diff --git a/apps/web/src/components/__tests__/dialog.test.tsx b/apps/web/src/components/__tests__/dialog.test.tsx
new file mode 100644
index 0000000..9c483f4
--- /dev/null
+++ b/apps/web/src/components/__tests__/dialog.test.tsx
@@ -0,0 +1,71 @@
+// @vitest-environment jsdom
+import { cleanup, render, screen } from "@testing-library/react";
+import { userEvent } from "@testing-library/user-event";
+import { afterEach, beforeAll, describe, expect, it, vi } from "vitest";
+import { Dialog, DialogHeader } from "../ui/dialog.js";
+
+beforeAll(() => {
+	HTMLDialogElement.prototype.showModal =
+		HTMLDialogElement.prototype.showModal ||
+		function showModal(this: HTMLDialogElement) {
+			this.setAttribute("open", "");
+		};
+	HTMLDialogElement.prototype.close =
+		HTMLDialogElement.prototype.close ||
+		function close(this: HTMLDialogElement) {
+			this.removeAttribute("open");
+		};
+});
+
+afterEach(cleanup);
+
+describe("Dialog", () => {
+	it("opens when open=true", () => {
+		render(
+			<Dialog open={true} onClose={() => {}}>
+				Content
+			</Dialog>,
+		);
+		expect(screen.getByText("Content")).toBeDefined();
+	});
+
+	it("closes when open changes from true to false", () => {
+		const { rerender } = render(
+			<Dialog open={true} onClose={() => {}}>
+				Content
+			</Dialog>,
+		);
+		const dialog = document.querySelector("dialog");
+		expect(dialog?.hasAttribute("open")).toBe(true);
+
+		rerender(
+			<Dialog open={false} onClose={() => {}}>
+				Content
+			</Dialog>,
+		);
+		expect(dialog?.hasAttribute("open")).toBe(false);
+	});
+
+	it("calls onClose on cancel event", () => {
+		const onClose = vi.fn();
+		render(
+			<Dialog open={true} onClose={onClose}>
+				Content
+			</Dialog>,
+		);
+		const dialog = document.querySelector("dialog");
+		dialog?.dispatchEvent(new Event("cancel"));
+		expect(onClose).toHaveBeenCalledOnce();
+	});
+});
+
+describe("DialogHeader", () => {
+	it("renders title and close button", async () => {
+		const onClose = vi.fn();
+		render(<DialogHeader title="Test Title" onClose={onClose} />);
+
+		expect(screen.getByText("Test Title")).toBeDefined();
+		await userEvent.click(screen.getByRole("button"));
+		expect(onClose).toHaveBeenCalledOnce();
+	});
+});
diff --git a/apps/web/src/components/__tests__/tooltip.test.tsx b/apps/web/src/components/__tests__/tooltip.test.tsx
new file mode 100644
index 0000000..f160286
--- /dev/null
+++ b/apps/web/src/components/__tests__/tooltip.test.tsx
@@ -0,0 +1,42 @@
+// @vitest-environment jsdom
+import { cleanup, fireEvent, render, screen } from "@testing-library/react";
+import { afterEach, describe, expect, it } from "vitest";
+import { Tooltip } from "../ui/tooltip.js";
+
+afterEach(cleanup);
+
+describe("Tooltip", () => {
+	it("renders children", () => {
+		render(
+			<Tooltip content="Hint">
+				<button type="button">Hover me</button>
+			</Tooltip>,
+		);
+		expect(screen.getByText("Hover me")).toBeDefined();
+	});
+
+	it("does not show tooltip initially", () => {
+		render(
+			<Tooltip content="Hint">
+				<span>Target</span>
+			</Tooltip>,
+		);
+		expect(screen.queryByRole("tooltip")).toBeNull();
+	});
+
+	it("shows tooltip on pointer enter and hides on pointer leave", () => {
+		render(
+			<Tooltip content="Hint text">
+				<span>Target</span>
+			</Tooltip>,
+		);
+
+		const wrapper = screen.getByText("Target").closest("span");
+		fireEvent.pointerEnter(wrapper as HTMLElement);
+		expect(screen.getByRole("tooltip")).toBeDefined();
+		expect(screen.getByText("Hint text")).toBeDefined();
+
+		fireEvent.pointerLeave(wrapper as HTMLElement);
+		expect(screen.queryByRole("tooltip")).toBeNull();
+	});
+});
diff --git a/vitest.config.ts b/vitest.config.ts
index 0c38f55..ed448de 100644
--- a/vitest.config.ts
+++ b/vitest.config.ts
@@ -34,8 +34,8 @@ export default defineConfig({
 					branches: 55,
 				},
 				"apps/web/src/components/ui": {
-					lines: 86,
-					branches: 83,
+					lines: 93,
+					branches: 90,
 				},
 			},
 		},