diff --git a/website/templates/website/member.html b/website/templates/website/member.html
index b0f84304..e7b7e87a 100644
--- a/website/templates/website/member.html
+++ b/website/templates/website/member.html
@@ -50,9 +50,11 @@
 {% load thumbnail %}
 {% load ml_tags %}
 
-{# Title, description, og:type=profile, and canonical come from page_meta (see
-   website/views/member.py). Here we override the share image and add the
-   profile-specific structural OG tags. #}
+{% comment %}
+Title, description, og:type=profile, and canonical come from page_meta (see
+website/views/member.py). Here we override the share image and add the
+profile-specific structural OG tags.
+{% endcomment %}
 {% block social_image %}
 {% thumbnail person.image '1200x630' box=person.cropping crop=True upscale=True as og_img %}
 {% if og_img %}
diff --git a/website/templates/website/news_item.html b/website/templates/website/news_item.html
index d4522bc4..680993a5 100644
--- a/website/templates/website/news_item.html
+++ b/website/templates/website/news_item.html
@@ -42,9 +42,11 @@
 {% load thumbnail %}
 {% load ml_tags %}
 
-{# Title, description, og:type=article, and canonical come from page_meta (see
-   website/views/news_item.py). Here we override the share image and add the
-   article-specific structural OG tags. #}
+{% comment %}
+Title, description, og:type=article, and canonical come from page_meta (see
+website/views/news_item.py). Here we override the share image and add the
+article-specific structural OG tags.
+{% endcomment %}
 {% block social_image %}
 {% if news_item.image %}{% thumbnail news_item.image '1200x630' box=news_item.cropping crop=True upscale=True as og_img %}{% endif %}
 {% if og_img %}
diff --git a/website/templates/website/project.html b/website/templates/website/project.html
index 2b96e736..aeb16d5d 100644
--- a/website/templates/website/project.html
+++ b/website/templates/website/project.html
@@ -65,8 +65,10 @@
 {% load thumbnail %}
 {% load ml_tags %}
 
-{# Title, description, og:type, and canonical come from page_meta (see
-   website/views/project.py). Here we only override the social share image. #}
+{% comment %}
+Title, description, og:type, and canonical come from page_meta (see
+website/views/project.py). Here we only override the social share image.
+{% endcomment %}
 {% block social_image %}
 {% thumbnail project.gallery_image 1200x630 box=project.cropping crop=True upscale=True as og_img %}
 {% if og_img %}
diff --git a/website/tests/test_template_comments.py b/website/tests/test_template_comments.py
new file mode 100644
index 00000000..e8e7562e
--- /dev/null
+++ b/website/tests/test_template_comments.py
@@ -0,0 +1,65 @@
+"""
+Mechanical guard for a recurring bug: Django's ``{# … #}`` template comment is
+**single-line only**. A ``{# … #}`` that spans multiple lines is NOT tokenized as
+a comment — Django renders the whole thing (text and ``#}`` included) as visible
+page content. This shipped to prod once, printing a note on every award card
+(fixed in 2.14.2). For multi-line comments use ``{% comment %} … {% endcomment %}``.
+
+This is a ``SimpleTestCase`` (no DB), so it runs as part of the normal test suite
+in CI (.github/workflows/test.yml) on every push/PR, and locally via
+``manage.py test``. See the template-comment note in CLAUDE.md.
+"""
+
+from pathlib import Path
+
+from django.test import SimpleTestCase
+
+# Repo root: website/tests/this_file.py -> parents[2].
+REPO_ROOT = Path(__file__).resolve().parents[2]
+SKIP_DIRS = {".git", "node_modules", "static", "staticfiles", "media",
+             ".venv", "venv", "htmlcov", "__pycache__"}
+
+
+def _template_html_files():
+    """Yield every ``*.html`` living under any ``templates/`` directory in the repo."""
+    for path in REPO_ROOT.rglob("*.html"):
+        if "templates" not in path.parts:
+            continue
+        if SKIP_DIRS.intersection(path.parts):
+            continue
+        yield path
+
+
+def _multiline_comment_lines(text):
+    """Return the 1-based line numbers where a ``{#`` opens but doesn't close on
+    the same line (i.e. a multi-line ``{# #}`` comment)."""
+    bad = []
+    for n, line in enumerate(text.splitlines(), 1):
+        idx = line.find("{#")
+        if idx != -1 and "#}" not in line[idx + 2:]:
+            bad.append(n)
+    return bad
+
+
+class TemplateCommentLintTests(SimpleTestCase):
+    def test_no_multiline_django_comments(self):
+        offenders = []
+        for path in _template_html_files():
+            text = path.read_text(encoding="utf-8")
+            for n in _multiline_comment_lines(text):
+                offenders.append(f"{path.relative_to(REPO_ROOT)}:{n}")
+
+        self.assertEqual(
+            offenders, [],
+            "Multi-line Django `{# #}` comment(s) found — Django renders these as "
+            "visible page text. Use `{% comment %}…{% endcomment %}` instead:\n  "
+            + "\n  ".join(offenders),
+        )
+
+    def test_detector_catches_a_multiline_comment(self):
+        # Pin the detection logic itself so the guard can't silently rot.
+        self.assertEqual(_multiline_comment_lines("{# one line ok #}\n<p>x</p>"), [])
+        self.assertEqual(
+            _multiline_comment_lines("<p>x</p>\n{# this opens\n   and closes later #}\n"),
+            [2],
+        )