This repo is reproduction of a quirk in Hugo's .Summary method. As the title implies, using a blockquote that extends past the .Summary cutoff causes the content below {{ .Summary }} to be treated as part of the blockquote until the end of the parent tag.
$ hugo version
hugo v0.151.0+extended+withdeploy darwin/arm64 BuildDate=2025-10-02T13:30:36Z VendorInfo=brew$ hugo server -DYou will see this
In most modern browsers this html code will be parsed and rendered without errors
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width">
</head>
<body>
<main>
<blockquote>
<p>1</p>
</main>
</body>
</html>Leading to shown in browser as a source
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width">
</head>
<body>
<main>
<blockquote>
<p>1</p>
<!-- This blockquote end tag was automatically inserted -->
</blockquote>
</main>
</body>
</html>This is due to these parsing rules
An end tag whose tag name is one of: "address", "article", "aside", "blockquote", "button", "center", "details", "dialog", "dir", "div", "dl", "fieldset", "figcaption", "figure", "footer", "header", "hgroup", "listing", "main", "menu", "nav", "ol", "pre", "search", "section", "select", "summary", "ul"
If the stack of open elements does not have an element in scope that is an HTML element with the same tag name as that of the token, then this is a parse error; ignore the token. Otherwise, run these steps: Generate implied end tags. If the current node is not an HTML element with the same tag name as that of the token, then this is a parse error. Pop elements from the stack of open elements until an HTML element with the same tag name as the token has been popped from the stack.