The specification · Conformance

The chant cross-check

packages/conformance/src/chant-agreement.test.ts runs the fixture set against chant, and then runs both implementations against each other.

The pin is a real dependency. @intentius/chant is in this repository’s devDependencies at version 0.73.0, and the adapter in packages/conformance/src/adapters/chant.ts reaches it through its public entry only: fold, foldProject, collectConsts, FoldError, and, since chant-v0.64.0, findSubsetViolation for the shape half. What the suite tests is the version a user would install. With an older pin, the adapter would report shape "unavailable".

What it asserts

Five things. Three go through compareAdapters, which ignores what a fixture expects and asks only whether the two implementations answer the same.

• The pin passes every fixture through its public fold API, the same runFixtures pass the reference goes through.
• It agrees with the reference on every one. A fixture could be wrong about both and this check would still have something to say.
• Nothing whole-build is skipped. The adapter hands chant the fixture’s host as a package outside the lexicon convention, so a fixture naming a host reaches it like any other. A fixture chant cannot answer yet is held out by name against the issue that says why, and a guard asserts the reason still stands. The four round-trip fixtures skip, chant having no generator.
• On whole-build fixtures the two still agree. A seed and a taint casualty both produce run, so the comparison reaches past the final verdict to the verdict before taint and to the taint source.
• The shape classifier is available and agrees. The pinned release carries the export, so "unavailable" would be a regression, and it is asserted rather than assumed.

What it establishes

paper/measurements.md records the result at the pin.

The counts are read from the fixture tree at build time; the agreement figure is paper/measurements.md’s.

Every whole-build fixture is answered at the pin, and the two agree on each file’s final verdict and its verdict before taint; for every taint casualty they agree on the file the edge came from and on which rule it was.

Running it

This cross-check is part of the ordinary test run:

npm install
npm test

To run only this file:

npx vitest run packages/conformance/src/chant-agreement.test.ts

Nothing external is needed. The corpus cross-check is the one that needs a chant checkout.