postcss 8.5.25: Split CSS values using postcss.list space, comma, and split utilities while preserving nested parentheses, brackets, and quoted strings

Clean-room public code sample — generation instructions

Write a brand-new, minimal, self-contained code sample in this clean-room directory.
Do not copy, paraphrase, or reference any existing project source. Work only from this spec.

A csx.json manifest scaffold already exists. Do not recreate it from memory. Preserve its case.goal, packages and symbols; fill its empty case.contract with exact assertions and correct its environment, commands and verifierAdapter for the files you generate.

Goal: Split CSS values using postcss.list space, comma, and split utilities while preserving nested parentheses, brackets, and quoted strings
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/postcss@8.5.25
Demonstrate these symbols/APIs:
  - postcss.list.comma
  - postcss.list.space
  - postcss.list.split

Rules:
  - One focused purpose; the smallest project that proves the goal.
  - Include a contract test (test/contract.*) that runs OFFLINE and exits 0 exactly when the goal behavior works.
  - Pin every dependency with a lockfile so resolution is reproducible.
  - No secrets, credentials, or tokens. No real URLs (only example.com or localhost). No absolute paths.
  - No personal names, emails, company names, or project identifiers of any kind.
  - No binaries and no generated output (node_modules, dist, target, venv, .git, .env).
  - Keep it under 200 files and 256KB packed.

{"case":{"caseId":"case:sha256:e853b25a39097eb663c712ddcf5e67996c284843576c7f32b6035ba9fd6d7574","contract":["assert postcss.list.space splits whitespace-separated tokens into trimmed values while preserving nested functions, parenthesized expressions, and quoted strings","assert postcss.list.comma splits comma-separated CSS values while preserving nested commas within functional notation like rgb(), var(), and linear-gradient()","assert postcss.list.comma preserves empty trailing tokens when ending with a trailing delimiter while postcss.list.space omits trailing whitespace tokens","assert postcss.list.split splits a string by custom delimiter characters while ignoring delimiters inside quotes and parentheses","assert postcss.list helper methods return an empty array when given an empty string or whitespace-only input"],"goal":"Split CSS values using postcss.list space, comma, and split utilities while preserving nested parentheses, brackets, and quoted strings","kind":"HOW","packages":["pkg:npm/postcss@8.5.25"],"schemaVersion":1,"symbols":["postcss.list.comma","postcss.list.space","postcss.list.split"]},"contractCommand":["node","test/contract.mjs"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"npm","executionContext":"node","language":"javascript","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"npm","runtime":"node","runtimeVersion":"22.23.2","schemaVersion":1},"license":"MIT-0","packages":["pkg:npm/postcss@8.5.25"],"schemaVersion":1,"subject":"pkg:npm/postcss@8.5.25","symbols":["postcss.list.comma","postcss.list.space","postcss.list.split"],"verifierAdapter":"node-typescript@1"}

{
  "name": "sample-postcss-list",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-postcss-list",
      "version": "1.0.0",
      "license": "MIT-0",
      "dependencies": {
        "postcss": "8.5.25"
      }
    },
    "node_modules/nanoid": {
      "version": "3.3.18",
      "resolved": "https://registry.npmjs.org/nanoid/-/nanoid-3.3.18.tgz",
      "integrity": "sha512-DTg4MJbGMWkfi6VZFdNt2/caMbQy4Ou+Op/hJQvGEWcnVfoA1QA+xzRKAzw9jD6+GVOOeYr/mIcuDSdug6F6+w==",
      "funding": [
        {
          "type": "github",
          "url": "https://github.com/sponsors/ai"
        }
      ],
      "license": "MIT",
      "bin": {
        "nanoid": "bin/nanoid.cjs"
      },
      "engines": {
        "node": "^10 || ^12 || ^13.7 || ^14 || >=15.0.1"
      }
    },
    "node_modules/picocolors": {
      "version": "1.1.1",
      "resolved": "https://registry.npmjs.org/picocolors/-/picocolors-1.1.1.tgz",
      "integrity": "sha512-xceH2snhtb5M9liqDsmEw56le376mTZkEX/jEb/RxNFyegNul7eNslCXP9FDj/Lcu0X8KEyMceP2ntpaHrDEVA==",
      "license": "ISC"
    },
    "node_modules/postcss": {
      "version": "8.5.25",
      "resolved": "https://registry.npmjs.org/postcss/-/postcss-8.5.25.tgz",
      "integrity": "sha512-DTPx3RWSSnWyzLxQnlH0rJP+EW5ekl16ZU4/psbIhA0e53kJfdgaN5vKM+xP7yJtXVu+nfdVFmlgFDEKAe4Pyw==",
      "funding": [
        {
          "type": "opencollective",
          "url": "https://opencollective.com/postcss/"
        },
        {
          "type": "tidelift",
          "url": "https://tidelift.com/funding/github/npm/postcss"
        },
        {
          "type": "github",
          "url": "https://github.com/sponsors/ai"
        }
      ],
      "license": "MIT",
      "dependencies": {
        "nanoid": "^3.3.16",
        "picocolors": "^1.1.1",
        "source-map-js": "^1.2.1"
      },
      "engines": {
        "node": "^10 || ^12 || >=14"
      }
    },
    "node_modules/source-map-js": {
      "version": "1.2.1",
      "resolved": "https://registry.npmjs.org/source-map-js/-/source-map-js-1.2.1.tgz",
      "integrity": "sha512-UXWMKhLOwVKb728IUtQPXxfYU+usdybtUrK/8uGE8CQMvrhOpwvzDBwj0QhSL7MQc7vIsISBG8VQ8+IDQxpfQA==",
      "license": "BSD-3-Clause",
      "engines": {
        "node": ">=0.10.0"
      }
    }
  }
}

