fix: improve error handling in categories service

- Slug collision checks now properly propagate real DB errors instead of
  silently ignoring them
- GetCategory now verifies site ownership, matching the pattern used by
  UpdateCategory and DeleteCategory

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

cmds/server.go

@@ -109,9 +109,10 @@ Starting weiro without any arguments will start the server.
 
 			ih := handlers.IndexHandler{SiteService: svcs.Sites}
 			lh := handlers.LoginHandler{Config: cfg, AuthService: svcs.Auth}
-			ph := handlers.PostsHandler{PostService: svcs.Posts}
+			ph := handlers.PostsHandler{PostService: svcs.Posts, CategoryService: svcs.Categories}
 			uh := handlers.UploadsHandler{UploadsService: svcs.Uploads}
 			ssh := handlers.SiteSettingsHandler{SiteService: svcs.Sites}
+			ch := handlers.CategoriesHandler{CategoryService: svcs.Categories}
 
 			app.Get("/login", lh.Login)
 			app.Post("/login", lh.DoLogin)
@@ -141,6 +142,13 @@ Starting weiro without any arguments will start the server.
 			siteGroup.Get("/settings", ssh.General)
 			siteGroup.Post("/settings", ssh.UpdateGeneral)
 
+			siteGroup.Get("/categories", ch.Index)
+			siteGroup.Get("/categories/new", ch.New)
+			siteGroup.Get("/categories/:categoryID", ch.Edit)
+			siteGroup.Post("/categories", ch.Create)
+			siteGroup.Post("/categories/:categoryID", ch.Update)
+			siteGroup.Post("/categories/:categoryID/delete", ch.Delete)
+
 			app.Get("/", middleware.OptionalUser(svcs.Auth), ih.Index)
 			app.Get("/first-run", ih.FirstRun)
 			app.Post("/first-run", ih.FirstRunSubmit)

docs/superpowers/specs/2026-03-18-categories-design.md

@@ -17,6 +17,7 @@ CREATE TABLE categories (
     slug        TEXT    NOT NULL,
     description TEXT    NOT NULL DEFAULT '',
     created_at  INTEGER NOT NULL,
+    updated_at  INTEGER NOT NULL,
     FOREIGN KEY (site_id) REFERENCES sites (id) ON DELETE CASCADE
 );
 CREATE INDEX idx_categories_site ON categories (site_id);
@@ -44,11 +45,13 @@ type Category struct {
     Slug        string    `json:"slug"`
     Description string    `json:"description"`
     CreatedAt   time.Time `json:"created_at"`
+    UpdatedAt   time.Time `json:"updated_at"`
 }
 ```
 
 - `slug` is auto-generated from `name` (e.g. "Go Programming" -> `go-programming`), editable by the user.
 - `description` is Markdown, rendered on the category archive page. Defaults to empty string.
+- DB provider must use the existing `timeToInt()`/`time.Unix()` helpers for timestamp conversion, consistent with how posts are handled.
 
 ## Admin UI
 
@@ -66,7 +69,7 @@ Templates: `views/categories/index.html`, `views/categories/edit.html`.
 
 ### Post Edit Form Changes
 
-- A multi-select checkbox list of all available categories, displayed in a **right sidebar** alongside the main title/body editing area on the left.
+- A multi-select checkbox list of all available categories (sorted alphabetically by name), displayed in a **right sidebar** alongside the main title/body editing area on the left.
 - Selected category IDs sent with the form submission.
 - `CreatePostParams` gains `CategoryIDs []int64`.
 
@@ -114,8 +117,8 @@ New file: `sql/queries/categories.sql`
 - `SelectCategory` — single category by ID
 - `SelectCategoryByGUID` — single category by GUID
 - `SelectCategoriesOfPost` — categories for a given post (via join table)
-- `SelectPostsOfCategory` — published, non-deleted posts in a category, ordered by `published_at` desc
-- `CountPostsOfCategory` — count of published posts per category
+- `SelectPostsOfCategory` — published, non-deleted posts in a category (`state = 0 AND deleted_at = 0`), ordered by `published_at` desc
+- `CountPostsOfCategory` — count of published posts per category (same `state = 0 AND deleted_at = 0` filter)
 - `InsertCategory` / `UpdateCategory` / `DeleteCategory` — CRUD
 - `InsertPostCategory` / `DeletePostCategory` — manage the join table
 - `DeletePostCategoriesByPost` — clear all categories for a post (delete-then-reinsert on save)
@@ -128,25 +131,28 @@ New file: `sql/queries/categories.sql`
 
 - `ListCategories(ctx) ([]Category, error)` — all categories for the current site (from context)
 - `GetCategory(ctx, id) (*Category, error)`
-- `CreateCategory(ctx, params) (*Category, error)` — auto-generates slug from name
-- `UpdateCategory(ctx, params) (*Category, error)`
+- `CreateCategory(ctx, params) (*Category, error)` — auto-generates slug from name. If the slug collides with an existing one for the same site, return a validation error.
+- `UpdateCategory(ctx, params) (*Category, error)` — same slug collision check on update.
 - `DeleteCategory(ctx, id) error` — deletes category and post associations, queues site rebuild
 
+All mutation methods verify site ownership (same pattern as post service authorization checks).
+
 ### Changes to `services/posts`
 
-- `UpdatePost` — after saving the post, deletes existing `post_categories` rows and re-inserts for the selected category IDs
+- `UpdatePost` — after saving the post, deletes existing `post_categories` rows and re-inserts for the selected category IDs. The post save and category reassignment must run within a single database transaction to ensure atomicity.
 - `GetPost` / `ListPosts` — loads each post's categories for admin display
 
 ### Changes to Publishing Pipeline
 
 - `pubmodel.Site` gains new fields:
-  - Category list (with post counts and description excerpts for the index page)
-  - A function to iterate published posts by category
+  - `Categories []CategoryWithCount` — category list with post counts and description excerpts for the index page
+  - `PostIterByCategory func(ctx context.Context, categoryID int64) iter.Seq[models.Maybe[*models.Post]]` — iterator for posts in a specific category
 - `sitebuilder.Builder.BuildSite` gains additional goroutines for:
   - Rendering the category index page
   - Rendering each category archive page
   - Rendering per-category feeds
-- New templates: `tmplNameCategoryList`, `tmplNameCategorySingle`
+- New templates: `tmplNameCategoryList`, `tmplNameCategorySingle` (must be added to the `ParseFS` call in `sitebuilder.New()`)
+- `postSingleData` gains a `Categories []Category` field so post templates can render category links
 
 ### Rebuild Triggers
 
@@ -155,3 +161,9 @@ Saving or deleting a category queues a site rebuild, same as post state changes.
 ## DB Provider
 
 `providers/db/` gains wrapper methods for all new sqlc queries, following the same pattern as existing post methods (e.g. `SaveCategory`, `SelectCategoriesOfPost`, etc.).
+
+## Design Decisions
+
+- **Hard delete for categories** — unlike posts which use soft-delete, categories are hard-deleted. They are simpler entities and don't need a trash/restore workflow.
+- **No sort_order column** — categories are sorted alphabetically by name. Manual ordering can be added later if needed.
+- **Existing microblog-crosspost feed** — kept as-is. Per-category feeds are a separate, additive feature.

