perf(highlighter): lazy-init Shiki at module level without blocking

frontend/src/components/MdProcessor.tsx

@@ -4,12 +4,13 @@ import {
     useMemo,
     type ComponentPropsWithoutRef,
     type ReactElement,
+    type ReactNode,
 } from "react";
 import ReactMarkdown from "react-markdown";
 import remarkGfm from "remark-gfm";
 import rehypeRaw from "rehype-raw";
 import rehypeSanitize from "rehype-sanitize";
-import highlighter from "../utils/highlighter";
+import { getHighlighter } from "../utils/highlighter";
 
 function CopyButton({ code }: { code: string }): ReactElement {
     return (
@@ -23,13 +24,59 @@ function CopyButton({ code }: { code: string }): ReactElement {
                     }, 1500);
                 });
             }}
-            className="absolute top-1 right-1 px-2 py-1 text-base font-mono text-ctp-subtext0 hover:text-ctp-green transition-colors cursor-pointer select-none z-10 font-[NerdFontSymbols]"
+            className="absolute top-1 right-1 px-2 py-1 text-base leading-none text-ctp-subtext0 hover:text-ctp-green transition-colors cursor-pointer select-none z-10 font-[NerdFontSymbols]"
         >
             
         </button>
     );
 }
 
+function HighlightedBlock({
+    code,
+    lang,
+    children,
+}: {
+    code: string;
+    lang: string;
+    children: ReactNode;
+}): ReactElement {
+    const [html, setHtml] = useState<string | null>(null);
+
+    useEffect(() => {
+        getHighlighter().then((hl) => {
+            setHtml(
+                hl.codeToHtml(code, {
+                    lang,
+                    themes: {
+                        dark: "catppuccin-macchiato",
+                        light: "catppuccin-latte",
+                    },
+                    defaultColor: false,
+                }),
+            );
+        });
+    }, [code, lang]);
+
+    return (
+        <div className="relative border-2 border-ctp-text/50 rounded-md overflow-hidden my-6 bg-ctp-base">
+            <span className="absolute top-0 left-0 px-2 py-1 text-xs font-mono text-ctp-mauve">
+                {lang}
+            </span>
+            <CopyButton code={code} />
+            {html ? (
+                <div
+                    className="overflow-x-auto text-sm p-4 pt-7"
+                    dangerouslySetInnerHTML={{ __html: html }}
+                />
+            ) : (
+                <pre className="overflow-x-auto text-sm p-4 pt-7 m-0">
+                    {children}
+                </pre>
+            )}
+        </div>
+    );
+}
+
 const toRawUrl = (repoUrl: string): string => {
     if (!repoUrl) return repoUrl;
 
@@ -180,34 +227,11 @@ export default function MdProcessor({
                 }
             }
 
-            const highlighted =
-                lang && code
-                    ? highlighter.codeToHtml(code, {
-                          lang,
-                          themes: {
-                              dark: "catppuccin-macchiato",
-                              light: "catppuccin-latte",
-                          },
-                          defaultColor: false,
-                      })
-                    : null;
-
-            if (highlighted) {
+            if (lang && code) {
                 return (
-                    <div className="relative border-2 border-ctp-text/50 rounded-md overflow-hidden my-6 bg-ctp-base">
-                        {lang && (
-                            <span className="absolute top-0 left-0 px-2 py-1 text-xs font-mono text-ctp-mauve">
-                                {lang}
-                            </span>
-                        )}
-                        <CopyButton code={code} />
-                        <div
-                            className={`overflow-x-auto text-sm p-4 ${lang ? "pt-7" : ""}`}
-                            dangerouslySetInnerHTML={{
-                                __html: highlighted,
-                            }}
-                        />
-                    </div>
+                    <HighlightedBlock code={code} lang={lang}>
+                        {children}
+                    </HighlightedBlock>
                 );
             }
 

frontend/src/utils/highlighter.ts

@@ -1,6 +1,6 @@
-import { createHighlighter } from "shiki";
+import { createHighlighter, type Highlighter } from "shiki";
 
-export default await createHighlighter({
+const highlighterPromise = createHighlighter({
     themes: ["catppuccin-macchiato", "catppuccin-latte"],
     langs: [
         "javascript",
@@ -69,3 +69,7 @@ export default await createHighlighter({
         "tex",
     ],
 });
+
+export function getHighlighter(): Promise<Highlighter> {
+    return highlighterPromise;
+}