fix(explorer): harden markdown viewer review findings

explorer/package-lock.json

@@ -80,6 +80,7 @@
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       "dev": true,
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "@babel/code-frame": "^7.29.0",
         "@babel/generator": "^7.29.6",
@@ -1602,8 +1603,7 @@
       "version": "2.0.46",
       "resolved": "https://registry.npmjs.org/@types/hammerjs/-/hammerjs-2.0.46.tgz",
       "integrity": "sha512-ynRvcq6wvqexJ9brDMS4BnBLzmr0e14d6ZJTEShTBWKymQiHwlAyGu0ZPEFI2Fh1U53F7tN9ufClWM5KvqkKOw==",
-      "license": "MIT",
+      "license": "MIT"
-      "peer": true
     },
     "node_modules/@types/hast": {
       "version": "3.0.5",
@@ -1642,6 +1642,7 @@
       "integrity": "sha512-A1sre26ke7HDIuY/M23nd9gfB+nrmhtYyMINbjI1zHJxYteKR6qSMX56FsmjMcDb3SMcjJg5BiRRgOCC/yBD0g==",
       "devOptional": true,
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "undici-types": "~7.16.0"
       }
@@ -1651,6 +1652,7 @@
       "resolved": "https://registry.npmjs.org/@types/react/-/react-19.2.14.tgz",
       "integrity": "sha512-ilcTH/UniCkMdtexkoCN0bI7pMcJDvmQFPvuPvmEaYA/NSfFTAgdUSLAoVjaRJm7+6PvcM+q1zYOwS4wTYMF9w==",
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "csstype": "^3.2.2"
       }
@@ -1670,8 +1672,7 @@
       "resolved": "https://registry.npmjs.org/@types/trusted-types/-/trusted-types-2.0.7.tgz",
       "integrity": "sha512-ScaPdn1dQczgbl0QFTeTOmVHFULt394XJgOQNoyVhZ6r2vLnMLJfBPd53SB52T/3G36VI1/g2MZaX0cwDuXsfw==",
       "license": "MIT",
-      "optional": true,
+      "optional": true
-      "peer": true
     },
     "node_modules/@types/unist": {
       "version": "3.0.3",
@@ -1724,6 +1725,7 @@
       "integrity": "sha512-/Zb/xaIDfxeJnvishjGdcR4jmr7S+bda8PKNhRGdljDM+elXhlvN0FyPSsMnLmJUrVG9aPO6dof80wjMawsASg==",
       "dev": true,
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "@typescript-eslint/scope-manager": "8.58.2",
         "@typescript-eslint/types": "8.58.2",
@@ -1993,6 +1995,7 @@
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       "dev": true,
       "license": "MIT",
+      "peer": true,
       "bin": {
         "acorn": "bin/acorn"
       },
@@ -2112,6 +2115,7 @@
         }
       ],
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "baseline-browser-mapping": "^2.10.12",
         "caniuse-lite": "^1.0.30001782",
@@ -2217,8 +2221,7 @@
       "version": "2.20.3",
       "resolved": "https://registry.npmjs.org/commander/-/commander-2.20.3.tgz",
       "integrity": "sha512-GpVkmM8vF2vQUkj2LvZmD35JxeJOLCwJ9cUkugyk2nuhbv3+mJvpLYYt+0+USMxE+oj+ey/lJEnhZw75x/OMcQ==",
-      "license": "MIT",
+      "license": "MIT"
-      "peer": true
     },
     "node_modules/component-emitter": {
       "version": "1.3.1",
@@ -2256,8 +2259,7 @@
       "version": "0.0.10",
       "resolved": "https://registry.npmjs.org/cssfilter/-/cssfilter-0.0.10.tgz",
       "integrity": "sha512-FAaLDaplstoRsDR8XGYH51znUN0UY7nMc6Z9/fvE8EXGwvJE9hu7W2vHwx1+bd6gCYnln9nLbzxFTrcO9YQDZw==",
-      "license": "MIT",
+      "license": "MIT"
-      "peer": true
     },
     "node_modules/csstype": {
       "version": "3.2.3",
@@ -2322,6 +2324,7 @@
       "resolved": "https://registry.npmjs.org/d3-selection/-/d3-selection-3.0.0.tgz",
       "integrity": "sha512-fmTRWbNMmsmWq6xJV8D19U/gw/bwrHfNXxrIN+HfZgnzqTHp9jOmKMhsTUjXOJnZOdZY9Q28y4yebKzqDKlxlQ==",
       "license": "ISC",
+      "peer": true,
       "engines": {
         "node": ">=12"
       }
@@ -2454,7 +2457,6 @@
       "resolved": "https://registry.npmjs.org/dompurify/-/dompurify-3.4.13.tgz",
