feat(auth): add SignupForm component with validation and password toggle

Form with name/email/password fields, client-side validation,
inline error messages, and password show/hide toggle.
Uses native form action for progressive enhancement.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/package-lock.json

@@ -19,6 +19,7 @@
 				"@tailwindcss/vite": "^4.2.2",
 				"@testing-library/jest-dom": "^6.9.1",
 				"@testing-library/svelte": "^5.3.1",
+				"@testing-library/user-event": "^14.6.1",
 				"@types/node": "^25.5.0",
 				"@vitest/ui": "^4.1.2",
 				"jsdom": "^29.0.1",
@@ -1809,6 +1810,20 @@
 				"svelte": "^3 || ^4 || ^5 || ^5.0.0-next.0"
 			}
 		},
+		"node_modules/@testing-library/user-event": {
+			"version": "14.6.1",
+			"resolved": "https://registry.npmjs.org/@testing-library/user-event/-/user-event-14.6.1.tgz",
+			"integrity": "sha512-vq7fv0rnt+QTXgPxr5Hjc210p6YKq2kmdziLgnsZGgLJ9e6VAShx1pACLuRjd/AS/sr7phAR58OIIpf0LlmQNw==",
+			"dev": true,
+			"license": "MIT",
+			"engines": {
+				"node": ">=12",
+				"npm": ">=6"
+			},
+			"peerDependencies": {
+				"@testing-library/dom": ">=7.21.4"
+			}
+		},
 		"node_modules/@types/aria-query": {
 			"version": "5.0.4",
 			"resolved": "https://registry.npmjs.org/@types/aria-query/-/aria-query-5.0.4.tgz",

frontend/package.json

@@ -25,6 +25,7 @@
 		"@tailwindcss/vite": "^4.2.2",
 		"@testing-library/jest-dom": "^6.9.1",
 		"@testing-library/svelte": "^5.3.1",
+		"@testing-library/user-event": "^14.6.1",
 		"@types/node": "^25.5.0",
 		"@vitest/ui": "^4.1.2",
 		"jsdom": "^29.0.1",