handlers/categories.go

@@ -0,0 +1,101 @@
+package handlers
+
+import (
+	"fmt"
+	"strconv"
+
+	"github.com/gofiber/fiber/v3"
+	"lmika.dev/lmika/weiro/models"
+	"lmika.dev/lmika/weiro/services/categories"
+)
+
+type CategoriesHandler struct {
+	CategoryService *categories.Service
+}
+
+func (ch CategoriesHandler) Index(c fiber.Ctx) error {
+	cats, err := ch.CategoryService.ListCategoriesWithCounts(c.Context())
+	if err != nil {
+		return err
+	}
+
+	return c.Render("categories/index", fiber.Map{
+		"categories": cats,
+	})
+}
+
+func (ch CategoriesHandler) New(c fiber.Ctx) error {
+	cat := models.Category{
+		GUID: models.NewNanoID(),
+	}
+	return c.Render("categories/edit", fiber.Map{
+		"category": cat,
+		"isNew":    true,
+	})
+}
+
+func (ch CategoriesHandler) Edit(c fiber.Ctx) error {
+	catID, err := strconv.ParseInt(c.Params("categoryID"), 10, 64)
+	if err != nil {
+		return fiber.ErrBadRequest
+	}
+
+	cat, err := ch.CategoryService.GetCategory(c.Context(), catID)
+	if err != nil {
+		return err
+	}
+
+	return c.Render("categories/edit", fiber.Map{
+		"category": cat,
+		"isNew":    false,
+	})
+}
+
+func (ch CategoriesHandler) Create(c fiber.Ctx) error {
+	var req categories.CreateCategoryParams
+	if err := c.Bind().Body(&req); err != nil {
+		return err
+	}
+
+	_, err := ch.CategoryService.CreateCategory(c.Context(), req)
+	if err != nil {
+		return err
+	}
+
+	site := models.MustGetSite(c.Context())
+	return c.Redirect().To(fmt.Sprintf("/sites/%v/categories", site.ID))
+}
+
+func (ch CategoriesHandler) Update(c fiber.Ctx) error {
+	catID, err := strconv.ParseInt(c.Params("categoryID"), 10, 64)
+	if err != nil {
+		return fiber.ErrBadRequest
+	}
+
+	var req categories.CreateCategoryParams
+	if err := c.Bind().Body(&req); err != nil {
+		return err
+	}
+
+	_, err = ch.CategoryService.UpdateCategory(c.Context(), catID, req)
+	if err != nil {
+		return err
+	}
+
+	site := models.MustGetSite(c.Context())
+	return c.Redirect().To(fmt.Sprintf("/sites/%v/categories", site.ID))
+}
+
+func (ch CategoriesHandler) Delete(c fiber.Ctx) error {
+	catID, err := strconv.ParseInt(c.Params("categoryID"), 10, 64)
+	if err != nil {
+		return fiber.ErrBadRequest
+	}
+
+	if err := ch.CategoryService.DeleteCategory(c.Context(), catID); err != nil {
+		return err
+	}
+
+	site := models.MustGetSite(c.Context())
+	return c.Redirect().To(fmt.Sprintf("/sites/%v/categories", site.ID))
+}

handlers/posts.go

@@ -6,11 +6,13 @@ import (
 
 	"github.com/gofiber/fiber/v3"
 	"lmika.dev/lmika/weiro/models"
+	"lmika.dev/lmika/weiro/services/categories"
 	"lmika.dev/lmika/weiro/services/posts"
 )
 
 type PostsHandler struct {
 	PostService     *posts.Service
+	CategoryService *categories.Service
 }
 
 func (ph PostsHandler) Index(c fiber.Ctx) error {
@@ -42,8 +44,15 @@ func (ph PostsHandler) New(c fiber.Ctx) error {
 		State: models.StateDraft,
 	}
 
+	cats, err := ph.CategoryService.ListCategories(c.Context())
+	if err != nil {
+		return err
+	}
+
 	return c.Render("posts/edit", fiber.Map{
 		"post":               p,
+		"categories":         cats,
+		"selectedCategories": map[int64]bool{},
 	})
 }
 
@@ -62,11 +71,28 @@ func (ph PostsHandler) Edit(c fiber.Ctx) error {
 		return err
 	}
 
+	cats, err := ph.CategoryService.ListCategories(c.Context())
+	if err != nil {
+		return err
+	}
+
+	postCats, err := ph.PostService.GetPostCategories(c.Context(), postID)
+	if err != nil {
+		return err
+	}
+
+	selectedCategories := make(map[int64]bool)
+	for _, pc := range postCats {
+		selectedCategories[pc.ID] = true
+	}
+
 	return accepts(c, json(func() any {
 		return post
 	}), html(func(c fiber.Ctx) error {
 		return c.Render("posts/edit", fiber.Map{
 			"post":               post,
+			"categories":         cats,
+			"selectedCategories": selectedCategories,
 		})
 	}))
 }

layouts/simplecss/categories_list.html

@@ -0,0 +1,9 @@
+<h2>Categories</h2>
+<ul>
+{{ range .Categories }}
+  <li>
+    <a href="{{ url_abs .Path }}">{{ .Name }}</a> ({{ .PostCount }})
+    {{ if .DescriptionBrief }}<br><small>{{ .DescriptionBrief }}</small>{{ end }}
+  </li>
+{{ end }}
+</ul>

layouts/simplecss/categories_single.html

@@ -0,0 +1,16 @@
+<h2>{{ .Category.Name }}</h2>
+{{ if .DescriptionHTML }}
+  <div>{{ .DescriptionHTML }}</div>
+{{ end }}
+{{ range .Posts }}
+  {{ if .Post.Title }}<h3>{{ .Post.Title }}</h3>{{ end }}
+  {{ .HTML }}
+  <a href="{{ url_abs .Path }}">{{ format_date .Post.PublishedAt }}</a>
+  {{ if .Categories }}
+    <p>
+    {{ range .Categories }}
+      <a href="{{ url_abs (printf "/categories/%s" .Slug) }}">{{ .Name }}</a>
+    {{ end }}
+    </p>
+  {{ end }}
+{{ end }}

layouts/simplecss/posts_list.html

@@ -2,4 +2,11 @@
   {{ if .Post.Title }}<h3>{{ .Post.Title }}</h3>{{ end }}
   {{ .HTML }}
   <a href="{{ url_abs .Path }}">{{ format_date .Post.PublishedAt }}</a>
+  {{ if .Categories }}
+    <p>
+    {{ range .Categories }}
+      <a href="{{ url_abs (printf "/categories/%s" .Slug) }}">{{ .Name }}</a>
+    {{ end }}
+    </p>
+  {{ end }}
 {{ end }}

layouts/simplecss/posts_single.html

@@ -1,3 +1,10 @@
 {{ if .Post.Title }}<h3>{{ .Post.Title }}</h3>{{ end }}
 {{ .HTML }}
 <a href="{{ url_abs .Path }}">{{ format_date .Post.PublishedAt }}</a>
+{{ if .Categories }}
+  <p>
+  {{ range .Categories }}
+    <a href="{{ url_abs (printf "/categories/%s" .Slug) }}">{{ .Name }}</a>
+  {{ end }}
+  </p>
+{{ end }}

models/categories.go

@@ -0,0 +1,61 @@
+package models
+
+import (
+	"strings"
+	"time"
+	"unicode"
+)
+
+type Category struct {
+	ID          int64     `json:"id"`
+	SiteID      int64     `json:"site_id"`
+	GUID        string    `json:"guid"`
+	Name        string    `json:"name"`
+	Slug        string    `json:"slug"`
+	Description string    `json:"description"`
+	CreatedAt   time.Time `json:"created_at"`
+	UpdatedAt   time.Time `json:"updated_at"`
+}
+
+// CategoryWithCount is a Category plus the count of published posts in it.
+type CategoryWithCount struct {
+	Category
+	PostCount        int
+	DescriptionBrief string
+}
+
+// GenerateCategorySlug creates a URL-safe slug from a category name.
+// e.g. "Go Programming" -> "go-programming"
+func GenerateCategorySlug(name string) string {
+	var sb strings.Builder
+	prevDash := false
+	for _, c := range strings.TrimSpace(name) {
+		if unicode.IsLetter(c) || unicode.IsNumber(c) {
+			sb.WriteRune(unicode.ToLower(c))
+			prevDash = false
+		} else if unicode.IsSpace(c) || c == '-' || c == '_' {
+			if !prevDash && sb.Len() > 0 {
+				sb.WriteRune('-')
+				prevDash = true
+			}
+		}
+	}
+	result := sb.String()
+	return strings.TrimRight(result, "-")
+}
+
+// BriefDescription returns the first sentence or line of the description.
+func BriefDescription(desc string) string {
+	if desc == "" {
+		return ""
+	}
+	for i, c := range desc {
+		if c == '\n' {
+			return desc[:i]
+		}
+		if c == '.' && i+1 < len(desc) {
+			return desc[:i+1]
+		}
+	}
+	return desc
+}

models/categories_test.go

@@ -0,0 +1,28 @@
+package models_test
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"lmika.dev/lmika/weiro/models"
+)
+
+func TestGenerateCategorySlug(t *testing.T) {
+	tests := []struct {
+		name string
+		want string
+	}{
+		{"Go Programming", "go-programming"},
+		{"  Travel  ", "travel"},
+		{"hello---world", "hello-world"},
+		{"UPPER CASE", "upper-case"},
+		{"one", "one"},
+		{"with_underscores", "with-underscores"},
+		{"special!@#chars", "specialchars"},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			assert.Equal(t, tt.want, models.GenerateCategorySlug(tt.name))
+		})
+	}
+}

models/errors.go

@@ -7,3 +7,4 @@ var PermissionError = errors.New("permission denied")
 var NotFoundError = errors.New("not found")
 var SiteRequiredError = errors.New("site required")
 var DeleteDebounceError = errors.New("permanent delete too soon, try again in a few seconds")
+var SlugConflictError = errors.New("a category with this slug already exists")

models/pubmodel/sites.go

@@ -11,11 +11,11 @@ import (
 type Site struct {
 	models.Site
 	BaseURL string
-	//Posts   []*models.Post
 	Uploads []models.Upload
 
 	OpenUpload         func(u models.Upload) (io.ReadCloser, error)
-
-	// PostItr returns a new post iterator
 	PostIter           func(ctx context.Context) iter.Seq[models.Maybe[*models.Post]]
+	Categories         []models.CategoryWithCount
+	PostIterByCategory func(ctx context.Context, categoryID int64) iter.Seq[models.Maybe[*models.Post]]
+	CategoriesOfPost   func(ctx context.Context, postID int64) ([]*models.Category, error)
 }

providers/db/categories.go

@@ -0,0 +1,132 @@
+package db
+
+import (
+	"context"
+	"time"
+
+	"lmika.dev/lmika/weiro/models"
+	"lmika.dev/lmika/weiro/providers/db/gen/sqlgen"
+)
+
+func (db *Provider) SelectCategoriesOfSite(ctx context.Context, siteID int64) ([]*models.Category, error) {
+	rows, err := db.queries.SelectCategoriesOfSite(ctx, siteID)
+	if err != nil {
+		return nil, err
+	}
+	cats := make([]*models.Category, len(rows))
+	for i, row := range rows {
+		cats[i] = dbCategoryToCategory(row)
+	}
+	return cats, nil
+}
+
+func (db *Provider) SelectCategory(ctx context.Context, id int64) (*models.Category, error) {
+	row, err := db.queries.SelectCategory(ctx, id)
+	if err != nil {
+		return nil, err
+	}
+	return dbCategoryToCategory(row), nil
+}
+
+func (db *Provider) SelectCategoryBySlugAndSite(ctx context.Context, siteID int64, slug string) (*models.Category, error) {
+	row, err := db.queries.SelectCategoryBySlugAndSite(ctx, sqlgen.SelectCategoryBySlugAndSiteParams{
+		SiteID: siteID,
+		Slug:   slug,
+	})
+	if err != nil {
+		return nil, err
+	}
+	return dbCategoryToCategory(row), nil
+}
+
+func (db *Provider) SaveCategory(ctx context.Context, cat *models.Category) error {
+	if cat.ID == 0 {
+		newID, err := db.queries.InsertCategory(ctx, sqlgen.InsertCategoryParams{
+			SiteID:      cat.SiteID,
+			Guid:        cat.GUID,
+			Name:        cat.Name,
+			Slug:        cat.Slug,
+			Description: cat.Description,
+			CreatedAt:   timeToInt(cat.CreatedAt),
+			UpdatedAt:   timeToInt(cat.UpdatedAt),
+		})
+		if err != nil {
+			return err
+		}
+		cat.ID = newID
+		return nil
+	}
+
+	return db.queries.UpdateCategory(ctx, sqlgen.UpdateCategoryParams{
+		ID:          cat.ID,
+		Name:        cat.Name,
+		Slug:        cat.Slug,
+		Description: cat.Description,
+		UpdatedAt:   timeToInt(cat.UpdatedAt),
+	})
+}
+
+func (db *Provider) DeleteCategory(ctx context.Context, id int64) error {
+	return db.queries.DeleteCategory(ctx, id)
+}
+
+func (db *Provider) SelectCategoriesOfPost(ctx context.Context, postID int64) ([]*models.Category, error) {
+	rows, err := db.queries.SelectCategoriesOfPost(ctx, postID)
+	if err != nil {
+		return nil, err
+	}
+	cats := make([]*models.Category, len(rows))
+	for i, row := range rows {
+		cats[i] = dbCategoryToCategory(row)
+	}
+	return cats, nil
+}
+
+func (db *Provider) SelectPostsOfCategory(ctx context.Context, categoryID int64, pp PagingParams) ([]*models.Post, error) {
+	rows, err := db.queries.SelectPostsOfCategory(ctx, sqlgen.SelectPostsOfCategoryParams{
+		CategoryID: categoryID,
+		Limit:      pp.Limit,
+		Offset:     pp.Offset,
+	})
+	if err != nil {
+		return nil, err
+	}
+	posts := make([]*models.Post, len(rows))
+	for i, row := range rows {
+		posts[i] = dbPostToPost(row)
+	}
+	return posts, nil
+}
+
+func (db *Provider) CountPostsOfCategory(ctx context.Context, categoryID int64) (int64, error) {
+	return db.queries.CountPostsOfCategory(ctx, categoryID)
+}
+
+// SetPostCategories replaces all category associations for a post.
