diff --git a/.github/workflows/Test.yml b/.github/workflows/Test.yml
index 5f9faf8a..b7688d4f 100644
--- a/.github/workflows/Test.yml
+++ b/.github/workflows/Test.yml
@@ -15,4 +15,6 @@ jobs:
       - uses: actions/setup-node@v4
         with:
           node-version: 22
+      - run: npm install --ignore-scripts
+      - run: npx playwright install --with-deps chromium
       - run: npm test
diff --git a/Update.json b/Update.json
index bf40a3c4..5a93f36b 100644
--- a/Update.json
+++ b/Update.json
@@ -3791,6 +3791,17 @@
                 }
             ],
             "Notes": "No release notes were provided for this release."
+        },
+        "3.7.2": {
+            "UpdateDate": 1791030955802,
+            "Prerelease": true,
+            "UpdateContents": [
+                {
+                    "PR": 1031,
+                    "Description": "fix: preserve problem Markdown and add full-statement copying"
+                }
+            ],
+            "Notes": "No release notes were provided for this release."
         }
     }
 }
\ No newline at end of file
diff --git a/XMOJ.user.js b/XMOJ.user.js
index 731c52ad..47fc2f93 100644
--- a/XMOJ.user.js
+++ b/XMOJ.user.js
@@ -1,6 +1,6 @@
 // ==UserScript==
 // @name         XMOJ
-// @version      3.7.1
+// @version      3.7.2
 // @description  XMOJ增强脚本
 // @author       @XMOJ-Script-dev, @langningchen and the community
 // @namespace    https://github/langningchen
@@ -2653,13 +2653,7 @@ async function InitializeContestWebApp() {
         }
         // Sample boxes are cards, as on the legacy page.
         for (const pre of root.querySelectorAll(".xmoj-problem-body .in-out pre")) pre.classList.add("card");
-        if (UtilityEnabled("CopyMD")) {
-            for (const section of root.querySelectorAll(".xmoj-problem-body .cnt-row")) {
-                const heading = section.querySelector(".cnt-row-head");
-                const body = section.querySelector(".cnt-row-body");
-                if (heading && body && !body.querySelector(".sampledata")) AddCopy(heading, "copy-section", () => GetMDText(body).trim());
-            }
-        }
+        if (UtilityEnabled("CopyMD")) InitializeProblemMarkdownCopy(root, root, AddCopy);
         // Built from this page's API response rather than a cached copy.
         if (UtilityEnabled("ProblemSwitcher") && Array.isArray(routeData?.problems) && !document.querySelector(`[${owned}="problem-switcher"]`)) {
             const list = routeData.problems.map(item => ({title: item.problemTitle || item.title || item.num, url: new URL(GetContestProblemURL(route.cid, item.num), location.origin).href}));
@@ -3887,25 +3881,8 @@ async function main() {
                                 return Response.text();
                             }).then((Response) => {
                                 let ParsedDocument = new DOMParser().parseFromString(Response, "text/html");
-                                let Temp = ParsedDocument.querySelectorAll(".cnt-row-body");
-                                if (UtilityEnabled("DebugMode")) console.log(Temp);
-                                for (let i = 0; i < Temp.length; i++) {
-                                    if (Temp[i].children[0].className === "content lang_cn") {
-                                        let CopyMDButton = document.createElement("button");
-                                        CopyMDButton.className = "btn btn-sm btn-outline-secondary copy-btn";
-                                        CopyMDButton.innerText = "复制";
-                                        CopyMDButton.style.marginLeft = "10px";
-                                        CopyMDButton.type = "button";
-                                        document.querySelectorAll(".cnt-row-head.title")[i].appendChild(CopyMDButton);
-                                        CopyMDButton.addEventListener("click", () => {
-                                            GM_setClipboard(GetMDText(Temp[i].children[0]).trim().replaceAll("\n\t", "\n").replaceAll("\n\n", "\n"));
-                                            CopyMDButton.innerText = "复制成功";
-                                            setTimeout(() => {
-                                                CopyMDButton.innerText = "复制";
-                                            }, 1000);
-                                        });
-                                    }
-                                }
+                                InitializeProblemMarkdownCopy(document.querySelector(".mt-3") || document,
+                                    ParsedDocument.querySelector(".jumbotron") || ParsedDocument);
                             });
                         }
 
@@ -7683,10 +7660,132 @@ function GetMDText(element) {
         'TABLE', 'THEAD', 'TBODY', 'TFOOT', 'TR'
     ]);
     const cellTags = new Set(['TD', 'TH']);
+    const mathItems = new Map();
+    const mathDocument = (typeof unsafeWindow === 'undefined' ? window : unsafeWindow).MathJax?.startup?.document;
+    // XMOJ also serves MathJax 3.0, before getMathItemsWithin was available.
+    const items = typeof mathDocument?.getMathItemsWithin === 'function' ?
+        mathDocument.getMathItemsWithin([element]) : mathDocument?.math || [];
+    for (const math of items) {
+        if (math.typesetRoot && element.contains(math.typesetRoot) && typeof math.math === 'string') {
+            mathItems.set(math.typesetRoot, math);
+        }
+    }
+
+    function AppendBreak(count) {
+        if (!result) return;
+        const trailing = result.match(/\n*$/)[0].length;
+        if (trailing < count) result += '\n'.repeat(count - trailing);
+    }
+
+    function AppendContent(content, cell) {
+        if (cell?.breakPending) {
+            AppendBreak(1);
+            cell.breakPending = false;
+        }
+        result += content;
+    }
+
+    function ReadMath(node) {
+        const math = mathItems.get(node);
+        if (math) return math;
+        if (node.nodeType === Node.ELEMENT_NODE && (node.classList.contains('katex') ||
+            node.classList.contains('katex-display') || node.nodeName.toUpperCase() === 'MATH')) {
+            const annotation = node.querySelector('annotation[encoding="application/x-tex"]');
+            if (annotation) return {math: annotation.textContent, display: node.classList.contains('katex-display') ||
+                node.parentElement?.classList.contains('katex-display') || node.getAttribute('display') === 'block'};
+        }
+        return null;
+    }
+
+    function AppendTable(table) {
+        const rows = [...table.rows];
+        const first = rows[0];
+        const hasHeader = first && first.cells.length > 0 && (first.parentElement.nodeName === 'THEAD' ||
+            [...first.cells].every(cell => cell.nodeName === 'TH'));
+        // Pipe tables require a header and cannot represent merged cells, nested tables or code blocks.
