diff --git a/apps/web/src/components/knowledge/__tests__/KnowledgeEditor.test.tsx b/apps/web/src/components/knowledge/__tests__/KnowledgeEditor.test.tsx
new file mode 100644
index 0000000..14821dc
--- /dev/null
+++ b/apps/web/src/components/knowledge/__tests__/KnowledgeEditor.test.tsx
@@ -0,0 +1,89 @@
+import React from "react";
+import { render, screen } from "@testing-library/react";
+import { describe, it, expect, vi, beforeEach } from "vitest";
+import { KnowledgeEditor } from "../KnowledgeEditor";
+
+// Mock Tiptap since it requires a full DOM with contenteditable support
+vi.mock("@tiptap/react", () => {
+  const EditorContent = ({ editor }: { editor: unknown }): React.JSX.Element => (
+    <div data-testid="editor-content" data-editor={editor ? "ready" : "null"} />
+  );
+
+  return {
+    useEditor: (): null => null,
+    EditorContent,
+  };
+});
+
+// Mock tiptap-markdown
+vi.mock("tiptap-markdown", () => ({
+  Markdown: {
+    configure: vi.fn().mockReturnValue({}),
+  },
+}));
+
+// Mock lowlight
+vi.mock("lowlight", () => ({
+  common: {},
+  createLowlight: vi.fn().mockReturnValue({}),
+}));
+
+// Mock extensions
+vi.mock("@tiptap/starter-kit", () => ({
+  default: { configure: vi.fn().mockReturnValue({}) },
+}));
+vi.mock("@tiptap/extension-link", () => ({
+  default: { configure: vi.fn().mockReturnValue({}) },
+}));
+vi.mock("@tiptap/extension-table", () => ({
+  Table: { configure: vi.fn().mockReturnValue({}) },
+}));
+vi.mock("@tiptap/extension-table-row", () => ({
+  TableRow: {},
+}));
+vi.mock("@tiptap/extension-table-cell", () => ({
+  TableCell: {},
+}));
+vi.mock("@tiptap/extension-table-header", () => ({
+  TableHeader: {},
+}));
+vi.mock("@tiptap/extension-code-block-lowlight", () => ({
+  default: { configure: vi.fn().mockReturnValue({}) },
+}));
+vi.mock("@tiptap/extension-placeholder", () => ({
+  default: { configure: vi.fn().mockReturnValue({}) },
+}));
+
+describe("KnowledgeEditor", (): void => {
+  const defaultProps = {
+    content: "",
+    onChange: vi.fn(),
+  };
+
+  beforeEach((): void => {
+    vi.clearAllMocks();
+  });
+
+  it("should render loading state when editor is null", (): void => {
+    render(<KnowledgeEditor {...defaultProps} />);
+    expect(screen.getByText("Loading editor...")).toBeInTheDocument();
+  });
+
+  it("should render with knowledge-editor class", (): void => {
+    // When editor is null, the loading fallback renders instead
+    const { container } = render(<KnowledgeEditor {...defaultProps} />);
+    expect(container.firstChild).toBeInTheDocument();
+  });
+
+  it("should accept optional placeholder prop", (): void => {
+    // Smoke test that it doesn't crash with custom placeholder
+    render(<KnowledgeEditor {...defaultProps} placeholder="Custom placeholder" />);
+    expect(screen.getByText("Loading editor...")).toBeInTheDocument();
+  });
+
+  it("should accept optional editable prop", (): void => {
+    // Smoke test that it doesn't crash when read-only
+    render(<KnowledgeEditor {...defaultProps} editable={false} />);
+    expect(screen.getByText("Loading editor...")).toBeInTheDocument();
+  });
+});
diff --git a/apps/web/src/components/widgets/__tests__/WidgetConfigDialog.test.tsx b/apps/web/src/components/widgets/__tests__/WidgetConfigDialog.test.tsx
new file mode 100644
index 0000000..e07d9cd
--- /dev/null
+++ b/apps/web/src/components/widgets/__tests__/WidgetConfigDialog.test.tsx
@@ -0,0 +1,63 @@
+import React from "react";
+import { render, screen } from "@testing-library/react";
+import userEvent from "@testing-library/user-event";
+import { describe, it, expect, vi, beforeEach } from "vitest";
+import { WidgetConfigDialog } from "../WidgetConfigDialog";
+
+describe("WidgetConfigDialog", (): void => {
+  const defaultProps = {
+    widgetId: "TasksWidget-abc123",
+    open: true,
+    onClose: vi.fn(),
+  };
+
+  beforeEach((): void => {
+    vi.clearAllMocks();
+  });
+
+  it("should render nothing when closed", (): void => {
+    const { container } = render(<WidgetConfigDialog {...defaultProps} open={false} />);
+    expect(container.innerHTML).toBe("");
+  });
+
+  it("should render dialog when open", (): void => {
+    render(<WidgetConfigDialog {...defaultProps} />);
+    expect(screen.getByRole("dialog", { name: "Widget Settings" })).toBeInTheDocument();
+  });
+
+  it("should show widget name in header", (): void => {
+    render(<WidgetConfigDialog {...defaultProps} />);
+    // TasksWidget is registered with displayName "Tasks"
+    expect(screen.getByText(/Tasks.*Settings/)).toBeInTheDocument();
+  });
+
+  it("should show placeholder message when no config schema", (): void => {
+    render(<WidgetConfigDialog {...defaultProps} />);
+    expect(
+      screen.getByText("No configuration options available for this widget yet.")
