From bc3e9c23f0284ba1777fd767712317ceacfb748d Mon Sep 17 00:00:00 2001
From: SecPan <qq2579937786@gmail.com>
Date: Thu, 16 Jul 2026 04:52:03 -0700
Subject: [PATCH 1/4] Port upstream 4844: keep soft line breaks on export via
 CSS

---
 .../muya/src/assets/styles/exportStyle.css    | 16 ++++++++
 .../__tests__/softBreakExportHtml.spec.ts     | 37 +++++++++++++++++++
 2 files changed, 53 insertions(+)
 create mode 100644 third_party/muya/src/state/__tests__/softBreakExportHtml.spec.ts

diff --git a/third_party/muya/src/assets/styles/exportStyle.css b/third_party/muya/src/assets/styles/exportStyle.css
index e362724..333faba 100644
--- a/third_party/muya/src/assets/styles/exportStyle.css
+++ b/third_party/muya/src/assets/styles/exportStyle.css
@@ -89,6 +89,22 @@
     white-space: pre-wrap;
 }
 
+/* Render soft line breaks (Shift+Enter → a bare `\n` inside a block) the way
+   the editor does (`.mu-content` is pre-wrap) instead of emitting a
+   non-standard `<br>`, so the exported HTML stays CommonMark-conformant (the
+   `\n` is a plain line ending) yet still shows the break (marktext#3676).
+
+   `li:not(:has(> p))` targets only tight list items, whose soft break is a
+   bare `\n` directly inside the `<li>`. Loose items wrap their content in
+   `<p>` (handled by the `p` rule); giving them `li` pre-wrap would expose
+   marked's pretty-printing newline between `</p>` and `</li>` as a stray blank
+   line, so they are deliberately excluded. Specificity stays level with the
+   earlier `.toc-container ul li` rule (no-descending-specificity). */
+.markdown-body p,
+.markdown-body li:not(:has(> p)) {
+    white-space: pre-wrap;
+}
+
 .markdown-body table {
     display: table;
 }
diff --git a/third_party/muya/src/state/__tests__/softBreakExportHtml.spec.ts b/third_party/muya/src/state/__tests__/softBreakExportHtml.spec.ts
new file mode 100644
index 0000000..81fc69f
--- /dev/null
+++ b/third_party/muya/src/state/__tests__/softBreakExportHtml.spec.ts
@@ -0,0 +1,37 @@
+import { describe, expect, it } from 'vitest';
+import { getHighlightHtml } from '../../utils/marked';
+
+// marktext#3676 — a soft line break (Shift+Enter, serialized as a bare `\n`
+// inside a block) shows as a line break in the editor (`.mu-content` is
+// pre-wrap) but was lost on export because marked renders a soft break as a
+// space. Rather than emit a non-standard `<br>` (which CommonMark reserves for
+// hard breaks), the export keeps the conformant `\n` and renders it with
+// `white-space: pre-wrap` on `.markdown-body p` and `li:not(:has(> p))`
+// (tight items only).
+//
+// These assert the HTML stays conformant — the soft break is a preserved
+// newline, never a `<br>`, and hard breaks are untouched. The pre-wrap
+// rendering itself (and the `:has()` exclusion of loose items) is a CSS
+// concern verified in a real browser against the export stylesheet.
+
+const OPTS = { math: false, superSubScript: false, footnote: false, frontMatter: false };
+
+describe('#3676 — soft line breaks survive export as a conformant newline', () => {
+    it('keeps a paragraph soft break as a newline, never a <br>', () => {
+        const html = getHighlightHtml('line one\nline two', OPTS);
+        expect(html).toContain('<p>line one\nline two</p>');
+        expect(html).not.toMatch(/<br\s*\/?>/);
+    });
+
+    it('keeps a soft break inside a tight list item, never a <br>', () => {
+        const html = getHighlightHtml('- line A\n  line B', OPTS);
+        expect(html).toMatch(/<li>line A\nline B<\/li>/);
+        expect(html).not.toMatch(/<br\s*\/?>/);
+    });
+
+    it('leaves a real hard break (two trailing spaces) as <br>', () => {
+        // Sanity: the change only touches soft breaks; hard breaks are untouched.
+        const html = getHighlightHtml('line one  \nline two', OPTS);
+        expect(html).toMatch(/<br\s*\/?>/);
+    });
+});

