feat: add no-reference-like-urls rule

README.md

@@ -101,6 +101,7 @@ export default defineConfig([
 | [`no-missing-label-refs`](./docs/rules/no-missing-label-refs.md) | Disallow missing label references | yes |
 | [`no-missing-link-fragments`](./docs/rules/no-missing-link-fragments.md) | Disallow link fragments that do not reference valid headings | yes |
 | [`no-multiple-h1`](./docs/rules/no-multiple-h1.md) | Disallow multiple H1 headings in the same document | yes |
+| [`no-reference-like-url`](./docs/rules/no-reference-like-url.md) | Disallow URLs that match defined reference identifiers | no |
 | [`no-reversed-media-syntax`](./docs/rules/no-reversed-media-syntax.md) | Disallow reversed link and image syntax | yes |
 | [`require-alt-text`](./docs/rules/require-alt-text.md) | Require alternative text for images | yes |
 | [`table-column-count`](./docs/rules/table-column-count.md) | Disallow data rows in a GitHub Flavored Markdown table from having more cells than the header row | yes |

docs/rules/no-reference-like-url.md

@@ -0,0 +1,57 @@
+# no-reference-like-url
+
+Disallow URLs that match defined reference identifiers.
+
+## Background
+
+In Markdown, you can create links using either inline syntax `[text](url)` or reference syntax `[text][id]` with a separate definition `[id]: url`. This rule encourages reference syntax when a link's URL matches an existing reference identifier.
+
+For example, if you have a definition like `[mercury]: https://example.com/mercury/`, then using `[text](mercury)` should be written as `[text][mercury]` instead.
+
+## Rule Details
+
+This rule flags URLs that match defined reference identifiers.
+
+Examples of **incorrect** code for this rule:
+
+```markdown
+<!-- eslint markdown/no-reference-like-url: "error" -->
+
+[**Mercury**](mercury) is the first planet from the sun.
+
+[mercury]: https://example.com/mercury/
+```
+
+```markdown
+<!-- eslint markdown/no-reference-like-url: "error" -->
+
+![**Venus** is a planet](venus).
+
+[venus]: https://example.com/venus.jpg
+```
+
+Examples of **correct** code for this rule:
+
+```markdown
+<!-- eslint markdown/no-reference-like-url: "error" -->
+
+[**Mercury**][mercury] is the first planet from the sun.
+
+[mercury]: https://example.com/mercury/
+```
+
+```markdown
+<!-- eslint markdown/no-reference-like-url: "error" -->
+
+![**Venus** is a planet][venus].
+
+[venus]: https://example.com/venus.jpg
+```
+
+## When Not to Use It
+
+If you prefer inline link syntax even when reference definitions are available, or if you're working in an environment where reference syntax is not preferred, you can safely disable this rule.
+
+## Prior Art
+
+* [remark-lint-no-reference-like-url](https://github.com/remarkjs/remark-lint/tree/main/packages/remark-lint-no-reference-like-url)

src/rules/no-reference-like-url.js

@@ -0,0 +1,99 @@
+/**
+ * @fileoverview Rule to enforce reference-style links when URL matches a defined identifier.
+ * @author TKDev7
+ */
+
+//-----------------------------------------------------------------------------
+// Type Definitions
+//-----------------------------------------------------------------------------
+
+/** @typedef {import("mdast").Node} Node */
+/** @typedef {import("mdast").Link} LinkNode */
+/** @typedef {import("mdast").Image} ImageNode */
+/** @typedef {import("mdast").Definition} DefinitionNode */
+/**
+ * @typedef {import("../types.ts").MarkdownRuleDefinition<{ RuleOptions: []; }>}
+ * NoReferenceLikeUrlRuleDefinition
+ */
+
+//-----------------------------------------------------------------------------
+// Rule Definition
+//-----------------------------------------------------------------------------
+
+/** @type {NoReferenceLikeUrlRuleDefinition} */
+export default {
+	meta: {
+		type: "problem",
+
+		docs: {
+			description:
+				"Disallow URLs that match defined reference identifiers",
+			url: "https://github.com/eslint/markdown/blob/main/docs/rules/no-reference-like-url.md",
+		},
+
+		fixable: "code",
+
+		messages: {
+			referenceLikeUrl:
+				"Unexpected resource {{type}} with URL that matches a definition identifier. Use [text][id] syntax instead.",
+		},
+	},
+
+	create(context) {
+		const { sourceCode } = context;
+		/** @type {Set<string>} */
+		const definitionIdentifiers = new Set();
+		/** @type {Array<LinkNode|ImageNode>} */
+		const resources = [];
+
+		return {
+			"root:exit"() {
+				for (const node of resources) {
+					const url = node.url.toLowerCase();
+
+					if (definitionIdentifiers.has(url)) {
+						context.report({
+							node,
+							messageId: "referenceLikeUrl",
+							data: {
+								type: node.type,
+							},
+							fix(fixer) {
+								const text = sourceCode.getText(node);
+
+								const bracketParenIndex = text.indexOf("](");
+								const closeParenIndex = text.lastIndexOf(")");
+
+								const startOffset =
+									node.position.start.offset +
+									bracketParenIndex +
+									1;
+								const endOffset =
+									node.position.start.offset +
+									closeParenIndex +
+									1;
+
+								return fixer.replaceTextRange(
+									[startOffset, endOffset],
+									`[${node.url}]`,
+								);
+							},
+						});
+					}
+				}
+			},
+
+			definition(node) {
+				definitionIdentifiers.add(node.identifier.toLowerCase());
+			},
+
+			link(node) {
+				resources.push(node);
+			},
+
+			image(node) {
+				resources.push(node);
+			},
+		};
+	},
+};