stylelint · ybiquitous · Aug 12, 2025 · Jul 22, 2025 · Jul 22, 2025 · Jul 22, 2025
diff --git a/.changeset/great-geese-wink.md b/.changeset/great-geese-wink.md
@@ -0,0 +1,5 @@
+---
+"stylelint": minor
+---
+
+Added: `declaration-block-nesting-at-rule-required-list` rule
diff --git a/docs/user-guide/rules.md b/docs/user-guide/rules.md
@@ -196,6 +196,7 @@ Allow, disallow or require things with these `allowed-list`, `disallowed-list`,
 <!-- prettier-ignore-start -->
 | | | |
 | :-- | :-: | :-: |
+| [`declaration-block-nesting-at-rule-required-list`](../../lib/rules/declaration-block-nesting-at-rule-required-list/README.md)<br/>Require specific at-rules to be present around CSS declarations. | | |
 | [`declaration-no-important`](../../lib/rules/declaration-no-important/README.md)<br/>Disallow `!important` within declarations. | | |
 | [`declaration-property-unit-allowed-list`](../../lib/rules/declaration-property-unit-allowed-list/README.md)<br/>Specify a list of allowed property and unit pairs within declarations. | | |
 | [`declaration-property-unit-disallowed-list`](../../lib/rules/declaration-property-unit-disallowed-list/README.md)<br/>Specify a list of disallowed property and unit pairs within declarations. | | |

diff --git a/lib/rules/declaration-block-nesting-at-rule-required-list/README.md b/lib/rules/declaration-block-nesting-at-rule-required-list/README.md
@@ -0,0 +1,52 @@
+# declaration-block-nesting-at-rule-required-list
+
+Require specific at-rules to be present around CSS declarations.
+
+<!-- prettier-ignore -->
+```css
+a { color: red; }
+/**    ↑
+ * This declaration */
+```
+
+## Options
+
+`array|string|regex`: `["layer"]`
+
+Given:
+
+```json
+["layer"]
+```
+
+The following patterns are considered problems:
+
+<!-- prettier-ignore -->
+```css
+a { color: red; }
+```
+
+<!-- prettier-ignore -->
+```css
+@media all {
+  a { color: red; }
+}
+```
+
+The following patterns are _not_ considered problems:
+
+<!-- prettier-ignore -->
+```css
+@layer {
+  a { color: red; }
+}
+```
+
+<!-- prettier-ignore -->
+```css
+a {
+  @layer {
+    color: red;
+  }
+}
+```
diff --git a/lib/rules/declaration-block-nesting-at-rule-required-list/__tests__/index.mjs b/lib/rules/declaration-block-nesting-at-rule-required-list/__tests__/index.mjs
@@ -0,0 +1,158 @@
+import rule from '../index.mjs';
+const { messages, ruleName } = rule;
+
+testRule({
+	ruleName,
+	config: ['layer', '/^s/'],
+
+	accept: [
+		{
+			code: '@layer { a { color: red; } }',
+			description: 'declaration within @layer at-rule',
+		},
+		{
+			code: 'a { @layer { color: red; } }',
+			description: 'declaration within nested @layer at-rule',
+		},
+		{
+			code: '@supports (color: red) { a { color: red; } }',
+			description: 'declaration within @supports at-rule (matches regex)',
+		},
+		{
+			code: '@scope (a) { a { color: red; } }',
+			description: 'declaration within @scope at-rule (matches regex)',
+		},
+		{
+			code: '@media all {}',
+			description: 'empty at-rule',
+		},
+		{
+			code: '@layer { @media all { a { color: red; } } }',
+			description: 'declaration within nested required at-rule',
+		},
+	],
+
+	reject: [
+		{
+			code: 'a { color: red; }',
+			description: 'declaration without required at-rule',
+			message: messages.expected('layer, /^s/'),
+			line: 1,
+			column: 5,
+			endLine: 1,
+			endColumn: 16,
+		},
+		{
+			code: 'a { color: red; color: blue; }',
+			description: 'multiple declarations without required at-rule',
+			warnings: [
+				{
+					message: messages.expected('layer, /^s/'),
+					line: 1,
+					column: 5,
+					endLine: 1,
+					endColumn: 16,
+				},
+				{
+					message: messages.expected('layer, /^s/'),
+					line: 1,
+					column: 17,
+					endLine: 1,
+					endColumn: 29,
+				},
+			],
+		},
+		{
+			code: '@media all { a { color: red; } }',
+			description: 'declaration within non-required at-rule',
+			message: messages.expected('layer, /^s/'),
+			line: 1,
+			column: 18,
+			endLine: 1,
+			endColumn: 29,
+		},
+		{
+			code: 'a { @media all { color: red; } }',
+			description: 'declaration within nested non-required at-rule',
+			message: messages.expected('layer, /^s/'),
+			line: 1,
