diff --git a/Gemfile b/Gemfile
index 349fd2cd..6f52e427 100644
--- a/Gemfile
+++ b/Gemfile
@@ -23,6 +23,7 @@ gem "stimulus-rails"
 
 # Other
 gem "jbuilder"
+gem "prawn", "~> 2.5"
 gem "redcarpet", "~> 3.6"
 gem "rouge", "~> 4.5"
 gem "bcrypt", "~> 3.1.7"
diff --git a/Gemfile.lock b/Gemfile.lock
index 204ec003..0361471f 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -115,7 +115,7 @@ GEM
     ast (2.4.2)
     base64 (0.3.0)
     bcrypt (3.1.22)
-    bigdecimal (4.1.0)
+    bigdecimal (3.3.1)
     bindex (0.8.1)
     brakeman (7.0.2)
       racc
@@ -215,8 +215,13 @@ GEM
     parser (3.3.3.0)
       ast (~> 2.4.1)
       racc
+    pdf-core (0.10.0)
     pp (0.6.3)
       prettyprint
+    prawn (2.5.0)
+      matrix (~> 0.4)
+      pdf-core (~> 0.10.0)
+      ttfunk (~> 1.8)
     prettyprint (0.2.0)
     prism (1.9.0)
     propshaft (1.0.0)
@@ -347,6 +352,8 @@ GEM
     tilt (2.4.0)
     timeout (0.6.1)
     tsort (0.2.0)
+    ttfunk (1.8.0)
+      bigdecimal (~> 3.1)
     turbo-rails (2.0.11)
       actionpack (>= 6.0.0)
       railties (>= 6.0.0)
@@ -386,6 +393,7 @@ DEPENDENCIES
   image_processing (~> 1.13)
   importmap-rails
   jbuilder
+  prawn (~> 2.5)
   propshaft
   puma (~> 7.2, >= 7.2.1)
   rails!
diff --git a/app/assets/fonts/inter/Inter-Bold.ttf b/app/assets/fonts/inter/Inter-Bold.ttf
new file mode 100644
index 00000000..be359192
Binary files /dev/null and b/app/assets/fonts/inter/Inter-Bold.ttf differ
diff --git a/app/assets/fonts/inter/Inter-BoldItalic.ttf b/app/assets/fonts/inter/Inter-BoldItalic.ttf
new file mode 100644
index 00000000..d433dd0d
Binary files /dev/null and b/app/assets/fonts/inter/Inter-BoldItalic.ttf differ
diff --git a/app/assets/fonts/inter/Inter-Italic.ttf b/app/assets/fonts/inter/Inter-Italic.ttf
new file mode 100644
index 00000000..1069d569
Binary files /dev/null and b/app/assets/fonts/inter/Inter-Italic.ttf differ
diff --git a/app/assets/fonts/inter/Inter-Regular.ttf b/app/assets/fonts/inter/Inter-Regular.ttf
new file mode 100644
index 00000000..5ac1f221
Binary files /dev/null and b/app/assets/fonts/inter/Inter-Regular.ttf differ
diff --git a/app/assets/fonts/inter/OFL.txt b/app/assets/fonts/inter/OFL.txt
new file mode 100644
index 00000000..9b2ca37b
--- /dev/null
+++ b/app/assets/fonts/inter/OFL.txt
@@ -0,0 +1,92 @@
+Copyright (c) 2016 The Inter Project Authors (https://github.com/rsms/inter)
+
+This Font Software is licensed under the SIL Open Font License, Version 1.1.
+This license is copied below, and is also available with a FAQ at:
+http://scripts.sil.org/OFL
+
+-----------------------------------------------------------
+SIL OPEN FONT LICENSE Version 1.1 - 26 February 2007
+-----------------------------------------------------------
+
+PREAMBLE
+The goals of the Open Font License (OFL) are to stimulate worldwide
+development of collaborative font projects, to support the font creation
+efforts of academic and linguistic communities, and to provide a free and
+open framework in which fonts may be shared and improved in partnership
+with others.
