# Tailwindcss Foundation

> Use when porting Tailwind CSS v4 compiler mechanics — the `compile()`/`compileAst()` incremental build kernel, `@theme` design-system ingestion and resolution, candidate parsing/compilation and its deterministic sort ladder, or the variant application protocol — into another utility-CSS engine or a host integration (Vite/PostCSS/CLI driver). Source code and direct tests are ground truth; references carry decisive excerpts and graph retrieval.

- Skill: `ryan-brosas/tailwindcss-foundation` (Agent Skill, multi-file: 12 files)
- Install (CLI): `npx skillmds@latest add ryan-brosas/tailwindcss-foundation`
- Raw SKILL.md: https://api.skillmd.com/api/skills/ryan-brosas/tailwindcss-foundation/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Web & Frontend
- Author: ryan-brosas (https://skillmd.com/u/ryan-brosas)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/ryan-brosas/tailwindcss-foundation

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# tailwindcss: v4 core compiler foundation

## Foundation contract

This is a cold, source-specific foundation, not an operational procedure. It is
historical, revision-pinned evidence rather than timeless guidance. Current
project source, tests, requirements, and runtime behavior outrank this
projection and decide what ships.

## Provenance and revision

- Source record: `tailwindcss`; portable upstream identity, license, coverage caveats, and retrieval history are preserved in the index.
- Recorded revision: `main@90f8ff41c8e2a4d17bc76921e23e9d672123da76`.
- Full provenance, coverage caveats, boundaries, and preserved evidence:
  `references/index.md`.

## Topic map

- Representative topics: Incremental build kernel; Candidate sort ladder;
  Design-system memo lattice; Variant application protocol; Theme namespace
  reset; Theme resolve var/inline; @theme ingestion; Candidate parse pipeline.
- Scope and retrieval questions: `references/index.md#use-this-for`.
- Complete capsule chooser: `references/index.md#load-the-matching-source-dump`.
- Detailed grouped map: `references/index.md#capsule-map`.
- Source limitations and portability boundaries: `references/index.md#boundaries`.

## Retrieval

Open the index, choose one capsule matching the active question, and load only
that capsule. Revalidate its cited source and revision before relying on it. Do
not bulk-load the inventory, treat historical claims as current truth, or apply
this foundation as a procedure.