+func (db *Provider) SetPostCategories(ctx context.Context, postID int64, categoryIDs []int64) error {
+	if err := db.queries.DeletePostCategoriesByPost(ctx, postID); err != nil {
+		return err
+	}
+	for _, catID := range categoryIDs {
+		if err := db.queries.InsertPostCategory(ctx, sqlgen.InsertPostCategoryParams{
+			PostID:     postID,
+			CategoryID: catID,
+		}); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func dbCategoryToCategory(row sqlgen.Category) *models.Category {
+	return &models.Category{
+		ID:          row.ID,
+		SiteID:      row.SiteID,
+		GUID:        row.Guid,
+		Name:        row.Name,
+		Slug:        row.Slug,
+		Description: row.Description,
+		CreatedAt:   time.Unix(row.CreatedAt, 0).UTC(),
+		UpdatedAt:   time.Unix(row.UpdatedAt, 0).UTC(),
+	}
+}

providers/db/gen/sqlgen/categories.sql.go

@@ -0,0 +1,305 @@
+// Code generated by sqlc. DO NOT EDIT.
+// versions:
+//   sqlc v1.28.0
+// source: categories.sql
+
+package sqlgen
+
+import (
+	"context"
+)
+
+const countPostsOfCategory = `-- name: CountPostsOfCategory :one
+SELECT COUNT(*) FROM posts p
+INNER JOIN post_categories pc ON pc.post_id = p.id
+WHERE pc.category_id = ? AND p.state = 0 AND p.deleted_at = 0
+`
+
+func (q *Queries) CountPostsOfCategory(ctx context.Context, categoryID int64) (int64, error) {
+	row := q.db.QueryRowContext(ctx, countPostsOfCategory, categoryID)
+	var count int64
+	err := row.Scan(&count)
+	return count, err
+}
+
+const deleteCategory = `-- name: DeleteCategory :exec
+DELETE FROM categories WHERE id = ?
+`
+
+func (q *Queries) DeleteCategory(ctx context.Context, id int64) error {
+	_, err := q.db.ExecContext(ctx, deleteCategory, id)
+	return err
+}
+
+const deletePostCategoriesByPost = `-- name: DeletePostCategoriesByPost :exec
+DELETE FROM post_categories WHERE post_id = ?
+`
+
+func (q *Queries) DeletePostCategoriesByPost(ctx context.Context, postID int64) error {
+	_, err := q.db.ExecContext(ctx, deletePostCategoriesByPost, postID)
+	return err
+}
+
+const insertCategory = `-- name: InsertCategory :one
+INSERT INTO categories (
+    site_id, guid, name, slug, description, created_at, updated_at
+) VALUES (?, ?, ?, ?, ?, ?, ?)
+RETURNING id
+`
+
+type InsertCategoryParams struct {
+	SiteID      int64
+	Guid        string
+	Name        string
+	Slug        string
+	Description string
+	CreatedAt   int64
+	UpdatedAt   int64
+}
+
+func (q *Queries) InsertCategory(ctx context.Context, arg InsertCategoryParams) (int64, error) {
+	row := q.db.QueryRowContext(ctx, insertCategory,
+		arg.SiteID,
+		arg.Guid,
+		arg.Name,
+		arg.Slug,
+		arg.Description,
+		arg.CreatedAt,
+		arg.UpdatedAt,
+	)
+	var id int64
+	err := row.Scan(&id)
+	return id, err
+}
+
+const insertPostCategory = `-- name: InsertPostCategory :exec
+INSERT OR IGNORE INTO post_categories (post_id, category_id) VALUES (?, ?)
+`
+
+type InsertPostCategoryParams struct {
+	PostID     int64
+	CategoryID int64
+}
+
+func (q *Queries) InsertPostCategory(ctx context.Context, arg InsertPostCategoryParams) error {
+	_, err := q.db.ExecContext(ctx, insertPostCategory, arg.PostID, arg.CategoryID)
+	return err
+}
+
+const selectCategoriesOfPost = `-- name: SelectCategoriesOfPost :many
+SELECT c.id, c.site_id, c.guid, c.name, c.slug, c.description, c.created_at, c.updated_at FROM categories c
+INNER JOIN post_categories pc ON pc.category_id = c.id
+WHERE pc.post_id = ?
+ORDER BY c.name ASC
+`
+
+func (q *Queries) SelectCategoriesOfPost(ctx context.Context, postID int64) ([]Category, error) {
+	rows, err := q.db.QueryContext(ctx, selectCategoriesOfPost, postID)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	var items []Category
+	for rows.Next() {
+		var i Category
+		if err := rows.Scan(
+			&i.ID,
+			&i.SiteID,
+			&i.Guid,
+			&i.Name,
+			&i.Slug,
+			&i.Description,
+			&i.CreatedAt,
+			&i.UpdatedAt,
+		); err != nil {
+			return nil, err
+		}
+		items = append(items, i)
+	}
+	if err := rows.Close(); err != nil {
+		return nil, err
+	}
+	if err := rows.Err(); err != nil {
+		return nil, err
+	}
+	return items, nil
+}
+
+const selectCategoriesOfSite = `-- name: SelectCategoriesOfSite :many
+SELECT id, site_id, guid, name, slug, description, created_at, updated_at FROM categories
+WHERE site_id = ? ORDER BY name ASC
+`
+
+func (q *Queries) SelectCategoriesOfSite(ctx context.Context, siteID int64) ([]Category, error) {
+	rows, err := q.db.QueryContext(ctx, selectCategoriesOfSite, siteID)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	var items []Category
+	for rows.Next() {
+		var i Category
+		if err := rows.Scan(
+			&i.ID,
+			&i.SiteID,
+			&i.Guid,
+			&i.Name,
+			&i.Slug,
+			&i.Description,
+			&i.CreatedAt,
+			&i.UpdatedAt,
+		); err != nil {
+			return nil, err
+		}
+		items = append(items, i)
+	}
+	if err := rows.Close(); err != nil {
+		return nil, err
+	}
+	if err := rows.Err(); err != nil {
+		return nil, err
+	}
+	return items, nil
+}
+
+const selectCategory = `-- name: SelectCategory :one
+SELECT id, site_id, guid, name, slug, description, created_at, updated_at FROM categories WHERE id = ? LIMIT 1
+`
+
+func (q *Queries) SelectCategory(ctx context.Context, id int64) (Category, error) {
+	row := q.db.QueryRowContext(ctx, selectCategory, id)
+	var i Category
+	err := row.Scan(
+		&i.ID,
+		&i.SiteID,
+		&i.Guid,
+		&i.Name,
+		&i.Slug,
+		&i.Description,
+		&i.CreatedAt,
+		&i.UpdatedAt,
+	)
+	return i, err
+}
+
+const selectCategoryByGUID = `-- name: SelectCategoryByGUID :one
+SELECT id, site_id, guid, name, slug, description, created_at, updated_at FROM categories WHERE guid = ? LIMIT 1
+`
+
+func (q *Queries) SelectCategoryByGUID(ctx context.Context, guid string) (Category, error) {
+	row := q.db.QueryRowContext(ctx, selectCategoryByGUID, guid)
+	var i Category
+	err := row.Scan(
+		&i.ID,
+		&i.SiteID,
+		&i.Guid,
+		&i.Name,
+		&i.Slug,
+		&i.Description,
+		&i.CreatedAt,
+		&i.UpdatedAt,
+	)
+	return i, err
+}
+
+const selectCategoryBySlugAndSite = `-- name: SelectCategoryBySlugAndSite :one
+SELECT id, site_id, guid, name, slug, description, created_at, updated_at FROM categories WHERE site_id = ? AND slug = ? LIMIT 1
+`
+
+type SelectCategoryBySlugAndSiteParams struct {
+	SiteID int64
+	Slug   string
+}
+
+func (q *Queries) SelectCategoryBySlugAndSite(ctx context.Context, arg SelectCategoryBySlugAndSiteParams) (Category, error) {
+	row := q.db.QueryRowContext(ctx, selectCategoryBySlugAndSite, arg.SiteID, arg.Slug)
+	var i Category
+	err := row.Scan(
+		&i.ID,
+		&i.SiteID,
+		&i.Guid,
+		&i.Name,
+		&i.Slug,
+		&i.Description,
+		&i.CreatedAt,
+		&i.UpdatedAt,
+	)
+	return i, err
+}
+
+const selectPostsOfCategory = `-- name: SelectPostsOfCategory :many
+SELECT p.id, p.site_id, p.state, p.guid, p.title, p.body, p.slug, p.created_at, p.updated_at, p.published_at, p.deleted_at FROM posts p
+INNER JOIN post_categories pc ON pc.post_id = p.id
+WHERE pc.category_id = ? AND p.state = 0 AND p.deleted_at = 0
+ORDER BY p.published_at DESC
+LIMIT ? OFFSET ?