+        // Also retain HTML for links so their destinations are preserved.
+        // Replace rendered math with its source.
+        if (!hasHeader || table.querySelector('table, pre, a') || rows.some(row => [...row.cells].some(cell => cell.colSpan !== 1 || cell.rowSpan !== 1)) ||
+            table.tHead?.rows.length > 1) {
+            const copy = table.cloneNode(true);
+            function RestoreMath(original, clone) {
+                if (original.nodeName === 'PRE') return;
+                const math = ReadMath(original);
+                if (math) {
+                    clone.replaceWith(document.createTextNode((math.display ? '$$' : '$') + math.math + (math.display ? '$$' : '$')));
+                    return;
+                }
+                for (const attribute of ['src', 'href']) {
+                    const value = original.getAttribute?.(attribute);
+                    if (value) {
+                        try {
+                            clone.setAttribute(attribute, new URL(value, location.href).href);
+                        } catch (e) {
+                            // Keep the source value when it is not a valid URL.
+                        }
+                    }
+                }
+                const children = [...clone.childNodes];
+                [...original.childNodes].forEach((child, index) => RestoreMath(child, children[index]));
+            }
+            RestoreMath(table, copy);
+            AppendBreak(2);
+            // Encode literal line endings so blank lines inside HTML do not end
+            // the Markdown HTML block. PRE contents retain them after rendering.
+            AppendContent(copy.outerHTML.replace(/\r\n|\r|\n/g, '&#10;'));
+            AppendBreak(2);
+            return;
+        }
+        if (table.caption) {
+            AppendBreak(2);
+            Traverse(table.caption);
+            AppendBreak(2);
+        }
+        if (!rows.length || !rows.some(row => row.cells.length)) return;
+        const values = rows.map(row => [...row.cells].map(cell => {
+            const previous = result;
+            result = '';
+            Traverse(cell);
+            const value = result.replace(/\t$/, '').trim().replace(/(\\*)\|/g, (_, slashes) => slashes + slashes + '\\|')
+                .replace(/ *\r?\n/g, '<br>');
+            result = previous;
+            return value;
+        }));
+        const width = Math.max(...values.map(row => row.length));
+        const header = values.shift();
+        const Line = row => '| ' + Array.from({length: width}, (_, index) => row[index] || '').join(' | ') + ' |';
+        const separators = Array.from({length: width}, (_, index) => {
+            const cell = first.cells[index];
+            const alignment = cell?.style.textAlign || cell?.getAttribute('align');
+            return alignment === 'center' ? ':---:' : alignment === 'right' ? '---:' : alignment === 'left' ? ':---' : '---';
+        });
+        AppendBreak(2);
+        AppendContent([Line(header), Line(separators), ...values.map(Line)].join('\n'));
+        AppendBreak(2);
+    }
 
-    function traverse(node) {
+    function AppendMath(tex, display, inCell) {
+        // Keep a table cell on its row, including its trailing tab separator.
+        if (display && !inCell) AppendBreak(2);
+        AppendContent(display ? (inCell ? '$$' + tex + '$$' : '$$\n' + tex + '\n$$') : '$' + tex + '$', inCell);
+        if (display && !inCell) AppendBreak(2);
+    }
+
+    function Traverse(node, inPre = false, inCell = false) {
         if (node.nodeType === Node.TEXT_NODE) {
-            result += node.textContent;
+            // Serialized HTML often has indentation between blocks and cells.
+            // Keep inline spaces and all preformatted text.
+            const boundary = node => blockTags.has(node?.nodeName) || cellTags.has(node?.nodeName);
+            const before = boundary(node.previousSibling) || (boundary(node.parentElement) && !node.previousSibling);
+            const after = boundary(node.nextSibling) || (boundary(node.parentElement) && !node.nextSibling);
+            let text = node.textContent;
+            if (!inPre && /^[ \t\r\n]*$/.test(text) && (before || after)) return;
+            if (!inPre) {
+                text = text.replace(/[ \t\r\n]+/g, ' ');
+                if (before) text = text.replace(/^ +/, '');
+                if (after) text = text.replace(/ +$/, '');
+            }
+            AppendContent(text, inCell);
             return;
         }
 
@@ -7696,9 +7795,44 @@ function GetMDText(element) {
 
         const tag = node.nodeName.toUpperCase();
 
+        if (tag === 'PRE' && !inPre) {
+            // Read literal code (including highlighted spans) without converting math
+            // or collapsing its indentation. BR is also used by older editors.
+            function ReadCode(child) {
+                if (child.nodeType === Node.TEXT_NODE) return child.textContent;
+                if (child.nodeName === 'BR') return '\n';
+                return [...child.childNodes].map(ReadCode).join('');
+            }
+            const code = ReadCode(node);
+            if (inCell) {
+                inCell.breakPending = true;
+                AppendContent(code, inCell);
+                inCell.breakPending = true;
+            } else {
+                const classes = [node.querySelector('code')?.className, node.className].filter(Boolean).join(' ');
+                const language = classes.match(/(?:^|\s)(?:language|lang)-([\w+-]+)(?=\s|$)/)?.[1] || 'plain';
+                AppendBreak(2);
+                AppendContent(GetMarkdownCodeBlock(code, language));
+                AppendBreak(2);
+            }
+            return;
+        }
+
+        if (tag === 'TABLE') {
+            AppendTable(node);
+            return;
+        }
+
+        // Copy the source once, rather than the visual and accessibility trees.