From 8ebbff110de254a0b5081d653a9407a88e46388a Mon Sep 17 00:00:00 2001
From: SecPan <qq2579937786@gmail.com>
Date: Thu, 16 Jul 2026 16:43:54 -0700
Subject: [PATCH 2/4] Address review: strip marked's formatting whitespace in
 pre-wrap list contexts

---
 tests/e2e/export-soft-break-layout.spec.ts    | 74 +++++++++++++++++++
 .../__tests__/softBreakExportHtml.spec.ts     | 51 ++++++++++++-
 third_party/muya/src/state/markdownToHtml.ts  | 41 ++++++++++
 3 files changed, 162 insertions(+), 4 deletions(-)
 create mode 100644 tests/e2e/export-soft-break-layout.spec.ts

diff --git a/tests/e2e/export-soft-break-layout.spec.ts b/tests/e2e/export-soft-break-layout.spec.ts
new file mode 100644
index 0000000..28954ea
--- /dev/null
+++ b/tests/e2e/export-soft-break-layout.spec.ts
@@ -0,0 +1,74 @@
+import { readFileSync } from 'node:fs'
+import { expect, test, type Page } from '@playwright/test'
+
+// Browser layout coverage for the #3676 export soft-break fix (PR review):
+// the export stylesheet renders tight list items `white-space: pre-wrap`, and
+// `white-space` inherits — so marked's formatting-only newlines around nested
+// block children would each render as a visible empty line box. The export
+// pipeline strips that serializer whitespace (markdownToHtml,
+// `_stripListFormattingWhitespace`; shape pinned by
+// third_party/muya/src/state/__tests__/softBreakExportHtml.spec.ts). This
+// spec closes the loop in a real Chromium: the stylesheet plus the pipeline's
+// output shape lay out without phantom blank rows, while authored soft
+// breaks still render as real line breaks.
+
+// Playwright runs from the repo root; the config's testDir keeps that cwd.
+const exportCss = readFileSync('third_party/muya/src/assets/styles/exportStyle.css', 'utf8')
+
+async function measureListItemHeight(page: Page, listInner: string, extraCss = '') {
+  await page.setContent(
+    `<!doctype html><style>${exportCss}</style><style>${extraCss}</style>` +
+      `<article class="markdown-body"><ul>${listInner}</ul></article>`,
+  )
+  return page.evaluate(
+    () => document.querySelector('.markdown-body > ul > li')!.getBoundingClientRect().height,
+  )
+}
+
+test('an authored soft break in a tight item renders as a real second line', async ({ page }) => {
+  const single = await measureListItemHeight(page, '<li>line A</li>')
+  const soft = await measureListItemHeight(page, '<li>line A\nline B</li>')
+
+  expect(soft).toBeGreaterThan(single * 1.8)
+  expect(soft).toBeLessThan(single * 2.6)
+})
+
+test('the cleaned nested-list shape adds no phantom blank rows', async ({ page }) => {
+  // Exactly what the export pipeline emits for `- line A\n  - child`.
+  const cleaned = '<li>line A<ul><li>child</li></ul></li>'
+  const withPreWrap = await measureListItemHeight(page, cleaned)
+  const control = await measureListItemHeight(
+    page,
+    cleaned,
+    '.markdown-body li { white-space: normal !important; }',
+  )
+
+  expect(withPreWrap).toBe(control)
+})
+
+test("marked's uncleaned serializer newlines DO create blank rows (premise)", async ({ page }) => {
+  // marked's raw serialization for the same markdown — the shape the
+  // pipeline strip exists to prevent. If this stops failing tall, the strip
+  // (and this suite) can be reconsidered.
+  const raw = '<li>line A\n<ul>\n<li>child</li>\n</ul>\n</li>'
+  const withPreWrap = await measureListItemHeight(page, raw)
+  const control = await measureListItemHeight(
+    page,
+    raw,
+    '.markdown-body li { white-space: normal !important; }',
+  )
+
+  expect(withPreWrap).toBeGreaterThan(control)
+})
+
+test('the cleaned nested-blockquote shape adds no phantom blank rows', async ({ page }) => {
+  const cleaned = '<li>line A<blockquote><p>quoted</p></blockquote></li>'
+  const withPreWrap = await measureListItemHeight(page, cleaned)
+  const control = await measureListItemHeight(
+    page,
+    cleaned,
+    '.markdown-body li { white-space: normal !important; }',
+  )
+
+  expect(withPreWrap).toBe(control)
+})
diff --git a/third_party/muya/src/state/__tests__/softBreakExportHtml.spec.ts b/third_party/muya/src/state/__tests__/softBreakExportHtml.spec.ts
index 81fc69f..1817e7f 100644
--- a/third_party/muya/src/state/__tests__/softBreakExportHtml.spec.ts
+++ b/third_party/muya/src/state/__tests__/softBreakExportHtml.spec.ts
@@ -1,4 +1,7 @@
+// @vitest-environment happy-dom
+
 import { describe, expect, it } from 'vitest';
+import { MarkdownToHtml } from '../markdownToHtml';
 import { getHighlightHtml } from '../../utils/marked';
 
