Prevent hover hangs outside single-line display math

packages/quarto-core/src/markdown/cursor.ts

@@ -87,7 +87,7 @@ function isLatexCodeBlock(token: Token) {
 }
 
 const kInlineMathPattern = /\$([^ ].*?[^ ]?)\$/g;
-const kSingleLineDisplayMathPattern = /\$\$([^\n]+?)\$\$/;
+const kSingleLineDisplayMathPattern = /\$\$([^\n]+?)\$\$/g;
 
 function inlineMathRange(pos: Position, line: string, pattern: RegExp) {
   pattern.lastIndex = 0;

packages/quarto-core/test/cursor.test.ts

@@ -0,0 +1,61 @@
+/*
+ * cursor.test.ts
+ *
+ * Copyright (C) 2026 by Posit Software, PBC
+ */
+
+import assert from "node:assert/strict";
+import test from "node:test";
+import { runInNewContext } from "node:vm";
+
+import { Position, Range } from "vscode-languageserver-types";
+
+import { Document } from "../src/document";
+import { mathRange } from "../src/markdown/cursor";
+import { markdownitParser } from "../src/markdown/parsers/markdownit";
+
+function document(text: string): Document {
+  return {
+    uri: "file:///math.qmd",
+    languageId: "quarto",
+    version: 1,
+    lineCount: 1,
+    getText: () => text,
+    positionAt: (offset) => Position.create(0, offset),
+  };
+}
+
+for (const [text, character] of [
+  ["Before $$x$$ after", 0],
+  ["Before $$x$$ after", 16],
+  ["Before $$x$$ and $$y$$ after", 14],
+  ["Before $$x$$ and $$y$$ after", 26],
+] as const) {
+  test(`returns no math at character ${character} in ${JSON.stringify(text)}`, () => {
+    assert.equal(
+      runInNewContext(
+        "mathRange(parser, doc, position)",
+        { mathRange, parser: markdownitParser(), doc: document(text), position: Position.create(0, character) },
+        { timeout: 1000 }
+      ),
+      null
+    );
+  });
+}
+
+test("finds later display math and resets the search for repeated requests", () => {
+  const parser = markdownitParser();
+  const doc = document("Before $$x$$ and $$y$$ after");
+  for (const character of [22, 12, 22, 12]) {
+    assert.deepEqual(
+      runInNewContext(
+        "mathRange(parser, doc, position)",
+        { mathRange, parser, doc, position: Position.create(0, character) },
+        { timeout: 1000 }
+      ),
+      character === 22
+        ? { math: "y", range: Range.create(0, 17, 0, 22) }
+        : { math: "x", range: Range.create(0, 7, 0, 12) }
+    );
+  }
+});