+        const math = ReadMath(node);
+        if (math) {
+            AppendMath(math.math, math.display, inCell);
+            return;
+        }
+
         // Preserve line breaks for <br>
         if (tag === 'BR') {
-            result += '\n';
+            AppendContent(inPre ? '\n' : '  \n', inCell);
             return;
         }
 
@@ -7712,40 +7846,157 @@ function GetMDText(element) {
                 } catch (e) {
                     // Fallback to the raw src if URL construction fails
                 }
-                result += `![](${resolvedSrc})`;
+                AppendContent(`![](${resolvedSrc})`, inCell);
             }
             return;
         }
 
         const isBlock = blockTags.has(tag);
         const isCell = cellTags.has(tag);
-
-        if (isBlock && !result.endsWith('\n')) {
-            result += '\n';
+        const breaks = tag === 'TR' ? 1 : 2;
+
+        // Each cell has its own buffer. Defer block breaks until its next content
+        // so nested paragraphs separate without leading/trailing row breaks.
+        if (isCell) {
+            const previous = result;
+            result = '';
+            const cell = {breakPending: false};
+            for (const child of node.childNodes) Traverse(child, inPre, cell);
+            result = previous + result + '\t';
+            return;
         }
 
-        // Keep table cells visually separated when copied as plain text.
-        if (isCell && result.length > 0 && !result.endsWith('\n') && !result.endsWith('\t') && !result.endsWith(' ')) {
-            result += '\t';
+        if (isBlock && !inPre) {
+            if (inCell) inCell.breakPending = true;
+            else AppendBreak(breaks);
         }
 
         for (let child of node.childNodes) {
-            traverse(child);
+            Traverse(child, inPre || tag === 'PRE', inCell);
         }
 
-        if (isCell && !result.endsWith('\n') && !result.endsWith('\t')) {
-            result += '\t';
+        if (isBlock && !inPre) {
+            if (inCell) inCell.breakPending = true;
+            else AppendBreak(breaks);
         }
+    }
+
+    Traverse(element);
+    return result;
+}
+
+function GetMarkdownCodeBlock(code, language = "plain") {
+    // A backtick run in the source must not terminate the copied code block.
+    const runs = [...code.matchAll(/`+/g)].map(match => match[0].length + 1);
+    const fence = "`".repeat(Math.max(3, ...runs));
+    return fence + language + "\n" + code + (code.endsWith("\n") ? "" : "\n") + fence;
+}
+
+// Use the displayed section labels, excluding copy controls and alternate languages.
+function GetProblemCopyHeading(element, language = "zh") {
+    if (!element) return "";
+    const copy = element.cloneNode(true);
+    const otherLanguage = language === "en" ? ".lang_cn" : ".lang_en";
+    for (const node of copy.querySelectorAll("button, .copy-btn, [data-xmoj-script], " + otherLanguage)) node.remove();
+    return copy.textContent.replace(/\s+/g, " ").trim();
+}
 
-        if (isBlock && !result.endsWith('\n')) {
-            result += '\n';
+function GetProblemCopyLanguage(root) {
+    const english = root.querySelector(".content.lang_en");
+    return english?.isConnected && !english.closest("[hidden], .hidden, .d-none") &&
+        getComputedStyle(english).display !== "none" ? "en" : "zh";
+}
+
+function GetProblemSectionMarkdown(section, language = "zh") {
+    const heading = GetProblemCopyHeading(section.querySelector(".cnt-row-head"), language);
+    const body = section.querySelector(".cnt-row-body");
+    if (!heading || !body) return "";
+    let content;
+    if (body.querySelector(".sampledata, .data-sample, .in-out-item")) {
+        const parts = [];
+        const samples = [...body.querySelectorAll(".data-sample")];
+        const groups = samples.length ? samples : [...body.querySelectorAll(".in-out")];
+        function Visit(node) {
+            if (node.nodeType !== Node.ELEMENT_NODE ||
+                node.classList.contains(language === "en" ? "lang_cn" : "lang_en")) return;
+            if (node.classList.contains("in-out-item")) {
+                const sample = node.querySelector(".sampledata");
+                if (!sample || sample.textContent === "") return;
+                let label = GetProblemCopyHeading(node.querySelector(".title"), language);
+                const group = node.closest(samples.length ? ".data-sample" : ".in-out");
+                if (!/#\s*\d+/.test(label)) label += " #" + (Math.max(0, groups.indexOf(group)) + 1);
+                const code = sample.textContent;
+                parts.push("### " + label + "\n\n" + GetMarkdownCodeBlock(code));
+                return;
+            }
+            if (node.classList.contains("title")) {
+                const label = GetProblemCopyHeading(node, language);
+                if (label) parts.push("### " + label);
+                return;
+            }
+            // Legacy pages wrap the complete sample section in .content.