+			column: 18,
+			endLine: 1,
+			endColumn: 29,
+		},
+	],
+});
+
+testRule({
+	ruleName,
+	config: ['layer'],
+
+	accept: [
+		{
+			code: '@layer { a { color: red; } }',
+			description: 'declaration within @layer at-rule',
+		},
+		{
+			code: 'a { @layer { color: red; } }',
+			description: 'declaration within nested @layer at-rule',
+		},
+	],
+
+	reject: [
+		{
+			code: 'a { color: red; }',
+			description: 'declaration without required at-rule',
+			message: messages.expected('layer'),
+			line: 1,
+			column: 5,
+			endLine: 1,
+			endColumn: 16,
+		},
+		{
+			code: '@supports (color: red) { a { color: red; } }',
+			description: 'declaration within non-required at-rule',
+			message: messages.expected('layer'),
+			line: 1,
+			column: 30,
+			endLine: 1,
+			endColumn: 41,
+		},
+	],
+});
+
+testRule({
+	ruleName,
+	config: ['/^s/'],
+
+	accept: [
+		{
+			code: '@supports (color: red) { a { color: red; } }',
+			description: 'declaration within @supports at-rule (matches regex)',
+		},
+		{
+			code: '@scope (a) { a { color: red; } }',
+			description: 'declaration within @scope at-rule (matches regex)',
+		},
+	],
+
+	reject: [
+		{
+			code: 'a { color: red; }',
+			description: 'declaration without required at-rule',
+			message: messages.expected('/^s/'),
+			line: 1,
+			column: 5,
+			endLine: 1,
+			endColumn: 16,
+		},
+		{
+			code: '@layer { a { color: red; } }',
+			description: 'declaration within non-matching at-rule',
+			message: messages.expected('/^s/'),
+			line: 1,
+			column: 14,
+			endLine: 1,
+			endColumn: 25,
+		},
+	],
+});
diff --git a/lib/rules/declaration-block-nesting-at-rule-required-list/index.cjs b/lib/rules/declaration-block-nesting-at-rule-required-list/index.cjs
diff --git a/lib/rules/declaration-block-nesting-at-rule-required-list/index.mjs b/lib/rules/declaration-block-nesting-at-rule-required-list/index.mjs
@@ -0,0 +1,80 @@
+import { isRegExp, isString } from '../../utils/validateTypes.mjs';
+import eachDeclarationBlock from '../../utils/eachDeclarationBlock.mjs';
+import isStandardSyntaxDeclaration from '../../utils/isStandardSyntaxDeclaration.mjs';
+import matchesStringOrRegExp from '../../utils/matchesStringOrRegExp.mjs';
+import report from '../../utils/report.mjs';
+import ruleMessages from '../../utils/ruleMessages.mjs';
+import validateOptions from '../../utils/validateOptions.mjs';
+
+const ruleName = 'declaration-block-nesting-at-rule-required-list';
+
+const messages = ruleMessages(ruleName, {
+	expected: (atRule) => `Expected nesting at-rule "${atRule}" for declaration`,
+});
+
+const meta = {
+	url: 'https://stylelint.io/user-guide/rules/declaration-block-nesting-at-rule-required-list',
+};
+
+/** @type {import('stylelint').CoreRules[ruleName]} */
+const rule = (primary) => {
+	return (root, result) => {
+		const validOptions = validateOptions(result, ruleName, {
+			actual: primary,
+			possible: [isString, isRegExp],
+		});
+
+		if (!validOptions) return;
+
+		eachDeclarationBlock(root, (eachDecl) => {
+			eachDecl((decl) => {
+				if (!isStandardSyntaxDeclaration(decl)) return;
+
+				// Skip if declaration already has a required at-rule ancestor
+				if (hasRequiredAtRuleAncestor(decl, primary)) return;
+
+				report({
+					message: messages.expected,
+					messageArgs: [Array.isArray(primary) ? primary.join(', ') : primary],
+					node: decl,
+					result,
+					ruleName,
+				});
+			});
+		});
+	};
+};
+
+/**
+ * @param {import('postcss').Declaration} decl
+ * @param {string | RegExp | Array<string | RegExp>} requiredAtRules
+ * @returns {boolean}
+ */
+function hasRequiredAtRuleAncestor(decl, requiredAtRules) {
+	let current = decl.parent;
+
+	while (current) {
+		if (current.type === 'atrule') {
+			const atRuleName = current.name;
+
+			// Check if at-rule name matches any of the required patterns
+			if (matchesStringOrRegExp(atRuleName, requiredAtRules)) {
+				return true;
+			}
+		}
+
+		if (current.type === 'root') {
+			break;
+		}
+
+		current = current.parent;
+	}
+
+	return false;
+}
+
+rule.primaryOptionArray = true;
+rule.ruleName = ruleName;
+rule.messages = messages;
+rule.meta = meta;
+export default rule;