+`
+
+type SelectPostsOfCategoryParams struct {
+	CategoryID int64
+	Limit      int64
+	Offset     int64
+}
+
+func (q *Queries) SelectPostsOfCategory(ctx context.Context, arg SelectPostsOfCategoryParams) ([]Post, error) {
+	rows, err := q.db.QueryContext(ctx, selectPostsOfCategory, arg.CategoryID, arg.Limit, arg.Offset)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	var items []Post
+	for rows.Next() {
+		var i Post
+		if err := rows.Scan(
+			&i.ID,
+			&i.SiteID,
+			&i.State,
+			&i.Guid,
+			&i.Title,
+			&i.Body,
+			&i.Slug,
+			&i.CreatedAt,
+			&i.UpdatedAt,
+			&i.PublishedAt,
+			&i.DeletedAt,
+		); err != nil {
+			return nil, err
+		}
+		items = append(items, i)
+	}
+	if err := rows.Close(); err != nil {
+		return nil, err
+	}
+	if err := rows.Err(); err != nil {
+		return nil, err
+	}
+	return items, nil
+}
+
+const updateCategory = `-- name: UpdateCategory :exec
+UPDATE categories SET
+    name = ?,
+    slug = ?,
+    description = ?,
+    updated_at = ?
+WHERE id = ?
+`
+
+type UpdateCategoryParams struct {
+	Name        string
+	Slug        string
+	Description string
+	UpdatedAt   int64
+	ID          int64
+}
+
+func (q *Queries) UpdateCategory(ctx context.Context, arg UpdateCategoryParams) error {
+	_, err := q.db.ExecContext(ctx, updateCategory,
+		arg.Name,
+		arg.Slug,
+		arg.Description,
+		arg.UpdatedAt,
+		arg.ID,
+	)
+	return err
+}

providers/db/gen/sqlgen/db.go

@@ -1,6 +1,6 @@
 // Code generated by sqlc. DO NOT EDIT.
 // versions:
-//   sqlc v1.30.0
+//   sqlc v1.28.0
 
 package sqlgen
 

providers/db/gen/sqlgen/models.go

@@ -1,9 +1,20 @@
 // Code generated by sqlc. DO NOT EDIT.
 // versions:
-//   sqlc v1.30.0
+//   sqlc v1.28.0
 
 package sqlgen
 
+type Category struct {
+	ID          int64
+	SiteID      int64
+	Guid        string
+	Name        string
+	Slug        string
+	Description string
+	CreatedAt   int64
+	UpdatedAt   int64
+}
+
 type PendingUpload struct {
 	ID              int64
 	SiteID          int64
@@ -29,6 +40,11 @@ type Post struct {
 	DeletedAt   int64
 }
 
+type PostCategory struct {
+	PostID     int64
+	CategoryID int64
+}
+
 type PublishTarget struct {
 	ID         int64
 	SiteID     int64

providers/db/gen/sqlgen/pending_uploads.sql.go

@@ -1,6 +1,6 @@
 // Code generated by sqlc. DO NOT EDIT.
 // versions:
-//   sqlc v1.30.0
+//   sqlc v1.28.0
 // source: pending_uploads.sql
 
 package sqlgen

providers/db/gen/sqlgen/posts.sql.go

@@ -1,6 +1,6 @@
 // Code generated by sqlc. DO NOT EDIT.
 // versions:
-//   sqlc v1.30.0
+//   sqlc v1.28.0
 // source: posts.sql
 
 package sqlgen

providers/db/gen/sqlgen/pubtargets.sql.go

@@ -1,6 +1,6 @@
 // Code generated by sqlc. DO NOT EDIT.
 // versions:
-//   sqlc v1.30.0
+//   sqlc v1.28.0
 // source: pubtargets.sql
 
 package sqlgen

providers/db/gen/sqlgen/sites.sql.go

@@ -1,6 +1,6 @@
 // Code generated by sqlc. DO NOT EDIT.
 // versions:
-//   sqlc v1.30.0
+//   sqlc v1.28.0
 // source: sites.sql
 
 package sqlgen

providers/db/gen/sqlgen/uploads.sql.go

@@ -1,6 +1,6 @@
 // Code generated by sqlc. DO NOT EDIT.
 // versions:
-//   sqlc v1.30.0
+//   sqlc v1.28.0
 // source: uploads.sql
 
 package sqlgen

providers/db/gen/sqlgen/users.sql.go

@@ -1,6 +1,6 @@
 // Code generated by sqlc. DO NOT EDIT.
 // versions:
-//   sqlc v1.30.0
+//   sqlc v1.28.0
 // source: users.sql
 
 package sqlgen

providers/db/provider.go

@@ -40,6 +40,17 @@ func (db *Provider) Close() error {
 	return db.drvr.Close()
 }
 
+func (db *Provider) BeginTx(ctx context.Context) (*sql.Tx, error) {
+	return db.drvr.BeginTx(ctx, nil)
+}
+
+func (db *Provider) QueriesWithTx(tx *sql.Tx) *Provider {
+	return &Provider{
+		drvr:    db.drvr,
+		queries: db.queries.WithTx(tx),
+	}
+}
+
 func (db *Provider) SoftDeletePost(ctx context.Context, postID int64) error {
 	return db.queries.SoftDeletePost(ctx, sqlgen.SoftDeletePostParams{
 		DeletedAt: time.Now().Unix(),

providers/db/provider_test.go

@@ -158,7 +158,7 @@ func TestProvider_Posts(t *testing.T) {
 		require.NoError(t, err)
 		assert.NotZero(t, post.ID)
 
-		posts, err := p.SelectPostsOfSite(ctx, site.ID, false)
+		posts, err := p.SelectPostsOfSite(ctx, site.ID, false, db.PagingParams{})
 		require.NoError(t, err)
 		require.Len(t, posts, 1)
 		assert.Equal(t, post.ID, posts[0].ID)
@@ -205,7 +205,7 @@ func TestProvider_Posts(t *testing.T) {
 		require.NoError(t, p.SavePost(ctx, post1))
 		require.NoError(t, p.SavePost(ctx, post2))
 
-		posts, err := p.SelectPostsOfSite(ctx, site2.ID, false)
+		posts, err := p.SelectPostsOfSite(ctx, site2.ID, false, db.PagingParams{})
 		require.NoError(t, err)
 		require.Len(t, posts, 2)
 		assert.Equal(t, "New Post", posts[0].Title)
@@ -220,7 +220,7 @@ func TestProvider_Posts(t *testing.T) {
 		}
 		require.NoError(t, p.SaveSite(ctx, emptySite))
 
-		posts, err := p.SelectPostsOfSite(ctx, emptySite.ID, false)
+		posts, err := p.SelectPostsOfSite(ctx, emptySite.ID, false, db.PagingParams{})
 		require.NoError(t, err)
 		assert.Empty(t, posts)
 	})
@@ -283,6 +283,165 @@ func TestProvider_PublishTargets(t *testing.T) {
 	})
 }
 
+func TestProvider_Categories(t *testing.T) {
+	ctx := context.Background()
+	p := newTestDB(t)
+
+	user := &models.User{Username: "testuser", PasswordHashed: []byte("password")}
+	require.NoError(t, p.SaveUser(ctx, user))
+
+	site := &models.Site{OwnerID: user.ID, Title: "My Blog", Tagline: "test"}
+	require.NoError(t, p.SaveSite(ctx, site))
+
+	t.Run("save and select categories", func(t *testing.T) {
+		now := time.Date(2026, 3, 18, 12, 0, 0, 0, time.UTC)
+		cat := &models.Category{
+			SiteID:      site.ID,
+			GUID:        "cat-001",
+			Name:        "Go Programming",
+			Slug:        "go-programming",
+			Description: "Posts about Go",
+			CreatedAt:   now,
+			UpdatedAt:   now,
+		}
+
+		err := p.SaveCategory(ctx, cat)
+		require.NoError(t, err)
+		assert.NotZero(t, cat.ID)
+
+		cats, err := p.SelectCategoriesOfSite(ctx, site.ID)
+		require.NoError(t, err)
+		require.Len(t, cats, 1)
+		assert.Equal(t, "Go Programming", cats[0].Name)
+		assert.Equal(t, "go-programming", cats[0].Slug)
+		assert.Equal(t, "Posts about Go", cats[0].Description)
+	})
+
+	t.Run("update category", func(t *testing.T) {
+		now := time.Date(2026, 3, 18, 12, 0, 0, 0, time.UTC)
+		cat := &models.Category{
+			SiteID:    site.ID,
+			GUID:      "cat-002",
+			Name:      "Original",
+			Slug:      "original",
+			CreatedAt: now,
+			UpdatedAt: now,
+		}
+		require.NoError(t, p.SaveCategory(ctx, cat))
+
+		cat.Name = "Updated"
+		cat.Slug = "updated"
+		cat.UpdatedAt = now.Add(time.Hour)
+		require.NoError(t, p.SaveCategory(ctx, cat))
+
+		got, err := p.SelectCategory(ctx, cat.ID)
+		require.NoError(t, err)
+		assert.Equal(t, "Updated", got.Name)
+		assert.Equal(t, "updated", got.Slug)
+	})
+
+	t.Run("delete category", func(t *testing.T) {
+		now := time.Date(2026, 3, 18, 12, 0, 0, 0, time.UTC)
+		cat := &models.Category{
+			SiteID:    site.ID,
+			GUID:      "cat-003",
+			Name:      "ToDelete",
+			Slug:      "to-delete",
+			CreatedAt: now,
+			UpdatedAt: now,