       "integrity": "sha512-2vmYIoqjze2d+kakP8S/nS5shfsl587kzwEjcGlTdiksUVgFHnFCsLYDVj/JNqJVOQZGSYBTmuycv0PodwmnMQ==",
       "license": "(MPL-2.0 OR Apache-2.0)",
-      "peer": true,
       "optionalDependencies": {
         "@types/trusted-types": "^2.0.7"
       }
@@ -2537,6 +2539,7 @@
       "integrity": "sha512-nuKKvN+oIBO0koN7Tm7dlkmnkc21mtt0QJLwAKzjLq14y6lRTdVG36MZHJ8eQHwdJMwZbQNMlPOYedMq/oVJvQ==",
       "dev": true,
       "license": "MIT",
+      "peer": true,
       "workspaces": [
         "packages/*"
       ],
@@ -3336,7 +3339,6 @@
       "resolved": "https://registry.npmjs.org/marked/-/marked-14.0.0.tgz",
       "integrity": "sha512-uIj4+faQ+MgHgwUW1l2PsPglZLOLOT1uErt06dAPtx2kjteLAkbsd/0FiYg/MGS+i7ZKLb7w2WClxHkzOOuryQ==",
       "license": "MIT",
-      "peer": true,
       "bin": {
         "marked": "bin/marked.js"
       },
@@ -4412,6 +4414,7 @@
       "integrity": "sha512-QP88BAKvMam/3NxH6vj2o21R6MjxZUAd6nlwAS/pnGvN9IVLocLHxGYIzFhg6fUQ+5th6P4dv4eW9jX3DSIj7A==",
       "dev": true,
       "license": "MIT",
+      "peer": true,
       "engines": {
         "node": ">=12"
       },
@@ -4548,6 +4551,7 @@
       "resolved": "https://registry.npmjs.org/react/-/react-19.2.5.tgz",
       "integrity": "sha512-llUJLzz1zTUBrskt2pwZgLq59AemifIftw4aB7JxOqf1HY2FDaGDxgwpAPVzHU1kdWabH7FauP4i1oEeer2WCA==",
       "license": "MIT",
+      "peer": true,
       "engines": {
         "node": ">=0.10.0"
       }
@@ -4613,6 +4617,7 @@
       "resolved": "https://registry.npmjs.org/react-dom/-/react-dom-19.2.5.tgz",
       "integrity": "sha512-J5bAZz+DXMMwW/wV3xzKke59Af6CHY7G4uYLN1OvBcKEsWOs4pQExj86BBKamxl/Ik5bx9whOrvBlSDfWzgSag==",
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "scheduler": "^0.27.0"
       },
@@ -4858,6 +4863,7 @@
       "resolved": "https://registry.npmjs.org/sigma/-/sigma-3.0.2.tgz",
       "integrity": "sha512-/BUbeOwPGruiBOm0YQQ6ZMcLIZ6tf/W+Jcm7dxZyAX0tK3WP9/sq7/NAWBxPIxVahdGjCJoGwej0Gdrv0DxlQQ==",
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "events": "^3.3.0",
         "graphology-utils": "^2.5.2"
@@ -4983,6 +4989,7 @@
       "integrity": "sha512-X8EX+XV4QR5xCsrgxaED954zTDfY8KqlDtskKEL0cHhyS/P8b4IFOvGDQpsC9Q1XnLq915wEfwwY/zzskCtmhg==",
       "dev": true,
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "esbuild": "~0.28.0"
       },
@@ -5015,6 +5022,7 @@
       "integrity": "sha512-jl1vZzPDinLr9eUt3J/t7V6FgNEw9QjvBPdysz9KfQDD41fQrC2Y4vKQdiaUpFT4bXlb1RHhLpp8wtm6M5TgSw==",
       "dev": true,
       "license": "Apache-2.0",
+      "peer": true,
       "bin": {
         "tsc": "bin/tsc",
         "tsserver": "bin/tsserver"
@@ -5238,6 +5246,7 @@
       "resolved": "https://registry.npmjs.org/vis-data/-/vis-data-8.0.3.tgz",
       "integrity": "sha512-jhnb6rJNqkKR1Qmlay0VuDXY9ZlvAnYN1udsrP4U+krgZEq7C0yNSKdZqmnCe13mdnf9AdVcdDGFOzy2mpPoqw==",
       "license": "(Apache-2.0 OR MIT)",
+      "peer": true,
       "funding": {
         "type": "opencollective",
         "url": "https://opencollective.com/visjs"
@@ -5292,6 +5301,7 @@
       "integrity": "sha512-NTKlcQjlAK7MlQoyb6LgaqHc8sso/pVyUJYWMws3jg21uTJw/LddqIFPcPqP6PzpgbIcZyKI85sFE4HBrQDA8A==",
       "dev": true,
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "esbuild": "^0.25.0",
         "fdir": "^6.4.4",
@@ -5430,6 +5440,7 @@
       "integrity": "sha512-rftlrkhHZOcjDwkGlnUtZZkvaPHCsDATp4pGpuOOMDaTdDDXF91wuVDJoWoPsKX/3YPQ5fHuF3STjcYyKr+Qhg==",
       "dev": true,
       "license": "MIT",
+      "peer": true,
       "funding": {
         "url": "https://github.com/sponsors/colinhacks"
       }

