diff --git a/src/components/__tests__/Header.test.tsx b/src/components/__tests__/Header.test.tsx
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+++ b/src/components/__tests__/Header.test.tsx
@@ -0,0 +1,413 @@
+import { describe, it, expect, vi, beforeEach } from "vitest";
+import { render, screen, fireEvent } from "@testing-library/react";
+import { Header } from "@/components/Header";
+
+// Mock the workflow store
+const mockSetWorkflowMetadata = vi.fn();
+const mockSaveToFile = vi.fn();
+const mockLoadWorkflow = vi.fn();
+const mockUseWorkflowStore = vi.fn();
+
+vi.mock("@/store/workflowStore", () => ({
+  useWorkflowStore: (selector?: (state: unknown) => unknown) => {
+    if (selector) {
+      return mockUseWorkflowStore(selector);
+    }
+    return mockUseWorkflowStore((s: unknown) => s);
+  },
+}));
+
+// Mock ProjectSetupModal
+vi.mock("@/components/ProjectSetupModal", () => ({
+  ProjectSetupModal: ({ isOpen, mode }: { isOpen: boolean; mode: string }) => (
+    isOpen ? <div data-testid="project-setup-modal" data-mode={mode}>Project Setup Modal</div> : null
+  ),
+}));
+
+// Mock CostIndicator
+vi.mock("@/components/CostIndicator", () => ({
+  CostIndicator: () => <div data-testid="cost-indicator">$0.00</div>,
+}));
+
+// Default store state factory
+const createDefaultState = (overrides = {}) => ({
+  workflowName: "",
+  workflowId: "",
+  saveDirectoryPath: "",
+  hasUnsavedChanges: false,
+  lastSavedAt: null,
+  isSaving: false,
+  setWorkflowMetadata: mockSetWorkflowMetadata,
+  saveToFile: mockSaveToFile,
+  loadWorkflow: mockLoadWorkflow,
+  ...overrides,
+});
+
+describe("Header", () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+    // Default mock implementation - unconfigured project
+    mockUseWorkflowStore.mockImplementation((selector) => {
+      return selector(createDefaultState());
+    });
+  });
+
+  describe("Basic Rendering", () => {
+    it("should render the app title", () => {
+      render(<Header />);
+      expect(screen.getByText("Node Banana")).toBeInTheDocument();
+    });
+
+    it("should render the banana icon", () => {
+      render(<Header />);
+      const icon = screen.getByAltText("Banana");
+      expect(icon).toBeInTheDocument();
+      expect(icon).toHaveAttribute("src", "/banana_icon.png");
+    });
+
+    it("should render 'Made by Willie' link", () => {
+      render(<Header />);
+      const link = screen.getByText("Made by Willie");
+      expect(link).toHaveAttribute("href", "https://x.com/ReflctWillie");
+    });
+
+    it("should render Discord support link", () => {
+      render(<Header />);
+      const link = screen.getByTitle("Support");
+      expect(link).toHaveAttribute("href", "https://discord.com/invite/89Nr6EKkTf");
+    });
+  });
+
+  describe("Unconfigured Project State", () => {
+    it("should show 'Untitled' when no project name is set", () => {
+      render(<Header />);
+      expect(screen.getByText("Untitled")).toBeInTheDocument();
+    });
+
+    it("should show 'Not saved' status when project is not configured", () => {
+      render(<Header />);
+      expect(screen.getByText("Not saved")).toBeInTheDocument();
+    });
+
+    it("should show save button with unsaved indicator (red dot)", () => {
+      const { container } = render(<Header />);
+      const redDot = container.querySelector(".bg-red-500.rounded-full");
+      expect(redDot).toBeInTheDocument();
+    });
+
+    it("should not render CostIndicator when project is not configured", () => {
+      render(<Header />);
+      expect(screen.queryByTestId("cost-indicator")).not.toBeInTheDocument();
+    });
+  });
+
+  describe("Configured Project State", () => {
+    beforeEach(() => {
+      mockUseWorkflowStore.mockImplementation((selector) => {
+        return selector(createDefaultState({
+          workflowName: "My Project",
+          workflowId: "project-123",
+          saveDirectoryPath: "/path/to/project",
+        }));
+      });
+    });
+
+    it("should show project name when configured", () => {
+      render(<Header />);
+      expect(screen.getByText("My Project")).toBeInTheDocument();
+    });
+
+    it("should render CostIndicator when project is configured", () => {
+      render(<Header />);
+      expect(screen.getByTestId("cost-indicator")).toBeInTheDocument();
+    });
+
+    it("should show 'Not saved' when no lastSavedAt timestamp", () => {
+      render(<Header />);
+      expect(screen.getByText("Not saved")).toBeInTheDocument();
+    });
+
+    it("should render Open Project Folder button when saveDirectoryPath is set", () => {
+      render(<Header />);
+      const folderButton = screen.getByTitle("Open Project Folder");
+      expect(folderButton).toBeInTheDocument();
+    });
+  });
+
+  describe("Save State Display", () => {
+    it("should show 'Saving...' when isSaving is true", () => {
+      mockUseWorkflowStore.mockImplementation((selector) => {
