diff --git a/apps/web/src/components/ui/Badge.test.tsx b/apps/web/src/components/ui/Badge.test.tsx
new file mode 100644
index 0000000..743ffd5
--- /dev/null
+++ b/apps/web/src/components/ui/Badge.test.tsx
@@ -0,0 +1,49 @@
+import { describe, expect, it } from "vitest";
+import { render, screen } from "~/test-utils.js";
+import { Badge } from "./Badge.js";
+
+describe("Badge", () => {
+  it("renders children text", () => {
+    render(<Badge>Active</Badge>);
+    expect(screen.getByText("Active")).toBeInTheDocument();
+  });
+
+  it("applies default variant classes when no variant is specified", () => {
+    render(<Badge>Default</Badge>);
+    const badge = screen.getByText("Default");
+    expect(badge.className).toContain("bg-gray-100");
+    expect(badge.className).toContain("text-gray-700");
+  });
+
+  it("applies success variant classes", () => {
+    render(<Badge variant="success">OK</Badge>);
+    const badge = screen.getByText("OK");
+    expect(badge.className).toContain("bg-green-100");
+    expect(badge.className).toContain("text-green-700");
+  });
+
+  it("applies danger variant classes", () => {
+    render(<Badge variant="danger">Error</Badge>);
+    expect(screen.getByText("Error").className).toContain("bg-red-100");
+  });
+
+  it("applies warning variant classes", () => {
+    render(<Badge variant="warning">Warn</Badge>);
+    expect(screen.getByText("Warn").className).toContain("bg-yellow-100");
+  });
+
+  it("applies info variant classes", () => {
+    render(<Badge variant="info">Info</Badge>);
+    expect(screen.getByText("Info").className).toContain("bg-blue-100");
+  });
+
+  it("merges custom className", () => {
+    render(<Badge className="custom-class">Test</Badge>);
+    expect(screen.getByText("Test").className).toContain("custom-class");
+  });
+
+  it("renders as a span element", () => {
+    render(<Badge>Span</Badge>);
+    expect(screen.getByText("Span").tagName).toBe("SPAN");
+  });
+});
diff --git a/apps/web/src/components/ui/Button.test.tsx b/apps/web/src/components/ui/Button.test.tsx
new file mode 100644
index 0000000..acf0c3f
--- /dev/null
+++ b/apps/web/src/components/ui/Button.test.tsx
@@ -0,0 +1,86 @@
+import { describe, expect, it, vi } from "vitest";
+import { render, screen } from "~/test-utils.js";
+import userEvent from "@testing-library/user-event";
+import { Button } from "./Button.js";
+
+describe("Button", () => {
+  it("renders children text", () => {
+    render(<Button>Click me</Button>);
+    expect(screen.getByRole("button", { name: "Click me" })).toBeInTheDocument();
+  });
+
+  it("applies primary variant by default", () => {
+    render(<Button>Primary</Button>);
+    expect(screen.getByRole("button").className).toContain("bg-brand-600");
+  });
+
+  it("applies secondary variant", () => {
+    render(<Button variant="secondary">Secondary</Button>);
+    expect(screen.getByRole("button").className).toContain("border-gray-300");
+  });
+
+  it("applies ghost variant", () => {
+    render(<Button variant="ghost">Ghost</Button>);
+    expect(screen.getByRole("button").className).toContain("hover:bg-gray-100");
+  });
+
+  it("applies danger variant", () => {
+    render(<Button variant="danger">Delete</Button>);
+    expect(screen.getByRole("button").className).toContain("bg-red-600");
+  });
+
+  it("applies small size", () => {
+    render(<Button size="sm">Small</Button>);
+    expect(screen.getByRole("button").className).toContain("px-3");
+    expect(screen.getByRole("button").className).toContain("text-xs");
+  });
+
+  it("applies medium size by default", () => {
+    render(<Button>Medium</Button>);
+    expect(screen.getByRole("button").className).toContain("px-4");
+    expect(screen.getByRole("button").className).toContain("text-sm");
+  });
+
+  it("applies large size", () => {
+    render(<Button size="lg">Large</Button>);
+    expect(screen.getByRole("button").className).toContain("px-6");
+    expect(screen.getByRole("button").className).toContain("text-base");
+  });
+
+  it("handles click events", async () => {
+    const onClick = vi.fn();
+    render(<Button onClick={onClick}>Click</Button>);
+    await userEvent.click(screen.getByRole("button"));
+    expect(onClick).toHaveBeenCalledOnce();
+  });
+
+  it("disables the button when disabled prop is true", () => {
+    render(<Button disabled>Disabled</Button>);
+    expect(screen.getByRole("button")).toBeDisabled();