+            if (node.classList.contains("content") && !node.querySelector(".sampledata, .data-sample, .in-out-item")) {
+                const text = GetMDText(node).trim();
+                if (text) parts.push(text);
+                return;
+            }
+            for (const child of node.children) Visit(child);
         }
+        for (const child of body.children) Visit(child);
+        content = parts.join("\n\n");
+    } else {
+        const translated = body.querySelector(language === "en" ? ".content.lang_en" : ".content.lang_cn");
+        const fallback = body.querySelector(".content.lang_cn") || body.querySelector(".content");
+        content = GetMDText(translated || fallback || body).trim();
     }
+    return content ? "## " + heading + "\n\n" + content : "";
+}
 
-    traverse(element);
-    return result;
+function GetProblemStatementMarkdown(root, language = "zh") {
+    const title = root.querySelector(".xmoj-problem-head h2") ||
+        root.querySelector(language === "en" ? "h2.lang_en" : "h2.lang_cn") || root.querySelector("h2");
+    const name = GetProblemCopyHeading(title, language)
+        .replace(/^(?:(?:问题|Problem)\s+[^:：]+|\d+)\s*[:：]\s*/i, "");
+    const body = root.querySelector(".xmoj-problem-body") || root;
+    const sections = [...body.querySelectorAll(".cnt-row")]
+        .map(section => GetProblemSectionMarkdown(section, language)).filter(Boolean);
+    return (name ? ["# " + name, ...sections] : sections).join("\n\n");
+}
+
+function InitializeProblemMarkdownCopy(root, sourceRoot = root, addCopy = null) {
+    if (!addCopy) addCopy = (parent, name, readText) => {
+        if (parent.querySelector('[data-xmoj-script="' + name + '"]')) return;
+        const button = document.createElement("button");
+        button.type = "button";
+        button.className = "btn btn-sm btn-outline-secondary copy-btn";
+        button.style.marginLeft = "10px";
+        button.setAttribute("data-xmoj-script", name);
+        button.textContent = "复制";
+        button.addEventListener("click", () => {
+            GM_setClipboard(readText());
+            button.textContent = "复制成功";
+            setTimeout(() => { button.textContent = "复制"; }, 1000);
+        });
+        parent.appendChild(button);
+    };
+    const titles = [...root.querySelectorAll(".xmoj-problem-head h2, h2.lang_cn, h2.lang_en")];
+    if (!titles.length && root.querySelector("h2")) titles.push(root.querySelector("h2"));
+    for (const title of titles) {
+        addCopy(title, "copy-problem", () => GetProblemStatementMarkdown(sourceRoot, GetProblemCopyLanguage(root)));
+    }
+    const body = root.querySelector(".xmoj-problem-body") || root;
+    const sourceBody = sourceRoot.querySelector(".xmoj-problem-body") || sourceRoot;
+    const sourceSections = [...sourceBody.querySelectorAll(".cnt-row")];
+    for (const [index, section] of [...body.querySelectorAll(".cnt-row")].entries()) {
+        const heading = section.querySelector(".cnt-row-head");
+        if (heading && section.querySelector(".cnt-row-body")) {
+            addCopy(heading, "copy-section", () =>
+                GetProblemSectionMarkdown(sourceSections[index] || section, GetProblemCopyLanguage(root)));
+        }
+    }
 }
 
+
 function InitializeImageEnlarger() {
         // Image Enlargement Feature
         if (UtilityEnabled("ImageEnlarger")) {
diff --git a/package.json b/package.json
index 36d1d15b..a4596849 100644
--- a/package.json
+++ b/package.json
@@ -1,10 +1,13 @@
 {
   "name": "xmoj-script",
-  "version": "3.7.1",
+  "version": "3.7.2",
   "description": "an improvement script for xmoj.tech",
   "main": "AddonScript.js",
   "scripts": {
-    "test": "node --test tests/contest-web.test.cjs"
+    "test": "node --test tests/contest-web.test.cjs tests/markdown-copy.test.cjs"
+  },
+  "devDependencies": {
+    "playwright": "1.59.1"
   },
   "repository": {
     "type": "git",
diff --git a/tests/markdown-copy.html b/tests/markdown-copy.html
new file mode 100644
index 00000000..10727025
--- /dev/null
+++ b/tests/markdown-copy.html
@@ -0,0 +1,289 @@
+<!doctype html>
+<meta charset="utf-8">
+<title>Markdown copy regression tests</title>
+<pre id="results">Running…</pre>
+<script>
+(async () => {
+    // Also runs automatically through tests/markdown-copy.test.cjs.
+    let source;
+    let GetMDText;
+    let GetProblemSectionMarkdown;
+    let GetProblemStatementMarkdown;
+    let InitializeProblemMarkdownCopy;
+    const results = [];
+    const fixture = document.createElement('div');
+    document.body.appendChild(fixture);
+
+    function Check(name, html, expected, setup = () => {}, trim = true, read = GetMDText) {
+        fixture.innerHTML = html;
+        delete window.MathJax;
+        setup(fixture);
+        const before = fixture.innerHTML;
+        const copied = read(fixture);
+        const actual = trim ? copied.trim() : copied;
+        if (actual !== expected) throw new Error(name + ': expected ' + JSON.stringify(expected) + ', got ' + JSON.stringify(actual));
+        if (fixture.innerHTML !== before) throw new Error(name + ': changed the page DOM');
+        results.push(name);
+    }
+
+    function Katex(tex) {
+        // KaTeX's default output includes both MathML and the visual HTML tree.
+        return '<span class="katex"><span class="katex-mathml"><math><semantics><mrow><mi>visual</mi></mrow>' +
+            '<annotation encoding="application/x-tex">' + tex + '</annotation></semantics></math></span>' +
+            '<span class="katex-html" aria-hidden="true"><span class="base">duplicate</span></span></span>';
+    }
+
+    try {
+        const response = await fetch('../XMOJ.user.js');
+        if (!response.ok) throw new Error('Cannot load XMOJ.user.js: HTTP ' + response.status);
+        source = await response.text();
+        const anchor = 'function GetMDText(';
