diff --git a/.gitignore b/.gitignore
index e6f64b4..9e15dc8 100644
--- a/.gitignore
+++ b/.gitignore
@@ -12,3 +12,4 @@ larkDocx2mdOutput/
 .qoder
 .agents
 coverage
+.claude
diff --git a/CHANGELOG.md b/CHANGELOG.md
index e8ec33b..a6609a5 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,11 @@
 # Changelog
 
+## 0.8.1
+
+### Fixed
+
+- **嵌套子块保留与未支持块回退**：飞书大纲/折叠场景下，任意叶子块（todo/heading/quote/equation/code/image 等）都可能携带 children，原实现只让容器型 parser 消费 children，导致这些子块被静默丢弃、导出文档章节内容缺失。本次让叶子块未自行消费的 children 统一挂到 `node.blocks`，序列化时在节点自身内容之后渲染；容器型 parser 标记 `consumesChildren` 避免重复挂载。未支持块类型不再整块丢弃，而是回退为 paragraph（尽量提取文本）并保留其嵌套子树，既无文本也无子块时才丢弃
+
 ## 0.8.0
 
 ### Removed
diff --git a/package.json b/package.json
index d04984e..8fa47ec 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "lark-docx2md",
-  "version": "0.8.0",
+  "version": "0.8.1",
   "description": "Convert Lark/Feishu documents to Markdown",
   "type": "module",
   "main": "./dist/converter.js",
diff --git a/src/md-ast/parser.ts b/src/md-ast/parser.ts
index e9bd009..59716b2 100644
--- a/src/md-ast/parser.ts
+++ b/src/md-ast/parser.ts
@@ -1,10 +1,17 @@
 import { Registry } from '../core/registry.js';
+import { createLogger } from '../lib/logger.js';
 import type { DocInfo, DocxBlock, TextBody, TextElement } from '../lib/types.js';
 import type { MdBlockNode, MdInlineNode } from './types.js';
 
+const logger = createLogger('parser');
+
 export interface BlockParser {
   blockType: number;
 
+  /** 容器型 parser（page/bullet/ordered/callout/quoteContainer/grid/table）自行消费 block.children，
+   *  置为 true；叶子型 parser 省略（false），由 Parser 框架统一解析 block.children 挂到 node.blocks。 */
+  consumesChildren?: boolean;
+
   parse (block: DocxBlock, ctx: ParserContext): MdBlockNode | null;
 }
 
@@ -37,13 +44,45 @@ export class Parser {
       blockMap,
       parseBlock: (block: DocxBlock): MdBlockNode | null => {
         const bt = block.block_type;
-        if (bt === undefined || bt === null) return null;
+        if (bt === undefined || bt === null) {
+          logger.warn(`Dropped block ${block.block_id}: missing block_type`);
+          return null;
+        }
         const parser = this.registry.get(bt);
-        if (parser) {
-          return parser.parse(block, ctx);
+        if (!parser) {
+          // 未注册的块类型（如 Bitable/File/Mindnote/Iframe/Diagram 等）：
+          // 回退为文案（尽量提取文本），并保留其嵌套子块——飞书任意块都可能挂 children，
+          // 若直接丢弃会把整棵子树一起丢掉。
+          const text = extractBlockText(block);
+          const hasChildren = (block.children?.length ?? 0) > 0;
+          if (!text && !hasChildren) {
+            // GridColumn(25) 由 Grid parser 内部处理；此处为既无文本也无子块的未支持块
+            logger.warn(`Dropped block ${block.block_id}: no parser for block_type=${bt} and no text/children (parent=${block.parent_id ?? '-'}) — ${previewBlock(block)}`);
+            return null;
+          }
+          logger.warn(`Fallback for block ${block.block_id}: no parser for block_type=${bt} (parent=${block.parent_id ?? '-'}) — rendered as paragraph; ${previewBlock(block)}`);
+          const node: MdBlockNode = {
+            type: 'paragraph',
+            children: text ? [{ type: 'text', content: text }] : [],
+          };
+          if (hasChildren) {
+            const nested = ctx.parseChildren(block);
+            if (nested.length > 0) node.blocks = nested;
+          }
+          return node;
+        }
+        const node = parser.parse(block, ctx);
+        if (!node) {
+          logger.warn(`Dropped block ${block.block_id}: parser(block_type=${bt}) returned null — ${previewBlock(block)}`);
+          return null;
         }
-        // GridColumn(25) is handled inside Grid parser
-        return null;
+        // 框架统一处理：叶子型块（未自行消费 children）若携带嵌套子块，挂到 node.blocks，
+        // 序列化时在节点自身内容之后渲染（飞书大纲/折叠等场景下，任意块都可能嵌套内容）。
+        if (!parser.consumesChildren && (block.children?.length ?? 0) > 0) {
+          const nested = ctx.parseChildren(block);
+          if (nested.length > 0) node.blocks = nested;
+        }
+        return node;
       },
       parseText: (body: TextBody): MdInlineNode[] => {
         const inline = body.elements.length > 1;
@@ -56,10 +95,12 @@ export class Parser {
         const children: MdBlockNode[] = [];
         for (const id of block.children ?? []) {
           const child = blockMap.get(id);
-          if (child) {
-            const node = ctx.parseBlock(child);
-            if (node) children.push(node);
+          if (!child) {
+            logger.warn(`Missing child block ${id} (parent=${block.block_id}, parent_type=${block.block_type}); referenced but absent from blockMap — expected under --filter-title, otherwise signals a pagination gap or API omission`);
+            continue;
           }
+          const node = ctx.parseBlock(child);
+          if (node) children.push(node);
         }
         return children;
       },
@@ -129,3 +170,37 @@ function parseTextRun (tr: NonNullable<TextElement['text_run']>): MdInlineNode {
 