+		}
+		require.NoError(t, p.SaveCategory(ctx, cat))
+
+		err := p.DeleteCategory(ctx, cat.ID)
+		require.NoError(t, err)
+
+		_, err = p.SelectCategory(ctx, cat.ID)
+		assert.Error(t, err)
+	})
+}
+
+func TestProvider_PostCategories(t *testing.T) {
+	ctx := context.Background()
+	p := newTestDB(t)
+
+	user := &models.User{Username: "testuser", PasswordHashed: []byte("password")}
+	require.NoError(t, p.SaveUser(ctx, user))
+
+	site := &models.Site{OwnerID: user.ID, Title: "My Blog", Tagline: "test"}
+	require.NoError(t, p.SaveSite(ctx, site))
+
+	now := time.Date(2026, 3, 18, 12, 0, 0, 0, time.UTC)
+	post := &models.Post{
+		SiteID:    site.ID,
+		GUID:      "post-pc-001",
+		Title:     "Test Post",
+		Body:      "body",
+		Slug:      "/test",
+		CreatedAt: now,
+	}
+	require.NoError(t, p.SavePost(ctx, post))
+
+	cat1 := &models.Category{SiteID: site.ID, GUID: "cat-pc-1", Name: "Alpha", Slug: "alpha", CreatedAt: now, UpdatedAt: now}
+	cat2 := &models.Category{SiteID: site.ID, GUID: "cat-pc-2", Name: "Beta", Slug: "beta", CreatedAt: now, UpdatedAt: now}
+	require.NoError(t, p.SaveCategory(ctx, cat1))
+	require.NoError(t, p.SaveCategory(ctx, cat2))
+
+	t.Run("set and get post categories", func(t *testing.T) {
+		err := p.SetPostCategories(ctx, post.ID, []int64{cat1.ID, cat2.ID})
+		require.NoError(t, err)
+
+		cats, err := p.SelectCategoriesOfPost(ctx, post.ID)
+		require.NoError(t, err)
+		require.Len(t, cats, 2)
+		assert.Equal(t, "Alpha", cats[0].Name)
+		assert.Equal(t, "Beta", cats[1].Name)
+	})
+
+	t.Run("replace post categories", func(t *testing.T) {
+		err := p.SetPostCategories(ctx, post.ID, []int64{cat2.ID})
+		require.NoError(t, err)
+
+		cats, err := p.SelectCategoriesOfPost(ctx, post.ID)
+		require.NoError(t, err)
+		require.Len(t, cats, 1)
+		assert.Equal(t, "Beta", cats[0].Name)
+	})
+
+	t.Run("clear post categories", func(t *testing.T) {
+		err := p.SetPostCategories(ctx, post.ID, []int64{})
+		require.NoError(t, err)
+
+		cats, err := p.SelectCategoriesOfPost(ctx, post.ID)
+		require.NoError(t, err)
+		assert.Empty(t, cats)
+	})
+
+	t.Run("count posts of category", func(t *testing.T) {
+		post.State = models.StatePublished
+		post.PublishedAt = now
+		require.NoError(t, p.SavePost(ctx, post))
+		require.NoError(t, p.SetPostCategories(ctx, post.ID, []int64{cat1.ID}))
+
+		count, err := p.CountPostsOfCategory(ctx, cat1.ID)
+		require.NoError(t, err)
+		assert.Equal(t, int64(1), count)
+
+		count, err = p.CountPostsOfCategory(ctx, cat2.ID)
+		require.NoError(t, err)
+		assert.Equal(t, int64(0), count)
+	})
+
+	t.Run("cascade delete category removes associations", func(t *testing.T) {
+		require.NoError(t, p.SetPostCategories(ctx, post.ID, []int64{cat1.ID, cat2.ID}))
+		require.NoError(t, p.DeleteCategory(ctx, cat1.ID))
+
+		cats, err := p.SelectCategoriesOfPost(ctx, post.ID)
+		require.NoError(t, err)
+		require.Len(t, cats, 1)
+		assert.Equal(t, "Beta", cats[0].Name)
+	})
+}
+
 // Verify that password encoding roundtrips correctly through base64
 func TestProvider_UserPasswordEncoding(t *testing.T) {
 	ctx := context.Background()

providers/sitebuilder/builder.go

@@ -31,7 +31,7 @@ type Builder struct {
 func New(site pubmodel.Site, opts Options) (*Builder, error) {
 	tmpls, err := template.New("").
 		Funcs(templateFns(site, opts)).
-		ParseFS(opts.TemplatesFS, tmplNamePostSingle, tmplNamePostList, tmplNameLayoutMain)
+		ParseFS(opts.TemplatesFS, tmplNamePostSingle, tmplNamePostList, tmplNameLayoutMain, tmplNameCategoryList, tmplNameCategorySingle)
 	if err != nil {
 		return nil, err
 	}
@@ -62,7 +62,13 @@ func (b *Builder) BuildSite(outDir string) error {
 			if err != nil {
 				return err
 			}
-			if err := b.writePost(buildCtx, post); err != nil {
+			rp, err := b.renderPostWithCategories(ctx, post)
+			if err != nil {
+				return err
+			}
+			if err := b.createAtPath(buildCtx, rp.Path, func(f io.Writer) error {
+				return b.renderTemplate(f, tmplNamePostSingle, rp)
+			}); err != nil {
 				return err
 			}
 		}
@@ -70,10 +76,7 @@ func (b *Builder) BuildSite(outDir string) error {
 	})
 
 	eg.Go(func() error {
-		if err := b.renderPostList(buildCtx, b.site.PostIter(ctx)); err != nil {
-			return err
-		}
-		return nil
+		return b.renderPostListWithCategories(buildCtx, ctx)
 	})
 
 	eg.Go(func() error {
@@ -93,43 +96,42 @@ func (b *Builder) BuildSite(outDir string) error {
 		return nil
 	})
 
+	// Category pages
+	eg.Go(func() error {
+		if err := b.renderCategoryList(buildCtx); err != nil {
+			return err
+		}
+		return b.renderCategoryPages(buildCtx, ctx)
+	})
+
 	// Copy uploads
 	eg.Go(func() error {
-		if err := b.writeUploads(buildCtx, b.site.Uploads); err != nil {
-			return err
-		}
-		return nil
+		return b.writeUploads(buildCtx, b.site.Uploads)
 	})
-	if err := eg.Wait(); err != nil {
-		return err
+
+	return eg.Wait()
 }
 
-	return nil
-}
-
-func (b *Builder) renderPostList(ctx buildContext, postIter iter.Seq[models.Maybe[*models.Post]]) error {
-	// TODO: paging
-	postCopy := make([]*models.Post, 0)
-	for mp := range postIter {
+func (b *Builder) renderPostListWithCategories(bctx buildContext, ctx context.Context) error {
+	var posts []postSingleData
+	for mp := range b.site.PostIter(ctx) {
 		post, err := mp.Get()
 		if err != nil {
 			return err
 		}
-		postCopy = append(postCopy, post)
+		rp, err := b.renderPostWithCategories(ctx, post)
+		if err != nil {
+			return err
+		}
+		posts = append(posts, rp)
 	}
 
 	pl := postListData{
 		commonData: commonData{Site: b.site},
-	}
-	for _, post := range postCopy {
-		rp, err := b.renderPost(post)
-		if err != nil {
-			return err
-		}
-		pl.Posts = append(pl.Posts, rp)
+		Posts:      posts,
 	}
 
-	return b.createAtPath(ctx, "", func(f io.Writer) error {
+	return b.createAtPath(bctx, "", func(f io.Writer) error {
 		return b.renderTemplate(f, tmplNamePostList, pl)
 	})
 }
@@ -156,6 +158,18 @@ func (b *Builder) renderFeeds(ctx buildContext, postIter iter.Seq[models.Maybe[*
 			return err
 		}
 
+		var catName string
+		if b.site.CategoriesOfPost != nil {
+			cats, err := b.site.CategoriesOfPost(context.Background(), post.ID)
+			if err == nil && len(cats) > 0 {
+				names := make([]string, len(cats))
+				for i, c := range cats {
+					names[i] = c.Name
+				}
+				catName = strings.Join(names, ", ")
+			}
+		}
+
 		postTitle := post.Title
 		if postTitle != "" {
 			postTitle = opts.titlePrefix + postTitle
@@ -166,6 +180,7 @@ func (b *Builder) renderFeeds(ctx buildContext, postIter iter.Seq[models.Maybe[*
 			Title:    postTitle,
 			Link:     &feedhub.Link{Href: renderedPost.PostURL},
 			Content:  string(renderedPost.HTML),
+			Category: catName,
 			// TO FIX: Created should be first published
 			Created: post.PublishedAt,
 			Updated: post.UpdatedAt,
@@ -243,14 +258,142 @@ func (b *Builder) renderPost(post *models.Post) (postSingleData, error) {
 	}, nil
 }
 
-func (b *Builder) writePost(ctx buildContext, post *models.Post) error {
+// renderPostWithCategories renders a post and attaches its categories.