+        const start = source.indexOf(anchor);
+        const end = source.indexOf('\nfunction InitializeImageEnlarger(', start);
+        if (start < 0 || source.indexOf(anchor, start + anchor.length) !== -1 || end <= start) {
+            throw new Error('Cannot locate a unique GetMDText function and its InitializeImageEnlarger boundary in XMOJ.user.js');
+        }
+        ({GetMDText, GetProblemSectionMarkdown, GetProblemStatementMarkdown, InitializeProblemMarkdownCopy} =
+            new Function(source.slice(start, end) +
+                '\nreturn {GetMDText, GetProblemSectionMarkdown, GetProblemStatementMarkdown, InitializeProblemMarkdownCopy};')());
+        const fence = '\x60\x60\x60';
+        Check('paragraphs and nested containers', '<div><p>First <span>paragraph</span>.</p><div><p>Second.</p></div></div>',
+            'First paragraph.\n\nSecond.');
+        Check('explicit Markdown hard breaks', '<p>First<br>Second<br><br>Fourth</p><p>Next.</p>',
+            'First  \nSecond  \n  \nFourth\n\nNext.');
+        Check('inline KaTeX source appears once', '<p>区间 ' + Katex('[a_i,b_i]') + ' 满足 ' + Katex('b_{i-1}&lt;a_i\\le b_i') + '。</p>',
+            '区间 $[a_i,b_i]$ 满足 $b_{i-1}<a_i\\le b_i$。');
+        Check('display KaTeX keeps its delimiters and paragraphs', '<p>Before.</p><span class="katex-display">' +
+            Katex('\\sum_{i=1}^{N} a_i') + '</span><p>After.</p>',
+            'Before.\n\n$$\n\\sum_{i=1}^{N} a_i\n$$\n\nAfter.');
+        Check('standalone MathML TeX annotation', '<math display="block"><semantics><mi>x</mi>' +
+            '<annotation encoding="application/x-tex">x^2</annotation></semantics></math>', '$$\nx^2\n$$');
+        Check('MathJax source and display mode', '<p>Value <mjx-container>visual</mjx-container>.</p>' +
+            '<mjx-container display="true">duplicate</mjx-container><p>Next.</p>',
+            'Value $a_i$.\n\n$$\na_i \\le b_i\n$$\n\nNext.', root => {
+                const nodes = root.querySelectorAll('mjx-container');
+                window.MathJax = {startup: {document: {getMathItemsWithin(elements) {
+                    if (elements.length !== 1 || elements[0] !== root) throw new Error('Wrong MathJax container');
+                    return [
+                        {typesetRoot: nodes[0], math: 'a_i', display: false},
+                        {typesetRoot: nodes[1], math: 'a_i \\le b_i', display: true}
+                    ];
+                }}}};
+            });
+        Check('MathJax 3.0 expression list fallback', '<p>Value <mjx-container>visual</mjx-container>.</p>',
+            'Value $a_i$.', root => {
+                window.MathJax = {startup: {document: {math: [
+                    {typesetRoot: root.querySelector('mjx-container'), math: 'a_i', display: false},
+                    {typesetRoot: document.createElement('mjx-container'), math: 'outside', display: true}
+                ]}}};
+            });
+        Check('raw TeX remains available before typesetting', '<p>Value $a_i$.</p><p>$$x^2$$</p>', 'Value $a_i$.\n\n$$x^2$$');
+        Check('preformatted edge whitespace and breaks', '<pre>  first\n\n    second<br>third  </pre>',
+            fence + 'plain\n  first\n\n    second\nthird  \n' + fence + '\n\n', () => {}, false);
+        Check('relative images and table cells', '<p>Image <img src="../Images/1.png"></p><table><tr><td>A</td><td>B</td></tr>' +
+            '<tr><td>C</td><td>D</td></tr></table>', 'Image ![](' + new URL('../Images/1.png', location.href).href + ')\n\n<table><tbody><tr><td>A</td><td>B</td></tr><tr><td>C</td><td>D</td></tr></tbody></table>');
+        Check('indented table cells retain columns', '<table>\n <tr>\n <th>\n  A\n </th>\n <th>B</th>\n </tr>\n' +
+            '<tr>\n <td> C </td>\n <td> D </td>\n </tr>\n</table>', '| A | B |\n| --- | --- |\n| C | D |');
+        Check('nested table cell paragraphs retain separation', '<table><tr><th>First</th><th>Second</th></tr><tr><td><div><p>A</p><p>B</p></div></td>' +
+            '<td><p>C</p>D<div>E</div>F</td></tr></table>', '| First | Second |\n| --- | --- |\n| A<br>B | C<br>D<br>E<br>F |');
+        Check('empty table cells retain columns', '<table><tr><td></td><td>A</td><td> </td><td>B</td></tr></table>',
+            '<table><tbody><tr><td></td><td>A</td><td> </td><td>B</td></tr></tbody></table>\n\n', () => {}, false);
+        Check('table cell preformatted whitespace is retained', '<table><tr><td><pre>  A\n\n B  </pre></td>' +
+            '<td>C</td></tr></table>', '<table><tbody><tr><td><pre>  A&#10;&#10; B  </pre></td><td>C</td></tr></tbody></table>\n\n', () => {}, false);
+        Check('prose formatting indentation is not copied', '<p>\n\tFirst sentence.\n</p>\n\t<p>\n\tSecond\n\tline.\n</p>',
+            'First sentence.\n\nSecond line.');
+        Check('highlighted code retains language and literal whitespace', '<pre><code class="language-cpp"><span>  int</span> x;\n\treturn 0;\n</code></pre>',
+            fence + 'cpp\n  int x;\n\treturn 0;\n' + fence);
+        Check('pre language survives code highlighting classes', '<pre class="language-cpp"><code class="hljs">int x;\n</code></pre>',
+            fence + 'cpp\nint x;\n' + fence);
+        Check('preformatted backticks cannot close their code fence', '<pre><code>' + fence + '\n  x\n</code></pre>',
+            fence + '\x60plain\n' + fence + '\n  x\n' + fence + '\x60');
+        Check('formatted HTML block boundaries', '\n  <p>A</p>\n  <p>B</p>\n  ', 'A\n\nB');
+        Check('inline whitespace is retained', '<p><span>A</span> <span>B</span>&nbsp;C</p>', 'A B\u00a0C');
+        Check('list item line separation', '<ul>\n  <li>A</li>\n  <li>B</li>\n</ul>', 'A\n\nB');
+        Check('KaTeX display math stays within table cells', '<table><tr><td>a</td><td><span class="katex-display">' +
