feat(recipe): compress hero image to 400px preview on save

Adds Thumbnailator-based ImageCompressor that resizes uploaded images
to a 400px-wide JPEG preview stored in hero_image_preview. The recipe
list uses the preview instead of the full image URL.

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

backend/pom.xml

@@ -55,6 +55,16 @@
 			<artifactId>postgresql</artifactId>
 			<scope>runtime</scope>
 		</dependency>
+		<dependency>
+			<groupId>net.coobird</groupId>
+			<artifactId>thumbnailator</artifactId>
+			<version>0.4.21</version>
+		</dependency>
+		<dependency>
+			<groupId>com.twelvemonkeys.imageio</groupId>
+			<artifactId>imageio-webp</artifactId>
+			<version>3.13.1</version>
+		</dependency>
 		<dependency>
 			<groupId>org.springframework.boot</groupId>
 			<artifactId>spring-boot-starter-test</artifactId>

backend/src/main/java/com/recipeapp/recipe/ImageCompressor.java

@@ -0,0 +1,60 @@
+package com.recipeapp.recipe;
+
+import net.coobird.thumbnailator.Thumbnails;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.stereotype.Component;
+
+import javax.imageio.ImageIO;
+import java.awt.image.BufferedImage;
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.util.Base64;
+
+@Component
+public class ImageCompressor {
+
+    private static final Logger log = LoggerFactory.getLogger(ImageCompressor.class);
+
+    private static final int PREVIEW_WIDTH = 400;
+    private static final double PREVIEW_QUALITY = 0.6;
+    private static final String DATA_URI_PREFIX = "data:image/";
+    private static final String BASE64_MARKER = ";base64,";
+    private static final String OUTPUT_PREFIX = "data:image/jpeg;base64,";
+
+    public String compressToPreview(String dataUri) {
+        if (dataUri == null || dataUri.isBlank()) return null;
+        if (!dataUri.startsWith(DATA_URI_PREFIX)) return null;
+
+        int markerIdx = dataUri.indexOf(BASE64_MARKER);
+        if (markerIdx < 0) return null;
+
+        byte[] imageBytes;
+        try {
+            imageBytes = Base64.getDecoder().decode(dataUri.substring(markerIdx + BASE64_MARKER.length()));
+        } catch (IllegalArgumentException e) {
+            return null;
+        }
+
+        try {
+            BufferedImage original = ImageIO.read(new ByteArrayInputStream(imageBytes));
+            if (original == null) {
+                log.warn("ImageIO could not decode image — unsupported format (data URI prefix: {})",
+                        dataUri.substring(0, Math.min(dataUri.indexOf(',') + 1, 40)));
+                return null;
+            }
+
+            int targetWidth = Math.min(original.getWidth(), PREVIEW_WIDTH);
+            ByteArrayOutputStream bos = new ByteArrayOutputStream();
+            Thumbnails.of(original)
+                    .width(targetWidth)
+                    .outputFormat("jpeg")
+                    .outputQuality(PREVIEW_QUALITY)
+                    .toOutputStream(bos);
+            return OUTPUT_PREFIX + Base64.getEncoder().encodeToString(bos.toByteArray());
+        } catch (Exception e) {
+            log.warn("Failed to generate image preview", e);
+            return null;
+        }
+    }
+}

backend/src/main/java/com/recipeapp/recipe/RecipeController.java

@@ -29,7 +29,6 @@ public class RecipeController {
             Principal principal,
             @RequestParam(required = false) String search,
             @RequestParam(required = false) String effort,
-            @RequestParam(required = false) Boolean isChildFriendly,
             @RequestParam(name = "cookTimeMin.lte", required = false) Integer cookTimeMaxMin,
             @RequestParam(required = false) String sort,
             @RequestParam(defaultValue = "20") int limit,
@@ -37,9 +36,9 @@ public class RecipeController {
 