+  });
+
+  it("does not fire click when disabled", async () => {
+    const onClick = vi.fn();
+    render(
+      <Button disabled onClick={onClick}>
+        Disabled
+      </Button>,
+    );
+    await userEvent.click(screen.getByRole("button"));
+    expect(onClick).not.toHaveBeenCalled();
+  });
+
+  it("merges custom className", () => {
+    render(<Button className="extra">Styled</Button>);
+    expect(screen.getByRole("button").className).toContain("extra");
+  });
+
+  it("passes through additional HTML attributes", () => {
+    render(
+      <Button type="submit" data-testid="submit-btn">
+        Submit
+      </Button>,
+    );
+    expect(screen.getByTestId("submit-btn")).toHaveAttribute("type", "submit");
+  });
+});
diff --git a/apps/web/src/components/ui/ConfirmDialog.test.tsx b/apps/web/src/components/ui/ConfirmDialog.test.tsx
new file mode 100644
index 0000000..66d03aa
--- /dev/null
+++ b/apps/web/src/components/ui/ConfirmDialog.test.tsx
@@ -0,0 +1,65 @@
+import { describe, expect, it, vi } from "vitest";
+import { render, screen } from "~/test-utils.js";
+import userEvent from "@testing-library/user-event";
+import { ConfirmDialog } from "./ConfirmDialog.js";
+
+describe("ConfirmDialog", () => {
+  const defaultProps = {
+    title: "Delete item?",
+    message: "This action cannot be undone.",
+    onConfirm: vi.fn(),
+    onCancel: vi.fn(),
+  };
+
+  it("renders title and message", () => {
+    render(<ConfirmDialog {...defaultProps} />);
+    expect(screen.getByText("Delete item?")).toBeInTheDocument();
+    expect(screen.getByText("This action cannot be undone.")).toBeInTheDocument();
+  });
+
+  it("uses default button labels", () => {
+    render(<ConfirmDialog {...defaultProps} />);
+    expect(screen.getByRole("button", { name: "Confirm" })).toBeInTheDocument();
+    expect(screen.getByRole("button", { name: "Cancel" })).toBeInTheDocument();
+  });
+
+  it("uses custom button labels", () => {
+    render(<ConfirmDialog {...defaultProps} confirmLabel="Yes, delete" cancelLabel="No, keep" />);
+    expect(screen.getByRole("button", { name: "Yes, delete" })).toBeInTheDocument();
+    expect(screen.getByRole("button", { name: "No, keep" })).toBeInTheDocument();
+  });
+
+  it("calls onConfirm when confirm button is clicked", async () => {
+    const onConfirm = vi.fn();
+    render(<ConfirmDialog {...defaultProps} onConfirm={onConfirm} />);
+    await userEvent.click(screen.getByRole("button", { name: "Confirm" }));
+    expect(onConfirm).toHaveBeenCalledOnce();
+  });
+
+  it("calls onCancel when cancel button is clicked", async () => {
+    const onCancel = vi.fn();
+    render(<ConfirmDialog {...defaultProps} onCancel={onCancel} />);
+    await userEvent.click(screen.getByRole("button", { name: "Cancel" }));
+    expect(onCancel).toHaveBeenCalledOnce();
+  });
+
+  it("applies danger styling to confirm button when variant is danger", () => {
+    render(<ConfirmDialog {...defaultProps} variant="danger" />);
+    const confirmBtn = screen.getByRole("button", { name: "Confirm" });
+    expect(confirmBtn.className).toContain("bg-red-600");
+  });
+
+  it("applies default styling to confirm button when variant is default", () => {
+    render(<ConfirmDialog {...defaultProps} variant="default" />);
+    const confirmBtn = screen.getByRole("button", { name: "Confirm" });
+    expect(confirmBtn.className).toContain("bg-brand-600");
+  });
+
+  it("calls onCancel when clicking the backdrop", async () => {
+    const onCancel = vi.fn();
+    const { container } = render(<ConfirmDialog {...defaultProps} onCancel={onCancel} />);
+    const backdrop = container.firstElementChild!;
+    await userEvent.click(backdrop);
+    expect(onCancel).toHaveBeenCalledOnce();
+  });
+});
diff --git a/apps/web/src/components/ui/EmptyState.test.tsx b/apps/web/src/components/ui/EmptyState.test.tsx
new file mode 100644
index 0000000..ffe7775
--- /dev/null
+++ b/apps/web/src/components/ui/EmptyState.test.tsx
@@ -0,0 +1,50 @@
+import { describe, expect, it, vi } from "vitest";
+import { render, screen } from "~/test-utils.js";
+import userEvent from "@testing-library/user-event";
+import { EmptyState } from "./EmptyState.js";
+
+describe("EmptyState", () => {
+  it("renders the title", () => {
+    render(<EmptyState title="No results" />);
+    expect(screen.getByText("No results")).toBeInTheDocument();
+  });
+
