Add a self-referencing canonical tag to every page (#586)

* Add a self-referencing canonical tag to every page

Pages without canonical_url had no canonical tag, so Google treats tracking-parameter URLs (?utm_source=..., ?ref=...) as duplicates.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* Point paginated list pages' canonical at themselves

/blog/2 and the other pager pages took .Permalink, which is page 1. The blog post list moves into a shared partial so head.html and blog-list.html paginate the same collection.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

Author: jasdeepbhangal-oss

themes/haystack/layouts/partials/blog-list-posts.html

@@ -0,0 +1,7 @@
+{{ $posts := where .Data.Pages "Params.hidden" "!=" true }}
+{{/* Append homepage to blogposts and hide it later - hack to get 1 less post on the first page, to show a
+larger featured post */}}
+{{ if not (or (eq .Type "authors") (eq .Type "tags")) }}
+  {{ $posts = slice site.Home | append $posts }}
+{{ end }}
+{{ return $posts }}

themes/haystack/layouts/partials/blog-list.html

@@ -109,11 +109,8 @@ <h2 class="section-title">
         {{ end }}
         {{/* Blog posts grid */}}
         <div class="blog-grid blog-grid-static">
-          {{/* Append homepage to blogposts and hide it later - hack to get 1 less post on the first page, to show a
-          larger featured post */}}
-          {{ if not (or (eq .Type "authors") (eq .Type "tags")) }}
-            {{ $blogPosts = slice site.Home | append $blogPosts }}
-          {{ end }}
+          {{/* Same list the canonical tag in head.html paginates, so both use one paginator */}}
+          {{ $blogPosts = partial "blog-list-posts" . }}
           {{ $paginatedBlogPosts := .Paginate $blogPosts }}
 
           {{/* Check if there is a next/previous page */}}

themes/haystack/layouts/partials/head.html

@@ -26,6 +26,15 @@
   {{/* Canonical url */}}
   {{ if .Params.canonical_url }}
     <link rel="canonical" href="{{ .Params.canonical_url }}" />
+  {{ else }}
+    {{ $canonical := .Permalink }}
+    {{/* Paginated lists: point each pager page at itself, not at page 1. Args must match the .Paginate call in the body. */}}
+    {{ if eq .Layout "release-notes" }}
+      {{ $canonical = (.Paginate .Data.Pages 12).URL | absURL }}
+    {{ else if or (eq .Layout "blog") (and (eq .Kind "term") (in (slice "authors" "tags") .Type)) }}
+      {{ $canonical = (.Paginate (partial "blog-list-posts" .)).URL | absURL }}
+    {{ end }}
+    <link rel="canonical" href="{{ $canonical | replaceRE "/$" "" }}" />
   {{ end }}
 
   {{/* Cookie management */}}