+func (b *Builder) renderPostWithCategories(ctx context.Context, post *models.Post) (postSingleData, error) {
 	rp, err := b.renderPost(post)
+	if err != nil {
+		return postSingleData{}, err
+	}
+
+	if b.site.CategoriesOfPost != nil {
+		cats, err := b.site.CategoriesOfPost(ctx, post.ID)
+		if err != nil {
+			return postSingleData{}, err
+		}
+		rp.Categories = cats
+	}
+
+	return rp, nil
+}
+
+func (b *Builder) renderCategoryList(ctx buildContext) error {
+	var items []categoryListItem
+	for _, cwc := range b.site.Categories {
+		if cwc.PostCount == 0 {
+			continue
+		}
+		items = append(items, categoryListItem{
+			CategoryWithCount: cwc,
+			Path:              fmt.Sprintf("/categories/%s", cwc.Slug),
+		})
+	}
+
+	if len(items) == 0 {
+		return nil
+	}
+
+	data := categoryListData{
+		commonData: commonData{Site: b.site},
+		Categories: items,
+	}
+
+	return b.createAtPath(ctx, "/categories", func(f io.Writer) error {
+		return b.renderTemplate(f, tmplNameCategoryList, data)
+	})
+}
+
+func (b *Builder) renderCategoryPages(ctx buildContext, goCtx context.Context) error {
+	for _, cwc := range b.site.Categories {
+		if cwc.PostCount == 0 {
+			continue
+		}
+
+		var posts []postSingleData
+		for mp := range b.site.PostIterByCategory(goCtx, cwc.ID) {
+			post, err := mp.Get()
 			if err != nil {
 				return err
 			}
+			rp, err := b.renderPostWithCategories(goCtx, post)
+			if err != nil {
+				return err
+			}
+			posts = append(posts, rp)
+		}
 
-	return b.createAtPath(ctx, rp.Path, func(f io.Writer) error {
-		return b.renderTemplate(f, tmplNamePostSingle, rp)
+		var descHTML bytes.Buffer
+		if cwc.Description != "" {
+			if err := b.mdRenderer.RenderTo(goCtx, &descHTML, cwc.Description); err != nil {
+				return err
+			}
+		}
+
+		data := categorySingleData{
+			commonData:      commonData{Site: b.site},
+			Category:        &cwc.Category,
+			DescriptionHTML: template.HTML(descHTML.String()),
+			Posts:           posts,
+			Path:            fmt.Sprintf("/categories/%s", cwc.Slug),
+		}
+
+		if err := b.createAtPath(ctx, data.Path, func(f io.Writer) error {
+			return b.renderTemplate(f, tmplNameCategorySingle, data)
+		}); err != nil {
+			return err
+		}
+
+		// Per-category feeds
+		if err := b.renderCategoryFeed(ctx, cwc, posts); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func (b *Builder) renderCategoryFeed(ctx buildContext, cwc models.CategoryWithCount, posts []postSingleData) error {
+	now := time.Now()
+	feed := &feedhub.Feed{
+		Title:       b.site.Title + " - " + cwc.Name,
+		Link:        &feedhub.Link{Href: b.site.BaseURL},
+		Description: cwc.DescriptionBrief,
+		Created:     now,
+	}
+
+	for i, rp := range posts {
+		if i >= b.opts.FeedItems {
+			break
+		}
+		feed.Items = append(feed.Items, &feedhub.Item{
+			Id:      filepath.Join(b.site.BaseURL, rp.Post.GUID),
+			Title:   rp.Post.Title,
+			Link:    &feedhub.Link{Href: rp.PostURL},
+			Content: string(rp.HTML),
+			Created: rp.Post.PublishedAt,
+			Updated: rp.Post.UpdatedAt,
+		})
+	}
+
+	prefix := fmt.Sprintf("/categories/%s/feed", cwc.Slug)
+
+	if err := b.createAtPath(ctx, prefix+".xml", func(f io.Writer) error {
+		rss, err := feed.ToRss()
+		if err != nil {
+			return err
+		}
+		_, err = io.WriteString(f, rss)
+		return err
+	}); err != nil {
+		return err
+	}
+
+	return b.createAtPath(ctx, prefix+".json", func(f io.Writer) error {
+		j, err := feed.ToJSON()
+		if err != nil {
+			return err
+		}
+		_, err = io.WriteString(f, j)
+		return err
 	})
 }
 

providers/sitebuilder/builder_test.go

@@ -1,6 +1,8 @@
 package sitebuilder_test
 
 import (
+	"context"
+	"iter"
 	"os"
 	"path/filepath"
 	"testing"
@@ -18,11 +20,11 @@ func TestBuilder_BuildSite(t *testing.T) {
 			"posts_single.html":      {Data: []byte(`{{ .HTML }}`)},
 			"posts_list.html":        {Data: []byte(`{{ range .Posts}}<a href="{{url_abs .Path}}">{{.Post.Title}}</a>,{{ end }}`)},
 			"layout_main.html":       {Data: []byte(`{{ .Body }}`)},
+			"categories_list.html":   {Data: []byte(`{{ range .Categories}}<a href="{{url_abs .Path}}">{{.Name}}</a>,{{ end }}`)},
+			"categories_single.html": {Data: []byte(`<h2>{{.Category.Name}}</h2>`)},
 		}
 
-		site := pubmodel.Site{
-			BaseURL: "https://example.com",
-			Posts: []*models.Post{
+		posts := []*models.Post{
 			{
 				Title: "Test Post",
 				Slug:  "/2026/02/18/test-post",
@@ -33,6 +35,18 @@ func TestBuilder_BuildSite(t *testing.T) {
 				Slug:  "/2026/02/20/another-post",
 				Body:  "This is **another** test post",
 			},
+		}
+
+		site := pubmodel.Site{
+			BaseURL: "https://example.com",
+			PostIter: func(ctx context.Context) iter.Seq[models.Maybe[*models.Post]] {
+				return func(yield func(models.Maybe[*models.Post]) bool) {
+					for _, p := range posts {
+						if !yield(models.Maybe[*models.Post]{Value: p}) {
+							return
+						}
+					}
+				}
 			},
 		}
 		wantFiles := map[string]string{
@@ -58,5 +72,4 @@ func TestBuilder_BuildSite(t *testing.T) {
 			assert.Equal(t, content, string(fileContent))
 		}
 	})
-
 }

providers/sitebuilder/tmpls.go

@@ -20,6 +20,12 @@ const (
 
 	// tmplNameLayoutMain is the template for the main layout (layoutMainData)
 	tmplNameLayoutMain = "layout_main.html"
+
+	// tmplNameCategoryList is the template for the category index page
+	tmplNameCategoryList = "categories_list.html"
+
+	// tmplNameCategorySingle is the template for a single category page
+	tmplNameCategorySingle = "categories_single.html"
 )
 
 type Options struct {
@@ -45,6 +51,7 @@ type postSingleData struct {
 	HTML       template.HTML
 	Path       string
 	PostURL    string
+	Categories []*models.Category
 }
 
 type postListData struct {
@@ -56,3 +63,21 @@ type layoutData struct {
 	commonData
 	Body template.HTML
 }
+
+type categoryListData struct {
+	commonData
+	Categories []categoryListItem
+}
+
+type categoryListItem struct {
+	models.CategoryWithCount
+	Path string
+}
+
+type categorySingleData struct {
+	commonData
+	Category        *models.Category
+	DescriptionHTML template.HTML
+	Posts           []postSingleData
+	Path            string
+}

services/categories/service.go

@@ -0,0 +1,178 @@
+package categories
+
+import (
+	"context"
+	"time"
+
+	"lmika.dev/lmika/weiro/models"
+	"lmika.dev/lmika/weiro/providers/db"
+	"lmika.dev/lmika/weiro/services/publisher"
+)
+
+type CreateCategoryParams struct {
+	GUID        string `form:"guid" json:"guid"`
+	Name        string `form:"name" json:"name"`
+	Slug        string `form:"slug" json:"slug"`
+	Description string `form:"description" json:"description"`
+}
+
+type Service struct {
+	db        *db.Provider
+	publisher *publisher.Queue
+}
+
+func New(db *db.Provider, publisher *publisher.Queue) *Service {
+	return &Service{db: db, publisher: publisher}
+}
+
+func (s *Service) ListCategories(ctx context.Context) ([]*models.Category, error) {
+	site, ok := models.GetSite(ctx)
+	if !ok {
+		return nil, models.SiteRequiredError
+	}
+	return s.db.SelectCategoriesOfSite(ctx, site.ID)
+}
+
+// ListCategoriesWithCounts returns all categories for the site with published post counts.