+    ).toBeInTheDocument();
+  });
+
+  it("should call onClose when close button is clicked", async (): Promise<void> => {
+    const user = userEvent.setup();
+    render(<WidgetConfigDialog {...defaultProps} />);
+
+    await user.click(screen.getByLabelText("Close"));
+    expect(defaultProps.onClose).toHaveBeenCalledTimes(1);
+  });
+
+  it("should call onClose when footer Close button is clicked", async (): Promise<void> => {
+    const user = userEvent.setup();
+    render(<WidgetConfigDialog {...defaultProps} />);
+
+    // Footer has a "Close" text button
+    await user.click(screen.getByText("Close"));
+    expect(defaultProps.onClose).toHaveBeenCalledTimes(1);
+  });
+
+  it("should handle unknown widget type gracefully", (): void => {
+    render(<WidgetConfigDialog {...defaultProps} widgetId="UnknownWidget-xyz" />);
+    // Should show fallback "Widget Settings" when type is not in registry
+    expect(screen.getByText("Widget Settings")).toBeInTheDocument();
+  });
+});
diff --git a/apps/web/src/components/widgets/__tests__/WidgetPicker.test.tsx b/apps/web/src/components/widgets/__tests__/WidgetPicker.test.tsx
new file mode 100644
index 0000000..dfc680a
--- /dev/null
+++ b/apps/web/src/components/widgets/__tests__/WidgetPicker.test.tsx
@@ -0,0 +1,101 @@
+/* eslint-disable @typescript-eslint/no-non-null-assertion */
+
+import React from "react";
+import { render, screen } from "@testing-library/react";
+import userEvent from "@testing-library/user-event";
+import { describe, it, expect, vi, beforeEach } from "vitest";
+import { WidgetPicker } from "../WidgetPicker";
+import type { WidgetPlacement } from "@mosaic/shared";
+
+describe("WidgetPicker", (): void => {
+  const defaultProps = {
+    open: true,
+    onClose: vi.fn(),
+    onAddWidget: vi.fn(),
+    currentLayout: [] as WidgetPlacement[],
+  };
+
+  beforeEach((): void => {
+    vi.clearAllMocks();
+  });
+
+  it("should render nothing when closed", (): void => {
+    const { container } = render(<WidgetPicker {...defaultProps} open={false} />);
+    expect(container.innerHTML).toBe("");
+  });
+
+  it("should render dialog when open", (): void => {
+    render(<WidgetPicker {...defaultProps} />);
+    expect(screen.getByRole("dialog", { name: "Add Widget" })).toBeInTheDocument();
+  });
+
+  it("should display Add Widget heading", (): void => {
+    render(<WidgetPicker {...defaultProps} />);
+    expect(screen.getByText("Add Widget")).toBeInTheDocument();
+  });
+
+  it("should render search input", (): void => {
+    render(<WidgetPicker {...defaultProps} />);
+    expect(screen.getByPlaceholderText("Search widgets...")).toBeInTheDocument();
+  });
+
+  it("should display available widgets", (): void => {
+    render(<WidgetPicker {...defaultProps} />);
+    // Widget registry has multiple widgets; at least one Add button should appear
+    const addButtons = screen.getAllByText("Add");
+    expect(addButtons.length).toBeGreaterThan(0);
+  });
+
+  it("should filter widgets by search text", async (): Promise<void> => {
+    const user = userEvent.setup();
+    render(<WidgetPicker {...defaultProps} />);
+
+    const searchInput = screen.getByPlaceholderText("Search widgets...");
+    // Type a search term that won't match any widget
+    await user.type(searchInput, "zzz-nonexistent-widget-zzz");
+
+    expect(screen.getByText("No widgets found")).toBeInTheDocument();
+  });
+
+  it("should call onAddWidget when Add is clicked", async (): Promise<void> => {
+    const user = userEvent.setup();
+    const onAdd = vi.fn();
+    render(<WidgetPicker {...defaultProps} onAddWidget={onAdd} />);
+
+    const addButtons = screen.getAllByText("Add");
+    await user.click(addButtons[0]!);
+
+    expect(onAdd).toHaveBeenCalledTimes(1);
+    const placement = onAdd.mock.calls[0]![0] as WidgetPlacement;
+    expect(placement).toHaveProperty("i");
+    expect(placement).toHaveProperty("x");
+    expect(placement).toHaveProperty("y");
+    expect(placement).toHaveProperty("w");
+    expect(placement).toHaveProperty("h");
+  });
+
+  it("should call onClose when close button is clicked", async (): Promise<void> => {
+    const user = userEvent.setup();
+    render(<WidgetPicker {...defaultProps} />);
+
+    await user.click(screen.getByLabelText("Close"));
+    expect(defaultProps.onClose).toHaveBeenCalledTimes(1);
+  });
+
+  it("should place new widgets after existing layout items", async (): Promise<void> => {
+    const user = userEvent.setup();
+    const onAdd = vi.fn();
+    const existingLayout: WidgetPlacement[] = [
+      { i: "test-1", x: 0, y: 0, w: 6, h: 3 },
+      { i: "test-2", x: 0, y: 3, w: 6, h: 2 },
+    ];
+    render(<WidgetPicker {...defaultProps} onAddWidget={onAdd} currentLayout={existingLayout} />);
+
+    const addButtons = screen.getAllByText("Add");
+    await user.click(addButtons[0]!);
+
+    const placement = onAdd.mock.calls[0]![0] as WidgetPlacement;
+    // Should be placed at y=5 (3+2) to avoid overlap
+    expect(placement.y).toBe(5);
+  });
+});