+
+The OFL allows the licensed fonts to be used, studied, modified and
+redistributed freely as long as they are not sold by themselves. The
+fonts, including any derivative works, can be bundled, embedded,
+redistributed and/or sold with any software provided that any reserved
+names are not used by derivative works. The fonts and derivatives,
+however, cannot be released under any other type of license. The
+requirement for fonts to remain under this license does not apply
+to any document created using the fonts or their derivatives.
+
+DEFINITIONS
+"Font Software" refers to the set of files released by the Copyright
+Holder(s) under this license and clearly marked as such. This may
+include source files, build scripts and documentation.
+
+"Reserved Font Name" refers to any names specified as such after the
+copyright statement(s).
+
+"Original Version" refers to the collection of Font Software components as
+distributed by the Copyright Holder(s).
+
+"Modified Version" refers to any derivative made by adding to, deleting,
+or substituting -- in part or in whole -- any of the components of the
+Original Version, by changing formats or by porting the Font Software to a
+new environment.
+
+"Author" refers to any designer, engineer, programmer, technical
+writer or other person who contributed to the Font Software.
+
+PERMISSION AND CONDITIONS
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of the Font Software, to use, study, copy, merge, embed, modify,
+redistribute, and sell modified and unmodified copies of the Font
+Software, subject to the following conditions:
+
+1) Neither the Font Software nor any of its individual components,
+in Original or Modified Versions, may be sold by itself.
+
+2) Original or Modified Versions of the Font Software may be bundled,
+redistributed and/or sold with any software, provided that each copy
+contains the above copyright notice and this license. These can be
+included either as stand-alone text files, human-readable headers or
+in the appropriate machine-readable metadata fields within text or
+binary files as long as those fields can be easily viewed by the user.
+
+3) No Modified Version of the Font Software may use the Reserved Font
+Name(s) unless explicit written permission is granted by the corresponding
+Copyright Holder. This restriction only applies to the primary font name as
+presented to the users.
+
+4) The name(s) of the Copyright Holder(s) or the Author(s) of the Font
+Software shall not be used to promote, endorse or advertise any
+Modified Version, except to acknowledge the contribution(s) of the
+Copyright Holder(s) and the Author(s) or with their explicit written
+permission.
+
+5) The Font Software, modified or unmodified, in part or in whole,
+must be distributed entirely under this license, and must not be
+distributed under any other license. The requirement for fonts to
+remain under this license does not apply to any document created
+using the Font Software.
+
+TERMINATION
+This license becomes null and void if any of the above conditions are
+not met.
+
+DISCLAIMER
+THE FONT SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
+OF COPYRIGHT, PATENT, TRADEMARK, OR OTHER RIGHT. IN NO EVENT SHALL THE
+COPYRIGHT HOLDER BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+INCLUDING ANY GENERAL, SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL
+DAMAGES, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+FROM, OUT OF THE USE OR INABILITY TO USE THE FONT SOFTWARE OR FROM
+OTHER DEALINGS IN THE FONT SOFTWARE.
diff --git a/app/controllers/books_controller.rb b/app/controllers/books_controller.rb
index eda26210..32101cda 100644
--- a/app/controllers/books_controller.rb
+++ b/app/controllers/books_controller.rb
@@ -27,6 +27,14 @@ def show
     respond_to do |format|
       format.html
       format.md
+      format.pdf do
+        size = pdf_page_size
+        # Conditional GET: skip regeneration when the book is unchanged.
+        if stale?(etag: [ @book, size ], last_modified: @book.updated_at, public: @book.published?)
+          send_data Book::Pdf.new(@book, @leaves, page_size: size).render,
+            filename: pdf_filename(size), type: "application/pdf", disposition: "inline"
+        end
+      end
     end
   end
 
@@ -48,6 +56,15 @@ def destroy
   end
 
   private
+    # Default to US Letter; `.A4.pdf` selects A4 (`.letter.pdf` is the same as `.pdf`).