explorer/src/workspaces/GraphWorkspace/GraphInspectorPanel.tsx

@@ -414,13 +414,19 @@ export function GraphInspectorPanel({
         </div>
       ) : null}
 
-      {/* Content Section */}
+      {/* Content Section — only rendered when the node carries actual content.
-      <details className="node-panel-collapse" open>
+           This matches the existing inspector convention: sections that have no
-        <summary className="node-panel-summary">Content</summary>
+           data for the current node are either hidden (temporal bounds) or closed
-        <div className="node-panel-body" style={{ marginTop: 8 }}>
+           by default (Source Attribution, Properties).  Always showing an open
-          <MarkdownContentViewer content={nodeContent} />
+           empty panel would add noise for every relationship/predicate node. */}
-        </div>
+      {nodeContent && (
-      </details>
+        <details className="node-panel-collapse" open>
+          <summary className="node-panel-summary">Content</summary>
+          <div className="node-panel-body" style={{ marginTop: 8 }}>
+            <MarkdownContentViewer content={nodeContent} />
+          </div>
+        </details>
+      )}
 
       {/* Actions */}
       <section style={sectionStyle}>

explorer/src/workspaces/GraphWorkspace/MarkdownContentViewer.tsx

@@ -13,6 +13,11 @@ export interface MarkdownContentViewerProps {
 export function isSafeUrl(url?: string): boolean {
   if (!url) return false;
   const trimmed = url.trim();
+  // Reject whitespace-only strings — new URL("", base) would resolve to the base
+  // protocol and produce a false positive. This guards direct callers of the exported
+  // function; markdown parsers normalise whitespace-only destinations to "" which
+  // already fails the !url check above.
+  if (!trimmed) return false;
   if (trimmed.startsWith("//")) return false;
   if (trimmed.startsWith("#")) return true;
   if (trimmed.startsWith("/")) return true;
@@ -31,8 +36,24 @@ export function MarkdownContentViewer({
 }: MarkdownContentViewerProps) {
   const [activeMode, setActiveMode] = useState<"preview" | "source">(defaultMode);
   const [copied, setCopied] = useState(false);
+  // Track the content value for which the copied indicator is valid.
+  // When content changes (i.e. the user selects a different node), reset the
+  // copied indicator inline during render rather than in a useEffect — this
+  // avoids a cascading-render lint error and is the React-recommended pattern
+  // for resetting derived visual state on prop changes.
+  const [copiedForContent, setCopiedForContent] = useState<string | null | undefined>(content);
+  if (copiedForContent !== content) {
+    setCopiedForContent(content);
+    if (copied) {
+      // Clear the stale indicator synchronously so the new node's copy button
+      // never shows "Copied" from the previous selection.
+      setCopied(false);
+    }
+  }
+
   const copyTimeoutRef = useRef<ReturnType<typeof setTimeout> | null>(null);
 