         UUID householdId = householdResolver.resolve(principal.getName());
         List<RecipeSummaryResponse> recipes = recipeService.listRecipes(
-                householdId, search, effort, isChildFriendly, cookTimeMaxMin, sort, limit, offset);
+                householdId, search, effort, cookTimeMaxMin, sort, limit, offset);
         long total = recipeService.countRecipes(
-                householdId, search, effort, isChildFriendly, cookTimeMaxMin);
+                householdId, search, effort, cookTimeMaxMin);
 
         var pagination = new ApiResponse.Pagination(total, limit, offset, offset + limit < total);
         var meta = new ApiResponse.Meta(pagination);

backend/src/main/java/com/recipeapp/recipe/RecipeRepository.java

@@ -18,13 +18,12 @@ public interface RecipeRepository extends JpaRepository<Recipe, UUID> {
 
     @Query("""
             SELECT new com.recipeapp.recipe.dto.RecipeSummaryResponse(
-                r.id, r.name, r.serves, r.cookTimeMin, r.effort, r.isChildFriendly, r.heroImageUrl)
+                r.id, r.name, r.serves, r.cookTimeMin, r.effort, r.heroImagePreview)
             FROM Recipe r
             WHERE r.household.id = :householdId
               AND r.deletedAt IS NULL
               AND (:search IS NULL OR LOWER(r.name) LIKE LOWER(CONCAT('%', CAST(:search AS string), '%')))
               AND (:effort IS NULL OR r.effort = CAST(:effort AS string))
-              AND (:isChildFriendly IS NULL OR r.isChildFriendly = :isChildFriendly)
               AND (:cookTimeMaxMin IS NULL OR r.cookTimeMin <= :cookTimeMaxMin)
             ORDER BY r.createdAt DESC
             """)
@@ -32,7 +31,6 @@ public interface RecipeRepository extends JpaRepository<Recipe, UUID> {
             @Param("householdId") UUID householdId,
             @Param("search") String search,
             @Param("effort") String effort,
-            @Param("isChildFriendly") Boolean isChildFriendly,
             @Param("cookTimeMaxMin") Integer cookTimeMaxMin,
             @Param("sort") String sort,
             @Param("limit") int limit,
@@ -45,13 +43,11 @@ public interface RecipeRepository extends JpaRepository<Recipe, UUID> {
               AND r.deletedAt IS NULL
               AND (:search IS NULL OR LOWER(r.name) LIKE LOWER(CONCAT('%', CAST(:search AS string), '%')))
               AND (:effort IS NULL OR r.effort = CAST(:effort AS string))
-              AND (:isChildFriendly IS NULL OR r.isChildFriendly = :isChildFriendly)
               AND (:cookTimeMaxMin IS NULL OR r.cookTimeMin <= :cookTimeMaxMin)
             """)
     long countFiltered(
             @Param("householdId") UUID householdId,
             @Param("search") String search,
             @Param("effort") String effort,
-            @Param("isChildFriendly") Boolean isChildFriendly,
             @Param("cookTimeMaxMin") Integer cookTimeMaxMin);
 }

backend/src/main/java/com/recipeapp/recipe/RecipeService.java

@@ -2,6 +2,7 @@ package com.recipeapp.recipe;
 
 import com.recipeapp.common.ConflictException;
 import com.recipeapp.common.ResourceNotFoundException;
+import com.recipeapp.common.ValidationException;
 import com.recipeapp.household.HouseholdRepository;
 import com.recipeapp.household.entity.Household;
 import com.recipeapp.recipe.dto.*;
@@ -22,31 +23,31 @@ public class RecipeService {
     private final TagRepository tagRepository;
     private final IngredientCategoryRepository ingredientCategoryRepository;
     private final HouseholdRepository householdRepository;
+    private final ImageCompressor imageCompressor;
 
     public RecipeService(RecipeRepository recipeRepository,
                               IngredientRepository ingredientRepository,
                               TagRepository tagRepository,
                               IngredientCategoryRepository ingredientCategoryRepository,
-                              HouseholdRepository householdRepository) {
+                              HouseholdRepository householdRepository,
+                              ImageCompressor imageCompressor) {
         this.recipeRepository = recipeRepository;
         this.ingredientRepository = ingredientRepository;
         this.tagRepository = tagRepository;
         this.ingredientCategoryRepository = ingredientCategoryRepository;
         this.householdRepository = householdRepository;
+        this.imageCompressor = imageCompressor;
     }
 
