From 0d08cc1b2110012f5f43b7b18eb59f8db11a42e5 Mon Sep 17 00:00:00 2001
From: mck09 <mck097@gmail.com>
Date: Sun, 30 Aug 2026 13:40:40 +0200
Subject: [PATCH 1/2] fix: remove up to the fence indentation from each content
 line

CommonMark removes up to N spaces from each line of a fenced code block when
the opening fence is indented by N. indentCodeCompensation only stripped lines
indented at least N, so a line indented less kept all of its indentation.

Fixes CommonMark example 133. The spec suite did not catch it because
htmlIsEqual leaves html-differ's ignoreWhitespaces at its default of true.
---
 src/Tokenizer.ts         |  8 +++-----
 test/unit/marked.test.js | 12 ++++++++++++
 2 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/src/Tokenizer.ts b/src/Tokenizer.ts
index 5f7d878599..16834b86bf 100644
--- a/src/Tokenizer.ts
+++ b/src/Tokenizer.ts
@@ -68,11 +68,9 @@ function indentCodeCompensation(raw: string, text: string, rules: Rules) {
 
       const [indentInNode] = matchIndentInNode;
 
-      if (indentInNode.length >= indentToCode.length) {
-        return node.slice(indentToCode.length);
-      }
-
-      return node;
+      // Up to the fence's own indentation is removed from each line, so a line
+      // indented less than the fence loses whatever indentation it has.
+      return node.slice(Math.min(indentInNode.length, indentToCode.length));
     })
     .join('\n');
 }
diff --git a/test/unit/marked.test.js b/test/unit/marked.test.js
index 5d1449b4aa..93b86efd1d 100644
--- a/test/unit/marked.test.js
+++ b/test/unit/marked.test.js
@@ -22,6 +22,18 @@ describe('marked unit', () => {
     });
   });
 
+  describe('fenced code block indentation', () => {
+    it('should remove up to the fence indentation from each line', () => {
+      const md = '   ```\n   aaa\n    aaa\n  aaa\n   ```\n';
+      assert.strictEqual(marked.parse(md), '<pre><code>aaa\n aaa\naaa\n</code></pre>\n');
+    });
+
+    it('should leave lines indented more than the fence with the remainder', () => {
+      const md = '  ```\n      aaa\n  ```\n';
+      assert.strictEqual(marked.parse(md), '<pre><code>    aaa\n</code></pre>\n');
+    });
+  });
+
   describe('changeDefaults', () => {
     it('should change global defaults', async() => {
       const { defaults, setOptions } = await import('../../lib/marked.esm.js');

From 671374724e7c759a3810a0c3345872f1b0cb229a Mon Sep 17 00:00:00 2001
From: mck09 <mck097@gmail.com>
Date: Thu, 3 Sep 2026 04:45:30 +0200
Subject: [PATCH 2/2] test: move the fence indentation tests to test/specs/new

Uses renderExact so the fixture compares exactly, which htmlIsEqual
does not, and keeps the assertions out of marked.test.js.
---
 test/specs/new/fence_indent_stripping.html |  7 +++++++
 test/specs/new/fence_indent_stripping.md   | 14 ++++++++++++++
 test/unit/marked.test.js                   | 12 ------------
 3 files changed, 21 insertions(+), 12 deletions(-)
 create mode 100644 test/specs/new/fence_indent_stripping.html
 create mode 100644 test/specs/new/fence_indent_stripping.md

diff --git a/test/specs/new/fence_indent_stripping.html b/test/specs/new/fence_indent_stripping.html
new file mode 100644
index 0000000000..b3feaa5773
--- /dev/null
+++ b/test/specs/new/fence_indent_stripping.html
@@ -0,0 +1,7 @@
+<pre><code>aaa
+ aaa
+aaa
+</code></pre>
+<p>sep</p>
+<pre><code>    aaa
+</code></pre>
diff --git a/test/specs/new/fence_indent_stripping.md b/test/specs/new/fence_indent_stripping.md
new file mode 100644
index 0000000000..ea8bba01e6
--- /dev/null
+++ b/test/specs/new/fence_indent_stripping.md
@@ -0,0 +1,14 @@
+---
+renderExact: true
+---
+   ```
+   aaa
+    aaa
+  aaa
+   ```
+
+sep
+
+  ```
+      aaa
+  ```
diff --git a/test/unit/marked.test.js b/test/unit/marked.test.js
index 93b86efd1d..5d1449b4aa 100644
--- a/test/unit/marked.test.js
+++ b/test/unit/marked.test.js
@@ -22,18 +22,6 @@ describe('marked unit', () => {
     });
   });
 
-  describe('fenced code block indentation', () => {
-    it('should remove up to the fence indentation from each line', () => {
-      const md = '   ```\n   aaa\n    aaa\n  aaa\n   ```\n';
-      assert.strictEqual(marked.parse(md), '<pre><code>aaa\n aaa\naaa\n</code></pre>\n');
-    });
-
-    it('should leave lines indented more than the fence with the remainder', () => {
-      const md = '  ```\n      aaa\n  ```\n';
-      assert.strictEqual(marked.parse(md), '<pre><code>    aaa\n</code></pre>\n');
-    });
-  });
-
   describe('changeDefaults', () => {
     it('should change global defaults', async() => {
       const { defaults, setOptions } = await import('../../lib/marked.esm.js');