feat: baseline rule

fixes #26

README.md

@@ -55,14 +55,13 @@ export default [
 <!-- NOTE: The following table is autogenerated. Do not manually edit. -->
 
 <!-- Rule Table Start -->
-
-| **Rule Name**                                                    | **Description**                  | **Recommended** |
-| :--------------------------------------------------------------- | :------------------------------- | :-------------: |
-| [`no-duplicate-imports`](./docs/rules/no-duplicate-imports.md)   | Disallow duplicate @import rules |       yes       |
-| [`no-empty-blocks`](./docs/rules/no-empty-blocks.md)             | Disallow empty blocks            |       yes       |
-| [`no-invalid-at-rules`](./docs/rules/no-invalid-at-rules.md)     | Disallow invalid at-rules        |       yes       |
-| [`no-invalid-properties`](./docs/rules/no-invalid-properties.md) | Disallow invalid properties      |       yes       |
-
+| **Rule Name** | **Description** | **Recommended** |
+| :- | :- | :-: |
+| [`baseline`](./docs/rules/baseline.md) | Enforce the use of baseline features | yes |
+| [`no-duplicate-imports`](./docs/rules/no-duplicate-imports.md) | Disallow duplicate @import rules | yes |
+| [`no-empty-blocks`](./docs/rules/no-empty-blocks.md) | Disallow empty blocks | yes |
+| [`no-invalid-at-rules`](./docs/rules/no-invalid-at-rules.md) | Disallow invalid at-rules | yes |
+| [`no-invalid-properties`](./docs/rules/no-invalid-properties.md) | Disallow invalid properties | yes |
 <!-- Rule Table End -->
 
 **Note:** This plugin does not provide formatting rules. We recommend using a source code formatter such as [Prettier](https://prettier.io) for that purpose.

docs/rules/baseline.md

@@ -0,0 +1,39 @@
+# baseline
+
+Enforce the use of baseline features
+
+## Background
+
+[Baseline](https://web.dev/baseline) is an effort by the [W3C WebDX Community Group](https://github.com/web-platform-dx) to document which features are available in four core browsers: Chrome (desktop and Android), Edge, Firefox (desktop and Android), and Safari (macOS and iOS). This data allows developers to choose the technologies that are best supported for their audience. As part of this effort, Baseline tracks which CSS features are available in which browsers.
+
+Features are grouped into three levels:
+
+- **Widely available** features are those supported by all core browsers for at least 30 months.
+- **Newly available** features are those supported by all core browsers for less than 30 months.
+- **Limited availability** features are those supported by some but not all core browsers.
+
+Generally speaking, it's preferable to stick to widely available features to ensure the greatest interoperability across browsers.
+
+## Rule Details
+
+This rule warns when it finds a CSS property or at-rule that isn't widely available or otherwise isn't enclosed in a `@supports` block. The data is provided via the [web-features](https://npmjs.com/package/web-features) package.
+
+Here are some examples:
+
+```css
+/* invalid - accent-color is not widely available */
+a {
+	accent-color: red;
+}
+
+/* valid - @supports indicates you're choosing a limited availability property */
+@supports (accent-color: auto) {
+	a {
+		accent-color: red;
+	}
+}
+```
+
+## When Not to Use It
+
+If your web application targets just one browser then you can safely disable this rule.

package.json

@@ -35,7 +35,10 @@
       "prettier --write"
     ],
     "!(*.js)": "prettier --write --ignore-unknown",
-    "{src/rules/*.js,tools/update-rules-docs.js}": "npm run build:update-rules-docs"
+    "{src/rules/*.js,tools/update-rules-docs.js}": [
+      "node tools/update-rules-docs.js",
+      "git add README.md "
+    ]
   },
   "repository": {
     "type": "git",
@@ -48,9 +51,10 @@
   "scripts": {
     "build:dedupe-types": "node tools/dedupe-types.js dist/cjs/index.cjs dist/esm/index.js",
     "build:cts": "node -e \"fs.copyFileSync('dist/esm/index.d.ts', 'dist/cjs/index.d.cts')\"",
-    "build": "rollup -c && npm run build:dedupe-types && tsc -p tsconfig.esm.json && npm run build:cts",
+    "build": "npm run build:baseline && rollup -c && npm run build:dedupe-types && tsc -p tsconfig.esm.json && npm run build:cts",
     "build:readme": "node tools/update-readme.js",
     "build:update-rules-docs": "node tools/update-rules-docs.js",
+    "build:baseline": "node tools/generate-baseline.js",
     "test:jsr": "npx jsr@latest publish --dry-run",
     "pretest": "npm run build",
     "lint": "eslint",
@@ -89,6 +93,7 @@
     "rollup": "^4.16.2",
     "rollup-plugin-copy": "^3.5.0",
     "typescript": "^5.4.5",
+    "web-features": "^2.11.0",
     "yorkie": "^2.0.0"
   },
   "engines": {

src/data/README.md

@@ -0,0 +1,9 @@
+# Autogenerated Data
+
+The files in this directory are auto-generated and should not be modified manually.
+
+To generate baseline data, run:
+
+```shell
+npm run build:baseline
+```