+func (s *Service) ListCategoriesWithCounts(ctx context.Context) ([]models.CategoryWithCount, error) {
+	site, ok := models.GetSite(ctx)
+	if !ok {
+		return nil, models.SiteRequiredError
+	}
+
+	cats, err := s.db.SelectCategoriesOfSite(ctx, site.ID)
+	if err != nil {
+		return nil, err
+	}
+
+	result := make([]models.CategoryWithCount, len(cats))
+	for i, cat := range cats {
+		count, err := s.db.CountPostsOfCategory(ctx, cat.ID)
+		if err != nil {
+			return nil, err
+		}
+		result[i] = models.CategoryWithCount{
+			Category:         *cat,
+			PostCount:        int(count),
+			DescriptionBrief: models.BriefDescription(cat.Description),
+		}
+	}
+	return result, nil
+}
+
+func (s *Service) GetCategory(ctx context.Context, id int64) (*models.Category, error) {
+	site, ok := models.GetSite(ctx)
+	if !ok {
+		return nil, models.SiteRequiredError
+	}
+
+	cat, err := s.db.SelectCategory(ctx, id)
+	if err != nil {
+		return nil, err
+	}
+	if cat.SiteID != site.ID {
+		return nil, models.NotFoundError
+	}
+	return cat, nil
+}
+
+func (s *Service) CreateCategory(ctx context.Context, params CreateCategoryParams) (*models.Category, error) {
+	site, ok := models.GetSite(ctx)
+	if !ok {
+		return nil, models.SiteRequiredError
+	}
+
+	now := time.Now()
+	slug := params.Slug
+	if slug == "" {
+		slug = models.GenerateCategorySlug(params.Name)
+	}
+
+	// Check for slug collision
+	if _, err := s.db.SelectCategoryBySlugAndSite(ctx, site.ID, slug); err == nil {
+		return nil, models.SlugConflictError
+	} else if !db.ErrorIsNoRows(err) {
+		return nil, err
+	}
+
+	cat := &models.Category{
+		SiteID:      site.ID,
+		GUID:        params.GUID,
+		Name:        params.Name,
+		Slug:        slug,
+		Description: params.Description,
+		CreatedAt:   now,
+		UpdatedAt:   now,
+	}
+	if cat.GUID == "" {
+		cat.GUID = models.NewNanoID()
+	}
+
+	if err := s.db.SaveCategory(ctx, cat); err != nil {
+		return nil, err
+	}
+
+	s.publisher.Queue(site)
+	return cat, nil
+}
+
+func (s *Service) UpdateCategory(ctx context.Context, id int64, params CreateCategoryParams) (*models.Category, error) {
+	site, ok := models.GetSite(ctx)
+	if !ok {
+		return nil, models.SiteRequiredError
+	}
+
+	cat, err := s.db.SelectCategory(ctx, id)
+	if err != nil {
+		return nil, err
+	}
+	if cat.SiteID != site.ID {
+		return nil, models.NotFoundError
+	}
+
+	slug := params.Slug
+	if slug == "" {
+		slug = models.GenerateCategorySlug(params.Name)
+	}
+
+	// Check slug collision (exclude self)
+	if existing, err := s.db.SelectCategoryBySlugAndSite(ctx, site.ID, slug); err == nil && existing.ID != cat.ID {
+		return nil, models.SlugConflictError
+	} else if err != nil && !db.ErrorIsNoRows(err) {
+		return nil, err
+	}
+
+	cat.Name = params.Name
+	cat.Slug = slug
+	cat.Description = params.Description
+	cat.UpdatedAt = time.Now()
+
+	if err := s.db.SaveCategory(ctx, cat); err != nil {
+		return nil, err
+	}
+
+	s.publisher.Queue(site)
+	return cat, nil
+}
+
+func (s *Service) DeleteCategory(ctx context.Context, id int64) error {
+	site, ok := models.GetSite(ctx)
+	if !ok {
+		return models.SiteRequiredError
+	}
+
+	cat, err := s.db.SelectCategory(ctx, id)
+	if err != nil {
+		return err
+	}
+	if cat.SiteID != site.ID {
+		return models.NotFoundError
+	}
+
+	if err := s.db.DeleteCategory(ctx, id); err != nil {
+		return err
+	}
+
+	s.publisher.Queue(site)
+	return nil
+}

services/posts/create.go

@@ -14,6 +14,7 @@ type CreatePostParams struct {
 	Title       string  `form:"title" json:"title"`
 	Body        string  `form:"body" json:"body"`
 	Action      string  `form:"action" json:"action"`
+	CategoryIDs []int64 `form:"category_ids" json:"category_ids"`
 }
 
 func (s *Service) UpdatePost(ctx context.Context, params CreatePostParams) (*models.Post, error) {
@@ -53,7 +54,21 @@ func (s *Service) UpdatePost(ctx context.Context, params CreatePostParams) (*mod
 		// Leave unchanged
 	}
 
-	if err := s.db.SavePost(ctx, post); err != nil {
+	// Use a transaction for atomicity of post save + category reassignment
+	tx, err := s.db.BeginTx(ctx)
+	if err != nil {
+		return nil, err
+	}
+	defer tx.Rollback()
+
+	txDB := s.db.QueriesWithTx(tx)
+	if err := txDB.SavePost(ctx, post); err != nil {
+		return nil, err
+	}
+	if err := txDB.SetPostCategories(ctx, post.ID, params.CategoryIDs); err != nil {
+		return nil, err
+	}
+	if err := tx.Commit(); err != nil {
 		return nil, err
 	}
 

services/posts/list.go

@@ -7,7 +7,12 @@ import (
 	"lmika.dev/lmika/weiro/providers/db"
 )
 
-func (s *Service) ListPosts(ctx context.Context, showDeleted bool) ([]*models.Post, error) {
+type PostWithCategories struct {
+	*models.Post
+	Categories []*models.Category
+}
+
+func (s *Service) ListPosts(ctx context.Context, showDeleted bool) ([]*PostWithCategories, error) {
 	site, ok := models.GetSite(ctx)
 	if !ok {
 		return nil, models.SiteRequiredError
@@ -21,7 +26,15 @@ func (s *Service) ListPosts(ctx context.Context, showDeleted bool) ([]*models.Po
 		return nil, err
 	}
 
-	return posts, nil
+	result := make([]*PostWithCategories, len(posts))
+	for i, post := range posts {
+		cats, err := s.db.SelectCategoriesOfPost(ctx, post.ID)
+		if err != nil {
+			return nil, err
+		}
+		result[i] = &PostWithCategories{Post: post, Categories: cats}
+	}
+	return result, nil
 }
 
 func (s *Service) GetPost(ctx context.Context, pid int64) (*models.Post, error) {
@@ -32,3 +45,7 @@ func (s *Service) GetPost(ctx context.Context, pid int64) (*models.Post, error)
 
 	return post, nil
 }
+
+func (s *Service) GetPostCategories(ctx context.Context, postID int64) ([]*models.Category, error) {
+	return s.db.SelectCategoriesOfPost(ctx, postID)
+}

services/publisher/iter.go

@@ -8,7 +8,7 @@ import (
 	"lmika.dev/lmika/weiro/providers/db"
 )
 
-// PostIter returns a post iterator which returns posts in reverse chronological order.
+// postIter returns a post iterator which returns posts in reverse chronological order.
 func (s *Publisher) postIter(ctx context.Context, site int64) iter.Seq[models.Maybe[*models.Post]] {
 	return func(yield func(models.Maybe[*models.Post]) bool) {
 		paging := db.PagingParams{Offset: 0, Limit: 50}
@@ -39,3 +39,26 @@ func (s *Publisher) postIter(ctx context.Context, site int64) iter.Seq[models.Ma
 		}
 	}
 }
+
+// postIterByCategory returns a post iterator for posts in a specific category.
+func (s *Publisher) postIterByCategory(ctx context.Context, categoryID int64) iter.Seq[models.Maybe[*models.Post]] {
+	return func(yield func(models.Maybe[*models.Post]) bool) {
+		paging := db.PagingParams{Offset: 0, Limit: 50}
+		for {
+			page, err := s.db.SelectPostsOfCategory(ctx, categoryID, paging)
+			if err != nil {
+				yield(models.Maybe[*models.Post]{Err: err})
+				return
+			}
+			if len(page) == 0 {
+				return
+			}
+			for _, post := range page {
+				if !yield(models.Maybe[*models.Post]{Value: post}) {
+					return
+				}
+			}
+			paging.Offset += paging.Limit
+		}
+	}
+}

services/publisher/service.go

@@ -46,6 +46,24 @@ func (p *Publisher) Publish(ctx context.Context, site models.Site) error {
 		return err
 	}
 
+	// Fetch categories with counts
+	cats, err := p.db.SelectCategoriesOfSite(ctx, site.ID)
+	if err != nil {
+		return err
+	}
+	var catsWithCounts []models.CategoryWithCount
+	for _, cat := range cats {
+		count, err := p.db.CountPostsOfCategory(ctx, cat.ID)
+		if err != nil {
+			return err
+		}
+		catsWithCounts = append(catsWithCounts, models.CategoryWithCount{
+			Category:         *cat,
+			PostCount:        int(count),
+			DescriptionBrief: models.BriefDescription(cat.Description),
+		})
+	}
+
 	for _, target := range targets {
 		if !target.Enabled {
 			continue
@@ -58,6 +76,13 @@ func (p *Publisher) Publish(ctx context.Context, site models.Site) error {
 			},
 			BaseURL:    target.BaseURL,
 			Uploads:    uploads,
+			Categories: catsWithCounts,
+			PostIterByCategory: func(ctx context.Context, categoryID int64) iter.Seq[models.Maybe[*models.Post]] {
+				return p.postIterByCategory(ctx, categoryID)
+			},
+			CategoriesOfPost: func(ctx context.Context, postID int64) ([]*models.Category, error) {
+				return p.db.SelectCategoriesOfPost(ctx, postID)
+			},
 			OpenUpload: func(u models.Upload) (io.ReadCloser, error) {
 				return p.up.OpenUpload(site, u)
 			},

services/services.go

@@ -7,6 +7,7 @@ import (
 	"lmika.dev/lmika/weiro/providers/db"
 	"lmika.dev/lmika/weiro/providers/uploadfiles"
 	"lmika.dev/lmika/weiro/services/auth"
+	"lmika.dev/lmika/weiro/services/categories"
 	"lmika.dev/lmika/weiro/services/posts"
 	"lmika.dev/lmika/weiro/services/publisher"
 	"lmika.dev/lmika/weiro/services/sites"
@@ -21,6 +22,7 @@ type Services struct {
 	Posts          *posts.Service
 	Sites          *sites.Service
 	Uploads        *uploads.Service
+	Categories     *categories.Service
 }
 
 func New(cfg config.Config) (*Services, error) {
@@ -37,6 +39,7 @@ func New(cfg config.Config) (*Services, error) {
 	postService := posts.New(dbp, publisherQueue)
 	siteService := sites.New(dbp)
 	uploadService := uploads.New(dbp, ufp, filepath.Join(cfg.ScratchDir, "uploads", "pending"))
+	categoriesService := categories.New(dbp, publisherQueue)
 
 	return &Services{
 		DB:             dbp,
@@ -46,6 +49,7 @@ func New(cfg config.Config) (*Services, error) {
 		Posts:          postService,
 		Sites:          siteService,
 		Uploads:        uploadService,
+		Categories:     categoriesService,
 	}, nil
 }
 

sql/queries/categories.sql

@@ -0,0 +1,53 @@
+-- name: SelectCategoriesOfSite :many
+SELECT * FROM categories
+WHERE site_id = ? ORDER BY name ASC;
+
+-- name: SelectCategory :one
+SELECT * FROM categories WHERE id = ? LIMIT 1;
+
+-- name: SelectCategoryByGUID :one
+SELECT * FROM categories WHERE guid = ? LIMIT 1;
+
+-- name: SelectCategoryBySlugAndSite :one
+SELECT * FROM categories WHERE site_id = ? AND slug = ? LIMIT 1;
+
+-- name: SelectCategoriesOfPost :many
+SELECT c.* FROM categories c
+INNER JOIN post_categories pc ON pc.category_id = c.id
+WHERE pc.post_id = ?