     @Transactional(readOnly = true)
     public List<RecipeSummaryResponse> listRecipes(UUID householdId, String search, String effort,
-                                                    Boolean isChildFriendly, Integer cookTimeMaxMin,
+                                                    Integer cookTimeMaxMin, String sort, int limit, int offset) {
-                                                    String sort, int limit, int offset) {
+        return recipeRepository.findFiltered(householdId, search, effort, cookTimeMaxMin, sort, limit, offset);
-        return recipeRepository.findFiltered(householdId, search, effort, isChildFriendly,
-                cookTimeMaxMin, sort, limit, offset);
     }
 
     @Transactional(readOnly = true)
-    public long countRecipes(UUID householdId, String search, String effort,
+    public long countRecipes(UUID householdId, String search, String effort, Integer cookTimeMaxMin) {
-                             Boolean isChildFriendly, Integer cookTimeMaxMin) {
+        return recipeRepository.countFiltered(householdId, search, effort, cookTimeMaxMin);
-        return recipeRepository.countFiltered(householdId, search, effort, isChildFriendly, cookTimeMaxMin);
     }
 
     @Transactional(readOnly = true)
@@ -60,11 +61,14 @@ public class RecipeService {
         Household household = householdRepository.findById(householdId)
                 .orElseThrow(() -> new ResourceNotFoundException("Household not found"));
 
+        validateHeroImageUrl(request.heroImageUrl());
+
         Recipe recipe = new Recipe(household, request.name(),
                 request.serves() != null ? request.serves().shortValue() : 0,
                 request.cookTimeMin() != null ? request.cookTimeMin().shortValue() : 0,
-                request.effort(), false);
+                request.effort());
         recipe.setHeroImageUrl(request.heroImageUrl());
+        recipe.setHeroImagePreview(imageCompressor.compressToPreview(request.heroImageUrl()));
 
         addIngredients(recipe, household, request.ingredients());
         addSteps(recipe, request.steps());
@@ -79,11 +83,14 @@ public class RecipeService {
         Recipe recipe = findRecipe(householdId, recipeId);
         Household household = recipe.getHousehold();
 
+        validateHeroImageUrl(request.heroImageUrl());
+
         recipe.setName(request.name());
         recipe.setServes(request.serves() != null ? request.serves().shortValue() : 0);
         recipe.setCookTimeMin(request.cookTimeMin() != null ? request.cookTimeMin().shortValue() : 0);
         recipe.setEffort(request.effort());
         recipe.setHeroImageUrl(request.heroImageUrl());
+        recipe.setHeroImagePreview(imageCompressor.compressToPreview(request.heroImageUrl()));
 
         recipe.getIngredients().clear();
         recipe.getSteps().clear();
@@ -181,6 +188,18 @@ public class RecipeService {
         return new IngredientCategoryResponse(category.getId(), category.getName());
     }
 
+    // ── Image validation ──
+
+    private static final java.util.regex.Pattern ALLOWED_IMAGE_PATTERN =
+            java.util.regex.Pattern.compile("^data:image/(jpeg|jpg|png|gif|webp);base64,");
+
+    private void validateHeroImageUrl(String heroImageUrl) {
+        if (heroImageUrl == null || heroImageUrl.isBlank()) return;
+        if (!ALLOWED_IMAGE_PATTERN.matcher(heroImageUrl).find()) {
+            throw new ValidationException("Ungültiger Bildtyp. Erlaubt sind: JPEG, PNG, GIF, WebP.");
+        }
+    }
+
     // ── Private helpers ──
 
     private Recipe findRecipe(UUID householdId, UUID recipeId) {
@@ -239,7 +258,7 @@ public class RecipeService {
 
         return new RecipeDetailResponse(
                 recipe.getId(), recipe.getName(), recipe.getServes(), recipe.getCookTimeMin(),
-                recipe.getEffort(), recipe.isChildFriendly(), recipe.getHeroImageUrl(),
+                recipe.getEffort(), recipe.getHeroImageUrl(),
                 ingredients, steps, tags);
     }
 