+            Katex('x') + '</span></td><td>b</td></tr><tr><td>c</td><td>d</td><td>e</td></tr></table>',
+            '<table><tbody><tr><td>a</td><td>$$x$$</td><td>b</td></tr><tr><td>c</td><td>d</td><td>e</td></tr></tbody></table>');
+        Check('MathJax display math stays within table cells', '<table><tr><td>a</td><td><mjx-container>visual</mjx-container>' +
+            '</td><td>b</td></tr></table>', '<table><tbody><tr><td>a</td><td>$$x$$</td><td>b</td></tr></tbody></table>', root => {
+                window.MathJax = {startup: {document: {math: [
+                    {typesetRoot: root.querySelector('mjx-container'), math: 'x', display: true}
+                ]}}};
+            });
+
+        Check('table captions, alignment and short rows', '<p>Before.</p><table><caption>Scores</caption><thead><tr>' +
+            '<td align="left">Name</td><td style="text-align:right">Value</td></tr></thead><tbody>' +
+            '<tr><td>A</td><td>1</td></tr><tr><td>B</td></tr></tbody></table><p>After.</p>',
+            'Before.\n\nScores\n\n| Name | Value |\n| :--- | ---: |\n| A | 1 |\n| B |  |\n\nAfter.');
+        Check('table pipes, backslashes and TeX do not split columns', '<table><tr><th>Text</th><th>Math</th></tr>' +
+            '<tr><td>a|b\\|c<br>d</td><td>' + Katex('a\\mid b') + '</td></tr></table>',
+            '| Text | Math |\n| --- | --- |\n| a\\|b\\\\\\|c<br>d | $a\\mid b$ |');
+        Check('merged tables retain HTML structure and original TeX', '<table><tr><th colspan="2">Group</th></tr>' +
+            '<tr><td rowspan="2">' + Katex('a_i') + '</td><td>A</td></tr><tr><td>B</td></tr></table>',
+            '<table><tbody><tr><th colspan="2">Group</th></tr><tr><td rowspan="2">$a_i$</td><td>A</td></tr><tr><td>B</td></tr></tbody></table>');
+        Check('HTML table images and links keep their source URLs', '<table><tr><td><a href="../problem.php?id=1">' +
+            '<img src="../Images/1.png"></a></td></tr></table>', '<table><tbody><tr><td><a href="' +
+            new URL('../problem.php?id=1', location.href).href + '"><img src="' +
+            new URL('../Images/1.png', location.href).href + '"></a></td></tr></tbody></table>');
+        Check('header tables preserve link destinations and math', '<table><tr><th><a href="../problem.php?id=1">Problem</a></th><th>Value</th></tr>' +
+            '<tr><td><a href="https://example.com/task">Reference</a></td><td>' + Katex('x') + '</td></tr></table>',
+            '<table><tbody><tr><th><a href="' + new URL('../problem.php?id=1', location.href).href + '">Problem</a></th><th>Value</th></tr>' +
+            '<tr><td><a href="https://example.com/task">Reference</a></td><td>$x$</td></tr></tbody></table>');
+        Check('nested tables retain HTML structure', '<table><tr><td>Outer<table><tr><td>Inner</td></tr></table></td></tr></table>',
+            '<table><tbody><tr><td>Outer<table><tbody><tr><td>Inner</td></tr></tbody></table></td></tr></tbody></table>');
+        Check('merged tables restore MathJax source', '<table><tr><td colspan="2"><mjx-container>visual</mjx-container></td></tr></table>',
+            '<table><tbody><tr><td colspan="2">$$x$$</td></tr></tbody></table>', root => {
+                window.MathJax = {startup: {document: {math: [
+                    {typesetRoot: root.querySelector('mjx-container'), math: 'x', display: true}
+                ]}}};
+            });
+        const Section = (heading, content) => '<div class="cnt-row"><div class="cnt-row-head">' + heading +
+            '</div><div class="cnt-row-body">' + content + '</div></div>';
+        const sampleBody = '<div class="data-sample"><div class="in-out">' +
+            '<div class="in-out-item"><span class="title">样例输入 #1</span><a class="copy-btn">复制</a>' +
+            '<pre class="content"><span class="sampledata">  1\n2 </span></pre></div>' +
+            '<div class="in-out-item"><span class="title">样例输出 #1</span><a class="copy-btn">复制成功</a>' +
+            '<pre class="content"><span class="sampledata">3</span></pre></div></div>' +
+            '<div><div class="title">样例说明 #1</div><div class="content"><p>Sum $a+b$.</p></div></div></div>';
+        const sampleMarkdown = '## 样例输入输出\n\n### 样例输入 #1\n\n' + fence + 'plain\n  1\n2 \n' + fence +
+            '\n\n### 样例输出 #1\n\n' + fence + 'plain\n3\n' + fence + '\n\n### 样例说明 #1\n\nSum $a+b$.';
+        Check('sample sections include headings and fenced data', Section('样例输入输出', sampleBody),
+            sampleMarkdown, () => {}, true, root => GetProblemSectionMarkdown(root.firstElementChild));
+        Check('wrapped sample sections retain headings and fenced data',
+            Section('样例输入输出', '<div class="content"><div class="content">' + sampleBody + '</div></div>'),
+            sampleMarkdown, () => {}, true, root => GetProblemSectionMarkdown(root.firstElementChild));
+        Check('subsection copy includes its heading', Section('题目描述<button>复制成功</button>',
+            '<div class="content"><p>A</p>\n<p>B</p></div>'), '## 题目描述\n\nA\n\nB',
+            () => {}, true, root => GetProblemSectionMarkdown(root.firstElementChild));
+        const statement = '<div class="xmoj-problem-head"><h2>问题 A: Zoo<small data-xmoj-script="problem-id"> (1000)</small>' +
+            '<button data-xmoj-script="copy-problem">复制</button></h2></div><div class="xmoj-problem-body">' +
+            Section('题目描述', '<div class="content"><p>A</p>\n<p>B</p></div>') +
+            Section('输出', '<div class="content"></div>') + Section('样例输入输出', sampleBody) +
+            Section('数据范围', '<div class="content">1 ≤ N ≤ 10</div>') + '</div>' +
+            Section('导出', '<div class="content">Export tools</div>');
+        const statementMarkdown = '# Zoo\n\n## 题目描述\n\nA\n\nB\n\n' + sampleMarkdown + '\n\n## 数据范围\n\n1 ≤ N ≤ 10';
+        Check('full statement omits absent sections and export tools', statement, statementMarkdown,
