diff --git a/packages/ui/src/components/mdx-content/mdx-content.test.tsx b/packages/ui/src/components/mdx-content/mdx-content.test.tsx
new file mode 100644
index 00000000..1f8f20b6
--- /dev/null
+++ b/packages/ui/src/components/mdx-content/mdx-content.test.tsx
@@ -0,0 +1,68 @@
+import { render, screen } from "@testing-library/react";
+import type React from "react";
+import { afterEach, describe, expect, it, vi } from "vitest";
+
+import { MDXContent } from "./mdx-content";
+
+function Note({ children }: { children: React.ReactNode }) {
+  return <aside>{children}</aside>;
+}
+
+describe("MDXContent", () => {
+  afterEach(() => {
+    vi.restoreAllMocks();
+  });
+
+  it("renders markdown headings, links, and list items", async () => {
+    const node = await MDXContent({
+      content:
+        "## Getting started\n\nRead the [docs](https://example.com).\n\n- Install\n- Ship",
+    });
+
+    render(node);
+
+    expect(
+      screen.getByRole("heading", { name: "Getting started" }),
+    ).toBeInTheDocument();
+    expect(screen.getByRole("link", { name: "docs" })).toHaveAttribute(
+      "href",
+      "https://example.com",
+    );
+    expect(screen.getByText("Install")).toBeInTheDocument();
+    expect(screen.getByText("Ship")).toBeInTheDocument();
+  });
+
+  it("strips injected component imports before rendering MDX", async () => {
+    const node = await MDXContent({
+      components: { Note },
+      content:
+        'import { Note } from "./note";\n\n<Note>Imported component content</Note>',
+    });
+
+    render(node);
+
+    expect(screen.getByText("Imported component content")).toBeInTheDocument();
+    expect(document.body).not.toHaveTextContent(
+      'import { Note } from "./note"',
+    );
+  });
+
+  it("falls back to markdown when MDX evaluation fails", async () => {
+    const consoleError = vi
+      .spyOn(console, "error")
+      .mockImplementation(() => null);
+    const node = await MDXContent({
+      content: "## Fallback content\n\n<Broken",
+    });
+
+    render(node);
+
+    expect(
+      screen.getByRole("heading", { name: "Fallback content" }),
+    ).toBeInTheDocument();
+    expect(consoleError).toHaveBeenCalledWith(
+      "Error rendering MDX:",
+      expect.any(Error),
+    );
+  });
+});
diff --git a/packages/ui/src/components/model-selector/model-selector.test.tsx b/packages/ui/src/components/model-selector/model-selector.test.tsx
new file mode 100644
index 00000000..98e9f9b8
--- /dev/null
+++ b/packages/ui/src/components/model-selector/model-selector.test.tsx
@@ -0,0 +1,89 @@
+import { fireEvent, render, screen } from "@testing-library/react";
+import type React from "react";
+import { describe, expect, it, vi } from "vitest";
+
+import { type ModelInfo, ModelSelector } from "./model-selector";
+
+const models: ModelInfo[] = [
+  {
+    description: "Fast multimodal model",
+    id: "openai/gpt-4o",
+    name: "GPT-4o",
+    pricing: { input: 2.5, output: 10 },
+  },
+  {
+    description: "Long context reasoning model",
+    id: "anthropic/claude-3-5-sonnet",
+    name: "Claude 3.5 Sonnet",
+    pricing: { input: 3, output: 15 },
+  },
+  {
+    description: "Gemini family model",
+    id: "google/gemini-1.5-pro",
+    name: "Gemini 1.5 Pro",
+  },
+];
+
+function getModelItem(name: string): Element {
+  const item = screen.getByText(name).closest("[cmdk-item]");
+  if (!item) throw new Error(`Expected ${name} to render as a model item`);
+  return item;
+}
+
+function renderModelSelector(
+  overrides: Partial<React.ComponentProps<typeof ModelSelector>> = {},
+) {
+  const props = {
+    models,
+    onOpenChange: vi.fn(),
+    onSelectModel: vi.fn(),
+    open: true,
+    selectedModelId: "google/gemini-1.5-pro",
+    ...overrides,
+  };
+
+  render(<ModelSelector {...props} />);
+
+  return props;
+}
+
+describe("ModelSelector", () => {
+  it("renders the open dialog with selected model promoted and disabled", () => {
+    renderModelSelector();
+
+    expect(screen.getByText("Select Model")).toBeInTheDocument();
+    expect(screen.getByText("Selected")).toBeInTheDocument();
+    expect(getModelItem("Gemini 1.5 Pro")).toHaveAttribute(
+      "aria-disabled",
+      "true",
+    );
+    expect(screen.getByText("In: $2.50/1M")).toBeInTheDocument();