backend/src/main/java/com/recipeapp/recipe/dto/RecipeDetailResponse.java

@@ -10,7 +10,6 @@ public record RecipeDetailResponse(
         short serves,
         short cookTimeMin,
         String effort,
-        boolean isChildFriendly,
         String heroImageUrl,
         List<IngredientItem> ingredients,
         List<StepItem> steps,

backend/src/main/java/com/recipeapp/recipe/dto/RecipeSummaryResponse.java

@@ -8,6 +8,5 @@ public record RecipeSummaryResponse(
         short serves,
         short cookTimeMin,
         String effort,
-        boolean isChildFriendly,
+        String heroImagePreview
-        String heroImageUrl
 ) {}

backend/src/main/java/com/recipeapp/recipe/entity/Recipe.java

@@ -33,12 +33,12 @@ public class Recipe {
     @Column(nullable = false, length = 10)
     private String effort;
 
-    @Column(name = "is_child_friendly", nullable = false)
-    private boolean isChildFriendly;
-
     @Column(name = "hero_image_url", columnDefinition = "text")
     private String heroImageUrl;
 
+    @Column(name = "hero_image_preview", columnDefinition = "text")
+    private String heroImagePreview;
+
     @Column(name = "deleted_at")
     private Instant deletedAt;
 
@@ -64,14 +64,12 @@ public class Recipe {
 
     protected Recipe() {}
 
-    public Recipe(Household household, String name, short serves, short cookTimeMin,
+    public Recipe(Household household, String name, short serves, short cookTimeMin, String effort) {
-                  String effort, boolean isChildFriendly) {
         this.household = household;
         this.name = name;
         this.serves = serves;
         this.cookTimeMin = cookTimeMin;
         this.effort = effort;
-        this.isChildFriendly = isChildFriendly;
     }
 
     @PrePersist
@@ -95,10 +93,10 @@ public class Recipe {
     public void setCookTimeMin(short cookTimeMin) { this.cookTimeMin = cookTimeMin; }
     public String getEffort() { return effort; }
     public void setEffort(String effort) { this.effort = effort; }
-    public boolean isChildFriendly() { return isChildFriendly; }
-    public void setChildFriendly(boolean childFriendly) { isChildFriendly = childFriendly; }
     public String getHeroImageUrl() { return heroImageUrl; }
     public void setHeroImageUrl(String heroImageUrl) { this.heroImageUrl = heroImageUrl; }
+    public String getHeroImagePreview() { return heroImagePreview; }
+    public void setHeroImagePreview(String heroImagePreview) { this.heroImagePreview = heroImagePreview; }
     public Instant getDeletedAt() { return deletedAt; }
     public void setDeletedAt(Instant deletedAt) { this.deletedAt = deletedAt; }
     public Instant getCreatedAt() { return createdAt; }

backend/src/main/resources/application.yml

@@ -19,5 +19,10 @@ spring:
     enabled: true
     locations: classpath:db/migration
 
+  servlet:
+    multipart:
+      max-file-size: 5MB
+      max-request-size: 6MB
+
 server:
   port: 8080

backend/src/main/resources/db/migration/V024__add_hero_image_preview.sql

@@ -0,0 +1 @@
+ALTER TABLE recipe ADD COLUMN hero_image_preview text;

backend/src/main/resources/db/migration/V025__drop_is_child_friendly.sql

@@ -0,0 +1 @@
+ALTER TABLE recipe DROP COLUMN is_child_friendly;

backend/src/test/java/com/recipeapp/planning/PlanningServiceTest.java

@@ -55,7 +55,7 @@ class PlanningServiceTest {
     }
 
     private Recipe testRecipe(Household household, String name) {
-        var r = new Recipe(household, name, (short) 4, (short) 45, "medium", true);
+        var r = new Recipe(household, name, (short) 4, (short) 45, "medium");
         setId(r, Recipe.class, UUID.randomUUID());
         return r;
     }