+        return selector(createDefaultState({
+          workflowName: "My Project",
+          workflowId: "project-123",
+          saveDirectoryPath: "/path/to/project",
+          isSaving: true,
+        }));
+      });
+
+      render(<Header />);
+      expect(screen.getByText("Saving...")).toBeInTheDocument();
+    });
+
+    it("should show formatted save time when lastSavedAt is set", () => {
+      const timestamp = new Date("2024-01-15T14:30:00").getTime();
+      mockUseWorkflowStore.mockImplementation((selector) => {
+        return selector(createDefaultState({
+          workflowName: "My Project",
+          workflowId: "project-123",
+          saveDirectoryPath: "/path/to/project",
+          lastSavedAt: timestamp,
+        }));
+      });
+
+      render(<Header />);
+      // The exact format depends on locale, but should contain "Saved"
+      expect(screen.getByText(/Saved/)).toBeInTheDocument();
+    });
+  });
+
+  describe("Unsaved Changes Indicator", () => {
+    it("should show red dot when hasUnsavedChanges is true", () => {
+      mockUseWorkflowStore.mockImplementation((selector) => {
+        return selector(createDefaultState({
+          workflowName: "My Project",
+          workflowId: "project-123",
+          saveDirectoryPath: "/path/to/project",
+          hasUnsavedChanges: true,
+        }));
+      });
+
+      const { container } = render(<Header />);
+      const redDot = container.querySelector(".bg-red-500.rounded-full");
+      expect(redDot).toBeInTheDocument();
+    });
+
+    it("should not show red dot when hasUnsavedChanges is false and project is configured", () => {
+      mockUseWorkflowStore.mockImplementation((selector) => {
+        return selector(createDefaultState({
+          workflowName: "My Project",
+          workflowId: "project-123",
+          saveDirectoryPath: "/path/to/project",
+          hasUnsavedChanges: false,
+        }));
+      });
+
+      const { container } = render(<Header />);
+      // Find the save button area and check there's no red dot inside it
+      const saveButton = screen.getByTitle("Save project");
+      const redDotInSaveButton = saveButton.querySelector(".bg-red-500.rounded-full");
+      expect(redDotInSaveButton).not.toBeInTheDocument();
+    });
+
+    it("should not show red dot when isSaving is true even if hasUnsavedChanges", () => {
+      mockUseWorkflowStore.mockImplementation((selector) => {
+        return selector(createDefaultState({
+          workflowName: "My Project",
+          workflowId: "project-123",
+          saveDirectoryPath: "/path/to/project",
+          hasUnsavedChanges: true,
+          isSaving: true,
+        }));
+      });
+
+      const { container } = render(<Header />);
+      const saveButton = screen.getByTitle("Saving...");
+      const redDotInSaveButton = saveButton.querySelector(".bg-red-500.rounded-full");
+      expect(redDotInSaveButton).not.toBeInTheDocument();
+    });
+  });
+
+  describe("New Project Button", () => {
+    it("should open ProjectSetupModal in 'new' mode when save button clicked (unconfigured)", () => {
+      render(<Header />);
+
+      const saveButton = screen.getByTitle("Save project");
+      fireEvent.click(saveButton);
+
+      const modal = screen.getByTestId("project-setup-modal");
+      expect(modal).toBeInTheDocument();
+      expect(modal).toHaveAttribute("data-mode", "new");
+    });
+  });
+
+  describe("Open File Button", () => {
+    it("should render open file button when project is not configured", () => {
+      render(<Header />);
+      const openButton = screen.getByTitle("Open project");
+      expect(openButton).toBeInTheDocument();
+    });
+
+    it("should have hidden file input for loading workflows", () => {
+      const { container } = render(<Header />);
+      const fileInput = container.querySelector('input[type="file"]');
+      expect(fileInput).toBeInTheDocument();
+      expect(fileInput).toHaveAttribute("accept", ".json");
+      expect(fileInput).toHaveClass("hidden");
+    });
+
+    it("should trigger file input click when open button is clicked", () => {
+      const { container } = render(<Header />);
+      const openButton = screen.getByTitle("Open project");
+      const fileInput = container.querySelector('input[type="file"]') as HTMLInputElement;
+
+      // Mock click on file input
+      const clickSpy = vi.spyOn(fileInput, "click");
+      fireEvent.click(openButton);
+
+      expect(clickSpy).toHaveBeenCalled();
+    });
+  });
+
+  describe("Save Button", () => {
+    beforeEach(() => {
+      mockUseWorkflowStore.mockImplementation((selector) => {
+        return selector(createDefaultState({
+          workflowName: "My Project",
+          workflowId: "project-123",
+          saveDirectoryPath: "/path/to/project",
+        }));
+      });
+    });
+
+    it("should call saveToFile when clicked on configured project", () => {