frontend/src/lib/auth/SignupForm.svelte

@@ -0,0 +1,154 @@
+<script lang="ts">
+	let displayName = $state('');
+	let email = $state('');
+	let password = $state('');
+	let showPassword = $state(false);
+
+	let errors = $state({
+		displayName: '',
+		email: '',
+		password: ''
+	});
+
+	function handleSubmit(event: SubmitEvent) {
+		let hasError = false;
+
+		errors.displayName = '';
+		errors.email = '';
+		errors.password = '';
+
+		if (!displayName.trim()) {
+			errors.displayName = 'Name ist erforderlich';
+			hasError = true;
+		}
+
+		const emailPattern = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;
+		if (!emailPattern.test(email)) {
+			errors.email = 'Ungültige E-Mail-Adresse';
+			hasError = true;
+		}
+
+		if (password.length < 8) {
+			errors.password = 'Mindestens 8 Zeichen';
+			hasError = true;
+		}
+
+		if (hasError) {
+			event.preventDefault();
+		}
+	}
+</script>
+
+<form method="POST" novalidate onsubmit={handleSubmit}>
+	<h1
+		class="font-[var(--font-display)] text-[18px] font-medium tracking-[-0.02em] text-[var(--color-text)]
+			md:text-[28px]"
+	>
+		Konto erstellen
+	</h1>
+
+	<p
+		class="mb-[20px] text-[12px] text-[var(--color-text-muted)]
+			md:mb-[32px] md:text-[14px]"
+	>
+		Danach richtest du deinen Haushalt ein.
+	</p>
+
+	<!-- Name field -->
+	<div class="mb-[16px]">
+		<label
+			for="displayName"
+			class="mb-[6px] block text-[12px] font-medium text-[var(--color-text)]"
+		>
+			Dein Name
+		</label>
+		<input
+			type="text"
+			id="displayName"
+			name="displayName"
+			placeholder="z.B. Sarah"
+			bind:value={displayName}
+			class="w-full rounded-[var(--radius-md)] border bg-[var(--color-page)] px-[12px] py-[10px] font-[var(--font-sans)] text-[14px] text-[var(--color-text)] outline-none
+				{errors.displayName ? 'border-[var(--color-error)]' : 'border-[var(--color-border)]'}"
+		/>
+		{#if errors.displayName}
+			<p class="mt-1 font-[var(--font-sans)] text-[12px] text-[var(--color-error)]">
+				{errors.displayName}
+			</p>
+		{/if}
+	</div>
+
+	<!-- Email field -->
+	<div class="mb-[16px]">
+		<label
+			for="email"
+			class="mb-[6px] block text-[12px] font-medium text-[var(--color-text)]"
+		>
+			E-Mail
+		</label>
+		<input
+			type="email"
+			id="email"
+			name="email"
+			placeholder="du@beispiel.de"
+			bind:value={email}
+			class="w-full rounded-[var(--radius-md)] border bg-[var(--color-page)] px-[12px] py-[10px] font-[var(--font-sans)] text-[14px] text-[var(--color-text)] outline-none
+				{errors.email ? 'border-[var(--color-error)]' : 'border-[var(--color-border)]'}"
+		/>
+		{#if errors.email}
+			<p class="mt-1 font-[var(--font-sans)] text-[12px] text-[var(--color-error)]">
+				{errors.email}
+			</p>
+		{/if}
+	</div>
+
+	<!-- Password field -->
+	<div class="mb-[16px]">
+		<label
+			for="password"
+			class="mb-[6px] block text-[12px] font-medium text-[var(--color-text)]"
+		>
+			Passwort
+		</label>
+		<div class="relative">
+			<input
+				type={showPassword ? 'text' : 'password'}
+				id="password"
+				name="password"
+				placeholder="Mindestens 8 Zeichen"
+				bind:value={password}
+				class="w-full rounded-[var(--radius-md)] border bg-[var(--color-page)] px-[12px] py-[10px] pr-[44px] font-[var(--font-sans)] text-[14px] text-[var(--color-text)] outline-none
+					{errors.password ? 'border-[var(--color-error)]' : 'border-[var(--color-border)]'}"
+			/>
+			<button
+				type="button"
+				onclick={() => (showPassword = !showPassword)}
+				aria-label={showPassword ? 'Passwort verbergen' : 'Passwort anzeigen'}
+				class="absolute top-1/2 right-[12px] -translate-y-1/2 cursor-pointer bg-transparent p-0 text-[12px] text-[var(--color-text-muted)]"
+			>
+				{showPassword ? 'Verbergen' : 'Anzeigen'}
+			</button>
+		</div>
+		{#if errors.password}
+			<p class="mt-1 font-[var(--font-sans)] text-[12px] text-[var(--color-error)]">
+				{errors.password}
+			</p>
+		{/if}
+	</div>
+
+	<!-- Submit button -->
+	<button
+		type="submit"
+		class="w-full cursor-pointer rounded-[var(--radius-md)] bg-[var(--green)] px-[24px] py-[12px] text-[var(--btn-font-size)] font-[var(--btn-font-weight)] tracking-[var(--btn-letter-spacing)] text-white"
+	>
+		Konto erstellen &rarr;
+	</button>
+
+	<!-- Login link -->
+	<p
+		class="mt-[16px] text-center text-[12px] text-[var(--color-text-muted)]
+			md:text-[13px]"
+	>
+		Du hast bereits ein Konto? <a href="/login" class="text-[var(--color-text)] underline">Anmelden</a>
+	</p>
+</form>