   return node;
 }
+
+// ─── Diagnostics ─────────────────────────────────────────────────────────────
+
+/** 提取块的文本预览，便于在日志中定位被丢弃的内容 */
+function previewBlock (block: DocxBlock): string {
+  const text = extractBlockText(block);
+  if (text) return `text="${text.slice(0, 80)}"`;
+  return `raw=${JSON.stringify(block).slice(0, 120)}`;
+}
+
+const BLOCK_TEXT_FIELDS = ['text', 'heading1', 'heading2', 'heading3', 'heading4', 'heading5', 'heading6', 'heading7', 'heading8', 'heading9', 'bullet', 'ordered', 'code', 'quote', 'equation', 'todo', 'callout'];
+
+function extractBlockText (block: DocxBlock): string {
+  for (const f of BLOCK_TEXT_FIELDS) {
+    const t = extractBodyText((block as Record<string, unknown>)[f]);
+    if (t) return t;
+  }
+  return '';
+}
+
+function extractBodyText (body: unknown): string {
+  if (!body || typeof body !== 'object') return '';
+  const elements = (body as { elements?: unknown[] }).elements;
+  if (!Array.isArray(elements)) return '';
+  return elements
+    .map((el) => {
+      if (el && typeof el === 'object' && 'text_run' in el) {
+        const c = (el as { text_run?: { content?: string } }).text_run?.content;
+        if (c) return c;
+      }
+      return '';
+    })
+    .join('');
+}
diff --git a/src/md-ast/parsers/bullet.ts b/src/md-ast/parsers/bullet.ts
index caacaae..2d9fa03 100644
--- a/src/md-ast/parsers/bullet.ts
+++ b/src/md-ast/parsers/bullet.ts
@@ -4,6 +4,7 @@ import type { MdBlockNode } from '../types.js';
 
 export const bulletParser: BlockParser = {
   blockType: 12,
+  consumesChildren: true,
   parse (block: DocxBlock, ctx: ParserContext): MdBlockNode {
     return {
       type: 'bullet',
diff --git a/src/md-ast/parsers/callout.ts b/src/md-ast/parsers/callout.ts
index 4a5e3de..12a4b5c 100644
--- a/src/md-ast/parsers/callout.ts
+++ b/src/md-ast/parsers/callout.ts
@@ -4,6 +4,7 @@ import type { MdBlockNode } from '../types.js';
 
 export const calloutParser: BlockParser = {
   blockType: 19,
+  consumesChildren: true,
   parse (block: DocxBlock, ctx: ParserContext): MdBlockNode {
     return {
       type: 'callout',
diff --git a/src/md-ast/parsers/grid.ts b/src/md-ast/parsers/grid.ts
index d3ac172..388d8c6 100644
--- a/src/md-ast/parsers/grid.ts
+++ b/src/md-ast/parsers/grid.ts
@@ -4,6 +4,7 @@ import type { MdBlockNode } from '../types.js';
 