+    def pdf_page_size
+      params[:size].to_s.casecmp?("A4") ? "A4" : "LETTER"
+    end
+
+    def pdf_filename(size)
+      size == "A4" ? "#{@book.slug}.A4.pdf" : "#{@book.slug}.pdf"
+    end
+
     def set_book
       @book = Book.accessable_or_published.find params[:id]
     end
diff --git a/app/models/book/pdf.rb b/app/models/book/pdf.rb
new file mode 100644
index 00000000..6b316b23
--- /dev/null
+++ b/app/models/book/pdf.rb
@@ -0,0 +1,334 @@
+require "prawn"
+
+# Renders a Book as a PDF: full-bleed cover, table of contents, then one
+# section/page/picture per leaf, with page numbers in the footer. Pure Ruby
+# (Prawn + Nokogiri), so it adds no system dependencies. Reached via the `.pdf`
+# format on books#show, mirroring the `.md` export.
+#
+# Page bodies are markdown; we render that source to HTML with the same renderer
+# the app uses elsewhere (Page.preview_renderer) and walk it with Nokogiri,
+# emitting Prawn text. Images and tables are pulled out and drawn by Prawn
+# directly, since flowing text can't place or size them.
+class Book::Pdf
+  FONT_DIR = Rails.root.join("app/assets/fonts/inter")
+
+  DEFAULT_PAGE_SIZE = "LETTER"
+  MARGIN = 56
+  TOC_PER_PAGE = 30   # conservative, so the TOC never overflows its reserved pages
+  LINE = 18
+  HEADING_SIZES = { "h1" => 18, "h2" => 16, "h3" => 14, "h4" => 13, "h5" => 12, "h6" => 11 }.freeze
+  LIST_INDENT = 16
+  QUOTE_INDENT = 16
+
+  def initialize(book, leaves, page_size: DEFAULT_PAGE_SIZE)
+    @book = book
+    @leaves = leaves.to_a
+    @page_size = page_size
+    @entries = []
+  end
+
+  def render
+    @pdf = Prawn::Document.new(
+      page_size: @page_size, margin: MARGIN,
+      info: { Title: @book.title, Author: @book.author.presence })
+    use_inter_font
+
+    cover_page
+    reserve_toc_pages
+    content_pages
+    fill_toc
+    number_content_pages
+
+    @pdf.render
+  end
+
+  private
+    # Inter (bundled under app/assets/fonts/inter) covers Latin, Greek, Cyrillic,
+    # etc.; Prawn's built-in AFM fonts only cover Windows-1252.
+    def use_inter_font
+      @pdf.font_families.update("Inter" => {
+        normal: FONT_DIR.join("Inter-Regular.ttf").to_s,
+        bold: FONT_DIR.join("Inter-Bold.ttf").to_s,
+        italic: FONT_DIR.join("Inter-Italic.ttf").to_s,
+        bold_italic: FONT_DIR.join("Inter-BoldItalic.ttf").to_s })
+      @pdf.font "Inter"
+    end
+
+    def cover_page
+      @book.cover.attached? ? image_cover(blob_bytes(@book.cover)) : text_cover
+    end
+
+    # Fill the whole page edge-to-edge (cover, cropping overflow), no margins.
+    def image_cover(bytes)
+      width, height = image_dimensions(bytes)
+      return text_cover unless width
+
+      @pdf.canvas do
+        page_w, page_h = @pdf.bounds.width, @pdf.bounds.height
+        scale = [ page_w / width.to_f, page_h / height.to_f ].max
+        w, h = width * scale, height * scale
+        @pdf.image StringIO.new(bytes), width: w, height: h,
+          at: [ (page_w - w) / 2, page_h - (page_h - h) / 2 ]
+      end
+    rescue Prawn::Errors::UnsupportedImageType
+      text_cover
+    end
+
+    def text_cover
+      @pdf.move_down 220
+      @pdf.text @book.title, size: 32, style: :bold, align: :center
+      @pdf.move_down 14
+      @pdf.text @book.subtitle, size: 18, align: :center if @book.subtitle.present?
+      @pdf.move_down 28
+      @pdf.text @book.author, size: 14, align: :center if @book.author.present?
+    end
+
+    # Reserve blank pages now; each leaf's page number isn't known until the
+    # content is laid out, so we go back and fill these in afterwards.