+            () => {}, true, root => GetProblemStatementMarkdown(root));
+        const classic = '<center><h2 class="lang_cn">问题 1000: Graph: Paths</h2>' +
+            '<h2 class="lang_en" style="display:none">Problem 1000: Graph: English</h2></center>' +
+            Section('<span class="lang_cn">题目描述</span><span class="lang_en">Description</span>',
+                '<div class="content lang_cn"><p>A</p>\n<p>B</p></div><div class="content lang_en" style="display:none"><p>English.</p></div>') +
+            Section('样例输入输出', '<div class="content"><div class="in-out"><div class="in-out-item"><span class="title">样例输入</span>' +
+                '<pre class="content"><span class="sampledata">x</span></pre></div></div></div>');
+        Check('classic statement selects Chinese content and numbers samples', classic,
+            '# Graph: Paths\n\n## 题目描述\n\nA\n\nB\n\n## 样例输入输出\n\n### 样例输入 #1\n\n' + fence + 'plain\nx\n' + fence,
+            () => {}, true, root => GetProblemStatementMarkdown(root));
+        const classicFullEnglish = '# Graph: English\n\n## Description\n\nEnglish.\n\n## 样例输入输出\n\n### 样例输入 #1\n\n' + fence + 'plain\nx\n' + fence;
+        Check('classic statement selects English content', classic, classicFullEnglish,
+            () => {}, true, root => GetProblemStatementMarkdown(root, 'en'));
+        Check('sample code uses a fence longer than its backticks', Section('样例输入输出',
+            '<div class="in-out"><div class="in-out-item"><span class="title">Input #1</span><pre class="content">' +
+            '<span class="sampledata">' + fence + '</span></pre></div></div>'),
+            '## 样例输入输出\n\n### Input #1\n\n' + fence + '\x60plain\n' + fence + '\n' + fence + '\x60',
+            () => {}, true, root => GetProblemSectionMarkdown(root.firstElementChild));
+        Check('explanation-only samples remain copyable', Section('样例输入输出', '<div class="data-sample">' +
+            '<div><div class="title">样例说明 #2</div><div class="content">Explanation.</div></div></div>'),
+            '## 样例输入输出\n\n### 样例说明 #2\n\nExplanation.', () => {}, true,
+            root => GetProblemSectionMarkdown(root.firstElementChild));
+
+        fixture.innerHTML = '<h2>问题 1000: Table</h2>' + Section('题目描述', '<div class="content"><table>' +
+            '<tr><th>Name</th><th>Value</th></tr><tr><td>A</td><td>1</td></tr></table></div>');
+        let tableCopied;
+        window.GM_setClipboard = text => { tableCopied = text; };
+        InitializeProblemMarkdownCopy(fixture);
+        const tableSection = '## 题目描述\n\n| Name | Value |\n| --- | --- |\n| A | 1 |';
+        fixture.querySelector('[data-xmoj-script="copy-section"]').click();
+        if (tableCopied !== tableSection) throw new Error('human review table section copy: ' + JSON.stringify(tableCopied));
+        fixture.querySelector('[data-xmoj-script="copy-problem"]').click();
+        if (tableCopied !== '# Table\n\n' + tableSection) throw new Error('human review table full copy: ' + JSON.stringify(tableCopied));
+        delete window.GM_setClipboard;
+        results.push('human review table section and full copy controls');
+
+        // Reproduce the human review: fenced seat diagrams followed by indented HTML paragraphs.
+        const reviewParagraphs = [
+            '第一秒，每个人向右移动一个位置，$3$ 到了自己的座位 $1$。然后 $3$ 要花 $5$ 秒放行李，$1$ 和 $2$ 跟着等待。',
+            '之后 $1$ 和 $2$ 花 $3$ 秒同时移动到自己的座位，分别要花 $5$ 秒和 $10$ 秒放行李，总共放行李的时间是 $10$ 秒。',
+            '总时间是：$1+5+3+10=19$ 秒。'
+        ];
+        const diagrams = ['人  123\n       123 座位\n', '人      12\n       123 座位\n'];
+        const reviewExplanation = '<p>一开始的状况是：</p>\n<pre><code>' + diagrams[0] + '</code></pre>\n' +
+            '<p>\n\t' + reviewParagraphs[0] + '\n</p>\n<pre>' + diagrams[1] + '</pre>\n' +
+            '<p>\n\t' + reviewParagraphs[1] + '\n</p>\n<p>\n\t' + reviewParagraphs[2] + '\n</p>';
+        const reviewSamples = '<div class="data-sample"><div class="in-out">' +
+            '<div class="in-out-item"><span class="title">样例输入 #1</span><pre class="content"><span class="sampledata">3\n2 5\n3 10\n1 5</span></pre></div>' +
+            '<div class="in-out-item"><span class="title">样例输出 #1</span><pre class="content"><span class="sampledata">19</span></pre></div></div>' +
+            '<div class="title">样例说明 #1</div><div class="content">' + reviewExplanation + '</div></div>';
+        const reviewExpected = '## 样例输入输出\n\n### 样例输入 #1\n\n' + fence + 'plain\n3\n2 5\n3 10\n1 5\n' + fence +
+            '\n\n### 样例输出 #1\n\n' + fence + 'plain\n19\n' + fence + '\n\n### 样例说明 #1\n\n一开始的状况是：\n\n' +
+            fence + 'plain\n' + diagrams[0] + fence + '\n\n' + reviewParagraphs[0] + '\n\n' +
+            fence + 'plain\n' + diagrams[1] + fence + '\n\n' + reviewParagraphs[1] + '\n\n' + reviewParagraphs[2];
+        Check('human review sample diagrams and paragraphs', Section('样例输入输出', reviewSamples), reviewExpected,
+            () => {}, true, root => GetProblemSectionMarkdown(root.firstElementChild));
+        fixture.innerHTML = '<h2>问题 1000: Boarding</h2>' + Section('样例输入输出', reviewSamples);
+        let reviewCopied;
+        window.GM_setClipboard = text => { reviewCopied = text; };
+        InitializeProblemMarkdownCopy(fixture);
+        fixture.querySelector('[data-xmoj-script="copy-section"]').click();
+        if (reviewCopied !== reviewExpected) throw new Error('human review sample copy callback: ' + JSON.stringify(reviewCopied));
+        fixture.querySelector('[data-xmoj-script="copy-problem"]').click();
+        if (reviewCopied !== '# Boarding\n\n' + reviewExpected) throw new Error('human review full copy callback: ' + JSON.stringify(reviewCopied));
+        delete window.GM_setClipboard;
+        results.push('human review sample and full statement copy controls');
+
+        // Exercise the actual clipboard callbacks and their idempotent control setup.
