diff --git a/config/sus.rb b/config/sus.rb
index f517380d..354d59b0 100644
--- a/config/sus.rb
+++ b/config/sus.rb
@@ -5,3 +5,5 @@
 
 require "covered/sus"
 include Covered::Sus
+
+ENV["TRACES_BACKEND"] ||= "traces/backend/test"
diff --git a/lib/traces/provider/utopia.rb b/lib/traces/provider/utopia.rb
new file mode 100644
index 00000000..ef21f7eb
--- /dev/null
+++ b/lib/traces/provider/utopia.rb
@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+# Released under the MIT License.
+# Copyright, 2026, by Samuel Williams.
+
+require_relative "utopia/content/middleware"
+require_relative "utopia/static/middleware"
diff --git a/lib/traces/provider/utopia/content/middleware.rb b/lib/traces/provider/utopia/content/middleware.rb
new file mode 100644
index 00000000..e66b2e6d
--- /dev/null
+++ b/lib/traces/provider/utopia/content/middleware.rb
@@ -0,0 +1,20 @@
+# frozen_string_literal: true
+
+# Released under the MIT License.
+# Copyright, 2026, by Samuel Williams.
+
+require_relative "../../../../utopia/content/middleware"
+
+require "traces/provider"
+
+Traces::Provider(Utopia::Content::Middleware) do
+	def respond(link, request, localization: request.localization)
+		attributes = {
+			"link.key" => link.key,
+			"link.href" => link.href,
+			"link.locale" => localization&.locale,
+		}
+		
+		Traces.trace("utopia.content.middleware.respond", attributes: attributes){super}
+	end
+end
diff --git a/lib/traces/provider/utopia/static/middleware.rb b/lib/traces/provider/utopia/static/middleware.rb
new file mode 100644
index 00000000..a0b962cf
--- /dev/null
+++ b/lib/traces/provider/utopia/static/middleware.rb
@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+
+# Released under the MIT License.
+# Copyright, 2026, by Samuel Williams.
+
+require_relative "../../../../utopia/static/middleware"
+
+require "traces/provider"
+
+Traces::Provider(Utopia::Static::Middleware) do
+	def respond(request, path, extension, content_type, localization: request.localization)
+		attributes = {
+			path: path,
+			locale: localization&.locale,
+		}
+		
+		Traces.trace("utopia.static.respond", attributes: attributes){super}
+	end
+end
diff --git a/lib/utopia/content/middleware.rb b/lib/utopia/content/middleware.rb
index 2fee3fb1..e12fb9dd 100644
--- a/lib/utopia/content/middleware.rb
+++ b/lib/utopia/content/middleware.rb
@@ -16,7 +16,6 @@
 
 require "xrb/template"
 require "concurrent/map"
-require "traces/provider"
 
 module Utopia
 	module Content
@@ -226,16 +225,5 @@ def relative_tag(name, node)
 			end
 		end
 		
-		Traces::Provider(Middleware) do
-			def respond(link, request, localization: request.localization)
-				attributes = {
-					"link.key" => link.key,
-					"link.href" => link.href,
-					"link.locale" => localization&.locale,
-				}
-				
-				Traces.trace("utopia.content.middleware.respond", attributes: attributes){super}
-			end
-		end
 	end
 end
diff --git a/lib/utopia/static/middleware.rb b/lib/utopia/static/middleware.rb
index 8eb0e5e6..e18e5470 100644
--- a/lib/utopia/static/middleware.rb
+++ b/lib/utopia/static/middleware.rb
@@ -11,8 +11,6 @@
 require_relative "mime_types"
 require_relative "../localization/resolver"
 
-require "traces/provider"
-
 module Utopia
 	module Static
 		DEFAULT_CACHE_CONTROL = "public, max-age=3600".freeze
@@ -138,15 +136,5 @@ def call(request)
 			end
 		end
 		
