Unsupported features

GaleforceCSS targets Tailwind v3. The core utility/variant/directive surface is fully implemented and reaches zero diffs against the official Tailwind v3 oracle on seven real-world projects. The list below captures what's out of scope or deferred.

Out of scope

• Tailwind v4. Different architecture (CSS-first, no config). Not on the roadmap.
• Third-party plugins that rely on full PostCSS container semantics. The plugin runner ships a walkRules + modifySelectors shim. Plugins beyond that surface produce empty records + a warning.
• Byte-for-byte CSS formatting. Output is semantically equivalent to Tailwind after PostCSS normalization; whitespace and rule-order differences are not bugs.
• Browser WASM build. Node-only today.
• Tailwind v2 → v3 migration tooling. Use upstream npx tailwindcss-upgrade first.

Implemented with caveats

• Object-form screens config ({ md: { min: '768px', max: '1023px' } }). Treated as simple-string. Use the string form for now.
• Sort key. Simplified 5-tuple (tier, min_width, prefix, numeric, input_index). Conformance harness diffs unordered, so the simplification is invisible to fixtures. File an issue if you hit a real cascade conflict.
• @tailwind banner. Oracle emits /* ! tailwindcss ... */; Galeforce doesn't. Output is semantically equivalent.
• napi-rs native bindings deferred. JS package + Vite plugin route through the compile-stream CLI bridge. Bindings will replace the bridge without changing compile / createCompileStream.
• @apply inside nested @media / @supports @layer blocks. Pre-collect pass is top-level only; nested layers are silently dropped.
• Source maps. Not generated.
• Lightning CSS prefixing. Output unprefixed. Add a downstream autoprefixer pass for legacy browsers.

Diagnostic codes

Surface with --verbose or --diagnostics <path>, or read CompileResult.diagnostics in JS.

Code	Meaning
unknown-utility	Candidate parsed but matched no utility.
unsupported-candidate	Candidate uses a feature Galeforce doesn't model yet.
unsupported-apply	@apply <util> referenced a utility Galeforce can't compile.
unknown-theme-path	theme('x.y.z') didn't resolve.

If you hit one on something that should work, file an issue with the candidate + a minimal config.