frontend/src/lib/auth/SignupForm.test.ts

@@ -0,0 +1,125 @@
+import { describe, it, expect, vi } from 'vitest';
+import { render, screen } from '@testing-library/svelte';
+import { userEvent } from '@testing-library/user-event';
+import SignupForm from './SignupForm.svelte';
+
+describe('SignupForm', () => {
+	it('renders all form fields with correct labels', () => {
+		render(SignupForm);
+		expect(screen.getByLabelText('Dein Name')).toBeInTheDocument();
+		expect(screen.getByLabelText('E-Mail')).toBeInTheDocument();
+		expect(screen.getByLabelText('Passwort')).toBeInTheDocument();
+	});
+
+	it('renders submit button with correct text', () => {
+		render(SignupForm);
+		expect(screen.getByRole('button', { name: /konto erstellen/i })).toBeInTheDocument();
+	});
+
+	it('renders login link', () => {
+		render(SignupForm);
+		const link = screen.getByRole('link', { name: /anmelden/i });
+		expect(link).toHaveAttribute('href', '/login');
+	});
+
+	it('renders heading and subtitle', () => {
+		render(SignupForm);
+		expect(screen.getByText('Konto erstellen')).toBeInTheDocument();
+		expect(screen.getByText('Danach richtest du deinen Haushalt ein.')).toBeInTheDocument();
+	});
+
+	it('password field is initially of type password', () => {
+		render(SignupForm);
+		const input = screen.getByLabelText('Passwort');
+		expect(input).toHaveAttribute('type', 'password');
+	});
+
+	it('password toggle switches to text and back', async () => {
+		const user = userEvent.setup();
+		render(SignupForm);
+
+		const input = screen.getByLabelText('Passwort');
+		const toggle = screen.getByRole('button', { name: /passwort anzeigen/i });
+
+		await user.click(toggle);
+		expect(input).toHaveAttribute('type', 'text');
+
+		await user.click(toggle);
+		expect(input).toHaveAttribute('type', 'password');
+	});
+
+	it('shows validation error for empty name on submit', async () => {
+		const user = userEvent.setup();
+		render(SignupForm);
+
+		const email = screen.getByLabelText('E-Mail');
+		const password = screen.getByLabelText('Passwort');
+		await user.type(email, 'test@example.com');
+		await user.type(password, 'password123');
+
+		const submit = screen.getByRole('button', { name: /konto erstellen/i });
+		await user.click(submit);
+
+		expect(screen.getByText('Name ist erforderlich')).toBeInTheDocument();
+	});
+
+	it('shows validation error for invalid email on submit', async () => {
+		const user = userEvent.setup();
+		render(SignupForm);
+
+		const name = screen.getByLabelText('Dein Name');
+		const email = screen.getByLabelText('E-Mail');
+		const password = screen.getByLabelText('Passwort');
+		await user.type(name, 'Sarah');
+		await user.type(email, 'notanemail');
+		await user.type(password, 'password123');
+
+		const submit = screen.getByRole('button', { name: /konto erstellen/i });
+		await user.click(submit);
+
+		expect(screen.getByText('Ungültige E-Mail-Adresse')).toBeInTheDocument();
+	});
+
+	it('shows validation error for short password on submit', async () => {
+		const user = userEvent.setup();
+		render(SignupForm);
+
+		const name = screen.getByLabelText('Dein Name');
+		const email = screen.getByLabelText('E-Mail');
+		const password = screen.getByLabelText('Passwort');
+		await user.type(name, 'Sarah');
+		await user.type(email, 'test@example.com');
+		await user.type(password, 'short');
+
+		const submit = screen.getByRole('button', { name: /konto erstellen/i });
+		await user.click(submit);
+
+		expect(screen.getByText('Mindestens 8 Zeichen')).toBeInTheDocument();
+	});
+
+	it('shows no validation errors when all fields are valid', async () => {
+		const user = userEvent.setup();
+		render(SignupForm);
+
+		const name = screen.getByLabelText('Dein Name');
+		const email = screen.getByLabelText('E-Mail');
+		const password = screen.getByLabelText('Passwort');
+		await user.type(name, 'Sarah');
+		await user.type(email, 'test@example.com');
+		await user.type(password, 'password123');
+
+		const submit = screen.getByRole('button', { name: /konto erstellen/i });
+		await user.click(submit);
+
+		expect(screen.queryByText('Name ist erforderlich')).not.toBeInTheDocument();
+		expect(screen.queryByText('Ungültige E-Mail-Adresse')).not.toBeInTheDocument();
+		expect(screen.queryByText('Mindestens 8 Zeichen')).not.toBeInTheDocument();
+	});
+
+	it('renders placeholders on inputs', () => {
+		render(SignupForm);
+		expect(screen.getByPlaceholderText('z.B. Sarah')).toBeInTheDocument();
+		expect(screen.getByPlaceholderText('du@beispiel.de')).toBeInTheDocument();
+		expect(screen.getByPlaceholderText('Mindestens 8 Zeichen')).toBeInTheDocument();
+	});
+});