 // marktext#3676 — a soft line break (Shift+Enter, serialized as a bare `\n`
@@ -9,10 +12,13 @@ import { getHighlightHtml } from '../../utils/marked';
 // `white-space: pre-wrap` on `.markdown-body p` and `li:not(:has(> p))`
 // (tight items only).
 //
-// These assert the HTML stays conformant — the soft break is a preserved
-// newline, never a `<br>`, and hard breaks are untouched. The pre-wrap
-// rendering itself (and the `:has()` exclusion of loose items) is a CSS
-// concern verified in a real browser against the export stylesheet.
+// Because `white-space` inherits, marked's pretty-printing newlines around
+// nested block children (`line A\n<ul>`, `<ul>\n<li>`, `</ul>\n</li>`) would
+// each render as a visible empty line box under that rule, so the export
+// pipeline strips serializer-only whitespace from list/blockquote contexts
+// while leaving authored soft breaks (which always have text after them)
+// untouched. The pixel-level rendering of both halves is covered by the
+// Playwright layout spec (tests/e2e/export-soft-break-layout.spec.ts).
 
 const OPTS = { math: false, superSubScript: false, footnote: false, frontMatter: false };
 
@@ -35,3 +41,40 @@ describe('#3676 — soft line breaks survive export as a conformant newline', ()
         expect(html).toMatch(/<br\s*\/?>/);
     });
 });
+
+describe('export pipeline strips serializer whitespace in pre-wrap list contexts', () => {
+    it('a tight item with a nested list carries no formatting newlines', async () => {
+        const html = await new MarkdownToHtml('- line A\n  - child\n').renderHtml();
+
+        // marked emits `line A\n<ul>\n<li>child</li>\n</ul>\n</li>`; every one
+        // of those newlines is an empty line box under inherited pre-wrap.
+        expect(html).toContain('<li>line A<ul><li>child</li></ul></li>');
+    });
+
+    it('keeps the authored soft break while stripping the serializer newline', async () => {
+        const html = await new MarkdownToHtml('- line A\n  line B\n  - child\n').renderHtml();
+
+        // The `\n` between "line A" and "line B" is the user's; the `\n`
+        // between "line B" and the nested list is marked's.
+        expect(html).toContain('<li>line A\nline B<ul><li>child</li></ul></li>');
+    });
+
+    it('a nested blockquote in a tight item carries no formatting newlines', async () => {
+        const html = await new MarkdownToHtml('- line A\n  > quoted\n').renderHtml();
+
+        expect(html).toMatch(/<li>line A<blockquote>\s*<p>quoted<\/p>\s*<\/blockquote><\/li>/);
+        // The blockquote's own children are not under the tight-item pre-wrap
+        // text path, but strip its formatting whitespace too — `white-space`
+        // inherits into it.
+        expect(html).not.toMatch(/\n<\/li>/);
+    });
+
+    it('leaves paragraph soft breaks intact through the full pipeline', async () => {
+        // happy-dom's DOMPurify pass unwraps the <p> in this environment (a
+        // test-runtime artifact — the getHighlightHtml assertion above pins
+        // the real markup), so assert only what this suite owns: the strip
+        // never touches an authored newline.
+        const html = await new MarkdownToHtml('line one\nline two\n').renderHtml();
+        expect(html).toContain('line one\nline two');
+    });
+});
diff --git a/third_party/muya/src/state/markdownToHtml.ts b/third_party/muya/src/state/markdownToHtml.ts
index 615f480..14fc197 100644
--- a/third_party/muya/src/state/markdownToHtml.ts
+++ b/third_party/muya/src/state/markdownToHtml.ts
@@ -179,6 +179,45 @@ export class MarkdownToHtml {
         }
     }
 