-		Traces::Provider(Static) do
-			def respond(request, path, extension, content_type, localization: request.localization)
-				attributes = {
-					path: path,
-					locale: localization&.locale,
-				}
-				
-				Traces.trace("utopia.static.respond", attributes: attributes){super}
-			end
-		end
 	end
 end
diff --git a/test/traces/provider/utopia/content/middleware.rb b/test/traces/provider/utopia/content/middleware.rb
new file mode 100644
index 00000000..8d52fced
--- /dev/null
+++ b/test/traces/provider/utopia/content/middleware.rb
@@ -0,0 +1,55 @@
+# frozen_string_literal: true
+
+# Released under the MIT License.
+# Copyright, 2026, by Samuel Williams.
+
+require "traces/provider/utopia"
+
+require "utopia/content/link"
+require "utopia/localization/preferences"
+require "utopia/request"
+
+describe Utopia::Content::Middleware do
+	let(:middleware) do
+		subject.new(
+			Protocol::HTTP::Middleware::NotFound,
+			root: File.expand_path(".", __dir__),
+		)
+	end
+	
+	let(:request) {Utopia::Request["GET", "/example"]}
+	let(:localization) do
+		Utopia::Localization::Preferences.new(
+			all_locales: ["en"],
+			preferred_locales: ["en"],
+			default_locale: "en",
+		)
+	end
+	
+	it "traces content responses" do
+		traces = []
+		
+		mock(Traces) do |mock|
+			mock.wrap(:trace) do |original, name, attributes: nil, &block|
+				traces << [name, attributes]
+				original.call(name, attributes: attributes, &block)
+			end
+		end
+		
+		link = Utopia::Content::Link.new(:virtual, "example", "en", "/example", uri: "/target")
+		response = middleware.respond(link, request, localization: localization)
+		
+		expect(response.status).to be == 307
+		expect(traces).to be == [[
+			"utopia.content.middleware.respond",
+			{
+				"link.key" => "example.en",
+				"link.href" => "/target",
+				"link.locale" => "en",
+			},
+		]]
+	ensure
+		response&.close
+		middleware.close
+	end
+end
diff --git a/test/traces/provider/utopia/static/middleware.rb b/test/traces/provider/utopia/static/middleware.rb
new file mode 100644
index 00000000..1b6d2226
--- /dev/null
+++ b/test/traces/provider/utopia/static/middleware.rb
@@ -0,0 +1,40 @@
+# frozen_string_literal: true
+
+# Released under the MIT License.
+# Copyright, 2026, by Samuel Williams.
+
+require "traces/provider/utopia/static/middleware"
+
+require "utopia/request"
+
+describe Utopia::Static::Middleware do
+	let(:root) {File.expand_path("../../../../utopia/.static", __dir__)}
+	let(:middleware) {subject.new(Protocol::HTTP::Middleware::NotFound, root: root)}
+	let(:request) {Utopia::Request["GET", "/test.txt"]}
+	
+	it "traces static responses" do
+		traces = []
+		
+		mock(Traces) do |mock|
+			mock.wrap(:trace) do |original, name, attributes: nil, &block|
+				traces << [name, attributes]
+				original.call(name, attributes: attributes, &block)
+			end
+		end
+		
+		path = request.url.path
+		response = middleware.respond(request, path, ".txt", "text/plain", localization: nil)
+		
+		expect(response.status).to be == 200
+		expect(traces).to be == [[
+			"utopia.static.respond",
+			{
+				path: path,
+				locale: nil,
+			},
+		]]
+	ensure
+		response&.close
+		middleware.close
+	end
+end
diff --git a/test/utopia/static.rb b/test/utopia/static.rb
index f81d5719..bd567de2 100755
--- a/test/utopia/static.rb
+++ b/test/utopia/static.rb
@@ -29,6 +29,23 @@
 		expect(cache_control).to be(:frozen?)
 	end
 	
+	it "computes cache control from the served file" do
+		served_file = nil
+		application = Utopia::Application.build do
+			use Utopia::Static,
+				root: File.expand_path(".static", __dir__),
+				cache_control: proc{|file| served_file = file; "private, max-age=#{file.bytesize}"}
+		end
+		
+		response = application.call(Protocol::HTTP::Request["GET", "/test.txt"])
+		
+		expect(response.headers["cache-control"]).to be == ["private", "max-age=12"]
+		expect(served_file).to be_a(Utopia::Static::LocalFile)
+	ensure
+		response&.close
+		application.close
+	end
+	
 	let(:middleware) do
 		root = File.expand_path(".static", __dir__)
 		