+  it("renders detail text when provided", () => {
+    render(<EmptyState title="Empty" detail="Try adjusting your filters" />);
+    expect(screen.getByText("Try adjusting your filters")).toBeInTheDocument();
+  });
+
+  it("does not render detail when not provided", () => {
+    const { container } = render(<EmptyState title="Empty" />);
+    const paragraphs = container.querySelectorAll("p");
+    expect(paragraphs).toHaveLength(1);
+  });
+
+  it("renders an action button when action is provided", () => {
+    const action = { label: "Create new", onClick: vi.fn() };
+    render(<EmptyState title="Empty" action={action} />);
+    expect(screen.getByRole("button", { name: "Create new" })).toBeInTheDocument();
+  });
+
+  it("calls action onClick when button is clicked", async () => {
+    const onClick = vi.fn();
+    render(<EmptyState title="Empty" action={{ label: "Add", onClick }} />);
+    await userEvent.click(screen.getByRole("button", { name: "Add" }));
+    expect(onClick).toHaveBeenCalledOnce();
+  });
+
+  it("does not render action button when not provided", () => {
+    render(<EmptyState title="Empty" />);
+    expect(screen.queryByRole("button")).not.toBeInTheDocument();
+  });
+
+  it("renders icon when provided", () => {
+    render(<EmptyState title="Empty" icon={<span data-testid="icon">Icon</span>} />);
+    expect(screen.getByTestId("icon")).toBeInTheDocument();
+  });
+
+  it("applies testId to the container", () => {
+    render(<EmptyState title="Empty" testId="empty-state" />);
+    expect(screen.getByTestId("empty-state")).toBeInTheDocument();
+  });
+});
diff --git a/apps/web/src/components/ui/FilterBar.test.tsx b/apps/web/src/components/ui/FilterBar.test.tsx
new file mode 100644
index 0000000..688d03c
--- /dev/null
+++ b/apps/web/src/components/ui/FilterBar.test.tsx
@@ -0,0 +1,53 @@
+import { describe, expect, it, vi } from "vitest";
+import { render, screen } from "~/test-utils.js";
+import userEvent from "@testing-library/user-event";
+import { FilterBar } from "./FilterBar.js";
+
+describe("FilterBar", () => {
+  it("renders children", () => {
+    render(
+      <FilterBar>
+        <span>Filter content</span>
+      </FilterBar>,
+    );
+    expect(screen.getByText("Filter content")).toBeInTheDocument();
+  });
+
+  it("does not show clear button when no active filters", () => {
+    render(
+      <FilterBar hasActiveFilters={false} onClearFilters={vi.fn()}>
+        <span>Filters</span>
+      </FilterBar>,
+    );
+    expect(screen.queryByText("Clear filters")).not.toBeInTheDocument();
+  });
+
+  it("does not show clear button when onClearFilters is not provided", () => {
+    render(
+      <FilterBar hasActiveFilters>
+        <span>Filters</span>
+      </FilterBar>,
+    );
+    expect(screen.queryByText("Clear filters")).not.toBeInTheDocument();
+  });
+
+  it("shows clear button when hasActiveFilters and onClearFilters are both provided", () => {
+    render(
+      <FilterBar hasActiveFilters onClearFilters={vi.fn()}>
+        <span>Filters</span>
+      </FilterBar>,
+    );
+    expect(screen.getByText("Clear filters")).toBeInTheDocument();
+  });
+
+  it("calls onClearFilters when clear button is clicked", async () => {
+    const onClear = vi.fn();
+    render(
+      <FilterBar hasActiveFilters onClearFilters={onClear}>
+        <span>Filters</span>
+      </FilterBar>,
+    );
+    await userEvent.click(screen.getByText("Clear filters"));
+    expect(onClear).toHaveBeenCalledOnce();
+  });
+});
diff --git a/apps/web/src/hooks/useSelection.test.ts b/apps/web/src/hooks/useSelection.test.ts
new file mode 100644
index 0000000..6d5163a
--- /dev/null
+++ b/apps/web/src/hooks/useSelection.test.ts
@@ -0,0 +1,113 @@
+import { describe, expect, it } from "vitest";
+import { renderHook, act } from "@testing-library/react";
+import { useSelection } from "./useSelection.js";
+
+describe("useSelection", () => {
+  it("starts with empty selection", () => {
+    const { result } = renderHook(() => useSelection());
+    expect(result.current.count).toBe(0);
+    expect(result.current.selectedArray).toEqual([]);
+  });
+
+  it("toggles an item on", () => {
+    const { result } = renderHook(() => useSelection());
+    act(() => result.current.toggle("a"));
+    expect(result.current.selectedIds.has("a")).toBe(true);
+    expect(result.current.count).toBe(1);
+  });
+
+  it("toggles an item off", () => {