 export const gridParser: BlockParser = {
   blockType: 24,
+  consumesChildren: true,
   parse (block: DocxBlock, ctx: ParserContext): MdBlockNode {
     const children: MdBlockNode[] = [];
     for (const colId of block.children ?? []) {
diff --git a/src/md-ast/parsers/ordered.ts b/src/md-ast/parsers/ordered.ts
index bf8f58b..a98597a 100644
--- a/src/md-ast/parsers/ordered.ts
+++ b/src/md-ast/parsers/ordered.ts
@@ -4,6 +4,7 @@ import type { MdBlockNode } from '../types.js';
 
 export const orderedParser: BlockParser = {
   blockType: 13,
+  consumesChildren: true,
   parse (block: DocxBlock, ctx: ParserContext): MdBlockNode {
     const parent = block.parent_id ? ctx.blockMap.get(block.parent_id) : undefined;
     let order = 1;
diff --git a/src/md-ast/parsers/page.ts b/src/md-ast/parsers/page.ts
index f6a2ce2..f469957 100644
--- a/src/md-ast/parsers/page.ts
+++ b/src/md-ast/parsers/page.ts
@@ -4,6 +4,7 @@ import type { MdBlockNode } from '../types.js';
 
 export const pageParser: BlockParser = {
   blockType: 1,
+  consumesChildren: true,
   parse (block: DocxBlock, ctx: ParserContext): MdBlockNode {
     return {
       type: 'page',
diff --git a/src/md-ast/parsers/quoteContainer.ts b/src/md-ast/parsers/quoteContainer.ts
index 5c620ef..c87cdcc 100644
--- a/src/md-ast/parsers/quoteContainer.ts
+++ b/src/md-ast/parsers/quoteContainer.ts
@@ -4,6 +4,7 @@ import type { MdBlockNode } from '../types.js';
 
 export const quoteContainerParser: BlockParser = {
   blockType: 34,
+  consumesChildren: true,
   parse (block: DocxBlock, ctx: ParserContext): MdBlockNode {
     return {
       type: 'quote',
diff --git a/src/md-ast/parsers/table.ts b/src/md-ast/parsers/table.ts
index b913c68..6abb538 100644
--- a/src/md-ast/parsers/table.ts
+++ b/src/md-ast/parsers/table.ts
@@ -4,6 +4,7 @@ import type { MdBlockNode, MdInlineNode, MdTableRow } from '../types.js';
 
 export const tableParser: BlockParser = {
   blockType: 31,
+  consumesChildren: true,
   parse (block: DocxBlock, ctx: ParserContext): MdBlockNode {
     const t = block.table!;
     const cols = t.property.column_size;
diff --git a/src/md-ast/serializer.ts b/src/md-ast/serializer.ts
index 6e49a2b..691843d 100644
--- a/src/md-ast/serializer.ts
+++ b/src/md-ast/serializer.ts
@@ -33,10 +33,13 @@ export class MdSerializer {
       sourceType: options.sourceType ?? 'docx',
       serialize: (node: MdBlockNode, indent = 0): string => {
         const serializer = this.registry.get(node.type);
-        if (serializer) {
-          return serializer.serialize(node, ctx);
+        if (!serializer) return '';
+        let s = serializer.serialize(node, ctx);
+        // 通用：渲染节点携带的嵌套子块（飞书大纲/折叠等场景下叶子块的内容），位于节点自身内容之后
+        if (node.blocks?.length) {
+          for (const child of node.blocks) s += ctx.serialize(child, indent);
         }
-        return '';
+        return s;
       },
       serializeInline: (nodes: MdInlineNode[]): string => {
         return nodes.map(n => serializeInlineNode(n)).join('');
diff --git a/src/md-ast/transformer.ts b/src/md-ast/transformer.ts
index 6cc1c7e..9e64b4a 100644
--- a/src/md-ast/transformer.ts
+++ b/src/md-ast/transformer.ts
@@ -347,53 +347,56 @@ function replaceInAst (
     return;
   }
 
