diff --git a/src/renderer/components/modals/WelcomeDialog.tsx b/src/renderer/components/modals/WelcomeDialog.tsx
new file mode 100644
index 0000000..04329cc
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+++ b/src/renderer/components/modals/WelcomeDialog.tsx
@@ -0,0 +1,51 @@
+import { useState } from 'react';
+import { Dialog, DialogContent, DialogDescription, DialogFooter, DialogHeader, DialogTitle } from '@/components/ui/dialog';
+import { Button } from '@/components/ui/button';
+import { Checkbox } from '@/components/ui/checkbox';
+import { useAppStore } from '@/stores/app-store';
+import { useSettingsStore } from '@/stores/settings-store';
+
+export function WelcomeDialog() {
+  const closeModal = useAppStore((s) => s.closeModal);
+  const setSetting = useSettingsStore((s) => s.setSetting);
+  const [dontShow, setDontShow] = useState(false);
+
+  const handleClose = () => {
+    if (dontShow) setSetting('welcomeDismissed', true);
+    closeModal();
+  };
+
+  return (
+    <Dialog open onOpenChange={(o) => !o && handleClose()}>
+      <DialogContent aria-describedby="welcome-desc" className="max-w-xl">
+        <DialogHeader>
+          <DialogTitle>Welcome to MarkdownConverter</DialogTitle>
+          <DialogDescription id="welcome-desc">
+            A polished editor for Markdown, with PDF, DOCX, and HTML export.
+          </DialogDescription>
+        </DialogHeader>
+        <div className="space-y-3 text-sm">
+          <div className="rounded-md border border-border bg-card/30 p-3">
+            <h3 className="font-semibold">1. Open a folder</h3>
+            <p className="text-muted-foreground">File → Open Folder, or ⌘O. Your tree appears on the left.</p>
+          </div>
+          <div className="rounded-md border border-border bg-card/30 p-3">
+            <h3 className="font-semibold">2. Edit & preview</h3>
+            <p className="text-muted-foreground">Type on the left, see the rendered preview on the right. Toggle with ⌘\.</p>
+          </div>
+          <div className="rounded-md border border-border bg-card/30 p-3">
+            <h3 className="font-semibold">3. Export anywhere</h3>
+            <p className="text-muted-foreground">File → Export to PDF / DOCX / HTML, or batch convert a folder.</p>
+          </div>
+        </div>
+        <DialogFooter className="flex-row items-center justify-between sm:justify-between">
+          <label className="flex items-center gap-2 text-xs text-muted-foreground">
+            <Checkbox checked={dontShow} onCheckedChange={(c) => setDontShow(!!c)} aria-label="Don't show again" />
+            Don't show again
+          </label>
+          <Button onClick={handleClose}>Get started</Button>
+        </DialogFooter>
+      </DialogContent>
+    </Dialog>
+  );
+}
\ No newline at end of file
diff --git a/tests/component/modals/WelcomeDialog.test.tsx b/tests/component/modals/WelcomeDialog.test.tsx
new file mode 100644
index 0000000..5e84823
--- /dev/null
+++ b/tests/component/modals/WelcomeDialog.test.tsx
@@ -0,0 +1,34 @@
+import { describe, it, expect, beforeEach } from 'vitest';
+import { render, screen } from '@testing-library/react';
+import userEvent from '@testing-library/user-event';
+import { WelcomeDialog } from '@/components/modals/WelcomeDialog';
+import { useSettingsStore } from '@/stores/settings-store';
+import { useAppStore } from '@/stores/app-store';
+
+describe('WelcomeDialog', () => {
+  beforeEach(() => {
+    localStorage.clear();
+    useSettingsStore.setState(useSettingsStore.getInitialState());
+    useAppStore.setState({ modal: { kind: null } } as any);
+  });
+
+  it('renders a heading and quick-start content', () => {
+    render(<WelcomeDialog />);
+    expect(screen.getByRole('heading', { name: /welcome/i })).toBeInTheDocument();
+    expect(screen.getByText(/open a folder/i)).toBeInTheDocument();
+  });
+
+  it('closing without the checkbox does not dismiss future welcome dialogs', async () => {
+    render(<WelcomeDialog />);
+    await userEvent.click(screen.getByRole('button', { name: /get started/i }));
+    expect(useSettingsStore.getState().welcomeDismissed).toBe(false);
+    expect(useAppStore.getState().modal).toEqual({ kind: null });
+  });
+
+  it('checking "don\'t show again" persists the flag', async () => {
+    render(<WelcomeDialog />);
+    await userEvent.click(screen.getByRole('checkbox', { name: /don't show again/i }));
+    await userEvent.click(screen.getByRole('button', { name: /get started/i }));
+    expect(useSettingsStore.getState().welcomeDismissed).toBe(true);
+  });
+});