diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 74838149..bd4a95ec 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -233,6 +233,10 @@ jobs:
         working-directory: frontend
         run: npm run lint
 
+      - name: Frontend unit tests (Vitest)
+        working-directory: frontend
+        run: npm test
+
       - name: Next.js build (production bundle check)
         working-directory: frontend
         run: npm run build
diff --git a/frontend/src/components/chat/MessageBubble.test.tsx b/frontend/src/components/chat/MessageBubble.test.tsx
index f48acd9e..fd671a9f 100644
--- a/frontend/src/components/chat/MessageBubble.test.tsx
+++ b/frontend/src/components/chat/MessageBubble.test.tsx
@@ -1,7 +1,8 @@
-import { render, screen } from "@testing-library/react";
+import { fireEvent, render, screen, waitFor } from "@testing-library/react";
 import { describe, expect, it, vi } from "vitest";
 import MessageBubble from "./MessageBubble";
 import type { ChatMsg } from "@/store/chat-store";
+import { api } from "@/lib/api";
 
 vi.mock("@/lib/api", () => ({
   api: {
@@ -52,4 +53,37 @@ describe("MessageBubble", () => {
     expect(screen.getByLabelText("Copy response")).toBeInTheDocument();
     expect(screen.getByLabelText("Share response")).toBeInTheDocument();
   });
+
+  it("copies assistant message content to clipboard when copy button is clicked", () => {
+    const content = "This is some assistant response text";
+    render(<MessageBubble message={makeMessage({ content })} />);
+
+    fireEvent.click(screen.getByLabelText("Copy response"));
+
+    expect(navigator.clipboard.writeText).toHaveBeenCalledWith(content);
+    expect(screen.getByLabelText("Copied")).toBeInTheDocument();
+  });
+
+  it("shares assistant message via API and copies share link to clipboard", async () => {
+    vi.mocked(api.post).mockResolvedValueOnce({
+      message_id: "msg-1",
+      share_url: "/shared/abc-123",
+    });
+
+    render(
+      <MessageBubble
+        message={makeMessage({ content: "Share this content" })}
+      />,
+    );
+
+    fireEvent.click(screen.getByLabelText("Share response"));
+
+    await waitFor(() => {
+      expect(api.post).toHaveBeenCalledWith("/api/v1/chat/share/msg-1");
+    });
+
+    expect(navigator.clipboard.writeText).toHaveBeenCalledWith(
+      "http://localhost:3000/shared/abc-123",
+    );
+  });
 });
diff --git a/frontend/src/test/setup.ts b/frontend/src/test/setup.ts
index 51e7ef37..4309d5f5 100644
--- a/frontend/src/test/setup.ts
+++ b/frontend/src/test/setup.ts
@@ -7,6 +7,14 @@ afterEach(() => {
   vi.clearAllMocks();
 });
 
+Object.defineProperty(navigator, "clipboard", {
+  writable: true,
+  value: {
+    writeText: vi.fn(),
+    readText: vi.fn(),
+  },
+});
+
 Object.defineProperty(window, "matchMedia", {
   writable: true,
   value: vi.fn().mockImplementation((query: string) => ({