+    expect(screen.getByText("Out: $10.00/1M")).toBeInTheDocument();
+  });
+
+  it("filters models by search text across provider metadata", () => {
+    renderModelSelector();
+
+    fireEvent.change(
+      screen.getByPlaceholderText("Search models or providers..."),
+      {
+        target: { value: "anthropic" },
+      },
+    );
+
+    expect(screen.getByText("Claude 3.5 Sonnet")).toBeInTheDocument();
+    expect(screen.queryByText("GPT-4o")).not.toBeInTheDocument();
+    expect(screen.queryByText("Gemini 1.5 Pro")).not.toBeInTheDocument();
+  });
+
+  it("selects a non-current model and closes the dialog", () => {
+    const onOpenChange = vi.fn();
+    const onSelectModel = vi.fn();
+    renderModelSelector({ onOpenChange, onSelectModel });
+
+    fireEvent.click(getModelItem("Claude 3.5 Sonnet"));
+
+    expect(onSelectModel).toHaveBeenCalledWith("anthropic/claude-3-5-sonnet");
+    expect(onOpenChange).toHaveBeenCalledWith(false);
+  });
+});
diff --git a/packages/ui/src/components/slideshow/slideshow.test.tsx b/packages/ui/src/components/slideshow/slideshow.test.tsx
new file mode 100644
index 00000000..2db5d6e2
--- /dev/null
+++ b/packages/ui/src/components/slideshow/slideshow.test.tsx
@@ -0,0 +1,104 @@
+import { act, fireEvent, render, screen } from "@testing-library/react";
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+
+import { Slideshow, type SlideshowProps } from "./slideshow";
+
+const sections = [
+  { id: "intro", title: "Intro" },
+  { id: "setup", title: "Setup" },
+  { id: "finish", title: "Finish" },
+];
+
+function renderSlideshow(overrides: Partial<SlideshowProps> = {}) {
+  const props = {
+    completedSections: new Set<string>(),
+    currentIndex: 0,
+    onComplete: vi.fn(),
+    onExit: vi.fn(),
+    onNavigate: vi.fn(),
+    onToggleSection: vi.fn(),
+    renderContent: (section: { title: string }) => (
+      <article>{section.title} body</article>
+    ),
+    sections,
+    title: "Tutorial",
+    ...overrides,
+  };
+
+  const view = render(<Slideshow {...props} />);
+
+  return { props, view };
+}
+
+function advanceNavigationTimer() {
+  act(() => {
+    vi.advanceTimersByTime(150);
+  });
+}
+
+describe("Slideshow", () => {
+  beforeEach(() => {
+    vi.useFakeTimers();
+  });
+
+  afterEach(() => {
+    vi.useRealTimers();
+    document.body.style.overflow = "";
+  });
+
+  it("renders in a portal and restores body scroll lock on cleanup", () => {
+    const { view } = renderSlideshow();
+
+    expect(screen.getByText("Tutorial")).toBeInTheDocument();
+    expect(screen.getByText("Intro body")).toBeInTheDocument();
+    expect(document.body.style.overflow).toBe("hidden");
+
+    view.unmount();
+
+    expect(document.body.style.overflow).toBe("");
+  });
+
+  it("opens the completion dialog before navigating an incomplete section", () => {
+    const { props } = renderSlideshow();
+
+    fireEvent.click(screen.getByRole("button", { name: /next/i }));
+
+    expect(
+      screen.getByRole("dialog", { name: "Mark section as complete?" }),
+    ).toBeInTheDocument();
+
+    fireEvent.click(screen.getByRole("button", { name: /^done/i }));
+    advanceNavigationTimer();
+
+    expect(props.onToggleSection).toHaveBeenCalledWith("intro");
+    expect(props.onNavigate).toHaveBeenCalledWith(1);
+  });
+
+  it("navigates from the table of contents after the transition delay", () => {
+    const { props } = renderSlideshow();
+
+    fireEvent.click(
+      screen.getByRole("button", { name: "Open table of contents" }),
+    );
+    fireEvent.click(screen.getByRole("button", { name: "Setup" }));
+    advanceNavigationTimer();
+
+    expect(props.onNavigate).toHaveBeenCalledWith(1);
+    expect(
+      screen.getByRole("button", { name: "Open table of contents" }),
+    ).toBeInTheDocument();
+  });
+
+  it("handles keyboard exit and next navigation shortcuts", () => {
+    const { props } = renderSlideshow({
+      completedSections: new Set(["intro"]),
+    });
+
+    fireEvent.keyDown(document, { key: "ArrowRight" });
+    advanceNavigationTimer();
+    expect(props.onNavigate).toHaveBeenCalledWith(1);
+
+    fireEvent.keyDown(document, { key: "Escape" });
+    expect(props.onExit).toHaveBeenCalledTimes(1);
+  });
+});