+ORDER BY c.name ASC;
+
+-- name: SelectPostsOfCategory :many
+SELECT p.* FROM posts p
+INNER JOIN post_categories pc ON pc.post_id = p.id
+WHERE pc.category_id = ? AND p.state = 0 AND p.deleted_at = 0
+ORDER BY p.published_at DESC
+LIMIT ? OFFSET ?;
+
+-- name: CountPostsOfCategory :one
+SELECT COUNT(*) FROM posts p
+INNER JOIN post_categories pc ON pc.post_id = p.id
+WHERE pc.category_id = ? AND p.state = 0 AND p.deleted_at = 0;
+
+-- name: InsertCategory :one
+INSERT INTO categories (
+    site_id, guid, name, slug, description, created_at, updated_at
+) VALUES (?, ?, ?, ?, ?, ?, ?)
+RETURNING id;
+
+-- name: UpdateCategory :exec
+UPDATE categories SET
+    name = ?,
+    slug = ?,
+    description = ?,
+    updated_at = ?
+WHERE id = ?;
+
+-- name: DeleteCategory :exec
+DELETE FROM categories WHERE id = ?;
+
+-- name: InsertPostCategory :exec
+INSERT OR IGNORE INTO post_categories (post_id, category_id) VALUES (?, ?);
+
+-- name: DeletePostCategoriesByPost :exec
+DELETE FROM post_categories WHERE post_id = ?;

sql/schema/04_categories.up.sql

@@ -0,0 +1,23 @@
+CREATE TABLE categories (
+    id          INTEGER PRIMARY KEY AUTOINCREMENT,
+    site_id     INTEGER NOT NULL,
+    guid        TEXT    NOT NULL,
+    name        TEXT    NOT NULL,
+    slug        TEXT    NOT NULL,
+    description TEXT    NOT NULL DEFAULT '',
+    created_at  INTEGER NOT NULL,
+    updated_at  INTEGER NOT NULL,
+    FOREIGN KEY (site_id) REFERENCES sites (id) ON DELETE CASCADE
+);
+CREATE INDEX idx_categories_site ON categories (site_id);
+CREATE UNIQUE INDEX idx_categories_guid ON categories (guid);
+CREATE UNIQUE INDEX idx_categories_site_slug ON categories (site_id, slug);
+
+CREATE TABLE post_categories (
+    post_id     INTEGER NOT NULL,
+    category_id INTEGER NOT NULL,
+    PRIMARY KEY (post_id, category_id),
+    FOREIGN KEY (post_id) REFERENCES posts (id) ON DELETE CASCADE,
+    FOREIGN KEY (category_id) REFERENCES categories (id) ON DELETE CASCADE
+);
+CREATE INDEX idx_post_categories_category ON post_categories (category_id);

views/_common/nav.html

@@ -10,6 +10,9 @@
         <li class="nav-item">
           <a class="nav-link active" aria-current="page" href="/sites/{{.site.ID}}/posts">Posts</a>
         </li>
+        <li class="nav-item">
+          <a class="nav-link active" aria-current="page" href="/sites/{{.site.ID}}/categories">Categories</a>
+        </li>
         <li class="nav-item">
           <a class="nav-link active" aria-current="page" href="/sites/{{.site.ID}}/uploads">Uploads</a>
         </li>

views/categories/edit.html

@@ -0,0 +1,47 @@
+<main class="container">
+  <div class="my-4">
+    <h4>{{ if .isNew }}New Category{{ else }}Edit Category{{ end }}</h4>
+  </div>
+
+  {{ if .isNew }}
+    <form method="post" action="/sites/{{ .site.ID }}/categories">
+  {{ else }}
+    <form method="post" action="/sites/{{ .site.ID }}/categories/{{ .category.ID }}">
+  {{ end }}
+    <input type="hidden" name="guid" value="{{ .category.GUID }}">
+    <div class="row mb-3">
+      <label for="catName" class="col-sm-2 col-form-label">Name</label>
+      <div class="col-sm-6">
+        <input type="text" class="form-control" id="catName" name="name" value="{{ .category.Name }}">
+      </div>
+    </div>
+    <div class="row mb-3">
+      <label for="catSlug" class="col-sm-2 col-form-label">Slug</label>
+      <div class="col-sm-6">
+        <input type="text" class="form-control" id="catSlug" name="slug" value="{{ .category.Slug }}">
+        <div class="form-text">Auto-generated from name if left blank.</div>
+      </div>
+    </div>
+    <div class="row mb-3">
+      <label for="catDesc" class="col-sm-2 col-form-label">Description</label>
+      <div class="col-sm-9">
+        <textarea class="form-control" id="catDesc" name="description" rows="5">{{ .category.Description }}</textarea>
+        <div class="form-text">Markdown supported. Displayed on the category archive page.</div>
+      </div>
+    </div>
+    <div class="row mb-3">
+      <div class="col-sm-2"></div>
+      <div class="col-sm-9">
+        <button type="submit" class="btn btn-primary">{{ if .isNew }}Create{{ else }}Save{{ end }}</button>
+        {{ if not .isNew }}
+          <button type="button" class="btn btn-outline-danger ms-2"
+                  onclick="if(confirm('Delete this category? Posts will not be deleted.')) { document.getElementById('delete-form').submit(); }">Delete</button>
+        {{ end }}
+      </div>
+    </div>
+  </form>
+
+  {{ if not .isNew }}
+    <form id="delete-form" method="post" action="/sites/{{ .site.ID }}/categories/{{ .category.ID }}/delete" style="display:none;"></form>
+  {{ end }}
+</main>

views/categories/index.html

@@ -0,0 +1,35 @@
+<main class="container">
+  <div class="my-4 d-flex justify-content-between align-items-baseline">
+    <h4>Categories</h4>
+    <div>
+      <a href="/sites/{{ .site.ID }}/categories/new" class="btn btn-success">New Category</a>
+    </div>
+  </div>
+
+  <table class="table">
+    <thead>
+      <tr>
+        <th>Name</th>
+        <th>Slug</th>
+        <th>Posts</th>
+        <th></th>
+      </tr>
+    </thead>
+    <tbody>
+      {{ range .categories }}
+        <tr>
+          <td><a href="/sites/{{ $.site.ID }}/categories/{{ .ID }}">{{ .Name }}</a></td>
+          <td><code>{{ .Slug }}</code></td>
+          <td>{{ .PostCount }}</td>
+          <td>
+            <a href="/sites/{{ $.site.ID }}/categories/{{ .ID }}" class="btn btn-outline-secondary btn-sm">Edit</a>
+          </td>
+        </tr>
+      {{ else }}
+        <tr>
+          <td colspan="4" class="text-center text-muted py-4">No categories yet.</td>
+        </tr>
+      {{ end }}
+    </tbody>
+  </table>
+</main>

views/posts/edit.html

@@ -4,6 +4,8 @@
     data-controller="postedit"
         data-action="keydown.meta+s->postedit#save keydown.meta+enter->postedit#publish"
         data-postedit-save-action-value="{{ if $isPublished }}Update{{ else }}Save Draft{{ end }}">
+    <div class="row">
+      <div class="col-md-9">
         <input type="hidden" name="guid" value="{{ .post.GUID }}">
         <div class="mb-2">
           <input type="text" name="title" class="form-control" placeholder="Title" value="{{ .post.Title }}">
@@ -19,5 +21,24 @@
             <input type="submit" name="action" class="btn btn-secondary mt-2" value="Save Draft">
           {{ end }}
         </div>
+      </div>
+      <div class="col-md-3">
+        <div class="card">
+          <div class="card-header">Categories</div>
+          <div class="card-body">
+            {{ range .categories }}
+              <div class="form-check">
+                <input class="form-check-input" type="checkbox" name="category_ids"
+                       value="{{ .ID }}" id="cat-{{ .ID }}"
+                       {{ if index $.selectedCategories .ID }}checked{{ end }}>
+                <label class="form-check-label" for="cat-{{ .ID }}">{{ .Name }}</label>
+              </div>
+            {{ else }}
+              <span class="text-muted">No categories yet.</span>
+            {{ end }}
+          </div>
+        </div>
+      </div>
+    </div>
   </form>
 </main>

views/posts/index.html

@@ -26,11 +26,14 @@
         {{ if $p.Title }}<h4 class="mb-3">{{ $p.Title }}</h4>{{ end }}
         {{ markdown $p.Body $.site }}
 
-        <div class="mb-3 d-flex align-items-center">
-          {{ if eq .State 1 }}
-            <span class="text-muted">{{ $.user.FormatTime .UpdatedAt }}</span> <span class="ms-3 badge text-primary-emphasis bg-primary-subtle border border-primary-subtle">Draft</span>
+        <div class="mb-3 d-flex align-items-center flex-wrap gap-1">
+          {{ if eq $p.State 1 }}
+            <span class="text-muted">{{ $.user.FormatTime $p.UpdatedAt }}</span> <span class="ms-3 badge text-primary-emphasis bg-primary-subtle border border-primary-subtle">Draft</span>
           {{ else }}
-            <span class="text-muted">{{ $.user.FormatTime .PublishedAt }}</span>
+            <span class="text-muted">{{ $.user.FormatTime $p.PublishedAt }}</span>
+          {{ end }}
+          {{ range $p.Categories }}
+            <span class="ms-1 badge bg-secondary-subtle text-secondary-emphasis border border-secondary-subtle">{{ .Name }}</span>
           {{ end }}
         </div>