+    // The export stylesheet renders tight list items `white-space: pre-wrap`
+    // so authored soft breaks survive (marktext#3676) — but `white-space`
+    // inherits, and marked pretty-prints nested block children with
+    // formatting-only newlines (`line A\n<ul>`, `<ul>\n<li>`, `</ul>\n</li>`).
+    // Under pre-wrap each of those becomes a visible empty line box in the
+    // exported HTML/PDF (measured: a tight item with one nested child renders
+    // 105px instead of 42px). Strip the serializer whitespace: it is never
+    // authored text — an authored soft break always has text after it, so a
+    // newline touching a block-element sibling is marked's, not the user's.
+    private _stripListFormattingWhitespace(container: HTMLElement) {
+        const blockChild = new Set(['P', 'UL', 'OL', 'BLOCKQUOTE', 'PRE', 'TABLE', 'DIV']);
+        const isBlock = (node: Node | null): boolean =>
+            node?.nodeType === Node.ELEMENT_NODE
+            && blockChild.has((node as Element).tagName);
+
+        for (const parent of container.querySelectorAll('li, ul, ol, blockquote')) {
+            for (const node of Array.from(parent.childNodes)) {
+                if (node.nodeType !== Node.TEXT_NODE)
+                    continue;
+
+                const text = node.textContent ?? '';
+                if (!text.trim()) {
+                    // Whitespace-only nodes between block children are pure
+                    // serializer formatting (ul/ol may only contain li).
+                    node.remove();
+                    continue;
+                }
+
+                let trimmed = text;
+                if (isBlock(node.nextSibling))
+                    trimmed = trimmed.replace(/\n+$/, '');
+                if (isBlock(node.previousSibling))
+                    trimmed = trimmed.replace(/^\n+/, '');
+                if (trimmed !== text)
+                    node.textContent = trimmed;
+            }
+        }
+    }
+
     // render pure html by marked
     async renderHtml() {
         const footnote = this._muya?.options?.footnote ?? false;
@@ -205,6 +244,8 @@ export class MarkdownToHtml {
         exportContainer.innerHTML = html;
         document.body.appendChild(exportContainer);
 
+        this._stripListFormattingWhitespace(exportContainer);
+
         // render only render the light theme of mermaid and diagram...
         await this._renderMermaid();
         await this._renderDiagram();

From 17802bb701d840e1ce4e6ff8bffd8704e19d57d0 Mon Sep 17 00:00:00 2001
From: SecPan <qq2579937786@gmail.com>
Date: Thu, 16 Jul 2026 17:28:03 -0700
Subject: [PATCH 3/4] Address review: preserve authored whitespace between
 inline siblings

---
 tests/e2e/export-soft-break-layout.spec.ts    | 13 +++++++++++++
 .../__tests__/softBreakExportHtml.spec.ts     | 17 +++++++++++++++++
 third_party/muya/src/state/markdownToHtml.ts  | 19 ++++++++++++++++---
 3 files changed, 46 insertions(+), 3 deletions(-)

diff --git a/tests/e2e/export-soft-break-layout.spec.ts b/tests/e2e/export-soft-break-layout.spec.ts
index 28954ea..93f7dd9 100644
--- a/tests/e2e/export-soft-break-layout.spec.ts
+++ b/tests/e2e/export-soft-break-layout.spec.ts
@@ -33,6 +33,19 @@ test('an authored soft break in a tight item renders as a real second line', asy
   expect(soft).toBeLessThan(single * 2.6)
 })
 