+    def reserve_toc_pages
+      @toc_start = @pdf.page_number + 1
+      @toc_count = [ (@leaves.size / TOC_PER_PAGE.to_f).ceil, 1 ].max
+      @toc_count.times { @pdf.start_new_page }
+      @first_content_page = @pdf.page_number + 1
+    end
+
+    def fill_toc
+      page = @toc_start
+      @pdf.go_to_page(page)
+      @pdf.move_cursor_to @pdf.bounds.top
+      @pdf.text @book.title, size: 22, style: :bold   # header mirrors the web sidebar
+      @pdf.move_down LINE
+
+      @entries.each do |entry|
+        if @pdf.cursor < LINE && page < @toc_start + @toc_count - 1
+          page += 1
+          @pdf.go_to_page(page)
+          @pdf.move_cursor_to @pdf.bounds.top
+        end
+        toc_entry(entry)
+      end
+    end
+
+    NUMBER_WIDTH = 28
+
+    # Flat list of leaf titles, mirroring the web sidebar TOC.
+    def toc_entry(entry)
+      number = (entry[:page] - @first_content_page + 1).to_s
+      style = entry[:section] ? :bold : :normal   # section leaves are bold, like the web
+      title = entry[:title].to_s
+      top = @pdf.cursor
+      right = @pdf.bounds.width
+
+      @pdf.text_box link(entry[:anchor], escape(title)), at: [ 0, top ], inline_format: true,
+        width: right - NUMBER_WIDTH, height: LINE, overflow: :truncate, style: style
+      @pdf.text_box link(entry[:anchor], number), at: [ right - NUMBER_WIDTH, top ], inline_format: true,
+        width: NUMBER_WIDTH, height: LINE, align: :right
+      dotted_leader(@pdf.width_of(title, style: style) + 4, right - NUMBER_WIDTH - 4, top - 12)
+      @pdf.move_down LINE
+    end
+
+    def dotted_leader(from, to, y)
+      return unless to > from
+      @pdf.dash(1, space: 2)
+      @pdf.stroke_color "aaaaaa"
+      @pdf.stroke_horizontal_line from, to, at: y
+      @pdf.stroke_color "000000"
+      @pdf.undash
+    end
+
+    def link(anchor, content)
+      %(<link anchor="#{anchor}">#{content}</link>)
+    end
+
+    def content_pages
+      @leaves.each_with_index do |leaf, index|
+        @pdf.start_new_page
+        anchor = "leaf-#{index}"
+        @entries << { title: leaf.title, page: @pdf.page_number, anchor: anchor, section: leaf.section? }
+        @pdf.add_dest anchor, @pdf.dest_fit
+        render_leaf(leaf)
+      end
+    end
+
+    def render_leaf(leaf)
+      if leaf.section?
+        @pdf.move_down 160
+        @pdf.text leaf.section.body.to_s, size: 26, style: :bold, align: :center
+      elsif leaf.picture?
+        chapter_title leaf.title
+        place_image blob_bytes(leaf.picture.image) if leaf.picture.image.attached?
+        @pdf.move_down 8
+        @pdf.text leaf.picture.caption, style: :italic, align: :center, size: 11 if leaf.picture.caption.present?
+      else
+        render_page(leaf)
+      end
+    end
+
+    def render_page(leaf)
+      html = Page.preview_renderer.render(leaf.page.markable)
+      chapter_title leaf.title
+      # Pull images and tables out and draw them directly; flowing text can't
+      # place or size them. Splitting the raw HTML means an image mid-paragraph
+      # breaks its paragraph, but markdown keeps images on their own line.
+      strip_leading_title(html, leaf.title).split(%r{(<img\b[^>]*>|<table[\s\S]*?</table>)}i).each do |part|
+        next if part.blank?
+        case part
+        when /\A<img\b/i   then place_inline_image(part)
+        when /\A<table\b/i then place_table(part)
+        else append_html(part)
+        end
+      end
+    end
+
+    # Plain-text rows, no gridlines; swap to prawn-table if real gridlines are
+    # ever needed. Cells are HTML-unescaped so "R&D" doesn't print as "R&amp;D".
