socketry · sampokuokkanen · Aug 18, 2026 · Aug 20, 2026 · Aug 20, 2026
diff --git a/.gitignore b/.gitignore
@@ -5,3 +5,5 @@
 /gems.locked
 /.covered.db
 /external
+
+/node_modules
diff --git a/gems.rb b/gems.rb
@@ -14,6 +14,7 @@
 
 	gem "agent-context"
 
+	gem "utopia"
 	gem "utopia-project"
 
 	gem "decode"

diff --git a/lib/luna.rb b/lib/luna.rb
@@ -6,4 +6,6 @@
 require_relative "luna/version"
 
 module Luna
+	# The root directory for Luna's own assets, e.g. stylesheets and scripts.
+	PUBLIC_ROOT = File.expand_path("../public", __dir__)
 end
diff --git a/lib/luna/command/serve.rb b/lib/luna/command/serve.rb
@@ -24,6 +24,7 @@ class Serve < Samovar::Command
 				option "-i/--index <filename>", "Directory index", default: "index.html"
 				option "--[no]-directory-listing", "Enable directory listing", default: true
 				option "--[no]-markdown", "Enable Markdown rendering", default: true
+				option "--[no]-syntax-highlighting", "Enable syntax highlighting", default: true
 				option "-v/--[no]-verbose", "Verbose logging", default: false
 			end
 
@@ -55,7 +56,8 @@ def middleware
 					verbose: @options[:verbose],
 					markdown: @options[:markdown],
 					index: @options[:index],
-					directory_listing: @options[:directory_listing]
+					directory_listing: @options[:directory_listing],
+					syntax_highlighting: @options[:syntax_highlighting]
 				)
 			end
 
@@ -64,7 +66,7 @@ def call
 					buffer.puts "Luna v#{Luna::VERSION} serving..."
 					buffer.puts "- Root: #{File.expand_path(root_directory)}"
 					buffer.puts "- Bind: #{endpoint}"
-					buffer.puts "- Markdown: #{@options[:markdown]} | Index: #{@options[:index]} | Directory Listing: #{@options[:directory_listing]}"
+					buffer.puts "- Markdown: #{@options[:markdown]} | Index: #{@options[:index]} | Directory Listing: #{@options[:directory_listing]} | Syntax Highlighting: #{@options[:syntax_highlighting]}"
 				end
 
 				Async do |task|

diff --git a/lib/luna/document.rb b/lib/luna/document.rb
@@ -0,0 +1,59 @@
+# frozen_string_literal: true
+
+# Released under the MIT License.
+# Copyright, 2025, by Samuel Williams.
+
+module Luna
+	# Wraps rendered content in a minimal HTML document.
+	#
+	# Both the Markdown renderer and the directory listing use this, so that they
+	# agree on the document structure and share the same stylesheet.
+	class Document
+		# @parameter stylesheet [String | Nil] The stylesheet to link, if any.
+		# @parameter scripts [Array(String)] Module scripts to include.
+		def initialize(stylesheet: "/_static/luna.css", scripts: [])
+			@stylesheet = stylesheet
+			@scripts = scripts
+		end
+
+		# @attribute [String | Nil] The stylesheet to link, if any.
+		attr :stylesheet
+
+		# @attribute [Array(String)] Module scripts to include.
+		attr :scripts
+
+		# @parameter title [String] The title of the document.
+		# @parameter body [String] The rendered content.
+		# @returns [String] A complete HTML document.
+		def call(title, body)
+			<<~HTML
+				<!doctype html>
+				<meta charset="utf-8">
+				<meta name="viewport" content="width=device-width, initial-scale=1">
+				<title>#{escape_html(title)}</title>
+				#{head.join("\n")}
+				#{body}
+			HTML
+		end
+
+		private
+
+		def head
+			links = []
+
+			if @stylesheet
+				links << "<link rel=\"stylesheet\" href=\"#{escape_html(@stylesheet)}\">"
+			end
+
+			@scripts.each do |script|
+				links << "<script type=\"module\" src=\"#{escape_html(script)}\"></script>"
+			end
+
+			links
+		end
+
+		def escape_html(text)
+			text.to_s.gsub("&", "&amp;").gsub("<", "&lt;").gsub(">", "&gt;").gsub('"', "&quot;")
+		end
+	end
+end
diff --git a/lib/luna/middleware/markdown.rb b/lib/luna/middleware/markdown.rb
@@ -5,6 +5,8 @@
 
 require "protocol/http/middleware"
 
+require_relative "../document"
+
 begin
 	require "markly"
 rescue LoadError
@@ -16,14 +18,19 @@ module Middleware
 		# Render Markdown files to HTML on-the-fly.
 		# Intercepts requests that target .md/.markdown files.
 		class Markdown < Protocol::HTTP::Middleware
-			def initialize(app, root: Dir.pwd, index_candidates: ["index.md", "README.md"]) 
+			# The GitHub Flavored Markdown extensions, which are not enabled by default.
+			EXTENSIONS = [:table, :strikethrough, :autolink, :tagfilter, :tasklist].freeze
+
+			def initialize(app, root: Dir.pwd, index_candidates: ["index.md", "README.md"], document: Document.new)
 				super(app)
 				@root = File.expand_path(root)
 				@index_candidates = index_candidates
+				@document = document
 			end
 
 			attr :root
 			attr :index_candidates
+			attr :document
 
 			def safe_join(path)
 				full = File.expand_path(File.join(@root, path))
@@ -56,7 +63,7 @@ def markdown_file?(path)
 
