts/install-skill.sh` stamps consumer repos (plus a script-less `--zeroclaw-variant`, since ZeroClaw blocks script files in skills by default — its preflight runs from the checkout). Preflight refusal, spec conformance, mirror equality, and the installer are all asserted in CI (`skill-preflight`).
 
 **Phase 4 COMPLETE — all SPEC §5 exit criteria met. Phases 0–4 are all done.** Service-mode latency benchmarking shipped: a coordinated-omission-correct, open-loop, fixed-rate load generator (`crates/bench-runner/src/service.rs`) measuring latency from each request's intended send time (queueing counted, not hidden), interleaved A/B, exact percentiles, bootstrap p50/p99 CIs. A real service target — `targets/cjson/service.c`, a minimal HTTP server wrapping the patched `cJSON.c` (trust-layer, outside the workspace allowlist). Service calibration PASS (0/10 A/A false-positive, 10/10 injected-5%-latency-regression detection; `results/calibration/cjson-service-aa.json`). **The verified batch win phase3-cjson-002 measured under a 150 rps-target replay (20 interleaved rounds, 0 drops — the `phase4-cjson-service` ledger row records sessions=20, rate_rps=150, drop_rate=0.0; total request count is not machine-recorded): p50 latency +6.2%, 95% CI [+5.8%, +7.2%] — accepted; p99 NOT claimed (CI [0.07, 4.97], single-worker loopback tail jitter) — harness correctly rejected it.** Mechanical ROI report generator (`crates/report` bin, `just report`, SPEC §9): reads a ledger row + service-latency JSON → throughput→cores→dollars (27.5 cores / $9,621-per-year CI lower bound on a 500-core fleet) *and* latency percentiles, every figure with CI + workload + methodology inline; flags any non-accepted row. Case study: `results/phase4/`. **The roadmap is complete — the profile→hypothesize→patch→gated-verdict→ROI loop runs end to end across Rust and C, batch and service, with zero shipped false accepts across all phases.**