+    def place_table(html)
+      rows = html.scan(%r{<tr[^>]*>(.*?)</tr>}mi).map do |(row)|
+        row.scan(%r{<t[hd][^>]*>(.*?)</t[hd]>}mi).map { |(cell)| CGI.unescapeHTML(cell.gsub(/<[^>]+>/, " ")).squish }
+      end
+      return if rows.empty?
+      @pdf.move_down 4
+      rows.each { |cells| @pdf.text cells.join("   |   "), size: 10 }
+      @pdf.move_down 4
+    end
+
+    def chapter_title(title)
+      return if title.blank?
+      @pdf.text title, size: 20, style: :bold
+      @pdf.move_down 12
+    end
+
+    # Walk the Redcarpet-rendered HTML with Nokogiri and emit Prawn text. Only
+    # the tags markdown produces are handled; unknown tags fall through to their
+    # inline content.
+    def append_html(html)
+      Nokogiri::HTML.fragment(html).children.each do |node|
+        render_block(node)
+      rescue StandardError => e
+        # Skip a node we can't render rather than dropping the rest of the page.
+        Rails.logger.warn("Book::Pdf skipped <#{node.name}>: #{e.message}")
+      end
+    end
+
+    def render_block(node)
+      case node.name
+      when "h1", "h2", "h3", "h4", "h5", "h6"
+        @pdf.move_down 6
+        @pdf.text inline(node), inline_format: true, size: HEADING_SIZES[node.name], style: :bold
+        @pdf.move_down 4
+      when "ul", "ol"
+        render_list(node, ordered: node.name == "ol")
+      when "blockquote"
+        @pdf.indent(QUOTE_INDENT) { node.children.each { |child| render_block(child) } }
+      when "pre"
+        @pdf.move_down 4
+        @pdf.text node.text.strip, size: 10
+        @pdf.move_down 4
+      when "hr"
+        @pdf.move_down 6
+        @pdf.stroke_horizontal_rule
+        @pdf.move_down 6
+      when "text"
+        @pdf.text escape(node.text), inline_format: true unless node.text.strip.empty?
+      else   # p, and anything else carrying inline content
+        body = inline(node)
+        return if body.strip.empty?
+        @pdf.text body, inline_format: true
+        @pdf.move_down 6
+      end
+    end
+
+    def render_list(node, ordered:)
+      index = 0
+      node.element_children.each do |item|
+        next unless item.name == "li"
+        index += 1
+        marker = ordered ? "#{index}." : "•"
+        @pdf.indent(LIST_INDENT) do
+          inline_parts = item.children.reject { |c| c.element? && %w[ ul ol ].include?(c.name) }
+          text = inline_parts.map { |c| inline_node(c) }.join.strip
+          @pdf.text "#{marker}  #{text}", inline_format: true unless text.empty?
+          item.children.each { |c| render_block(c) if c.element? && %w[ ul ol ].include?(c.name) }
+        end
+      end
+      @pdf.move_down 4
+    end
+
+    # Convert a node's children into a Prawn inline-format string.
+    def inline(node)
+      node.children.map { |child| inline_node(child) }.join
+    end
+
+    def inline_node(node)
+      case node.name
+      when "text"               then escape(node.text)
+      when "strong", "b"        then "<b>#{inline(node)}</b>"
+      when "em", "i"            then "<i>#{inline(node)}</i>"
+      when "del", "s", "strike" then "<strikethrough>#{inline(node)}</strikethrough>"
+      when "code"               then escape(node.text)   # no monospace face bundled
+      when "br"                 then "\n"
+      when "a"                  then %(<link href="#{escape(node["href"])}">#{inline(node)}</link>)
+      else inline(node)
+      end
+    end
+
+    def place_inline_image(img_tag)
+      src = img_tag[/src=["']([^"']+)["']/i, 1]
+      bytes = upload_bytes(src)
+      place_image(bytes) if bytes
+    end
+
+    # Resolve a `/u/<slug>` markdown upload to its blob. External URLs (no
+    # matching attachment) are skipped — we can't fetch them.
+    def upload_bytes(src)
+      slug = src[%r{/u/(.+)\z}, 1]
+      slug && blob_bytes(ActiveStorage::Attachment.find_by(slug: slug))
+    end
+
+    # Download an attachment's bytes, returning nil if it's missing or the blob
+    # file is gone (a missing image shouldn't 500 the whole export).