@@ -263,69 +280,4 @@
 			end
 		end
 	end
-	
-	describe Utopia::Static::LocalFile do
-		it "uses a consistent metadata snapshot" do
-			Dir.mktmpdir do |directory|
-				path = File.join(directory, "test.txt")
-				File.write(path, "Original")
-				
-				file = subject.new(path)
-				mtime_date = file.mtime_date
-				etag = file.etag
-				
-				File.write(path, "Updated content")
-				
-				expect(file.bytesize).to be == 8
-				expect(file.mtime_date).to be == mtime_date
-				expect(file.etag).to be == etag
-			end
-		end
-		
-		it "includes subsecond modification time in entity tags" do
-			Dir.mktmpdir do |directory|
-				path = File.join(directory, "test.txt")
-				File.write(path, "Content")
-				
-				seconds = Time.now.to_i - 1
-				first_mtime = Time.at(seconds, 100_000_000, :nanosecond)
-				second_mtime = Time.at(seconds, 200_000_000, :nanosecond)
-				
-				File.utime(first_mtime, first_mtime, path)
-				first = subject.new(path)
-				
-				File.utime(second_mtime, second_mtime, path)
-				second = subject.new(path)
-				
-				expect(first.mtime_date).to be == second.mtime_date
-				expect(first.etag).not.to be == second.etag
-			end
-		end
-	end
-	
-	describe Utopia::Static::MIME_TYPES do
-		let(:extensions) {Utopia::Static::MimeTypeLoader.extensions_for(subject[:default])}
-		let(:script_extensions) {Utopia::Static::MimeTypeLoader.extensions_for(subject[:scripts])}
-		
-		it "groups script extensions" do
-			expect(script_extensions).to have_keys(
-				".js" => be == "text/javascript",
-				".mjs" => be == "text/javascript",
-				".wasm" => be == "application/wasm",
-			)
-		end
-		
-		it "should give the correct mime type" do
-			expect(extensions).to have_keys(
-				".txt" => be == "text/plain",
-				".mjs" => be == "text/javascript",
-				".wasm" => be == "application/wasm",
-				".webm" => be == "video/webm",
-				".weba" => be == "audio/webm",
-				".ogg" => be == "audio/vorbis",
-				".spx" => be == "audio/speex",
-				".html" => be == "text/html",
-			)
-		end
-	end
 end
diff --git a/test/utopia/static/local_file.rb b/test/utopia/static/local_file.rb
new file mode 100644
index 00000000..76de1879
--- /dev/null
+++ b/test/utopia/static/local_file.rb
@@ -0,0 +1,60 @@
+# frozen_string_literal: true
+
+# Released under the MIT License.
+# Copyright, 2026, by Samuel Williams.
+
+require "tmpdir"
+
+require "utopia/static/local_file"
+
+describe Utopia::Static::LocalFile do
+	it "uses a consistent metadata snapshot" do
+		Dir.mktmpdir do |directory|
+			path = File.join(directory, "test.txt")
+			File.write(path, "Original")
+			
+			file = subject.new(path)
+			mtime_date = file.mtime_date
+			etag = file.etag
+			
+			File.write(path, "Updated content")
+			
+			expect(file.bytesize).to be == 8
+			expect(file.mtime_date).to be == mtime_date
+			expect(file.etag).to be == etag
+		end
+	end
+	
+	it "includes subsecond modification time in entity tags" do
+		Dir.mktmpdir do |directory|
+			path = File.join(directory, "test.txt")
+			File.write(path, "Content")
+			
+			seconds = Time.now.to_i - 1
+			first_mtime = Time.at(seconds, 100_000_000, :nanosecond)
+			second_mtime = Time.at(seconds, 200_000_000, :nanosecond)
+			
+			File.utime(first_mtime, first_mtime, path)
+			first = subject.new(path)
+			
+			File.utime(second_mtime, second_mtime, path)
+			second = subject.new(path)
+			
+			expect(first.mtime_date).to be == second.mtime_date
+			expect(first.etag).not.to be == second.etag
+		end
+	end
+	
+	it "matches strong entity tags for range requests" do
+		Dir.mktmpdir do |directory|
+			path = File.join(directory, "test.txt")
+			File.write(path, "Content")
+			
+			file = subject.new(path)
+			file.instance_variable_set(:@etag, '"strong"')
+			
+			expect(file.send(:if_range?, '"strong"')).to be == true
+			expect(file.send(:if_range?, '"different"')).to be == false
+		end
+	end
+end
diff --git a/test/utopia/static/mime_types.rb b/test/utopia/static/mime_types.rb
new file mode 100644
index 00000000..db2a3381
--- /dev/null
+++ b/test/utopia/static/mime_types.rb
@@ -0,0 +1,61 @@
+# frozen_string_literal: true
+
+# Released under the MIT License.
+# Copyright, 2026, by Samuel Williams.
+
+require "utopia/static/mime_types"
+
+describe "Utopia::Static::MIME_TYPES" do
+	let(:mime_types) {Utopia::Static::MIME_TYPES}
+	let(:extensions) {Utopia::Static::MimeTypeLoader.extensions_for(mime_types[:default])}
+	let(:script_extensions) {Utopia::Static::MimeTypeLoader.extensions_for(mime_types[:scripts])}
+	
+	it "groups script extensions" do
+		expect(script_extensions).to have_keys(
+			".js" => be == "text/javascript",
+			".mjs" => be == "text/javascript",
+			".wasm" => be == "application/wasm",
+		)
+	end
+	
+	it "should give the correct mime type" do
+		expect(extensions).to have_keys(
+			".txt" => be == "text/plain",
+			".mjs" => be == "text/javascript",
+			".wasm" => be == "application/wasm",
+			".webm" => be == "video/webm",
+			".weba" => be == "audio/webm",
+			".ogg" => be == "audio/vorbis",
+			".spx" => be == "audio/speex",
+			".html" => be == "text/html",
+		)
+	end
+end
+
+describe Utopia::Static::MimeTypeLoader do
+	it "expands explicit extension mappings" do
+		extensions = subject.extensions_for([["example", "application/example"]])
+		
+		expect(extensions).to have_keys(
+			".example" => be == "application/example",
+		)
+	end
+	
+	it "rejects unknown file extensions" do
+		expect do
+			subject.extensions_for(["not-a-real-extension"])
+		end.to raise_exception(subject::ExpansionError, message: be =~ /Unknown file extension/)
+	end
+	
+	it "rejects unsupported definitions" do
+		expect do
+			subject.extensions_for([Object.new])
+		end.to raise_exception(subject::ExpansionError, message: be =~ /Unsupported MIME type definition/)
+	end
+	
+	it "wraps errors while expanding named groups" do
+		expect do
+			subject.extensions_for([:missing], {})
+		end.to raise_exception(subject::ExpansionError, message: be =~ /Error while processing :missing/)
+	end
+end