-  if (!hasBlockChildren(node)) return;
-
-  const children = node.children as MdBlockNode[];
-  for (let i = 0; i < children.length; i++) {
-    const child = children[i]!;
-    if (child.type === 'whiteboard') {
-      const replacement = whiteboardMap.get(child.token);
-      if (replacement) {
-        children[i] = replacement;
-        continue;
+  for (const arr of blockChildArrays(node)) {
+    for (let i = 0; i < arr.length; i++) {
+      const child = arr[i]!;
+      if (child.type === 'whiteboard') {
+        const replacement = whiteboardMap.get(child.token);
+        if (replacement) {
+          arr[i] = replacement;
+          continue;
+        }
       }
-    }
-    if (child.type === 'sheet') {
-      const replacement = sheetMap.get(child.token);
-      if (replacement) {
-        children[i] = replacement;
-        continue;
+      if (child.type === 'sheet') {
+        const replacement = sheetMap.get(child.token);
+        if (replacement) {
+          arr[i] = replacement;
+          continue;
+        }
       }
-    }
-    if (child.type === 'image') {
-      const newSrc = imageMap.get(child.src);
-      if (newSrc) {
-        (child as MdBlockNode & { src: string }).src = newSrc;
+      if (child.type === 'image') {
+        const newSrc = imageMap.get(child.src);
+        if (newSrc) {
+          (child as MdBlockNode & { src: string }).src = newSrc;
+        }
       }
+      replaceInAst(child, imageMap, whiteboardMap, sheetMap);
     }
-    replaceInAst(child, imageMap, whiteboardMap, sheetMap);
   }
 }
 
 function traverseBlockAst (node: MdBlockNode, visitor: (node: MdBlockNode) => void): void {
   visitor(node);
-  if (!hasBlockChildren(node)) return;
-  for (const child of (node.children as MdBlockNode[])) {
-    traverseBlockAst(child, visitor);
+  for (const arr of blockChildArrays(node)) {
+    for (const child of arr) {
+      traverseBlockAst(child, visitor);
+    }
   }
 }
 
-function hasBlockChildren (node: MdBlockNode): node is Extract<
-  MdBlockNode,
-  { type: 'page' | 'bullet' | 'ordered' | 'callout' | 'quote' | 'grid' }
-> {
-  return (
-    node.type === 'page' ||
-    node.type === 'bullet' ||
-    node.type === 'ordered' ||
-    node.type === 'callout' ||
-    node.type === 'quote' ||
-    node.type === 'grid'
-  );
+/**
+ * 返回节点持有的块级子节点数组（可变引用），供遍历/替换使用。
+ * 容器型（page/bullet/ordered/callout/quote/grid）子块在 children；
+ * 任意节点都可能携带嵌套 blocks（飞书大纲/折叠等场景下叶子块的内容）。
+ */
+function blockChildArrays (node: MdBlockNode): MdBlockNode[][] {
+  const arrs: MdBlockNode[][] = [];
+  if (
+    node.type === 'page' || node.type === 'bullet' || node.type === 'ordered' ||
+    node.type === 'callout' || node.type === 'quote' || node.type === 'grid'
+  ) {
+    arrs.push(node.children as MdBlockNode[]);
+  }
+  if (node.blocks) arrs.push(node.blocks);
+  return arrs;
 }
diff --git a/src/md-ast/types.ts b/src/md-ast/types.ts
index f1a1b84..e8ec0f5 100644
--- a/src/md-ast/types.ts
+++ b/src/md-ast/types.ts
@@ -2,24 +2,28 @@ import type { ResolvedSheet } from '../sheet/index.js';
 
