diff --git a/webui2/src/lib/shiki.ts b/webui2/src/lib/shiki.ts
index 5f9f7e183da8b4612b6a0baa45dad8c4facae07d..7dc542a20ca47394c6e1758244215ee1cd9641d3 100644
--- a/webui2/src/lib/shiki.ts
+++ b/webui2/src/lib/shiki.ts
@@ -13,7 +13,26 @@ export function getHighlighter(): Promise<HighlighterCore> {
         import("@shikijs/themes/github-light"),
         import("@shikijs/themes/github-dark"),
       ],
-      langs: [],
+      // Pre-load common languages for Markdown code blocks.
+      // FileViewer also loads additional languages on demand via loadLanguage().
+      langs: [
+        import("@shikijs/langs/javascript"),
+        import("@shikijs/langs/typescript"),
+        import("@shikijs/langs/jsx"),
+        import("@shikijs/langs/tsx"),
+        import("@shikijs/langs/json"),
+        import("@shikijs/langs/html"),
+        import("@shikijs/langs/css"),
+        import("@shikijs/langs/bash"),
+        import("@shikijs/langs/go"),
+        import("@shikijs/langs/yaml"),
+        import("@shikijs/langs/markdown"),
+        import("@shikijs/langs/python"),
+        import("@shikijs/langs/rust"),
+        import("@shikijs/langs/sql"),
+        import("@shikijs/langs/graphql"),
+        import("@shikijs/langs/diff"),
+      ],
       engine: createOnigurumaEngine(import("shiki/wasm")),
     });
   }