+test('a soft break between inline-wrapped lines renders as a real second line', async ({ page }) => {
+  // The authored newline lives in a whitespace-only text node BETWEEN two
+  // inline elements — the strip must not eat it (review round 2).
+  const single = await measureListItemHeight(page, '<li><strong>left</strong></li>')
+  const soft = await measureListItemHeight(
+    page,
+    '<li><strong>left</strong>\n<strong>right</strong></li>',
+  )
+
+  expect(soft).toBeGreaterThan(single * 1.8)
+  expect(soft).toBeLessThan(single * 2.6)
+})
+
 test('the cleaned nested-list shape adds no phantom blank rows', async ({ page }) => {
   // Exactly what the export pipeline emits for `- line A\n  - child`.
   const cleaned = '<li>line A<ul><li>child</li></ul></li>'
diff --git a/third_party/muya/src/state/__tests__/softBreakExportHtml.spec.ts b/third_party/muya/src/state/__tests__/softBreakExportHtml.spec.ts
index 1817e7f..81661cc 100644
--- a/third_party/muya/src/state/__tests__/softBreakExportHtml.spec.ts
+++ b/third_party/muya/src/state/__tests__/softBreakExportHtml.spec.ts
@@ -69,6 +69,23 @@ describe('export pipeline strips serializer whitespace in pre-wrap list contexts
         expect(html).not.toMatch(/\n<\/li>/);
     });
 
+    it('preserves the authored space between inline siblings', async () => {
+        const html = await new MarkdownToHtml('- **left** **right**\n').renderHtml();
+
+        // The space between the two <strong> elements is authored text, not
+        // serializer formatting — removing it would export "leftright".
+        expect(html).toContain('<strong>left</strong> <strong>right</strong>');
+    });
+
+    it('preserves a soft break whose lines are both wrapped in inline markup', async () => {
+        const html = await new MarkdownToHtml('- **left**\n  **right**\n').renderHtml();
+
+        // The newline lives in a whitespace-only text node between two
+        // inline siblings — exactly the soft break this feature exists to
+        // keep.
+        expect(html).toContain('<strong>left</strong>\n<strong>right</strong>');
+    });
+
     it('leaves paragraph soft breaks intact through the full pipeline', async () => {
         // happy-dom's DOMPurify pass unwraps the <p> in this environment (a
         // test-runtime artifact — the getHighlightHtml assertion above pins
diff --git a/third_party/muya/src/state/markdownToHtml.ts b/third_party/muya/src/state/markdownToHtml.ts
index 14fc197..a3354c4 100644
--- a/third_party/muya/src/state/markdownToHtml.ts
+++ b/third_party/muya/src/state/markdownToHtml.ts
@@ -195,15 +195,28 @@ export class MarkdownToHtml {
             && blockChild.has((node as Element).tagName);
 
         for (const parent of container.querySelectorAll('li, ul, ol, blockquote')) {
+            // Only list items mix inline content with block children — under
+            // ul/ol/blockquote every legal child is a block, so ALL
+            // whitespace-only text nodes there are serializer formatting.
+            const mixedContext = parent.tagName === 'LI';
             for (const node of Array.from(parent.childNodes)) {
                 if (node.nodeType !== Node.TEXT_NODE)
                     continue;
 
                 const text = node.textContent ?? '';
                 if (!text.trim()) {
-                    // Whitespace-only nodes between block children are pure
-                    // serializer formatting (ul/ol may only contain li).
-                    node.remove();
+                    // Authored whitespace between INLINE siblings must
+                    // survive: the space in `**left** **right**`, or a soft
+                    // break whose lines are both wrapped in inline markup.
+                    // Only whitespace touching a block child is marked's
+                    // pretty-printing.
+                    if (
+                        !mixedContext
+                        || isBlock(node.previousSibling)
+                        || isBlock(node.nextSibling)
+                    ) {
+                        node.remove();
+                    }
                     continue;
                 }
 

