From f68bac809ffb500765d6f4e81f68edb05bd48e05 Mon Sep 17 00:00:00 2001
From: Leon Mika <lmika@lmika.org>
Date: Sun, 22 Mar 2026 14:38:39 +1100
Subject: [PATCH] feat: add pagination to generated site category pages

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
---
 .../templates/categories_single.html          |  8 +-
 providers/sitebuilder/builder.go              | 75 +++++++++++++++----
 providers/sitebuilder/tmpls.go                |  3 +
 3 files changed, 71 insertions(+), 15 deletions(-)

diff --git a/layouts/simplecss/templates/categories_single.html b/layouts/simplecss/templates/categories_single.html
index deaeb02..e9e7116 100644
--- a/layouts/simplecss/templates/categories_single.html
+++ b/layouts/simplecss/templates/categories_single.html
@@ -8,4 +8,10 @@
     {{ .HTML }}
     {{ template "_post_meta.html" . }}
   </div>
-{{ end }}
\ No newline at end of file
+{{ end }}
+{{ if or .PrevURL .NextURL }}
+<nav class="pagination">
+  {{ if .PrevURL }}<a href="{{ .PrevURL }}">← Newer posts</a>{{ end }}
+  {{ if .NextURL }}<a href="{{ .NextURL }}">Older posts →</a>{{ end }}
+</nav>
+{{ end }}
diff --git a/providers/sitebuilder/builder.go b/providers/sitebuilder/builder.go
index 601db41..f18e00d 100644
--- a/providers/sitebuilder/builder.go
+++ b/providers/sitebuilder/builder.go
@@ -372,7 +372,8 @@ func (b *Builder) renderCategoryPages(ctx buildContext, goCtx context.Context) e
 			continue
 		}
 
-		var posts []postSingleData
+		// Collect all posts for this category
+		var allPosts []postSingleData
 		for mp := range b.site.PostIterByCategory(goCtx, cwc.ID) {
 			post, err := mp.Get()
 			if err != nil {
@@ -382,7 +383,7 @@ func (b *Builder) renderCategoryPages(ctx buildContext, goCtx context.Context) e
 			if err != nil {
 				return err
 			}
-			posts = append(posts, rp)
+			allPosts = append(allPosts, rp)
 		}
 
 		var descHTML bytes.Buffer
@@ -392,22 +393,68 @@ func (b *Builder) renderCategoryPages(ctx buildContext, goCtx context.Context) e
 			}
 		}
 
-		data := categorySingleData{
-			commonData:      commonData{Site: b.site},
-			Category:        &cwc.Category,
-			DescriptionHTML: template.HTML(descHTML.String()),
-			Posts:           posts,
-			Path:            fmt.Sprintf("/categories/%s", cwc.Slug),
+		postsPerPage := b.site.PostsPerPage
+		if postsPerPage < 1 {
+			postsPerPage = 10
 		}
 
-		if err := b.createAtPath(ctx, data.Path, func(f io.Writer) error {
-			return b.renderTemplate(f, tmplNameCategorySingle, data)
-		}); err != nil {
-			return err
+		totalPages := (len(allPosts) + postsPerPage - 1) / postsPerPage
+		if totalPages < 1 {
+			totalPages = 1
 		}
 
-		// Per-category feeds
-		if err := b.renderCategoryFeed(ctx, cwc, posts); err != nil {
+		basePath := fmt.Sprintf("/categories/%s", cwc.Slug)
+
+		for page := 1; page <= totalPages; page++ {
+			start := (page - 1) * postsPerPage
+			end := start + postsPerPage
+			if end > len(allPosts) {
+				end = len(allPosts)
+			}
+
+			pageInfo := models.PageInfo{
+				CurrentPage:  page,
+				TotalPages:   totalPages,
+				PostsPerPage: postsPerPage,
+			}
+
+			var prevURL, nextURL string
+			if page > 1 {
+				if page == 2 {
+					prevURL = basePath + "/"
+				} else {
+					prevURL = fmt.Sprintf("%s/page/%d/", basePath, page-1)
+				}
+			}
+			if page < totalPages {
+				nextURL = fmt.Sprintf("%s/page/%d/", basePath, page+1)
+			}
+
+			path := basePath
+			if page > 1 {
+				path = fmt.Sprintf("%s/page/%d", basePath, page)
+			}
+
+			data := categorySingleData{
+				commonData:      commonData{Site: b.site},
+				Category:        &cwc.Category,
+				DescriptionHTML: template.HTML(descHTML.String()),
+				Posts:           allPosts[start:end],
+				Path:            path,
+				PageInfo:        pageInfo,
+				PrevURL:         prevURL,
+				NextURL:         nextURL,
+			}
+
+			if err := b.createAtPath(ctx, path, func(f io.Writer) error {
+				return b.renderTemplate(f, tmplNameCategorySingle, data)
+			}); err != nil {
+				return err
+			}
+		}
+
+		// Per-category feeds (use all posts, not paginated)
+		if err := b.renderCategoryFeed(ctx, cwc, allPosts); err != nil {
 			return err
 		}
 	}
diff --git a/providers/sitebuilder/tmpls.go b/providers/sitebuilder/tmpls.go
index 2ba1c74..e0ece37 100644
--- a/providers/sitebuilder/tmpls.go
+++ b/providers/sitebuilder/tmpls.go
@@ -88,4 +88,7 @@ type categorySingleData struct {
 	DescriptionHTML template.HTML
 	Posts           []postSingleData
 	Path            string
+	PageInfo        models.PageInfo
+	PrevURL         string
+	NextURL         string
 }