 // ─── 块级节点 ───────────────────────────────────────────────────────────────
 
+/** 任意块节点都可能携带「未被自身 parser 消费的嵌套子块」，对应飞书大纲/折叠等场景下
+ *  叶子块所嵌套的内容；序列化时在节点自身内容之后渲染。 */
+interface NestedBlocks { blocks?: MdBlockNode[] }
+
 export type MdBlockNode =
-  | { type: 'page'; title: MdInlineNode[]; children: MdBlockNode[] }
-  | { type: 'heading'; level: number; children: MdInlineNode[] }
-  | { type: 'paragraph'; children: MdInlineNode[] }
-  | { type: 'bullet'; text: MdInlineNode[]; children: MdBlockNode[] }
-  | { type: 'ordered'; order: number; text: MdInlineNode[]; children: MdBlockNode[] }
-  | { type: 'codeBlock'; lang: string; content: string }
-  | { type: 'todo'; checked: boolean; text: MdInlineNode[] }
-  | { type: 'callout'; children: MdBlockNode[] }
-  | { type: 'quote'; children: MdBlockNode[] }
-  | { type: 'divider' }
-  | { type: 'image'; alt: string; src: string }
-  | { type: 'whiteboard'; token: string }
-  | { type: 'sheet'; token: string }
-  | { type: 'sheetResolved'; title: string; sheets: ResolvedSheet[] }
-  | { type: 'table'; rows: MdTableRow[] }
-  | { type: 'grid'; children: MdBlockNode[] }
-  | { type: 'html'; content: string };
+  | ({ type: 'page'; title: MdInlineNode[]; children: MdBlockNode[] } & NestedBlocks)
+  | ({ type: 'heading'; level: number; children: MdInlineNode[] } & NestedBlocks)
+  | ({ type: 'paragraph'; children: MdInlineNode[] } & NestedBlocks)
+  | ({ type: 'bullet'; text: MdInlineNode[]; children: MdBlockNode[] } & NestedBlocks)
+  | ({ type: 'ordered'; order: number; text: MdInlineNode[]; children: MdBlockNode[] } & NestedBlocks)
+  | ({ type: 'codeBlock'; lang: string; content: string } & NestedBlocks)
+  | ({ type: 'todo'; checked: boolean; text: MdInlineNode[] } & NestedBlocks)
+  | ({ type: 'callout'; children: MdBlockNode[] } & NestedBlocks)
+  | ({ type: 'quote'; children: MdBlockNode[] } & NestedBlocks)
+  | ({ type: 'divider' } & NestedBlocks)
+  | ({ type: 'image'; alt: string; src: string } & NestedBlocks)
+  | ({ type: 'whiteboard'; token: string } & NestedBlocks)
+  | ({ type: 'sheet'; token: string } & NestedBlocks)
+  | ({ type: 'sheetResolved'; title: string; sheets: ResolvedSheet[] } & NestedBlocks)
+  | ({ type: 'table'; rows: MdTableRow[] } & NestedBlocks)
+  | ({ type: 'grid'; children: MdBlockNode[] } & NestedBlocks)
+  | ({ type: 'html'; content: string } & NestedBlocks);
 
 export type MdTableRow = { cells: MdTableCell[] };
 export type MdTableCell = { content: MdInlineNode[]; rowSpan?: number; colSpan?: number };
diff --git a/tests/md-ast/parser.test.ts b/tests/md-ast/parser.test.ts
index 2bfe9c4..4a0789f 100644
--- a/tests/md-ast/parser.test.ts
+++ b/tests/md-ast/parser.test.ts
@@ -62,6 +62,48 @@ describe('Parser - end-to-end', () => {
     }
   });
 
+  it('parses a heading carrying nested children (Feishu outline/folded heading)', () => {
+    const blocks: DocxBlock[] = [
+      b({ block_id: 'root', block_type: 1, children: ['h'] }),
+      b({ block_id: 'h', block_type: 5, parent_id: 'root', heading3: { elements: [textRun('消息类型 msgType')] }, children: ['p1', 'h2'] }),
+      b({ block_id: 'p1', block_type: 2, parent_id: 'h', text: { elements: [textRun('intro text')] } }),
+      b({ block_id: 'h2', block_type: 6, parent_id: 'h', heading4: { elements: [textRun('子标题')] } }),
+    ];
+    const ast = buildParser().parse(doc, blocks);
+    if (ast.type !== 'page') throw new Error();
+    const h = ast.children[0]!;
+    expect(h).toMatchObject({ type: 'heading', level: 3 });
+    if (h.type !== 'heading') throw new Error();
+    expect(h.blocks).toHaveLength(2);
+    expect(h.blocks![0]).toMatchObject({ type: 'paragraph' });
+    expect(h.blocks![1]).toMatchObject({ type: 'heading', level: 4 });
+
+    const ser = new MdSerializer();
+    registerBuiltinSerializers(ser);
+    expect(ser.serialize(ast)).toBe('### 消息类型 msgType\n\nintro text\n\n#### 子标题\n\n');
+  });
+
+  it('parses a leaf block (todo) carrying nested children (generalized outline)', () => {
+    const blocks: DocxBlock[] = [
+      b({ block_id: 'root', block_type: 1, children: ['t'] }),
+      b({ block_id: 't', block_type: 17, parent_id: 'root', todo: { style: { done: false }, elements: [textRun('消息类型 msgType')] }, children: ['p1', 't2'] }),
+      b({ block_id: 'p1', block_type: 2, parent_id: 't', text: { elements: [textRun('intro')] } }),
+      b({ block_id: 't2', block_type: 17, parent_id: 't', todo: { style: { done: true }, elements: [textRun('sub todo')] } }),
+    ];
+    const ast = buildParser().parse(doc, blocks);
+    if (ast.type !== 'page') throw new Error();
+    const t = ast.children[0]!;
+    expect(t).toMatchObject({ type: 'todo', checked: false });
+    if (t.type !== 'todo') throw new Error();
+    expect(t.blocks).toHaveLength(2);
+    expect(t.blocks![0]).toMatchObject({ type: 'paragraph' });
+    expect(t.blocks![1]).toMatchObject({ type: 'todo', checked: true });
+
+    const ser = new MdSerializer();
+    registerBuiltinSerializers(ser);
+    expect(ser.serialize(ast)).toBe('- [ ] 消息类型 msgType\nintro\n\n- [x] sub todo\n');
+  });
+
   it('parses inline styles (bold/italic/underline/strikethrough/inlineCode/link)', () => {
     const blocks: DocxBlock[] = [
       b({ block_id: 'root', block_type: 1, children: ['p'] }),
@@ -438,6 +480,27 @@ describe('Parser - end-to-end', () => {
     expect(ast.children).toHaveLength(0);
   });
 
