Serialize import map URLs explicitly

lib/utopia/import_map.rb

@@ -268,13 +268,7 @@ def scope(scope_prefix, imports)
 		# 	page_map = import_map.relative_to("/foo/bar/")
 		# 	# Base becomes: "../../_components/"
 		def relative_to(path)
-			if @base
-				# Calculate the relative path from the page to the base
-				relative_path = @base.path.relative(path)
-				resolved_base = Protocol::URL::Relative.new(relative_path)
-			else
-				resolved_base = nil
-			end
+			resolved_base = @base&.relative_to(path)
 
 			instance = self.class.new(@imports.dup, @integrity.dup, @scopes.dup, base: resolved_base)
 
@@ -285,10 +279,12 @@ def relative_to(path)
 		#
 		# @parameter value [String] The import URL or path value.
 		# @parameter base [Protocol::URL | Nil] The base URL context for resolving relative paths.
-		# @returns [Protocol::URL | String] The resolved URL object or original string.
+		# @returns [Protocol::URL] The resolved URL.
 		private def resolve_value(value, base)
+			value = Protocol::URL[value]
+
 			if base
-				base + Protocol::URL[value]
+				base + value
 			else
 				value
 			end
@@ -303,7 +299,7 @@ def relative_to(path)
 			result = {}
 
 			imports.each do |specifier, value|
-				result[specifier] = resolve_value(value, base).to_s
+				result[specifier] = resolve_value(value, base).to_s(explicit: true)
 			end
 
 			result

test/utopia/import_map.rb

@@ -139,6 +139,23 @@
 			expect(page_map.base.to_s).to be == "../../_components/"
 		end
 
+		it "generates explicit same-directory URLs" do
+			import_map = subject.build(base: "/_components/") do |map|
+				map.import("app", "./app.js")
+			end
+			page_map = import_map.relative_to("/index")
+
+			expect(page_map.base.to_s).to be == "_components/"
+			expect(page_map.as_json.dig("imports", "app")).to be == "./_components/app.js"
+		end
+
+		it "preserves absolute bases" do
+			import_map = subject.new(base: "https://cdn.example.com/components/")
+			page_map = import_map.relative_to("/index")
+
+			expect(page_map.base.to_s).to be == "https://cdn.example.com/components/"
+		end
+
 		it "accepts a structured page path" do
 			import_map = subject.new(base: "/_components/")
 			path = Protocol::URL::Path["/foo/bar/"]
@@ -200,6 +217,14 @@
 				json = import_map.as_json
 				expect(json["imports"]["components/button"]).to be == "/components/button.js"
 			end
+
+			it "identifies ambiguous relative addresses explicitly" do
+				import_map = subject.build do |map|
+					map.import("app", "js/app.js")
+				end
+
+				expect(import_map.as_json.dig("imports", "app")).to be == "./js/app.js"
+			end
 		end
 
 		with "with base" do
@@ -242,15 +267,15 @@
 			it "resolves multiple relative path styles" do
 				json = import_map.as_json
 
-				# "pages/blog/" + "./app.js" => "pages/blog/app.js"
-				expect(json["imports"]["app"]).to be == "pages/blog/app.js"
+				# Import map addresses must be explicit relative URLs.
+				expect(json["imports"]["app"]).to be == "./pages/blog/app.js"
 			end
 
 			it "resolves parent directory references" do
 				json = import_map.as_json
 
-				# "pages/blog/" + "../vendor/lib.js" => "pages/vendor/lib.js"
-				expect(json["imports"]["vendor"]).to be == "pages/vendor/lib.js"
+				# The resolved address is in the current directory tree.
+				expect(json["imports"]["vendor"]).to be == "./pages/vendor/lib.js"
 			end
 
 			it "keeps CDN URLs unchanged" do
@@ -403,7 +428,7 @@
 			expect(json["imports"]["preact"]).to be(:start_with?, "//")
 
 			# Paths resolved with base
-			expect(json["imports"]["app"]).to be(:start_with?, "pages")
+			expect(json["imports"]["app"]).to be(:start_with?, "./pages")
 		end
 
 		it "supports full import map specification" do

utopia.gemspec

@@ -36,7 +36,7 @@ Gem::Specification.new do |spec|
 	spec.add_dependency "protocol-http", "~> 0.70"
 	spec.add_dependency "protocol-media", "~> 0.3"
 	spec.add_dependency "protocol-media-registry", "~> 0.1"
-	spec.add_dependency "protocol-url", "~> 0.16"
+	spec.add_dependency "protocol-url", "~> 0.18"
 	spec.add_dependency "samovar", "~> 2.1"
 	spec.add_dependency "traces", "~> 0.10"
 	spec.add_dependency "variant", "~> 0.1"