+  // Clean up any outstanding timeout on unmount.
   useEffect(() => {
     return () => {
       if (copyTimeoutRef.current) {
@@ -113,12 +134,41 @@ export function MarkdownContentViewer({
             <ReactMarkdown
               remarkPlugins={[remarkGfm]}
               components={{
-                a: ({ href, children, ...props }) => {
+                // C-1: react-markdown passes a HAST `node` prop (the raw AST
+                // Element) to every custom component override via passNode:true.
+                // In React 19 any unknown prop spreads onto a native element are
+                // serialised as HTML attributes, producing node="[object Object]"
+                // on every rendered link. Fix: destructure `node` by name so it
+                // is explicitly discarded, then spread `...rest` to preserve all
+                // other legitimate HAST/remark-gfm attributes — e.g. the `id`,
+                // `aria-describedby`, `aria-label`, `data-footnote-ref`,
+                // `data-footnote-backref`, and `class` attrs that GFM footnotes
+                // require for correct in-page navigation and accessibility.
+                //
+                // C-2: fragment links (#anchor, GFM footnote backlinks) must
+                // navigate within the current document. External links continue
+                // to use target="_blank" with noopener noreferrer.
+                //
+                // eslint-disable-next-line @typescript-eslint/no-unused-vars
+                a: ({ href, children, title, node: _node, ...rest }) => {
                   if (!isSafeUrl(href)) {
                     return <span style={{ color: GRAPH_THEME.ui.text.muted, textDecoration: "line-through" }}>{children}</span>;
                   }
+                  // isSafeUrl returning true guarantees href is a non-empty string.
+                  const safeHref = href ?? "";
+                  // Fragment links (#section, footnote backlinks like
+                  // #user-content-fnref-1) are in-document anchors. Opening them
+                  // in a new tab would break GFM footnote back-navigation.
+                  const isFragment = safeHref.startsWith("#");
+                  if (isFragment) {
+                    return (
+                      <a href={safeHref} title={title} style={linkStyle} {...rest}>
+                        {children}
+                      </a>
+                    );
+                  }
                   return (
-                    <a href={href} target="_blank" rel="noopener noreferrer" style={linkStyle} {...props}>
+                    <a href={safeHref} title={title} target="_blank" rel="noopener noreferrer" style={linkStyle} {...rest}>
                       {children}
                       <ExternalLink size={10} style={{ marginLeft: 3, verticalAlign: "middle", display: "inline" }} />
                     </a>
@@ -151,10 +201,12 @@ export function MarkdownContentViewer({
                 th: ({ children }) => <th style={{ padding: "6px 8px", textAlign: "left", fontWeight: 700, color: GRAPH_THEME.ui.text.strong, borderRight: `1px solid ${GRAPH_THEME.ui.surface.panelBorder}` }}>{children}</th>,
                 td: ({ children }) => <td style={{ padding: "6px 8px", color: GRAPH_THEME.ui.text.body, borderRight: `1px solid ${GRAPH_THEME.ui.surface.panelBorder}` }}>{children}</td>,
                 pre: ({ children }) => <pre style={preBlockStyle}>{children}</pre>,
-                code: ({ className: codeClass, children, ...props }) => {
+                // C-1: discard `node` here too — code elements are custom components
+                // and would otherwise receive node="[object Object]" in the DOM.
+                code: ({ className: codeClass, children }) => {
                   const isInline = !codeClass && typeof children === "string" && !children.includes("\n");
                   return (
-                    <code style={isInline ? inlineCodeStyle : blockCodeStyle} {...props}>
+                    <code style={isInline ? inlineCodeStyle : blockCodeStyle}>
                       {children}
                     </code>
                   );

explorer/tests/markdownContentViewer.test.ts

@@ -30,6 +30,18 @@ test("isSafeUrl rejects protocol-relative URLs and dangerous schemes", () => {
   assert.equal(isSafeUrl(undefined), false);
 });
 
