From adc251813d7f5deb8aba6aaa852818b5dc92c832 Mon Sep 17 00:00:00 2001
From: max-nothacker <max.nothacker@outlook.com>
Date: Sat, 25 Jul 2026 16:39:38 +0200
Subject: [PATCH] Fix single-line display math with attributes swallowing rest
 of document

The single-line close check in math_block() only recognized lines ending
in "$$", so "$$1+1$$ {#eq-spec0}" fell through to the multi-line scan,
which never finds a closing line and consumes the remainder of the
document into one math token. Everything after the equation (headings,
code cells) was no longer tokenized: no outline entries, no LaTeX
preview, and "Editor selection is not within an executable cell" when
running later cells.

Recognize an optional trailing attribute block in the single-line case,
mirroring the multi-line close regex, and store it in token.info the
same way. Adds unit tests for the single-line labeled, single-line
unlabeled, and multi-line labeled cases.

Fixes #976

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> in the session with id 6b8b182e
---
 packages/core/src/markdownit/math.ts       | 10 +++---
 packages/core/test/markdownit-math.test.ts | 42 ++++++++++++++++++++++
 2 files changed, 48 insertions(+), 4 deletions(-)
 create mode 100644 packages/core/test/markdownit-math.test.ts

diff --git a/packages/core/src/markdownit/math.ts b/packages/core/src/markdownit/math.ts
index 4abc7099c..959d0e2bf 100644
--- a/packages/core/src/markdownit/math.ts
+++ b/packages/core/src/markdownit/math.ts
@@ -163,13 +163,15 @@ function math_block(
   if (silent) {
     return true;
   }
-  if (firstLine.trim().slice(-2) === "$$") {
-    // Single line expression
-    firstLine = firstLine.trim().slice(0, -2);
+  let attrStr = undefined;
+  const singleLineMatch = firstLine.trim().match(/^(.*)\$\$\s*(\{.*\})?\s*$/);
+  if (singleLineMatch) {
+    // Single line expression, optionally followed by attributes (e.g. {#eq-label})
+    firstLine = singleLineMatch[1];
+    attrStr = singleLineMatch[2];
     found = true;
   }
 
-  let attrStr = undefined;
   for (next = start; !found; ) {
     next++;
 
diff --git a/packages/core/test/markdownit-math.test.ts b/packages/core/test/markdownit-math.test.ts
new file mode 100644
index 000000000..ba04be920
--- /dev/null
+++ b/packages/core/test/markdownit-math.test.ts
@@ -0,0 +1,42 @@
+import assert from "node:assert/strict";
+import test from "node:test";
+
+import MarkdownIt from "markdown-it";
+import { mathjaxPlugin } from "../src/markdownit/math";
+
+const parse = (src: string) => {
+  const md = new MarkdownIt({ html: true });
+  md.use(mathjaxPlugin);
+  return md.parse(src, {});
+};
+
+test("single-line math with attributes does not swallow the rest of the document", () => {
+  const tokens = parse(
+    "$$1+1$$ {#eq-spec0}\n\n```{python}\n2+2\n```\n"
+  );
+  const math = tokens.filter((t) => t.type === "math_block");
+  const fences = tokens.filter((t) => t.type === "fence");
+  assert.equal(math.length, 1);
+  assert.equal(math[0].info, "{#eq-spec0}");
+  assert.equal(math[0].content.trim(), "1+1");
+  assert.equal(fences.length, 1);
+});
+
+test("single-line math without attributes still parses", () => {
+  const tokens = parse("$$1+1$$\n\n```{python}\n2+2\n```\n");
+  const math = tokens.filter((t) => t.type === "math_block");
+  const fences = tokens.filter((t) => t.type === "fence");
+  assert.equal(math.length, 1);
+  assert.equal(math[0].content.trim(), "1+1");
+  assert.equal(fences.length, 1);
+});
+
+test("multi-line math with attributes on the closing line still parses", () => {
+  const tokens = parse("$$\n1+1\n$$ {#eq-spec0}\n\n```{python}\n2+2\n```\n");
+  const math = tokens.filter((t) => t.type === "math_block");
+  const fences = tokens.filter((t) => t.type === "fence");
+  assert.equal(math.length, 1);
+  assert.equal(math[0].info, "{#eq-spec0}");
+  assert.equal(math[0].content.trim(), "1+1");
+  assert.equal(fences.length, 1);
+});