backend/src/test/java/com/recipeapp/planning/SuggestionsTest.java

@@ -69,7 +69,7 @@ class SuggestionsTest {
     }
 
     private Recipe createRecipe(String name) {
-        var r = new Recipe(household, name, (short) 4, (short) 30, "medium", true);
+        var r = new Recipe(household, name, (short) 4, (short) 30, "medium");
         setId(r, Recipe.class, UUID.randomUUID());
         return r;
     }

backend/src/test/java/com/recipeapp/planning/VarietyScoreTest.java

@@ -69,7 +69,7 @@ class VarietyScoreTest {
     }
 
     private Recipe createRecipe(String name) {
-        var r = new Recipe(household, name, (short) 4, (short) 30, "medium", true);
+        var r = new Recipe(household, name, (short) 4, (short) 30, "medium");
         setId(r, Recipe.class, UUID.randomUUID());
         return r;
     }

backend/src/test/java/com/recipeapp/recipe/ImageCompressorTest.java

@@ -0,0 +1,98 @@
+package com.recipeapp.recipe;
+
+import org.junit.jupiter.api.Test;
+
+import javax.imageio.ImageIO;
+import java.awt.*;
+import java.awt.image.BufferedImage;
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.util.Base64;
+
+import static org.assertj.core.api.Assertions.*;
+
+class ImageCompressorTest {
+
+    private final ImageCompressor compressor = new ImageCompressor();
+
+    @Test
+    void compressToPreview_returnsJpegDataUri() throws Exception {
+        String dataUri = makePngDataUri(800, 600);
+        String result = compressor.compressToPreview(dataUri);
+        assertThat(result).startsWith("data:image/jpeg;base64,");
+    }
+
+    @Test
+    void compressToPreview_outputIsDecodableJpeg() throws Exception {
+        String dataUri = makePngDataUri(800, 600);
+        String result = compressor.compressToPreview(dataUri);
+
+        String base64 = result.substring("data:image/jpeg;base64,".length());
+        byte[] bytes = Base64.getDecoder().decode(base64);
+        BufferedImage img = ImageIO.read(new ByteArrayInputStream(bytes));
+
+        assertThat(img).isNotNull();
+        assertThat(img.getWidth()).isLessThanOrEqualTo(400);
+    }
+
+    @Test
+    void compressToPreview_preservesAspectRatio() throws Exception {
+        String dataUri = makePngDataUri(800, 400); // 2:1 ratio
+        String result = compressor.compressToPreview(dataUri);
+
+        String base64 = result.substring("data:image/jpeg;base64,".length());
+        BufferedImage img = ImageIO.read(new ByteArrayInputStream(Base64.getDecoder().decode(base64)));
+
+        assertThat(img).isNotNull();
+        double ratio = (double) img.getWidth() / img.getHeight();
+        assertThat(ratio).isCloseTo(2.0, within(0.1));
+    }
+
+    @Test
+    void compressToPreview_doesNotUpscaleSmallImages() throws Exception {
+        String dataUri = makePngDataUri(200, 150); // smaller than 400px
+        String result = compressor.compressToPreview(dataUri);
+
+        String base64 = result.substring("data:image/jpeg;base64,".length());
+        BufferedImage img = ImageIO.read(new ByteArrayInputStream(Base64.getDecoder().decode(base64)));
+
+        assertThat(img).isNotNull();
+        assertThat(img.getWidth()).isLessThanOrEqualTo(200);
+    }
+
+    @Test
+    void compressToPreview_returnsNullForNull() {
+        assertThat(compressor.compressToPreview(null)).isNull();
+    }
+
+    @Test
+    void compressToPreview_returnsNullForBlankString() {
+        assertThat(compressor.compressToPreview("  ")).isNull();
+    }
+
+    @Test
+    void compressToPreview_returnsNullForNonDataUri() {
+        assertThat(compressor.compressToPreview("https://example.com/image.jpg")).isNull();
+    }
+
+    @Test
+    void compressToPreview_returnsNullForInvalidBase64() {
+        assertThat(compressor.compressToPreview("data:image/jpeg;base64,!!!not-valid!!!")).isNull();
+    }
+
+    // ── helpers ──
+
+    private String makePngDataUri(int width, int height) throws Exception {
+        BufferedImage img = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
+        Graphics2D g = img.createGraphics();
+        // draw gradient so PNG and JPEG both have non-trivial content
+        for (int x = 0; x < width; x++) {
+            g.setColor(new Color(x * 255 / width, (x * 128 / width + height / 2) % 256, 128));
+            g.drawLine(x, 0, x, height);
+        }
+        g.dispose();
+        ByteArrayOutputStream bos = new ByteArrayOutputStream();
+        ImageIO.write(img, "png", bos);
+        return "data:image/png;base64," + Base64.getEncoder().encodeToString(bos.toByteArray());
+    }
+}

backend/src/test/java/com/recipeapp/recipe/RecipeControllerTest.java

@@ -47,13 +47,13 @@ class RecipeControllerTest {
     @Test
     void listRecipesShouldReturn200WithPagination() throws Exception {
         var summary = new RecipeSummaryResponse(RECIPE_ID, "Spaghetti Bolognese",
-                (short) 4, (short) 45, "medium", true, null);
+                (short) 4, (short) 45, "medium", null);
 
         when(householdResolver.resolve("sarah@example.com")).thenReturn(HOUSEHOLD_ID);
-        when(recipeService.listRecipes(eq(HOUSEHOLD_ID), isNull(), isNull(), isNull(), isNull(),
+        when(recipeService.listRecipes(eq(HOUSEHOLD_ID), isNull(), isNull(), isNull(),
                 isNull(), eq(20), eq(0)))
                 .thenReturn(List.of(summary));
-        when(recipeService.countRecipes(eq(HOUSEHOLD_ID), isNull(), isNull(), isNull(), isNull()))
+        when(recipeService.countRecipes(eq(HOUSEHOLD_ID), isNull(), isNull(), isNull()))
                 .thenReturn(1L);
 
         mockMvc.perform(get("/v1/recipes")
@@ -69,17 +69,16 @@ class RecipeControllerTest {
     @Test
     void listRecipesWithFiltersShouldPassParams() throws Exception {
         when(householdResolver.resolve("sarah@example.com")).thenReturn(HOUSEHOLD_ID);
-        when(recipeService.listRecipes(eq(HOUSEHOLD_ID), eq("pasta"), eq("easy"), eq(true),
+        when(recipeService.listRecipes(eq(HOUSEHOLD_ID), eq("pasta"), eq("easy"),
                 eq(30), eq("-cookTimeMin"), eq(10), eq(5)))
                 .thenReturn(List.of());
-        when(recipeService.countRecipes(eq(HOUSEHOLD_ID), eq("pasta"), eq("easy"), eq(true), eq(30)))
+        when(recipeService.countRecipes(eq(HOUSEHOLD_ID), eq("pasta"), eq("easy"), eq(30)))
                 .thenReturn(0L);
 
         mockMvc.perform(get("/v1/recipes")
                         .principal(() -> "sarah@example.com")
                         .param("search", "pasta")
                         .param("effort", "easy")
-                        .param("isChildFriendly", "true")
                         .param("cookTimeMin.lte", "30")
                         .param("sort", "-cookTimeMin")
                         .param("limit", "10")
@@ -162,6 +161,19 @@ class RecipeControllerTest {
         verify(recipeService).deleteRecipe(HOUSEHOLD_ID, RECIPE_ID);
     }
 
+    @Test
+    void createRecipeWithCapitalisedEffortShouldReturn400() throws Exception {
+        var body = """
+                {"name":"Test","effort":"Easy","tagIds":["%s"],"ingredients":[{"quantity":1,"unit":"g","newIngredientName":"x","sortOrder":0}]}
+                """.formatted(UUID.randomUUID());
+
+        mockMvc.perform(post("/v1/recipes")
+                        .principal(() -> "sarah@example.com")
+                        .contentType(org.springframework.http.MediaType.APPLICATION_JSON)
+                        .content(body))
+                .andExpect(status().isBadRequest());
+    }
+
     private RecipeCreateRequest sampleCreateRequest() {
         var ingredientId = UUID.randomUUID();
         return new RecipeCreateRequest(
@@ -175,7 +187,7 @@ class RecipeControllerTest {
     private RecipeDetailResponse sampleDetail() {
         var catRef = new RecipeDetailResponse.CategoryRef(UUID.randomUUID(), "pasta");
         return new RecipeDetailResponse(
-                RECIPE_ID, "Spaghetti Bolognese", (short) 4, (short) 45, "medium", true, null,
+                RECIPE_ID, "Spaghetti Bolognese", (short) 4, (short) 45, "medium", null,
                 List.of(new RecipeDetailResponse.IngredientItem(
                         UUID.randomUUID(), "spaghetti", catRef, new BigDecimal("400"), "g", (short) 1)),
                 List.of(new RecipeDetailResponse.StepItem((short) 1, "Boil water.")),

backend/src/test/java/com/recipeapp/recipe/RecipeServiceTest.java

@@ -27,6 +27,7 @@ class RecipeServiceTest {
     @Mock private TagRepository tagRepository;
     @Mock private IngredientCategoryRepository ingredientCategoryRepository;
     @Mock private HouseholdRepository householdRepository;
+    @Mock private ImageCompressor imageCompressor;
 
     @InjectMocks private RecipeService recipeService;
 
@@ -43,7 +44,7 @@ class RecipeServiceTest {
     }
 
     private Recipe testRecipe(Household household) {
-        var r = new Recipe(household, "Spaghetti Bolognese", (short) 4, (short) 45, "medium", true);
+        var r = new Recipe(household, "Spaghetti Bolognese", (short) 4, (short) 45, "medium");
         try {
             var field = Recipe.class.getDeclaredField("id");
             field.setAccessible(true);
@@ -525,6 +526,29 @@ class RecipeServiceTest {
                 .isInstanceOf(ResourceNotFoundException.class);
     }
 
+    @Test
+    void createRecipeWithNullServesAndCookTimeShouldStoreZero() {
+        var household = testHousehold();
+        when(householdRepository.findById(HOUSEHOLD_ID)).thenReturn(Optional.of(household));
+        when(recipeRepository.save(any(Recipe.class))).thenAnswer(i -> {
+            Recipe r = i.getArgument(0);
+            try {
+                var field = Recipe.class.getDeclaredField("id");
+                field.setAccessible(true);
+                field.set(r, UUID.randomUUID());
+            } catch (Exception e) { throw new RuntimeException(e); }
+            return r;
+        });
+
+        var request = new RecipeCreateRequest("Soup", null, null, "easy", null,
+                List.of(), List.of(), List.of());
+
+        RecipeDetailResponse result = recipeService.createRecipe(HOUSEHOLD_ID, request);
+
+        assertThat(result.serves()).isEqualTo((short) 0);
+        assertThat(result.cookTimeMin()).isEqualTo((short) 0);
+    }
+
     // ── Tag/Category edge cases ──
 
     @Test
@@ -547,6 +571,31 @@ class RecipeServiceTest {
                 .isInstanceOf(ResourceNotFoundException.class);
     }
 
+    @Test
+    void createRecipeWithDisallowedImageTypeShouldThrowValidationException() {
+        when(householdRepository.findById(HOUSEHOLD_ID)).thenReturn(Optional.of(testHousehold()));
+
+        var request = new RecipeCreateRequest(
+                "Test", null, null, "easy", "data:application/pdf;base64,abc",
+                List.of(), List.of(), List.of());
+
+        assertThatThrownBy(() -> recipeService.createRecipe(HOUSEHOLD_ID, request))
+                .isInstanceOf(com.recipeapp.common.ValidationException.class);
+    }
+
+    @Test
+    void createRecipeWithAllowedImageTypeShouldNotThrow() {
+        var household = testHousehold();
+        when(householdRepository.findById(HOUSEHOLD_ID)).thenReturn(Optional.of(household));
+        when(recipeRepository.save(any(Recipe.class))).thenAnswer(i -> i.getArgument(0));
+
+        var request = new RecipeCreateRequest(
+                "Test", null, null, "easy", "data:image/jpeg;base64,abc",
+                List.of(), List.of(), List.of());
+
+        assertThatNoException().isThrownBy(() -> recipeService.createRecipe(HOUSEHOLD_ID, request));
+    }
+
     @Test
     void listTagsShouldReturnEmptyList() {
         when(tagRepository.findByHouseholdId(HOUSEHOLD_ID)).thenReturn(List.of());