+    def blob_bytes(attachment)
+      attachment&.download
+    rescue StandardError
+      nil
+    end
+
+    def place_image(bytes)
+      return unless bytes
+      @pdf.start_new_page if @pdf.cursor < 220
+      @pdf.move_down 6
+      @pdf.image StringIO.new(bytes), fit: [ @pdf.bounds.width, @pdf.cursor - 12 ], position: :center
+      @pdf.move_down 6
+    rescue Prawn::Errors::UnsupportedImageType
+      # Prawn embeds only PNG/JPG; skip other formats (webp/gif).
+    end
+
+    def image_dimensions(bytes)
+      image = Prawn.image_handler.find(bytes).new(bytes)
+      [ image.width, image.height ]
+    rescue StandardError
+      [ nil, nil ]
+    end
+
+    # Drop a leading heading that just repeats the leaf title (pages
+    # conventionally open with `# Title`), so we don't print it twice.
+    def strip_leading_title(html, title)
+      html.sub(/\A\s*<h([1-6])>(.*?)<\/h\1>\s*/m) do
+        $2.gsub(/<[^>]+>/, "").strip.casecmp?(title.to_s.strip) ? "" : $&
+      end
+    end
+
+    def number_content_pages
+      first = @first_content_page
+      @pdf.number_pages "<page>",
+        start_count_at: 1, page_filter: ->(i) { i >= first },
+        at: [ 0, 0 ], width: @pdf.bounds.width, align: :center, size: 10
+    end
+
+    # Escape for Prawn inline formatting. Only &, <, > are markup to Prawn, so
+    # (unlike CGI/ERB escapers) we must not touch quotes — Prawn would render
+    # `&quot;` literally.
+    def escape(string)
+      string.to_s.gsub("&", "&amp;").gsub("<", "&lt;").gsub(">", "&gt;")
+    end
+end
diff --git a/app/views/books/show.html.erb b/app/views/books/show.html.erb
index b90644d1..605bf682 100644
--- a/app/views/books/show.html.erb
+++ b/app/views/books/show.html.erb
@@ -3,6 +3,7 @@
 
 <% content_for :head do %>
   <%= tag.link rel: "alternate", type: "text/markdown", href: book_slug_path(@book, format: :md) %>
+  <%= tag.link rel: "alternate", type: "application/pdf", href: book_slug_path(@book, format: :pdf) %>
   <%= tag.meta property: "og:title", content: @book.title %>
   <%= tag.meta property: "og:description", content: @book.subtitle %>
   <%= tag.meta property: "og:image", content: @book.cover.blank? ? asset_url("covers/cover-#{@book.theme}-og.png") : "#{root_url}#{url_for(@book.cover)}" %>
diff --git a/config/routes.rb b/config/routes.rb
index 6a759da6..afaad021 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -36,6 +36,9 @@
     resources :pages
   end
 
+  # PDF page size via suffix: `.pdf` defaults to Letter; `.A4.pdf`/`.letter.pdf` force a size.
+  get "/:id/:slug.:size.pdf", to: "books#show", constraints: { id: /\d+/, size: /A4|letter/i },
+    format: false, defaults: { format: "pdf" }, as: :sized_book_pdf
   get "/:id/:slug", to: "books#show", constraints: { id: /\d+/ }, as: :slugged_book
   get "/:book_id/:book_slug/:id/:slug", to: "leafables#show", constraints: { book_id: /\d+/, id: /\d+/ }, as: :slugged_leafable
 
diff --git a/test/controllers/books_controller_test.rb b/test/controllers/books_controller_test.rb
index 81d5f486..97b4e32a 100644
--- a/test/controllers/books_controller_test.rb
+++ b/test/controllers/books_controller_test.rb
@@ -114,4 +114,55 @@ class BooksControllerTest < ActionDispatch::IntegrationTest
     assert_response :success
     assert_select "link[rel=\"alternate\"][type=\"text/markdown\"][href=\"#{book_slug_path(books(:handbook), format: :md)}\"]"
   end
+
+  test "show with pdf format returns a pdf document" do
+    leaves(:welcome_page).leafable.update!(body: "# Welcome Content")
+
+    get book_slug_path(books(:handbook), format: :pdf)
+
+    assert_response :success
+    assert_equal "application/pdf", response.media_type
+    assert response.body.start_with?("%PDF"), "expected a PDF body"
+  end
+
+  test "show includes link to pdf format" do
+    get book_slug_path(books(:handbook))
+
+    assert_response :success
+    assert_select "link[rel=\"alternate\"][type=\"application/pdf\"][href=\"#{book_slug_path(books(:handbook), format: :pdf)}\"]"
+  end
+
+  test "pdf is cacheable via conditional GET" do
+    get book_slug_path(books(:handbook), format: :pdf)
+    assert_response :success
+    assert response.etag.present?