+        for (const [name, html, expected, sampleExpected] of [
+            ['new UI copy controls', statement, statementMarkdown, sampleMarkdown],
+            ['classic copy controls', classic,
+                '# Graph: Paths\n\n## 题目描述\n\nA\n\nB\n\n## 样例输入输出\n\n### 样例输入 #1\n\n' + fence + 'plain\nx\n' + fence,
+                '## 样例输入输出\n\n### 样例输入 #1\n\n' + fence + 'plain\nx\n' + fence]
+        ]) {
+            fixture.innerHTML = html;
+            for (const button of fixture.querySelectorAll('[data-xmoj-script="copy-problem"]')) button.remove();
+            const original = fixture.cloneNode(true);
+            const before = original.innerHTML;
+            let copied;
+            window.GM_setClipboard = text => { copied = text; };
+            InitializeProblemMarkdownCopy(fixture, original);
+            const count = fixture.querySelectorAll('[data-xmoj-script="copy-section"]').length;
+            InitializeProblemMarkdownCopy(fixture, original);
+            if (fixture.querySelectorAll('[data-xmoj-script="copy-section"]').length !== count) throw new Error(name + ': duplicate buttons');
+            fixture.querySelector('[data-xmoj-script="copy-problem"]').click();
+            if (copied !== expected) throw new Error(name + ': wrong full statement: ' + JSON.stringify(copied));
+            const buttons = fixture.querySelectorAll('.cnt-row-head [data-xmoj-script="copy-section"]');
+            buttons[0].click();
+            if (!copied.startsWith('## ') || !copied.includes('A\n\nB')) throw new Error(name + ': paragraph breaks or heading missing');
+            buttons[buttons.length - (name.startsWith('new') ? 2 : 1)].click();
+            if (copied !== sampleExpected) throw new Error(name + ': wrong samples: ' + JSON.stringify(copied));
+            if (name === 'classic copy controls') {
+                // Switch only the live DOM: the detached source still has English hidden.
+                for (const node of fixture.querySelectorAll('.lang_cn')) node.style.display = 'none';
+                for (const node of fixture.querySelectorAll('.lang_en')) node.style.display = '';
+                fixture.querySelector('h2.lang_en [data-xmoj-script="copy-problem"]').click();
+                if (copied !== classicFullEnglish) throw new Error(name + ': full copy did not follow English visibility: ' + JSON.stringify(copied));
+                buttons[0].click();
+                if (copied !== '## Description\n\nEnglish.') throw new Error(name + ': section copy did not follow English visibility');
+                for (const node of fixture.querySelectorAll('.lang_en')) node.style.display = 'none';
+                for (const node of fixture.querySelectorAll('.lang_cn')) node.style.display = '';
+                fixture.querySelector('h2.lang_cn [data-xmoj-script="copy-problem"]').click();
+                if (copied !== expected) throw new Error(name + ': full copy did not switch back to Chinese');
+                buttons[0].click();
+                if (copied !== '## 题目描述\n\nA\n\nB') throw new Error(name + ': section copy did not switch back to Chinese');
+                results.push('classic copy controls follow displayed language');
+            }
+            if (original.innerHTML !== before) throw new Error(name + ': changed the source DOM');
+            delete window.GM_setClipboard;
+            results.push(name);
+        }
+
+        window.markdownCopyResults = {passed: results.length, tests: results};
+        document.getElementById('results').textContent = results.map(name => 'PASS ' + name).join('\n');
+    } catch (error) {
+        window.markdownCopyResults = {error: error.message, passed: results.length};
+        document.getElementById('results').textContent = error.stack;
+        throw error;
+    } finally {
+        fixture.remove();
+        delete window.MathJax;
+    }
+})();
+</script>
diff --git a/tests/markdown-copy.test.cjs b/tests/markdown-copy.test.cjs
new file mode 100644
index 00000000..9eb87265
--- /dev/null
+++ b/tests/markdown-copy.test.cjs
@@ -0,0 +1,58 @@
+const test = require('node:test');
+const assert = require('node:assert/strict');
+const fs = require('node:fs');
+const path = require('node:path');
+const {chromium} = require('playwright');
+
+const source = fs.readFileSync(path.join(__dirname, '../XMOJ.user.js'), 'utf8');
+const fixture = fs.readFileSync(path.join(__dirname, 'markdown-copy.html'), 'utf8');
+
+// Uses the same browser fixture as the manual checks, with no external requests.
+async function RunFixture(browser, script) {
+    const page = await browser.newPage();
+    try {
+        await page.route('https://markdown-copy.test/**', route => {
+            const pathname = new URL(route.request().url()).pathname;
+            if (pathname === '/tests/markdown-copy.html') {
+                return route.fulfill({contentType: 'text/html', body: fixture});
+            }
+            if (pathname === '/XMOJ.user.js') {
+                return route.fulfill({contentType: 'text/javascript', body: script});
+            }
+            return route.fulfill({status: 404, body: ''});
+        });
+        await page.goto('https://markdown-copy.test/tests/markdown-copy.html');
+        await page.waitForFunction(() => window.markdownCopyResults);
+        return await page.evaluate(() => window.markdownCopyResults);
+    } finally {
+        await page.close();
+    }
+}
+
+test('Markdown copy browser regressions', {timeout: 60000}, async t => {
+    // XMOJ_CHROMIUM also lets developers reuse the browser from the live harness.
+    const browser = await chromium.launch({executablePath: process.env.XMOJ_CHROMIUM || undefined});
+    try {
+        await t.test('preserves math and formatting without changing the DOM', async () => {
+            const result = await RunFixture(browser, source);
+            assert.equal(result.error, undefined, result.error);
+            assert.ok(result.passed >= 16);
+            assert.equal(result.passed, result.tests.length);
+            t.diagnostic(result.tests.join(', '));
+        });
+        for (const anchor of ['function GetMDText(', 'function InitializeImageEnlarger(']) {
+            await t.test('reports a missing extraction anchor: ' + anchor, async () => {
+                const result = await RunFixture(browser, source.replace(anchor, 'function MissingAnchor('));
+                assert.match(result.error, /Cannot locate a unique GetMDText function/);
+                assert.equal(result.passed, 0);
+            });
+        }
+        await t.test('reports duplicate extraction anchors', async () => {
+            const result = await RunFixture(browser, source + '\nfunction GetMDText() {}');
+            assert.match(result.error, /Cannot locate a unique GetMDText function/);
+            assert.equal(result.passed, 0);
+        });
+    } finally {
+        await browser.close();
+    }
+});