FEATURE: Expose the bare-link judgment as AST::Url#bare?

Review feedback: consumers that intercept Url nodes need the same
bare-or-not decision the renderer makes (a deferred-link handler must
record nil text for a bare URL, or the importer rebuilds [url](url)
and re-breaks oneboxing). Keeping it private in UrlTag would force a
second copy that can drift.

Url#bare? judges the AST: no children, or a single Text child equal to
the href. UrlTag delegates to it and keeps one render-time extra — a
label that renders to nothing (e.g. an empty formatting child) also
falls back to the bare href, since [](url) shows nothing.

Author: gschlager

lib/markbridge/ast/url.rb

@@ -22,6 +22,21 @@ def initialize(href: nil)
         super()
         @href = href
       end
+
+      # Whether this link is "bare" — it has no link text of its own:
+      # either no children, or a single Text child whose content is
+      # exactly the href (how parsers model a URL that stands for
+      # itself). Consumers that record or rewrite links need this
+      # judgment too (a bare URL must stay bare to keep autolinking
+      # and oneboxing working), so it lives on the node rather than
+      # in the renderer.
+      #
+      # @return [Boolean]
+      def bare?
+        return true if children.empty?
+
+        children.size == 1 && children.first.instance_of?(Text) && children.first.text == href
+      end
     end
   end
 end

lib/markbridge/renderers/discourse/tags/url_tag.rb

@@ -28,7 +28,10 @@ def render(element, interface)
 
             if interface.html_mode?
               %(<a href="#{HtmlEscaper.escape(href)}">#{text}</a>)
-            elsif bare?(element, text)
+            elsif element.bare? || text.empty?
+              # Url#bare? judges the AST (so label escaping can't confuse
+              # it); the rendered-text check additionally catches labels
+              # that render to nothing (e.g. an empty formatting child).
               href
             else
               "[#{text}](#{markdown_destination(href)})"
@@ -50,18 +53,6 @@ def linkable?(href)
 
             !href.match?(SCHEME_LIKE)
           end
-
-          # Bare when there is no link text, or when the only child is a
-          # Text node whose content is exactly the href (compared on the
-          # AST, not on the rendered text, so Markdown escaping in the
-          # label cannot break the detection).
-          def bare?(element, rendered_text)
-            return true if rendered_text.empty?
-
-            children = element.children
-            children.size == 1 && children.first.instance_of?(AST::Text) &&
-              children.first.text == element.href
-          end
         end
       end
     end

spec/unit/markbridge/ast/url_spec.rb

@@ -33,4 +33,39 @@
 
     expect(element.children).to eq([text])
   end
+
+  describe "#bare?" do
+    it "is bare with no children" do
+      expect(described_class.new(href: "https://example.com").bare?).to be true
+    end
+
+    it "is bare when the only child is a Text equal to the href" do
+      element = described_class.new(href: "https://example.com")
+      element << Markbridge::AST::Text.new("https://example.com")
+
+      expect(element.bare?).to be true
+    end
+
+    it "is not bare when the text differs from the href" do
+      element = described_class.new(href: "https://example.com")
+      element << Markbridge::AST::Text.new("click here")
+
+      expect(element.bare?).to be false
+    end
+
+    it "is not bare when more children follow the href-equal text" do
+      element = described_class.new(href: "https://example.com")
+      element << Markbridge::AST::Text.new("https://example.com")
+      element << Markbridge::AST::Bold.new
+
+      expect(element.bare?).to be false
+    end
+
+    it "is not bare when the only child is a non-Text node" do
+      element = described_class.new(href: "https://example.com")
+      element << Markbridge::AST::Bold.new
+
+      expect(element.bare?).to be false
+    end
+  end
 end

spec/unit/markbridge/renderers/discourse/tags/url_tag_spec.rb

@@ -163,6 +163,15 @@
         expect(tag.render(element, interface)).to eq("https://example.com")
       end
 
+      it "renders the plain href when the label renders to nothing" do
+        # Not bare on the AST (a non-Text child exists), but the child
+        # produces no output — `[](url)` would show nothing.
+        element = Markbridge::AST::Url.new(href: "https://example.com")
+        element << Markbridge::AST::Bold.new
+
+        expect(tag.render(element, interface)).to eq("https://example.com")
+      end
+
       it "detects bareness on the AST, unaffected by Markdown escaping of the label" do
         # The rendered label would be "https://example.com/a\_b" — comparing
         # rendered text against the href would miss this bare URL.