Add Confluence task list renderer for GFM task lists

Convert GFM task list items (- [x] / - [ ]) to Confluence
ac:task-list XML format instead of HTML checkboxes.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

markdown/markdown.go

@@ -56,6 +56,7 @@ func (c *ConfluenceExtension) Extend(m goldmark.Markdown) {
 		util.Prioritized(crenderer.NewConfluenceImageRenderer(c.Stdlib, c, c.Path), 100),
 		util.Prioritized(crenderer.NewConfluenceParagraphRenderer(), 100),
 		util.Prioritized(crenderer.NewConfluenceLinkRenderer(), 100),
+		util.Prioritized(crenderer.NewConfluenceTaskListRenderer(), 100),
 	))
 
 	if slices.Contains(c.MarkConfig.Features, "mkdocsadmonitions") {

renderer/tasklist.go

@@ -0,0 +1,170 @@
+package renderer
+
+import (
+	"fmt"
+
+	"github.com/yuin/goldmark/ast"
+	ext_ast "github.com/yuin/goldmark/extension/ast"
+	"github.com/yuin/goldmark/renderer"
+	"github.com/yuin/goldmark/renderer/html"
+	"github.com/yuin/goldmark/util"
+)
+
+// ConfluenceTaskListRenderer renders GFM task lists as Confluence ac:task-list elements.
+type ConfluenceTaskListRenderer struct {
+	html.Config
+	taskID int
+}
+
+func NewConfluenceTaskListRenderer(opts ...html.Option) renderer.NodeRenderer {
+	return &ConfluenceTaskListRenderer{
+		Config: html.NewConfig(),
+	}
+}
+
+func (r *ConfluenceTaskListRenderer) RegisterFuncs(reg renderer.NodeRendererFuncRegisterer) {
+	reg.Register(ast.KindList, r.renderList)
+	reg.Register(ast.KindListItem, r.renderListItem)
+	reg.Register(ext_ast.KindTaskCheckBox, r.renderTaskCheckBox)
+}
+
+// isTaskList returns true only if every top-level list item is a task item.
+// A mixed list (some task items, some regular items) is not considered a task
+// list, because rendering it as <ac:task-list> while falling back to <li> for
+// non-task items produces invalid Confluence storage XML.
+func isTaskList(list *ast.List) bool {
+	hasChildren := false
+	for child := list.FirstChild(); child != nil; child = child.NextSibling() {
+		hasChildren = true
+		if getTaskCheckBox(child) == nil {
+			return false
+		}
+	}
+	return hasChildren
+}
+
+// getTaskCheckBox returns the TaskCheckBox node for a ListItem, or nil if not a task item.
+// The structure is: ListItem -> TextBlock -> TaskCheckBox
+func getTaskCheckBox(item ast.Node) *ext_ast.TaskCheckBox {
+	fc := item.FirstChild()
+	if fc == nil {
+		return nil
+	}
+	gfc := fc.FirstChild()
+	if gfc == nil {
+		return nil
+	}
+	checkbox, ok := gfc.(*ext_ast.TaskCheckBox)
+	if !ok {
+		return nil
+	}
+	return checkbox
+}
+
+func (r *ConfluenceTaskListRenderer) renderList(w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
+	n := node.(*ast.List)
+	if !isTaskList(n) {
+		return r.goldmarkRenderList(w, source, node, entering)
+	}
+	if entering {
+		r.taskID = 0
+		_, _ = w.WriteString("<ac:task-list>\n")
+	} else {
+		_, _ = w.WriteString("</ac:task-list>\n")
+	}
+	return ast.WalkContinue, nil
+}
+
+func (r *ConfluenceTaskListRenderer) renderListItem(w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
+	checkbox := getTaskCheckBox(node)
+	parentList, _ := node.Parent().(*ast.List)
+	if checkbox == nil || parentList == nil || !isTaskList(parentList) {
+		return r.goldmarkRenderListItem(w, source, node, entering)
+	}
+	if entering {
+		r.taskID++
+		status := "incomplete"
+		if checkbox.IsChecked {
+			status = "complete"
+		}
+		_, _ = fmt.Fprintf(w, "<ac:task>\n<ac:task-id>%d</ac:task-id>\n<ac:task-status>%s</ac:task-status>\n<ac:task-body>", r.taskID, status)
+	} else {
+		_, _ = w.WriteString("</ac:task-body>\n</ac:task>\n")
+	}
+	return ast.WalkContinue, nil
+}
+
+// renderTaskCheckBox skips checkbox rendering when inside an ac:task-list (status
+// is already encoded by renderListItem). For any other list (e.g. mixed lists that
+// fall back to plain <ul>/<ol>), a textual "[x]"/"[ ]" marker is emitted so that
+// completion state is not silently lost.
+func (r *ConfluenceTaskListRenderer) renderTaskCheckBox(w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
+	// Traverse up: TaskCheckBox -> TextBlock -> ListItem -> List
+	var parentList *ast.List
+	if tb := node.Parent(); tb != nil {
+		if li := tb.Parent(); li != nil {
+			parentList, _ = li.Parent().(*ast.List)
+		}
+	}
+	if parentList != nil && isTaskList(parentList) {
+		// Status is encoded by renderListItem; nothing to emit here.
+		return ast.WalkSkipChildren, nil
+	}
+	// Fallback: emit a textual marker so completion state is preserved.
+	if entering {
+		checkbox := node.(*ext_ast.TaskCheckBox)
+		if checkbox.IsChecked {
+			_, _ = w.WriteString("[x] ")
+		} else {
+			_, _ = w.WriteString("[ ] ")
+		}
+	}
+	return ast.WalkSkipChildren, nil
+}
+
+// goldmarkRenderList is the default list rendering from goldmark.
+func (r *ConfluenceTaskListRenderer) goldmarkRenderList(w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
+	n := node.(*ast.List)
+	tag := "ul"
+	if n.IsOrdered() {
+		tag = "ol"
+	}
+	if entering {
+		_ = w.WriteByte('<')
+		_, _ = w.WriteString(tag)
+		if n.IsOrdered() && n.Start != 1 {
+			_, _ = fmt.Fprintf(w, " start=\"%d\"", n.Start)
+		}
+		if n.Attributes() != nil {
+			html.RenderAttributes(w, n, html.ListAttributeFilter)
+		}
+		_, _ = w.WriteString(">\n")
+	} else {
+		_, _ = w.WriteString("</")
+		_, _ = w.WriteString(tag)
+		_, _ = w.WriteString(">\n")
+	}
+	return ast.WalkContinue, nil
+}
+
+// goldmarkRenderListItem is the default list item rendering from goldmark.
+func (r *ConfluenceTaskListRenderer) goldmarkRenderListItem(w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
+	if entering {
+		if node.Attributes() != nil {
+			_, _ = w.WriteString("<li")
+			html.RenderAttributes(w, node, html.ListItemAttributeFilter)
+			_ = w.WriteByte('>')
+		} else {
+			_, _ = w.WriteString("<li>")
+		}
+		fc := node.FirstChild()
+		if fc != nil {
+			if _, ok := fc.(*ast.TextBlock); !ok {
+				_ = w.WriteByte('\n')
+			}
+		}
+	} else {
+		_, _ = w.WriteString("</li>\n")
+	}
+	return ast.WalkContinue, nil
+}