+
+    get book_slug_path(books(:handbook), format: :pdf), headers: { "If-None-Match" => response.etag }
+    assert_response :not_modified
+  end
+
+  test "pdf is available in letter (default) and A4" do
+    book = books(:handbook)
+    paths = [
+      book_slug_path(book, format: :pdf),
+      sized_book_pdf_path(book, book.slug, "letter"),
+      sized_book_pdf_path(book, book.slug, "A4")
+    ]
+    paths.each do |path|
+      get path
+      assert_response :success, "#{path} should render a PDF"
+      assert_equal "application/pdf", response.media_type
+      assert response.body.start_with?("%PDF"), "#{path} should be a PDF"
+    end
+  end
+
+  test "editing a book busts the pdf cache" do
+    get book_slug_path(books(:handbook), format: :pdf)
+    etag = response.etag
+
+    books(:handbook).update!(title: "Renamed")
+
+    get book_slug_path(books(:handbook), format: :pdf), headers: { "If-None-Match" => etag }
+    assert_response :success
+  end
 end
diff --git a/test/models/book/pdf_test.rb b/test/models/book/pdf_test.rb
new file mode 100644
index 00000000..12932149
--- /dev/null
+++ b/test/models/book/pdf_test.rb
@@ -0,0 +1,62 @@
+require "test_helper"
+
+class Book::PdfTest < ActiveSupport::TestCase
+  setup do
+    @book = books(:handbook)
+    @leaves = @book.leaves.active.with_leafables.positioned
+  end
+
+  test "renders a valid pdf across every leaf type" do
+    leaves(:welcome_page).leafable.update!(body: "# Heading\n\nSome **bold** text and a list:\n\n- one\n- two")
+
+    pdf = Book::Pdf.new(@book, @leaves).render
+
+    assert pdf.start_with?("%PDF"), "expected PDF header"
+    assert_includes pdf, "%%EOF"
+    assert_operator pdf.bytesize, :>, 1000
+  end
+
+  test "respects the requested page size" do
+    letter = Book::Pdf.new(@book, @leaves, page_size: "LETTER").render
+    a4 = Book::Pdf.new(@book, @leaves, page_size: "A4").render
+
+    assert_match %r{/MediaBox \[0 0 612}, letter   # US Letter: 612 x 792 pt
+    assert_match %r{/MediaBox \[0 0 595}, a4        # A4: 595.28 x 841.89 pt
+  end
+
+  test "does not raise on non-Latin (Greek) content" do
+    leaves(:welcome_page).leafable.update!(body: "# Καλωσήρθες\n\nπερίληψη")
+
+    assert_nothing_raised do
+      Book::Pdf.new(@book, @leaves).render
+    end
+  end
+
+  test "renders every markdown construct without raising" do
+    leaves(:welcome_page).leafable.update!(body: <<~MD)
+      Paragraph with **bold**, _italic_, ~~struck~~, `code`, and a [link](https://example.com/?a=1&b=2).
+
+      1. first
+      2. second
+         - nested a
+         - nested b
+
+      > A quote.
+
+      ```
+      code block
+      ```
+
+      ---
+
+      | Name | R&D |
+      | ---- | --- |
+      | a    | b   |
+    MD
+
+    pdf = Book::Pdf.new(@book, @leaves).render
+
+    assert pdf.start_with?("%PDF")
+    assert_includes pdf, "%%EOF"
+  end
+end