From 42adfbb0ec66c66c08450299ec0e719d0c39b3eb Mon Sep 17 00:00:00 2001
From: SecPan <qq2579937786@gmail.com>
Date: Thu, 16 Jul 2026 17:51:49 -0700
Subject: [PATCH 4/4] Address review: raw blockquote inline flow and the full
 block-level tag set

---
 tests/e2e/export-soft-break-layout.spec.ts    | 15 ++++++++
 .../__tests__/softBreakExportHtml.spec.ts     | 35 +++++++++++++++++++
 third_party/muya/src/state/markdownToHtml.ts  | 27 ++++++++++----
 3 files changed, 71 insertions(+), 6 deletions(-)

diff --git a/tests/e2e/export-soft-break-layout.spec.ts b/tests/e2e/export-soft-break-layout.spec.ts
index 93f7dd9..208267b 100644
--- a/tests/e2e/export-soft-break-layout.spec.ts
+++ b/tests/e2e/export-soft-break-layout.spec.ts
@@ -74,6 +74,21 @@ test("marked's uncleaned serializer newlines DO create blank rows (premise)", as
   expect(withPreWrap).toBeGreaterThan(control)
 })
 
+test('a heading as the sole item child adds no phantom blank rows', async ({ page }) => {
+  // `- # heading` emits `<li><h1>…</h1>\n</li>`; H1 must count as a block
+  // child in the cleanup or the trailing newline renders as a phantom row
+  // (review round 3 measured 85px instead of 43px).
+  const cleaned = '<li><h1>heading</h1></li>'
+  const withPreWrap = await measureListItemHeight(page, cleaned)
+  const control = await measureListItemHeight(
+    page,
+    cleaned,
+    '.markdown-body li { white-space: normal !important; }',
+  )
+
+  expect(withPreWrap).toBe(control)
+})
+
 test('the cleaned nested-blockquote shape adds no phantom blank rows', async ({ page }) => {
   const cleaned = '<li>line A<blockquote><p>quoted</p></blockquote></li>'
   const withPreWrap = await measureListItemHeight(page, cleaned)
diff --git a/third_party/muya/src/state/__tests__/softBreakExportHtml.spec.ts b/third_party/muya/src/state/__tests__/softBreakExportHtml.spec.ts
index 81661cc..110b5cc 100644
--- a/third_party/muya/src/state/__tests__/softBreakExportHtml.spec.ts
+++ b/third_party/muya/src/state/__tests__/softBreakExportHtml.spec.ts
@@ -86,6 +86,41 @@ describe('export pipeline strips serializer whitespace in pre-wrap list contexts
         expect(html).toContain('<strong>left</strong>\n<strong>right</strong>');
     });
 
+    it('preserves authored whitespace between inline siblings in a raw blockquote', () => {
+        // Raw HTML blockquotes may carry inline flow content directly —
+        // unlike marked-generated ones, which always wrap children in
+        // blocks. happy-dom's sanitize unwraps top-level blockquotes, so
+        // drive the cleanup itself; the real-browser pipeline case lives in
+        // the upstream muya e2e suite.
+        const container = document.createElement('div');
+        container.innerHTML
+            = '<blockquote><strong>left</strong> <strong>right</strong></blockquote>';
+        (new MarkdownToHtml('') as unknown as {
+            _stripListFormattingWhitespace: (c: HTMLElement) => void;
+        })._stripListFormattingWhitespace(container);
+
+        expect(container.innerHTML).toBe(
+            '<blockquote><strong>left</strong> <strong>right</strong></blockquote>',
+        );
+    });
+
+    it('a heading as the sole list-item child carries no formatting newline', async () => {
+        // marked emits `<li><h1>heading</h1>\n</li>` for `- # heading`; H1
+        // must count as a block child or the newline renders as a phantom
+        // row under inherited pre-wrap.
+        const html = await new MarkdownToHtml('- # heading\n').renderHtml();
+
+        expect(html).toMatch(/<li><h1[^>]*>heading<\/h1><\/li>/);
+        expect(html).not.toMatch(/\n<\/li>/);
+    });
+
+    it('a thematic break as the sole list-item child carries no formatting newline', async () => {
+        const html = await new MarkdownToHtml('- * * *\n').renderHtml();
+
+        expect(html).toContain('<li><hr></li>');
+        expect(html).not.toMatch(/\n<\/li>/);
+    });
+
     it('leaves paragraph soft breaks intact through the full pipeline', async () => {
         // happy-dom's DOMPurify pass unwraps the <p> in this environment (a
         // test-runtime artifact — the getHighlightHtml assertion above pins
diff --git a/third_party/muya/src/state/markdownToHtml.ts b/third_party/muya/src/state/markdownToHtml.ts
index a3354c4..75bdb37 100644
--- a/third_party/muya/src/state/markdownToHtml.ts
+++ b/third_party/muya/src/state/markdownToHtml.ts
@@ -28,6 +28,18 @@ const CDN_STYLESHEET_LINKS = `  <!-- https://cdnjs.com/libraries/github-markdown
   <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/prism/9000.0.1/themes/prism.min.css" integrity="sha512-/mZ1FHPkg6EKcxo0fKXF51ak6Cr2ocgDi5ytaTBjsQZIH/RNs6GF6+oId/vPe3eJB836T36nXwVh/WBl/cWT4w==" crossorigin="anonymous" referrerpolicy="no-referrer" />`;
 
 export class MarkdownToHtml {
+    // Every tag the HTML spec treats as block-level flow content. marked can
+    // emit headings (`- # h`) and thematic breaks (`- * * *`) as direct
+    // list-item children — not just the common container tags — and any tag
+    // missing here resurfaces the phantom-row bug for that construct.
+    private static readonly _blockLevelTags = new Set([
+        'ADDRESS', 'ARTICLE', 'ASIDE', 'BLOCKQUOTE', 'DD', 'DETAILS',
+        'DIALOG', 'DIV', 'DL', 'DT', 'FIELDSET', 'FIGCAPTION', 'FIGURE',
+        'FOOTER', 'FORM', 'H1', 'H2', 'H3', 'H4', 'H5', 'H6', 'HEADER',
+        'HGROUP', 'HR', 'LI', 'MAIN', 'NAV', 'OL', 'P', 'PRE', 'SECTION',
+        'TABLE', 'UL',
+    ]);
+
     private _exportContainer: HTMLDivElement | null = null;
 
     constructor(public markdown: string, private _muya?: Muya) {}
@@ -189,16 +201,19 @@ export class MarkdownToHtml {
     // authored text — an authored soft break always has text after it, so a
     // newline touching a block-element sibling is marked's, not the user's.
     private _stripListFormattingWhitespace(container: HTMLElement) {
-        const blockChild = new Set(['P', 'UL', 'OL', 'BLOCKQUOTE', 'PRE', 'TABLE', 'DIV']);
         const isBlock = (node: Node | null): boolean =>
             node?.nodeType === Node.ELEMENT_NODE
-            && blockChild.has((node as Element).tagName);
+            && MarkdownToHtml._blockLevelTags.has((node as Element).tagName);
 
         for (const parent of container.querySelectorAll('li, ul, ol, blockquote')) {
-            // Only list items mix inline content with block children — under
-            // ul/ol/blockquote every legal child is a block, so ALL
-            // whitespace-only text nodes there are serializer formatting.
-            const mixedContext = parent.tagName === 'LI';
+            // List items AND raw HTML blockquotes may carry inline flow
+            // content directly (a marked-GENERATED blockquote always wraps
+            // its children in blocks, so its formatting whitespace is still
+            // removed via block adjacency below). Only under ul/ol is every
+            // legal child a block, making ALL whitespace-only text nodes
+            // serializer formatting.
+            const mixedContext
+                = parent.tagName === 'LI' || parent.tagName === 'BLOCKQUOTE';
             for (const node of Array.from(parent.childNodes)) {
                 if (node.nodeType !== Node.TEXT_NODE)
                     continue;