testdata/tasklists-mixed.html

@@ -0,0 +1,5 @@
+<ul>
+<li>[x] task item</li>
+<li>regular item</li>
+<li>[ ] another task item</li>
+</ul>

testdata/tasklists-mixed.md

@@ -0,0 +1,3 @@
+- [x] task item
+- regular item
+- [ ] another task item

testdata/tasklists.html

@@ -0,0 +1,17 @@
+<ac:task-list>
+<ac:task>
+<ac:task-id>1</ac:task-id>
+<ac:task-status>complete</ac:task-status>
+<ac:task-body>#739</ac:task-body>
+</ac:task>
+<ac:task>
+<ac:task-id>2</ac:task-id>
+<ac:task-status>incomplete</ac:task-status>
+<ac:task-body><a href="https://github.com/octo-org/octo-repo/issues/740">https://github.com/octo-org/octo-repo/issues/740</a></ac:task-body>
+</ac:task>
+<ac:task>
+<ac:task-id>3</ac:task-id>
+<ac:task-status>incomplete</ac:task-status>
+<ac:task-body>Add delight to the experience when all tasks are complete :tada:</ac:task-body>
+</ac:task>
+</ac:task-list>

testdata/tasklists.md

@@ -0,0 +1,3 @@
+- [x] #739
+- [ ] https://github.com/octo-org/octo-repo/issues/740
+- [ ] Add delight to the experience when all tasks are complete :tada: