feat(planner): add EmptyDayTile component

Dashed-border empty slot tile with + Gericht wählen CTA and lazy
reasoning tags (Neues Protein, Aufwand: leicht) derived from
topSuggestion prop via computeReasoningTags.

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

frontend/src/lib/planner/EmptyDayTile.svelte

@@ -0,0 +1,89 @@
+<script lang="ts">
+	import { computeReasoningTags } from './reasoningTags';
+
+	interface TagItem {
+		id?: string;
+		name?: string;
+		tagType?: string;
+	}
+
+	interface SuggestionRecipe {
+		id: string;
+		name: string;
+		cookTimeMin?: number;
+		effort?: string;
+		tags?: TagItem[];
+	}
+
+	interface TopSuggestion {
+		recipe: SuggestionRecipe;
+		scoreDelta: number;
+		hasConflict: boolean;
+	}
+
+	interface Slot {
+		id?: string;
+		slotDate?: string;
+		recipe?: any | null;
+	}
+
+	let {
+		slotDate,
+		slotId,
+		isPlanner,
+		slotMap,
+		topSuggestion,
+		onaddrecipe
+	}: {
+		slotDate: string;
+		slotId: string;
+		isPlanner: boolean;
+		slotMap: Record<string, Slot>;
+		topSuggestion?: TopSuggestion;
+		onaddrecipe?: () => void;
+	} = $props();
+
+	let reasoningTags = $derived(
+		topSuggestion ? computeReasoningTags(slotMap, topSuggestion.recipe) : []
+	);
+</script>
+
+<div
+	data-testid="empty-day-tile"
+	role="group"
+	class="h-full flex flex-col gap-2 p-3"
+	style="border: 1px dashed var(--color-border);"
+>
+	{#if isPlanner}
+		<button
+			type="button"
+			aria-label="Gericht wählen"
+			onclick={() => onaddrecipe?.()}
+			class="self-start font-[var(--font-sans)] text-[13px] text-[var(--color-text-muted)] hover:text-[var(--color-text)] transition-colors"
+		>
+			+ Gericht wählen
+		</button>
+	{/if}
+
+	{#if topSuggestion}
+		<p class="font-[var(--font-display)] text-[12px] text-[var(--color-text-muted)] leading-snug">
+			{topSuggestion.recipe.name}
+		</p>
+
+		{#if reasoningTags.length > 0}
+			<div class="flex flex-wrap gap-1">
+				{#each reasoningTags as tag (tag.id)}
+					<span
+						data-testid="reasoning-tag"
+						class="inline-block rounded px-1.5 py-0.5 font-[var(--font-sans)] text-[11px] font-medium"
+						style={tag.color === 'green'
+							? 'background: var(--green-tint); color: var(--green-dark);'
+							: 'background: var(--yellow-tint); color: var(--yellow-text);'}
+					>
+						{tag.label}
+					</span>
+				{/each}
+			</div>
+		{/if}
+	{/if}
+</div>

frontend/src/lib/planner/EmptyDayTile.test.ts

@@ -0,0 +1,88 @@
+import { describe, it, expect, vi } from 'vitest';
+import { render, screen } from '@testing-library/svelte';
+import { userEvent } from '@testing-library/user-event';
+import EmptyDayTile from './EmptyDayTile.svelte';
+
+const slotDate = '2026-04-14';
+const slotId = 'slot-1';
+
+const topSuggestionNewProtein = {
+	recipe: {
+		id: 'r1',
+		name: 'Lachs mit Gemüse',
+		cookTimeMin: 20,
+		effort: 'einfach',
+		tags: [{ id: 't1', name: 'Fisch', tagType: 'protein' }]
+	},
+	scoreDelta: 3.2,
+	hasConflict: false
+};
+
+const slotMapEmpty = {};
+
+describe('EmptyDayTile', () => {
+	describe('base render', () => {
+		it('shows + CTA for planner', () => {
+			render(EmptyDayTile, { props: { slotDate, slotId, isPlanner: true, slotMap: slotMapEmpty } });
+			expect(screen.getByRole('button', { name: /Gericht wählen/i })).toBeTruthy();
+		});
+
+		it('hides + CTA for non-planner', () => {
+			render(EmptyDayTile, { props: { slotDate, slotId, isPlanner: false, slotMap: slotMapEmpty } });
+			expect(screen.queryByRole('button', { name: /Gericht wählen/i })).toBeNull();
+		});
+
+		it('calls onaddrecipe when + CTA clicked', async () => {
+			const onaddrecipe = vi.fn();
+			const user = userEvent.setup();
+			render(EmptyDayTile, { props: { slotDate, slotId, isPlanner: true, slotMap: slotMapEmpty, onaddrecipe } });
+			await user.click(screen.getByRole('button', { name: /Gericht wählen/i }));
+			expect(onaddrecipe).toHaveBeenCalledOnce();
+		});
+
+		it('has data-testid="empty-day-tile"', () => {
+			render(EmptyDayTile, { props: { slotDate, slotId, isPlanner: true, slotMap: slotMapEmpty } });
+			expect(screen.getByTestId('empty-day-tile')).toBeTruthy();
+		});
+	});
+
+	describe('reasoning tags', () => {
+		it('shows no tags when no topSuggestion', () => {
+			render(EmptyDayTile, { props: { slotDate, slotId, isPlanner: true, slotMap: slotMapEmpty } });
+			expect(screen.queryByTestId('reasoning-tag')).toBeNull();
+		});
+
+		it('shows Neues Protein tag when topSuggestion has new protein', () => {
+			render(EmptyDayTile, {
+				props: { slotDate, slotId, isPlanner: true, slotMap: slotMapEmpty, topSuggestion: topSuggestionNewProtein }
+			});
+			expect(screen.getByText('Neues Protein')).toBeTruthy();
+		});
+
+		it('shows Aufwand tag for easy suggestion', () => {
+			render(EmptyDayTile, {
+				props: { slotDate, slotId, isPlanner: true, slotMap: slotMapEmpty, topSuggestion: topSuggestionNewProtein }
+			});
+			expect(screen.getByText('Aufwand: leicht')).toBeTruthy();
+		});
+
+		it('shows suggestion recipe name when topSuggestion provided', () => {
+			render(EmptyDayTile, {
+				props: { slotDate, slotId, isPlanner: true, slotMap: slotMapEmpty, topSuggestion: topSuggestionNewProtein }
+			});
+			expect(screen.getByText('Lachs mit Gemüse')).toBeTruthy();
+		});
+
+		it('does not show tags when suggestion has no matching conditions', () => {
+			const heavySuggestion = {
+				recipe: { id: 'r2', name: 'Roulade', cookTimeMin: 120, effort: 'aufwändig', tags: [] },
+				scoreDelta: 1.0,
+				hasConflict: false
+			};
+			render(EmptyDayTile, {
+				props: { slotDate, slotId, isPlanner: true, slotMap: slotMapEmpty, topSuggestion: heavySuggestion }
+			});
+			expect(screen.queryByTestId('reasoning-tag')).toBeNull();
+		});
+	});
+});