New note: polygot xhtml5

If a target URL has a fragment, it should match against the page URL
even without the fragment.

content/notes/polygot-xhtml5.md

@@ -0,0 +1,18 @@
+---
+title: "Polygot XHTML5"
+date: 2023-07-22T20:39:24-07:00
+syndicatedCopies:
+    - title: 'The Fediverse'
+      url: 'https://pleroma.envs.net/notice/AXyQMNhrMjeGLBrmim'
+---
+
+Why is my site's markup polygot XHTML5? I have had to deal with some really awful user-agents:
+
+- Bespoke markup parsers in RSS readers.
+- Link previews in obscure messaging apps.
+- A reader-mode bookmarklet-turned-browser-extension that hasn't been updated in twelve years.
+- Various search engines trying to parse the page without using a compliant parser.
+
+Most of my issues were solved by running my generated markup through both `xmllint` (XML syntax) and the Nu HTML Checker (HTML5). Optional elements tend to cause issues the most.
+
+Overly-aggressive validation tends to spot latent bugs. Even if something is valid without an optional closing tag, I may have meant to include one in my templates. If that becomes an issue when I change something else later, it'll be hard to track down the bug when it passes more lax validation.

layouts/partials/head.html

@@ -82,4 +82,5 @@
 	<meta property="og:image:height" content="{{ $og_image.Height }}" /><meta property="og:image:width" content="{{ $og_image.Width }}" />
 	<meta property="og:url" content="{{ .Site.Params.CanonicalBaseURL }}{{ $canonicalRelPermalink }}" />
 	<meta property="og:description" content="{{ $description }}" />
+	{{ hugo.Generator | replaceRE ">" " />" | safeHTML}}
 </head>

layouts/partials/webmentions.html

@@ -17,7 +17,21 @@
 		{{- $oldTarget := $target | replaceRE "/posts" "" | replaceRE "/$" ".html" -}}
 		{{ $targets = (slice $target $oldTarget) }}
 	{{- end -}}
-	{{- $webmentions := where $allMentions "target" "in" $targets -}}
+	{{- /* We can't just use a simple "where" function because we need to ignore URL anchors when making a comparison: https://discourse.gohugo.io/t/add-like-comparison-operator-to-the-where-function/42013/4 */ -}}
+	{{- $webmentions := slice -}}
+	{{- range $allMentions -}}
+		{{- if in $targets .target -}}
+			{{ $webmentions = $webmentions | append . }}
+		{{- else -}}
+			{{- $fragment := printf `#%s` (urls.Parse .target).Fragment -}}
+			{{- if gt (len $fragment) 1 -}}
+				{{- $trimmedTarget := strings.TrimSuffix $fragment .target -}}
+				{{- if in $targets $trimmedTarget -}}
+					{{ $webmentions = $webmentions | append . }}
+				{{- end -}}
+			{{- end -}}
+		{{- end -}}
+	{{- end -}}
 {{- /* Render webmentions if they exist */ -}}
 {{- $count := (len $webmentions) -}}
 {{- if gt $count 0 -}}