+      render(<Header />);
+      const saveButton = screen.getByTitle("Save project");
+      fireEvent.click(saveButton);
+
+      expect(mockSaveToFile).toHaveBeenCalled();
+    });
+
+    it("should be disabled when isSaving is true", () => {
+      mockUseWorkflowStore.mockImplementation((selector) => {
+        return selector(createDefaultState({
+          workflowName: "My Project",
+          workflowId: "project-123",
+          saveDirectoryPath: "/path/to/project",
+          isSaving: true,
+        }));
+      });
+
+      render(<Header />);
+      const saveButton = screen.getByTitle("Saving...");
+      expect(saveButton).toBeDisabled();
+    });
+
+    it("should open settings modal when project name is set but saveDirectoryPath is empty", () => {
+      mockUseWorkflowStore.mockImplementation((selector) => {
+        return selector(createDefaultState({
+          workflowName: "My Project",
+          workflowId: "",
+          saveDirectoryPath: "",
+        }));
+      });
+
+      render(<Header />);
+      const saveButton = screen.getByTitle("Configure save location");
+      fireEvent.click(saveButton);
+
+      const modal = screen.getByTestId("project-setup-modal");
+      expect(modal).toBeInTheDocument();
+      expect(modal).toHaveAttribute("data-mode", "settings");
+    });
+  });
+
+  describe("Settings Button", () => {
+    it("should open ProjectSetupModal in 'settings' mode when settings button clicked", () => {
+      mockUseWorkflowStore.mockImplementation((selector) => {
+        return selector(createDefaultState({
+          workflowName: "My Project",
+          workflowId: "project-123",
+          saveDirectoryPath: "/path/to/project",
+        }));
+      });
+
+      render(<Header />);
+      const settingsButton = screen.getByTitle("Project settings");
+      fireEvent.click(settingsButton);
+
+      const modal = screen.getByTestId("project-setup-modal");
+      expect(modal).toBeInTheDocument();
+      expect(modal).toHaveAttribute("data-mode", "settings");
+    });
+
+    it("should be visible for unconfigured projects", () => {
+      render(<Header />);
+      const settingsButton = screen.getByTitle("Project settings");
+      expect(settingsButton).toBeInTheDocument();
+    });
+  });
+
+  describe("Open Project Folder Button", () => {
+    it("should not be visible when saveDirectoryPath is not set", () => {
+      mockUseWorkflowStore.mockImplementation((selector) => {
+        return selector(createDefaultState({
+          workflowName: "My Project",
+          workflowId: "project-123",
+          saveDirectoryPath: "",
+        }));
+      });
+
+      render(<Header />);
+      expect(screen.queryByTitle("Open Project Folder")).not.toBeInTheDocument();
+    });
+
+    it("should be visible when saveDirectoryPath is set", () => {
+      mockUseWorkflowStore.mockImplementation((selector) => {
+        return selector(createDefaultState({
+          workflowName: "My Project",
+          workflowId: "project-123",
+          saveDirectoryPath: "/path/to/project",
+        }));
+      });
+
+      render(<Header />);
+      expect(screen.getByTitle("Open Project Folder")).toBeInTheDocument();
+    });
+
+    it("should call fetch to open-directory API when clicked", async () => {
+      mockUseWorkflowStore.mockImplementation((selector) => {
+        return selector(createDefaultState({
+          workflowName: "My Project",
+          workflowId: "project-123",
+          saveDirectoryPath: "/path/to/project",
+        }));
+      });
+
+      const mockFetch = vi.fn().mockResolvedValue({
+        ok: true,
+        json: () => Promise.resolve({ success: true }),
+      });
+      global.fetch = mockFetch;
+
+      render(<Header />);
+      const folderButton = screen.getByTitle("Open Project Folder");
+      fireEvent.click(folderButton);
+
+      expect(mockFetch).toHaveBeenCalledWith("/api/open-directory", {
+        method: "POST",
+        headers: { "Content-Type": "application/json" },
+        body: JSON.stringify({ path: "/path/to/project" }),
+      });
+    });
+  });
+
+  describe("File Loading", () => {
+    it("should not call loadWorkflow when no file is selected", () => {
+      const { container } = render(<Header />);
+      const fileInput = container.querySelector('input[type="file"]') as HTMLInputElement;
+
+      // Trigger file change with empty files
+      fireEvent.change(fileInput, { target: { files: [] } });
+
+      expect(mockLoadWorkflow).not.toHaveBeenCalled();
+    });
+
+    it("should reset file input value after file selection to allow re-selecting same file", () => {
+      const { container } = render(<Header />);
+      const fileInput = container.querySelector('input[type="file"]') as HTMLInputElement;
+
+      // File input should accept .json files
+      expect(fileInput).toHaveAttribute("accept", ".json");
+    });
+  });
+});