+  it('falls back an unknown block_type with text/children to a paragraph (preserves subtree)', () => {
+    const blocks: DocxBlock[] = [
+      b({ block_id: 'root', block_type: 1, children: ['u'] }),
+      b({ block_id: 'u', block_type: 999, parent_id: 'root', text: { elements: [textRun('未支持块正文')] }, children: ['p1'] } as any),
+      b({ block_id: 'p1', block_type: 2, parent_id: 'u', text: { elements: [textRun('嵌套子块')] } }),
+    ];
+    const ast = buildParser().parse(doc, blocks);
+    if (ast.type !== 'page') throw new Error();
+    expect(ast.children).toHaveLength(1);
+    const u = ast.children[0]!;
+    expect(u).toMatchObject({ type: 'paragraph' });
+    if (u.type !== 'paragraph') throw new Error();
+    expect(u.children[0]).toMatchObject({ type: 'text', content: '未支持块正文' });
+    expect(u.blocks).toHaveLength(1);
+    expect(u.blocks![0]).toMatchObject({ type: 'paragraph' });
+
+    const ser = new MdSerializer();
+    registerBuiltinSerializers(ser);
+    expect(ser.serialize(ast)).toBe('未支持块正文\n\n嵌套子块\n\n');
+  });
+
   // ─── Parser + Serializer integration ──────────────────────────────────────
   it('end-to-end: parse → serialize produces expected markdown', () => {
     const blocks: DocxBlock[] = [
diff --git a/tests/md-ast/serializer.test.ts b/tests/md-ast/serializer.test.ts
index 61bf025..1216385 100644
--- a/tests/md-ast/serializer.test.ts
+++ b/tests/md-ast/serializer.test.ts
@@ -29,6 +29,19 @@ describe('MdSerializer', () => {
       const node: MdBlockNode = { type: 'heading', level: 2, children: [bold('Important')] };
       expect(s.serialize(node)).toBe('## **Important**\n\n');
     });
+
+    it('renders nested block children after the heading line', () => {
+      const node: MdBlockNode = {
+        type: 'heading',
+        level: 2,
+        children: [text('Section')],
+        blocks: [
+          { type: 'paragraph', children: [text('Body')] },
+          { type: 'heading', level: 3, children: [text('Sub')] },
+        ],
+      };
+      expect(s.serialize(node)).toBe('## Section\n\nBody\n\n### Sub\n\n');
+    });
   });
 
   describe('paragraph', () => {
@@ -85,6 +98,19 @@ describe('MdSerializer', () => {
       const node: MdBlockNode = { type: 'todo', checked: true, text: [text('done')] };
       expect(s.serialize(node)).toBe('- [x] done\n');
     });
+
+    it('renders nested block children after the todo line', () => {
+      const node: MdBlockNode = {
+        type: 'todo',
+        checked: false,
+        text: [text('Task')],
+        blocks: [
+          { type: 'paragraph', children: [text('Detail')] },
+          { type: 'todo', checked: true, text: [text('Sub')] },
+        ],
+      };
+      expect(s.serialize(node)).toBe('- [ ] Task\nDetail\n\n- [x] Sub\n');
+    });
   });
 
   describe('divider', () => {