From f2b95c74e8d5d5da25dd56b6574c10f33c7febff Mon Sep 17 00:00:00 2001
From: Vincent Gao <gaobing1230@gmail.com>
Date: Thu, 25 Jun 2026 11:11:55 +0200
Subject: [PATCH] =?UTF-8?q?=F0=9F=90=9B=20FIX:=20html=5Fblock:=20stop=20ea?=
 =?UTF-8?q?rly=20at=20blank=20lines=20inside=20containers=20for=20non-blan?=
 =?UTF-8?q?k-line-terminator=20sequences?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

HTML blocks started with `<!--`, `<?`, `<!A`, `<![CDATA[`, or `<script>`/`<pre>`/`<style>`/`<textarea>`
(CommonMark types 1–5) have specific end conditions (e.g. `-->`).  Per the CommonMark spec §4.6,
these blocks continue until the matching end tag is found, or until the last line of the document /
container block — blank lines inside them do NOT terminate them.

When such a block appeared inside a container (e.g. a list item) a blank line within the comment
caused `state.sCount[nextLine] < state.blkIndent` to fire and break out of the scan loop early.
Blank lines always have `sCount = 0`, so any positive `blkIndent` would trigger the break even
though the blank line was still part of the containing list item.

Fix: skip the `sCount < blkIndent` guard for blank lines (`state.isEmpty(nextLine)`).
Blank lines that belong to a blank-line-terminator sequence (types 6–7, end condition `^$`) still
terminate correctly because an empty `lineText` matches `^$` via the end-condition check.

Fixes #377.
---
 markdown_it/rules_block/html_block.py         |  2 +-
 tests/test_port/fixtures/commonmark_extras.md | 24 +++++++++++++++++++
 2 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/markdown_it/rules_block/html_block.py b/markdown_it/rules_block/html_block.py
index 3d43f6ee..fee2a1a0 100644
--- a/markdown_it/rules_block/html_block.py
+++ b/markdown_it/rules_block/html_block.py
@@ -68,7 +68,7 @@ def html_block(state: StateBlock, startLine: int, endLine: int, silent: bool) ->
     # Let's roll down till block end.
     if not html_seq[1].search(lineText):
         while nextLine < endLine:
-            if state.sCount[nextLine] < state.blkIndent:
+            if state.sCount[nextLine] < state.blkIndent and not state.isEmpty(nextLine):
                 break
 
             pos = state.bMarks[nextLine] + state.tShift[nextLine]
diff --git a/tests/test_port/fixtures/commonmark_extras.md b/tests/test_port/fixtures/commonmark_extras.md
index f0b31dbd..0cb8d978 100644
--- a/tests/test_port/fixtures/commonmark_extras.md
+++ b/tests/test_port/fixtures/commonmark_extras.md
@@ -749,3 +749,27 @@ Issue #204. Combination of blockquotes, list and newlines causes an IndexError
 </li>
 </ul>
 .
+
+Issue #377. HTML comment block inside list item should not end at blank line
+.
+1. item
+
+    <!--
+    comment with
+
+    blank line inside
+    -->
+    paragraph
+.
+<ol>
+<li>
+<p>item</p>
+ <!--
+ comment with
+
+ blank line inside
+ -->
+<p>paragraph</p>
+</li>
+</ol>
+.