{
  "name": "sample-postcss-list",
  "version": "1.0.0",
  "type": "module",
  "license": "MIT-0",
  "dependencies": {
    "postcss": "8.5.25"
  }
}

{
  "schemaVersion": 1,
  "goal": "Split CSS values using postcss.list space, comma, and split utilities while preserving nested parentheses, brackets, and quoted strings",
  "kind": "HOW",
  "packages": [
    "pkg:npm/postcss@8.5.25"
  ],
  "symbols": [
    "postcss.list.comma",
    "postcss.list.space",
    "postcss.list.split"
  ]
}

import assert from 'node:assert/strict';
import postcss from 'postcss';

const { list } = postcss;

// 1. assert postcss.list.space splits whitespace-separated tokens into trimmed values while preserving nested functions, parenthesized expressions, and quoted strings
{
  const cssValue = 'calc(100% - 20px)   url("my asset file.png")   rgba(0, 0, 0, 0.75)   "custom font name"';
  const tokens = list.space(cssValue);
  assert.deepEqual(tokens, [
    'calc(100% - 20px)',
    'url("my asset file.png")',
    'rgba(0, 0, 0, 0.75)',
    '"custom font name"'
  ]);

  const border = '1px solid black';
  assert.deepEqual(list.space(border), ['1px', 'solid', 'black']);
}

// 2. assert postcss.list.comma splits comma-separated CSS values while preserving nested commas within functional notation like rgb(), var(), and linear-gradient()
{
  const complexValue = 'linear-gradient(90deg, #ff0000 0%, #0000ff 100%), var(--fallback, #ffffff), rgba(255, 255, 255, 0.8)';
  const items = list.comma(complexValue);
  assert.deepEqual(items, [
    'linear-gradient(90deg, #ff0000 0%, #0000ff 100%)',
    'var(--fallback, #ffffff)',
    'rgba(255, 255, 255, 0.8)'
  ]);

  const fontFamilies = 'Helvetica, "Times New Roman, serif", Arial, sans-serif';
  assert.deepEqual(list.comma(fontFamilies), [
    'Helvetica',
    '"Times New Roman, serif"',
    'Arial',
    'sans-serif'
  ]);
}

// 3. assert postcss.list.comma preserves empty trailing tokens when ending with a trailing delimiter while postcss.list.space omits trailing whitespace tokens
{
  const trailingComma = list.comma('font-size, color, ');
  assert.deepEqual(trailingComma, ['font-size', 'color', '']);

  const trailingSpace = list.space('font-size color \t\n ');
  assert.deepEqual(trailingSpace, ['font-size', 'color']);
}

// 4. assert postcss.list.split splits a string by custom delimiter characters while ignoring delimiters inside quotes and parentheses
{
  const customDelimited = 'minmax(100px, 1fr) / calc(200px / 2) / auto';
  const parts = list.split(customDelimited, ['/'], true);
  assert.deepEqual(parts, [
    'minmax(100px, 1fr)',
    'calc(200px / 2)',
    'auto'
  ]);

  const multiSeparators = list.split('a + b - c * d', ['+', '-', '*'], false);
  assert.deepEqual(multiSeparators, ['a', 'b', 'c', 'd']);
}

// 5. assert postcss.list helper methods return an empty array when given an empty string or whitespace-only input
{
  assert.deepEqual(list.space(''), []);
  assert.deepEqual(list.space('   \t\n  '), []);
  assert.deepEqual(list.comma(''), []);
  assert.deepEqual(list.split('', [','], true), []);
}