Conformance

GaleforceCSS is verified against the live tailwindcss@3.4.19 oracle on every push. Two layers:

Layer	Passing	What it checks
Fixture diff	894	Compile each fixture with both compilers, diff after PostCSS normalization.
Byte-sensitive snapshot	186	Exact-byte output for utilities where formatting/order matters.
Real-world projects	7	Full project compiles produce zero semantic diff.

Skipped: 67 upstream tests that rely on deep PostCSS internals GaleforceCSS doesn't model.

How a fixture works

A fixture is a JSON file in conformance/fixtures/:

{
  "name": "hover-flex",
  "candidates": ["flex", "hover:flex"]
}

The runner compiles the candidates with both compilers, normalizes with PostCSS, and diffs. Empty diff → pass. Default config is { corePlugins: { preflight: false } }; fixtures needing preflight set mode: "full".

Running it

cargo build -p galeforce-cli --release   # required: the harness spawns the binary
pnpm conformance:test

Against a real project:

pnpm --filter @galeforcecss/conformance exec tsx src/cli.ts --project /path/to/project

Probing the oracle

pnpm --filter @galeforcecss/oracle exec tsx -e "
import('@galeforcecss/oracle').then(async ({ compileWithTailwind3 }) => {
  const { css } = await compileWithTailwind3({
    candidates: ['hover:flex', 'md:bg-red-500'],
    inputCss: '@tailwind utilities;',
    config: { corePlugins: { preflight: false } },
  })
  console.log(css)
})
"

Known gaps

Tracked in CLAUDE.md; invisible to the harness but worth knowing:

• theme() opacity shorthand — theme('colors.red.500/50') not resolved.
• Object-form screens — { md: { min: '768px', max: '1023px' } } treated as a simple string.
• Nested @layer inside @media/@supports is silently dropped.
• Sort order — simplified 5-tuple key instead of upstream's bigint offset system. Diff-unordered, so invisible to fixtures.