From 3da07373ca8ffe2b51efc5c74f6f2fd1fe63721f Mon Sep 17 00:00:00 2001
From: Frost Ming <me@frostming.com>
Date: Mon, 5 Jan 2026 18:52:45 +0800
Subject: [PATCH 1/3] fix: Make github alert parsing case-insensitive

Signed-off-by: Frost Ming <me@frostming.com>
---
 CHANGELOG.md              |  6 ++++++
 marko/ext/gfm/elements.py |  6 ++++--
 tests/test_ext.py         | 22 +++++++++++++++-------
 3 files changed, 25 insertions(+), 9 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0346323..a60220d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,9 @@
+## Unreleased
+
+### Fixed
+
+- Fix a bug in GFM alert block parsing where alert types were case-sensitive.
+
 ## v2.2.1(2025-10-13)
 
 ### Changed
diff --git a/marko/ext/gfm/elements.py b/marko/ext/gfm/elements.py
index fa98289..d57960c 100644
--- a/marko/ext/gfm/elements.py
+++ b/marko/ext/gfm/elements.py
@@ -225,11 +225,13 @@ class Alert(block.Quote):
 
     @classmethod
     def match(cls, source):
-        return source.expect_re(r" {,3}>\s*\[\!(WARNING|NOTE|TIP|IMPORTANT|CAUTION)\]")
+        return source.expect_re(
+            r"(?i) {,3}>\s*\[\!(WARNING|NOTE|TIP|IMPORTANT|CAUTION)\]"
+        )
 
     @classmethod
     def parse(cls, source):
-        alert_type = source.match.group(1)
+        alert_type = source.match.group(1).upper()
         source.next_line(require_prefix=False)
         source.consume()
         state = cls(alert_type)
diff --git a/tests/test_ext.py b/tests/test_ext.py
index d20e2db..7e268c7 100644
--- a/tests/test_ext.py
+++ b/tests/test_ext.py
@@ -1,3 +1,5 @@
+import pytest
+
 from marko import Markdown
 
 
@@ -106,20 +108,26 @@ def setup_method(self):
         self.md_ast = Markdown(renderer=ASTRenderer, extensions=[GFM])
         self.md_html = Markdown(extensions=[GFM])
 
-    def test_alert_ast(self):
-        text = "> [!WARNING]\n> Foo bar\n> Bar\n"
+    @pytest.mark.parametrize(
+        "alert_type", ["WARNING", "CAUTION", "TIP", "warning", "Caution"]
+    )
+    def test_alert_ast(self, alert_type):
+        text = f"> [!{alert_type}]\n> Foo bar\n> Bar\n"
         ast = self.md_ast(text)
         admon = ast["children"][0]
         assert admon["element"] == "alert"
-        assert admon["alert_type"] == "WARNING"
+        assert admon["alert_type"] == alert_type.upper()
         inner = admon["children"][0]["children"]
         assert inner[0]["children"] == "Foo bar"
         assert inner[1]["element"] == "line_break"
         assert inner[2]["children"] == "Bar"
 
-    def test_alert_html(self):
-        text = "> [!WARNING]\n> Foo bar\n> Bar\n"
+    @pytest.mark.parametrize(
+        "alert_type", ["WARNING", "CAUTION", "TIP", "warning", "Caution"]
+    )
+    def test_alert_html(self, alert_type):
+        text = f"> [!{alert_type}]\n> Foo bar\n> Bar\n"
         html = self.md_html(text)
-        assert '<blockquote class="alert alert-warning">' in html
-        assert "<p>Warning</p>" in html
+        assert f'<blockquote class="alert alert-{alert_type.lower()}">' in html
+        assert f"<p>{alert_type.title()}</p>" in html
         assert "<p>Foo bar\nBar</p>" in html

From a8ecd62a6e82685814e7f31728b9a88d0a219121 Mon Sep 17 00:00:00 2001
From: Frost Ming <me@frostming.com>
Date: Mon, 5 Jan 2026 18:54:54 +0800
Subject: [PATCH 2/3] fix: Update GFM alert regex to disallow content on header
 line

Signed-off-by: Frost Ming <me@frostming.com>
---
 CHANGELOG.md              | 3 ++-
 marko/ext/gfm/elements.py | 2 +-
 tests/test_ext.py         | 6 ++++++
 3 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index a60220d..9aa152c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,8 +1,9 @@
-## Unreleased
+## v2.2.2(2026-01-05)
 
 ### Fixed
 
 - Fix a bug in GFM alert block parsing where alert types were case-sensitive.
+- Fix GFM alert regex to disallow content on header line.
 
 ## v2.2.1(2025-10-13)
 
diff --git a/marko/ext/gfm/elements.py b/marko/ext/gfm/elements.py
index d57960c..2edcaeb 100644
--- a/marko/ext/gfm/elements.py
+++ b/marko/ext/gfm/elements.py
@@ -226,7 +226,7 @@ class Alert(block.Quote):
     @classmethod
     def match(cls, source):
         return source.expect_re(
-            r"(?i) {,3}>\s*\[\!(WARNING|NOTE|TIP|IMPORTANT|CAUTION)\]"
+            r"(?im) {,3}>\s*\[\!(WARNING|NOTE|TIP|IMPORTANT|CAUTION)\]\s*$"
         )
 
     @classmethod
diff --git a/tests/test_ext.py b/tests/test_ext.py
index 7e268c7..0b3f04e 100644
--- a/tests/test_ext.py
+++ b/tests/test_ext.py
@@ -131,3 +131,9 @@ def test_alert_html(self, alert_type):
         assert f'<blockquote class="alert alert-{alert_type.lower()}">' in html
         assert f"<p>{alert_type.title()}</p>" in html
         assert "<p>Foo bar\nBar</p>" in html
+
+    def test_alert_disallow_content_on_header_line(self):
+        text = "> [!NOTE] This is not allowed.\n> Foo bar\n"
+        html = self.md_html(text)
+        # Should be treated as a normal blockquote.
+        assert "<blockquote>\n<p>[!NOTE] This is not allowed." in html

From 870dccfc90a881b6c18bb5a42de153aa81781744 Mon Sep 17 00:00:00 2001
From: Frost Ming <me@frostming.com>
Date: Mon, 5 Jan 2026 18:59:50 +0800
Subject: [PATCH 3/3] fix: Bump version to 2.2.2

Signed-off-by: Frost Ming <me@frostming.com>
---
 marko/__init__.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/marko/__init__.py b/marko/__init__.py
index 4aae580..a21e6dd 100644
--- a/marko/__init__.py
+++ b/marko/__init__.py
@@ -23,7 +23,7 @@
     from .block import Document
     from .parser import ElementType
 
-__version__ = "2.2.1"
+__version__ = "2.2.2"
 
 
 class SetupDone(Exception):