benchmark-methodology

# Benchmark methodology Authority: `docs/harness/ARCHAEOLOGY.md` (the benchmark rows), `benchmarks/METHODOLOGY.md`, `benchmarks/REPRODUCING.md`, CLAUDE.md Practice 4, `docs/harness/FINDINGS.md` F-10, F-13, F-17. Rules, each a pointer, none restated: 1. **Never hand-type a number.** Every figure comes from a run in THIS session or the CI-captured artifact `benchmarks/jcm_reference.json` (Practice 4). The comparators read that file; there is no estimator. 2. **Per row, never per total** (F-13): the total hid one cause behind another. Diff threshold ids one by one. 3. **Five mirrors move together** (Practice 4): `results.md`, `METHODOLOGY.md`, README, `provenance/measured.json`, `REPRODUCING.md`; `tests/test_provenance.py` is the gate and `--reference` rewrites them. 4. **The reference is captured where the gate runs** (F-13): `benchmark.yml` dispatch with `reference=true`; a dev-box number differs by CRLF, walk order and a HOME ledger (F-17). 5. **Deterministic configuration** is the bench tier itself: `--offline`, pinned corpora (`benchmarks/tasks.json`), the no-network fixture. Add no flags. 6. **A refusal is not a zero**: an absent value prints `n/a`. 7. **Floors live only in `harness/thresholds.json`**; read one with `uv run python -m harness threshold <id>`. 8. `benchmarks/schema_baseline.json` is the only source for schema-token figures (CLAUDE.md "Tier-switch pricing"); the harness counts a different payload and the two never agree d...