 			def render_html(markdown)
 				if defined?(::Markly)
-					::Markly.render_html(markdown)
+					::Markly.render_html(markdown, extensions: EXTENSIONS)
 				else
 					# Fallback minimal rendering if markly isn't available:
 					escape = ->(s){s.to_s.gsub("&","&amp;").gsub("<","&lt;").gsub(">","&gt;")}
@@ -66,7 +73,7 @@ def render_html(markdown)
 
 			def render_file(path, head: false)
 				content = File.read(path)
-				html = render_html(content)
+				html = @document.call(File.basename(path), render_html(content))
 				headers = [
 					["content-type", "text/html; charset=utf-8"]
 				]

diff --git a/lib/luna/middleware/static.rb b/lib/luna/middleware/static.rb
@@ -7,6 +7,8 @@
 require "protocol/http/body/file"
 require "time"
 
+require_relative "../document"
+
 module Luna
 	module Middleware
 		# Serve static files from a root directory, with optional index and directory listing.
@@ -29,16 +31,18 @@ class Static < Protocol::HTTP::Middleware
 				".zip" => "application/zip",
 			}.freeze
 
-			def initialize(app, root: Dir.pwd, index: "index.html", directory_listing: true)
+			def initialize(app, root: Dir.pwd, index: "index.html", directory_listing: true, document: Document.new)
 				super(app)
 				@root = File.expand_path(root)
 				@index = index
 				@directory_listing = directory_listing
+				@document = document
 			end
 
 			attr :root
 			attr :index
 			attr :directory_listing
+			attr :document
 
 			def mime_type_for_extension(ext)
 				MIME_TYPES[ext.downcase] || "application/octet-stream"
@@ -99,13 +103,8 @@ def serve_directory_listing(dir_path, request_path)
 					target += "/" if File.directory?(File.join(dir_path, e)) && !target.end_with?("/")
 					"<li><a href=\"#{escape_html(target)}\">#{escape_html(name)}</a></li>"
 				end.join("\n")
-				html = <<~HTML
-				<!doctype html>
-				<meta charset="utf-8">
-				<title>Index of #{escape_html(request_path)}</title>
-				<h1>Index of #{escape_html(request_path)}</h1>
-				<ul>#{links}</ul>
-			HTML
+				title = "Index of #{request_path}"
+				html = @document.call(title, "<h1>#{escape_html(title)}</h1>\n<ul>#{links}</ul>")
 
 				headers = [
 					["content-type", "text/html; charset=utf-8"]

diff --git a/lib/luna/server.rb b/lib/luna/server.rb
@@ -7,6 +7,8 @@
 require "protocol/http/middleware/builder"
 require "protocol/http/content_encoding"
 
+require_relative "../luna"
+require_relative "document"
 require_relative "middleware/verbose"
 require_relative "middleware/static"
 require_relative "middleware/markdown"
@@ -20,16 +22,26 @@ class Server < Async::HTTP::Server
 		# @param markdown [Boolean] Enable markdown rendering.
 		# @param index [String] Index file for directories.
 		# @param directory_listing [Boolean] Enable basic directory listing when no index exists.
-		def self.middleware(root: Dir.pwd, verbose: false, markdown: true, index: "index.html", directory_listing: true)
+		# @param syntax_highlighting [Boolean] Highlight code using Luna's bundled syntax highlighter.
+		def self.middleware(root: Dir.pwd, verbose: false, markdown: true, index: "index.html", directory_listing: true, syntax_highlighting: true)
+			scripts = syntax_highlighting ? ["/_static/application.js"] : []
+			document = Luna::Document.new(scripts: scripts)
+
 			::Protocol::HTTP::Middleware.build do
 				use Luna::Middleware::Verbose if verbose
 				use ::Protocol::HTTP::ContentEncoding
-				use Luna::Middleware::Markdown, root: root if markdown
-				run Luna::Middleware::Static.new(
-					->(request){Protocol::HTTP::Response[404, {"content-type"=>"text/plain"}, ["Not Found"]]},
+				use Luna::Middleware::Markdown, root: root, document: document if markdown
+				use Luna::Middleware::Static,
 					root: root,
 					index: index,
-					directory_listing: directory_listing
+					directory_listing: directory_listing,
+					document: document
+
+				# Luna's own assets are served last, so that files in the root take precedence:
+				run Luna::Middleware::Static.new(
+					->(request){Protocol::HTTP::Response[404, {"content-type"=>"text/plain"}, ["Not Found"]]},
+					root: Luna::PUBLIC_ROOT,
+					directory_listing: false
 				)
 			end
 		end

diff --git a/luna.gemspec b/luna.gemspec
@@ -21,7 +21,7 @@ Gem::Specification.new do |spec|
 		"source_code_uri" => "https://github.com/socketry/luna.git",
 	}
 
-	spec.files = Dir.glob(["{bin,examples,lib}/**/*", "*.md"], File::FNM_DOTMATCH, base: __dir__)
+	spec.files = Dir.glob(["{bin,examples,lib,public}/**/*", "*.md"], File::FNM_DOTMATCH, base: __dir__)
 
 	spec.executables = ["luna"]
 

diff --git a/package-lock.json b/package-lock.json
diff --git a/package.json b/package.json
@@ -0,0 +1,5 @@
+{
+  "dependencies": {
+    "@socketry/syntax": "^0.6.1"
+  }
+}