+// ─── C URL contract: whitespace-only strings ────────────────────────────────
+// The CommonMark parser normalises whitespace-only link destinations to "" so
+// these values are unreachable through normal markdown rendering. However, the
+// function is exported and its direct-call contract must be correct.
+test("isSafeUrl rejects whitespace-only strings (contract correctness)", () => {
+  assert.equal(isSafeUrl(" "), false, "single space must be rejected");
+  assert.equal(isSafeUrl("\t"), false, "tab must be rejected");
+  assert.equal(isSafeUrl("\n"), false, "newline must be rejected");
+  assert.equal(isSafeUrl("   "), false, "multiple spaces must be rejected");
+  assert.equal(isSafeUrl(" \t\n "), false, "mixed whitespace must be rejected");
+});
+
 test("renders Preview mode with formatted Markdown elements and tabs", () => {
   const markdown = `# Main Title\n\n**Bold Statement**\n\n* Item A\n* Item B`;
   const html = renderToString(React.createElement(MarkdownContentViewer, { content: markdown, defaultMode: "preview" }));
@@ -69,6 +81,118 @@ test("renders raw HTML safely as escaped text without executing elements", () =>
   assert.equal(html.includes("<script>"), true);
 });
 
+// ─── C-1: HAST node prop must not reach the DOM ─────────────────────────────
+// react-markdown passes a HAST `node` (Element) object to custom component
+// overrides. Before this fix, ...props spread caused React 19 to serialise it
+// as node="[object Object]" on every <a> and <code> element.
+test("rendered links do not expose the HAST node object as a DOM attribute", () => {
+  const content = `[Example](https://example.com)\n\nInline \`code\` here.`;
+  const html = renderToString(React.createElement(MarkdownContentViewer, { content, defaultMode: "preview" }));
+
+  // The rendered HTML must not contain the serialised HAST object
+  assert.equal(html.includes("node="), false, "node= attribute must not appear in rendered HTML");
+  assert.equal(html.includes("[object Object]"), false, "serialised HAST object must not appear in rendered HTML");
+
+  // The link must still render correctly with the right href
+  assert.equal(html.includes('href="https://example.com"'), true, "href must be present");
+});
+
+// ─── C-2: Fragment links must not open in a new tab ─────────────────────────
+// Links to in-document anchors such as #section or GFM footnote backlinks like
+// #user-content-fn-1 must stay in the current document. Only external links
+// use target="_blank".
+test("fragment links render in the current document without target blank", () => {
+  const content = `[Jump to section](#introduction)\n\n[External](https://example.com)`;
+  const html = renderToString(React.createElement(MarkdownContentViewer, { content, defaultMode: "preview" }));
+
+  // Fragment link must have the href
+  assert.equal(html.includes('href="#introduction"'), true, "fragment href must be present");
+
+  // Confirm no target=_blank attribute appears anywhere near the fragment link.
+  // We check that the output contains a fragment href WITHOUT target="_blank"
+  // by verifying the two strings are not both present (the external link has
+  // target blank; the fragment link must not).
+  const fragmentLinkIdx = html.indexOf('href="#introduction"');
+  assert.notEqual(fragmentLinkIdx, -1, "fragment link must be rendered");
+  // Inspect the 80 chars around the fragment href — should not contain target
+  const fragmentContext = html.slice(Math.max(0, fragmentLinkIdx - 10), fragmentLinkIdx + 90);
+  assert.equal(fragmentContext.includes('target="_blank"'), false, "fragment link must not have target=_blank");
+
+  // External link must still have target blank
+  assert.equal(html.includes('href="https://example.com"'), true, "external href must be present");
+  assert.equal(html.includes('target="_blank"'), true, "external link must have target=_blank");
+  assert.equal(html.includes('rel="noopener noreferrer"'), true, "external link must have rel");
+});
+
+test("GFM footnote backlinks render without target blank", () => {
+  // GFM footnote syntax: footnote ref in text + definition below
+  const content = `See the note[^1] for more.\n\n[^1]: This is the footnote text.`;
+  const html = renderToString(React.createElement(MarkdownContentViewer, { content, defaultMode: "preview" }));
+
+  // The footnote reference link (#user-content-fn-1) and backlink
+  // (#user-content-fnref-1) are fragment links and must not open in a new tab.