diff --git a/packages/ui/src/components/social-fab/social-fab.test.tsx b/packages/ui/src/components/social-fab/social-fab.test.tsx
new file mode 100644
index 00000000..2b415185
--- /dev/null
+++ b/packages/ui/src/components/social-fab/social-fab.test.tsx
@@ -0,0 +1,129 @@
+import { act, fireEvent, render, screen } from "@testing-library/react";
+import { afterEach, describe, expect, it, vi } from "vitest";
+
+import { SocialFAB, type SocialFabProps } from "./social-fab";
+
+const originalInnerWidth = window.innerWidth;
+
+const labels = {
+  close: "Close social actions",
+  share: "Share",
+};
+
+const actions = [
+  { id: "share", label: "Share", onClick: vi.fn() },
+  { id: "copy", label: "Copy link", onClick: vi.fn() },
+];
+
+function setViewportWidth(width: number) {
+  Object.defineProperty(window, "innerWidth", {
+    configurable: true,
+    value: width,
+  });
+  act(() => {
+    window.dispatchEvent(new Event("resize"));
+  });
+}
+
+function renderSocialFab(overrides: Partial<SocialFabProps> = {}) {
+  return render(
+    <SocialFAB
+      actions={actions}
+      labels={labels}
+      mainText="More"
+      {...overrides}
+    />,
+  );
+}
+
+function getMainButton(name: string): HTMLElement {
+  const buttons = screen.getAllByRole("button", { name });
+  const button = buttons.at(-1);
+  if (!button) throw new Error(`Expected main button named ${name}`);
+  return button;
+}
+
+function getFirstButton(name: string): HTMLElement {
+  const button = screen.getAllByRole("button", { name }).at(0);
+  if (!button) throw new Error(`Expected button named ${name}`);
+  return button;
+}
+
+describe("SocialFAB", () => {
+  afterEach(() => {
+    vi.restoreAllMocks();
+    setViewportWidth(originalInnerWidth);
+  });
+
+  it("renders nothing when hidden", () => {
+    const { container } = renderSocialFab({ hidden: true });
+
+    expect(container.firstChild).toBeNull();
+  });
+
+  it("opens and closes from desktop hover callbacks", () => {
+    const onClose = vi.fn();
+    const onOpen = vi.fn();
+    const { container } = renderSocialFab({ onClose, onOpen });
+    const wrapper = container.querySelector(".fixed");
+    if (!wrapper) throw new Error("Expected fixed FAB wrapper");
+
+    fireEvent.mouseEnter(wrapper);
+    expect(
+      screen.getByRole("button", { name: "Close social actions" }),
+    ).toHaveAttribute("aria-expanded", "true");
+    expect(onOpen).toHaveBeenCalledWith("hover", "desktop");
+
+    fireEvent.mouseLeave(wrapper);
+    expect(getMainButton("Share")).toHaveAttribute("aria-expanded", "false");
+    expect(onClose).toHaveBeenCalledWith("hover_leave");
+  });
+
+  it("uses a mobile backdrop to close expanded actions", () => {
+    setViewportWidth(390);
+    const onClose = vi.fn();
+    const onOpen = vi.fn();
+    renderSocialFab({ onClose, onOpen });
+
+    fireEvent.click(getMainButton("Share"));
+
+    expect(
+      screen.getByRole("button", { name: "Close social actions" }),
+    ).toHaveAttribute("aria-expanded", "true");
+    expect(onOpen).toHaveBeenCalledWith("tap", "mobile");
+
+    const backdrop = document.body.querySelector("[aria-hidden='true']");
+    if (!backdrop) throw new Error("Expected mobile backdrop");
+    fireEvent.click(backdrop);
+
+    expect(getMainButton("Share")).toHaveAttribute("aria-expanded", "false");
+    expect(onClose).toHaveBeenCalledWith("backdrop");
+  });
+
+  it("opens share platforms on desktop hover and launches selected share URL", () => {
+    const open = vi.spyOn(window, "open").mockImplementation(() => null);
+    const onAction = vi.fn();
+    renderSocialFab({
+      onAction,
+      sharePlatforms: [
+        {
+          buildUrl: (pageUrl, pageTitle) =>
+            `https://share.example/?url=${pageUrl}&title=${pageTitle}`,
+          key: "example",
+          label: "Example Network",
+        },
+      ],
+    });
+
+    fireEvent.click(getMainButton("Share"));
+    fireEvent.mouseEnter(getFirstButton("Share"));
+    fireEvent.click(screen.getByRole("button", { name: "Example Network" }));
+
+    expect(onAction).toHaveBeenCalledWith("share");
+    expect(open).toHaveBeenCalledWith(
+      expect.stringContaining("https://share.example/"),
+      "_blank",
+      "noopener,noreferrer",
+    );
+  });
+});