+    const { result } = renderHook(() => useSelection());
+    act(() => result.current.toggle("a"));
+    act(() => result.current.toggle("a"));
+    expect(result.current.selectedIds.has("a")).toBe(false);
+    expect(result.current.count).toBe(0);
+  });
+
+  it("toggleAll selects all items when none are selected", () => {
+    const { result } = renderHook(() => useSelection());
+    act(() => result.current.toggleAll(["a", "b", "c"]));
+    expect(result.current.count).toBe(3);
+    expect(result.current.selectedIds.has("a")).toBe(true);
+    expect(result.current.selectedIds.has("b")).toBe(true);
+    expect(result.current.selectedIds.has("c")).toBe(true);
+  });
+
+  it("toggleAll deselects all items when all are selected", () => {
+    const { result } = renderHook(() => useSelection());
+    act(() => result.current.toggleAll(["a", "b"]));
+    act(() => result.current.toggleAll(["a", "b"]));
+    expect(result.current.count).toBe(0);
+  });
+
+  it("toggleAll selects remaining items when some are selected", () => {
+    const { result } = renderHook(() => useSelection());
+    act(() => result.current.toggle("a"));
+    act(() => result.current.toggleAll(["a", "b", "c"]));
+    expect(result.current.count).toBe(3);
+  });
+
+  it("clear removes all selections", () => {
+    const { result } = renderHook(() => useSelection());
+    act(() => {
+      result.current.toggle("a");
+      result.current.toggle("b");
+    });
+    act(() => result.current.clear());
+    expect(result.current.count).toBe(0);
+  });
+
+  it("isAllSelected returns true when all given ids are selected", () => {
+    const { result } = renderHook(() => useSelection());
+    act(() => result.current.toggleAll(["a", "b"]));
+    expect(result.current.isAllSelected(["a", "b"])).toBe(true);
+  });
+
+  it("isAllSelected returns false when some ids are not selected", () => {
+    const { result } = renderHook(() => useSelection());
+    act(() => result.current.toggle("a"));
+    expect(result.current.isAllSelected(["a", "b"])).toBe(false);
+  });
+
+  it("isAllSelected returns false for empty ids array", () => {
+    const { result } = renderHook(() => useSelection());
+    expect(result.current.isAllSelected([])).toBe(false);
+  });
+
+  it("isIndeterminate returns true when some but not all are selected", () => {
+    const { result } = renderHook(() => useSelection());
+    act(() => result.current.toggle("a"));
+    expect(result.current.isIndeterminate(["a", "b"])).toBe(true);
+  });
+
+  it("isIndeterminate returns false when all are selected", () => {
+    const { result } = renderHook(() => useSelection());
+    act(() => result.current.toggleAll(["a", "b"]));
+    expect(result.current.isIndeterminate(["a", "b"])).toBe(false);
+  });
+
+  it("isIndeterminate returns false when none are selected", () => {
+    const { result } = renderHook(() => useSelection());
+    expect(result.current.isIndeterminate(["a", "b"])).toBe(false);
+  });
+
+  it("selectedArray reflects the current selection", () => {
+    const { result } = renderHook(() => useSelection());
+    act(() => {
+      result.current.toggle("x");
+      result.current.toggle("y");
+    });
+    expect(result.current.selectedArray.sort()).toEqual(["x", "y"]);
+  });
+
+  it("preserves other selections when toggling individual items", () => {
+    const { result } = renderHook(() => useSelection());
+    act(() => {
+      result.current.toggle("a");
+      result.current.toggle("b");
+    });
+    act(() => result.current.toggle("a"));
+    expect(result.current.selectedIds.has("b")).toBe(true);
+    expect(result.current.count).toBe(1);
+  });
+});
diff --git a/apps/web/src/vitest-setup.ts b/apps/web/src/vitest-setup.ts
index f149f27..e262193 100644
--- a/apps/web/src/vitest-setup.ts
+++ b/apps/web/src/vitest-setup.ts
@@ -1 +1,7 @@
 import "@testing-library/jest-dom/vitest";
+import { cleanup } from "@testing-library/react";
+import { afterEach } from "vitest";
+
+afterEach(() => {
+  cleanup();
+});
diff --git a/apps/web/vitest.config.mts b/apps/web/vitest.config.mts
index 83f4f73..8189c6a 100644
--- a/apps/web/vitest.config.mts
+++ b/apps/web/vitest.config.mts
@@ -2,6 +2,9 @@ import path from "node:path";
 import { defineConfig } from "vitest/config";
 
 export default defineConfig({
+  esbuild: {
+    jsx: "automatic",
+  },
   resolve: {
     alias: {
       "~": path.resolve(__dirname, "./src"),