+  // We verify no fragment href is paired with target=_blank.
+  // Extract all href="#..." occurrences and confirm none is adjacent to target=_blank.
+  const anchorMatches = [...html.matchAll(/href="#[^"]*"/g)];
+  assert.ok(anchorMatches.length > 0, "GFM footnotes must produce fragment links");
+  for (const match of anchorMatches) {
+    const start = match.index ?? 0;
+    const context = html.slice(Math.max(0, start - 10), start + 120);
+    assert.equal(
+      context.includes('target="_blank"'),
+      false,
+      `fragment link ${match[0]} must not have target=_blank`,
+    );
+  }
+});
+
+// ─── C-1-R: GFM footnote attributes must be preserved (regression test) ─────
+// The C-1 fix (removing the HAST `node` prop) must NOT silently drop other
+// legitimate HAST attributes. remark-gfm generates the following on footnote
+// links that are required for correct in-page navigation and accessibility:
+//
+//   Footnote reference anchor:
+//     id="user-content-fnref-1"           ← backlink target
+//     data-footnote-ref="true"
+//     aria-describedby="footnote-label"
+//
+//   Footnote back-link anchor:
+//     data-footnote-backref=""
+//     aria-label="Back to reference 1"    ← screen-reader label
+//     class="data-footnote-backref"
+//
+// If these are absent, clicking the ↩ back-link cannot scroll back to the
+// in-text reference, and screen readers cannot announce the backlink purpose.
+test("GFM footnote links preserve generated id, aria, and class attributes", () => {
+  const content = `See the note[^1] for more.\n\n[^1]: This is the footnote text.`;
+  const html = renderToString(React.createElement(MarkdownContentViewer, { content, defaultMode: "preview" }));
+
+  // The HAST `node` object must not appear serialised as a DOM attribute.
+  assert.equal(html.includes("node="), false, "node= attribute must not appear in HTML");
+  assert.equal(html.includes("[object Object]"), false, "serialised HAST object must not appear in HTML");
+
+  // Footnote reference anchor must retain its id so the backlink can navigate to it.
+  assert.equal(
+    html.includes('id="user-content-fnref-1"'),
+    true,
+    "footnote reference anchor must retain id for back-navigation",
+  );
+
+  // Footnote backlink must retain its aria-label for screen-reader accessibility.
+  assert.equal(
+    html.includes('aria-label="Back to reference 1"'),
+    true,
+    "footnote backlink must retain aria-label for accessibility",
+  );
+
+  // Footnote backlink must retain its class attribute.
+  assert.equal(
+    html.includes('class="data-footnote-backref"'),
+    true,
+    "footnote backlink must retain class attribute",
+  );
+});
+
 test("renders safe links as <a> with target blank and unclickable span for unsafe links", () => {
   const content = `[Safe Link](https://getsemantica.ai)\n\n[Unsafe Scheme](javascript:alert(1))\n\n[Protocol Relative](//evil.com)`;
   const html = renderToString(React.createElement(MarkdownContentViewer, { content, defaultMode: "preview" }));
@@ -118,3 +242,23 @@ test("handles very large Markdown content without failure", () => {
   const html = renderToString(React.createElement(MarkdownContentViewer, { content: largeContent, defaultMode: "preview" }));
   assert.equal(html.includes("Large Knowledge Node"), true);
 });
+
+// ─── H-2: Stale copied state lifecycle (SSR-compatible portion) ─────────────
+// Full state-transition testing (Node A → copy → Node B) requires an interactive
+// framework. The lifecycle correctness is guaranteed by the render-phase
+// previous-prop synchronisation pattern: a `copiedForContent` state value tracks
+// the content for which the copied indicator was set; when `content` changes, the
+// mismatch is detected during render and `copied` is reset to false in the same
+// React batch, before the new node's UI is painted. What we CAN verify in SSR
+// is that the initial render for any content value shows the Copy button (not the
+// Copied indicator), which confirms the initial state is always clean.
+test("copy button always starts in un-copied state on initial render", () => {
+  const html = renderToString(React.createElement(MarkdownContentViewer, {
+    content: "# Some Node\n\nDescription text.",
+    defaultMode: "preview",
+  }));
+
+  // Initial render must show 'Copy', never 'Copied'
+  assert.equal(html.includes("Copy"), true, "Copy button must be present on initial render");
+  assert.equal(html.includes("Copied"), false, "Copied indicator must NOT be present on initial render");
+});