diff --git a/packages/dashboard/src/components/CodeViewer.tsx b/packages/dashboard/src/components/CodeViewer.tsx
new file mode 100644
index 0000000..9d45b7a
--- /dev/null
+++ b/packages/dashboard/src/components/CodeViewer.tsx
@@ -0,0 +1,114 @@
+import Editor from "@monaco-editor/react";
+import { useDashboardStore } from "../store";
+
+const extensionToLanguage: Record<string, string> = {
+  ts: "typescript",
+  tsx: "typescript",
+  js: "javascript",
+  jsx: "javascript",
+  py: "python",
+  go: "go",
+  rs: "rust",
+  rb: "ruby",
+  java: "java",
+  kt: "kotlin",
+  cs: "csharp",
+  cpp: "cpp",
+  c: "c",
+  swift: "swift",
+  php: "php",
+  json: "json",
+  yaml: "yaml",
+  yml: "yaml",
+  md: "markdown",
+  html: "html",
+  css: "css",
+  sql: "sql",
+  sh: "shell",
+  bash: "shell",
+};
+
+function getLanguage(filePath: string | undefined): string {
+  if (!filePath) return "plaintext";
+  const ext = filePath.split(".").pop()?.toLowerCase() ?? "";
+  return extensionToLanguage[ext] ?? "plaintext";
+}
+
+export default function CodeViewer() {
+  const graph = useDashboardStore((s) => s.graph);
+  const selectedNodeId = useDashboardStore((s) => s.selectedNodeId);
+
+  const node = graph?.nodes.find((n) => n.id === selectedNodeId) ?? null;
+
+  if (!node) {
+    return (
+      <div className="h-full w-full flex items-center justify-center bg-gray-800 rounded-lg">
+        <p className="text-gray-400 text-sm">
+          Select a node to view its source code
+        </p>
+      </div>
+    );
+  }
+
+  const language = getLanguage(node.filePath);
+  const lineInfo = node.lineRange
+    ? `Lines ${node.lineRange[0]}-${node.lineRange[1]}`
+    : "Full file";
+
+  const placeholderCode = [
+    `// ${node.name}`,
+    `// Type: ${node.type}`,
+    `// File: ${node.filePath ?? "unknown"}`,
+    `// ${lineInfo}`,
+    `//`,
+    `// Summary:`,
+    `// ${node.summary}`,
+    `//`,
+    `// Note: Source code display requires file content access.`,
+    `// In a full integration, this panel will show the actual`,
+    `// source code from the analyzed project.`,
+    "",
+    ...(node.tags.length > 0
+      ? [`// Tags: ${node.tags.join(", ")}`]
+      : []),
+    ...(node.languageNotes
+      ? [`//`, `// Language Notes:`, `// ${node.languageNotes}`]
+      : []),
+  ].join("\n");
+
+  return (
+    <div className="h-full w-full flex flex-col bg-gray-800 rounded-lg overflow-hidden">
+      <div className="flex items-center gap-3 px-3 py-2 bg-gray-900 border-b border-gray-700 shrink-0">
+        <span className="text-[10px] font-semibold uppercase tracking-wider text-gray-400 bg-gray-700 px-2 py-0.5 rounded">
+          {node.type}
+        </span>
+        <span className="text-sm font-bold text-white truncate">
+          {node.name}
+        </span>
+        {node.filePath && (
+          <span className="text-xs text-gray-500 truncate ml-auto">
+            {node.filePath}
+          </span>
+        )}
+      </div>
+
+      <div className="flex-1 min-h-0">
+        <Editor
+          height="100%"
+          language={language}
+          value={placeholderCode}
+          theme="vs-dark"
+          options={{
+            readOnly: true,
+            minimap: { enabled: false },
+            fontSize: 13,
+            lineNumbers: "on",
+            scrollBeyondLastLine: false,
+            wordWrap: "on",
+            padding: { top: 8 },
+          }}
+        />
+      </div>
+    </div>
+  );
+}