backend/src/test/java/com/recipeapp/shopping/ShoppingServiceTest.java

@@ -60,7 +60,7 @@ class ShoppingServiceTest {
     }
 
     private Recipe testRecipe(Household household, String name) {
-        var r = new Recipe(household, name, (short) 4, (short) 45, "medium", true);
+        var r = new Recipe(household, name, (short) 4, (short) 45, "medium");
         setId(r, Recipe.class, UUID.randomUUID());
         return r;
     }

frontend/src/lib/api/schema.d.ts

@@ -552,7 +552,6 @@ export interface components {
             /** Format: int32 */
             cookTimeMin?: number;
             effort: string;
-            isChildFriendly?: boolean;
             heroImageUrl?: string;
             ingredients: components["schemas"]["IngredientEntry"][];
             steps?: components["schemas"]["StepEntry"][];
@@ -587,7 +586,6 @@ export interface components {
             /** Format: int32 */
             cookTimeMin?: number;
             effort?: string;
-            isChildFriendly?: boolean;
             heroImageUrl?: string;
             ingredients?: components["schemas"]["IngredientItem"][];
             steps?: components["schemas"]["StepItem"][];
@@ -934,8 +932,7 @@ export interface components {
             /** Format: int32 */
             cookTimeMin?: number;
             effort?: string;
-            isChildFriendly?: boolean;
+            heroImagePreview?: string;
-            heroImageUrl?: string;
         };
         ApiResponseListAdminUserResponse: {
             status?: string;

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

@@ -3,30 +3,44 @@ import { render, screen } from '@testing-library/svelte';
 import VarietyWarningCards from './VarietyWarningCards.svelte';
 
 const warnings = [
-	{ title: 'Chicken zweimal diese Woche', explanation: 'Mo, Mi — erwäge einen Tausch.' },
+	{
-	{ title: 'Tomaten in 3 Gerichten', explanation: 'Mo, Di, Mi — sorge für Abwechslung.' }
+		title: 'Chicken zweimal diese Woche',
+		items: [
+			{ dayShort: 'Mo', recipeName: 'Chicken Tikka', slotId: 1 },
+			{ dayShort: 'Mi', recipeName: 'Chicken Curry', slotId: 3 }
+		]
+	},
+	{
+		title: 'Tomaten in 3 Gerichten',
+		items: [
+			{ dayShort: 'Mo', recipeName: 'Pasta Pomodoro', slotId: 1 },
+			{ dayShort: 'Di', recipeName: 'Tomatensuppe', slotId: 2 },
+			{ dayShort: 'Mi', recipeName: 'Pizza Margherita', slotId: 3 }
+		]
+	}
 ];
 
 describe('VarietyWarningCards', () => {
 	it('renders one card per warning', () => {
-		render(VarietyWarningCards, { props: { warnings } });
+		render(VarietyWarningCards, { props: { warnings, weekStart: '2026-04-07' } });
 		const cards = screen.getAllByTestId('warning-card');
 		expect(cards.length).toBe(2);
 	});
 
 	it('renders warning titles', () => {
-		render(VarietyWarningCards, { props: { warnings } });
+		render(VarietyWarningCards, { props: { warnings, weekStart: '2026-04-07' } });
 		expect(screen.getByText(/Chicken zweimal/)).toBeTruthy();
 		expect(screen.getByText(/Tomaten in 3/)).toBeTruthy();
 	});
 
 	it('renders warning explanations', () => {
-		render(VarietyWarningCards, { props: { warnings } });
+		render(VarietyWarningCards, { props: { warnings, weekStart: '2026-04-07' } });
-		expect(screen.getByText(/erwäge einen Tausch/)).toBeTruthy();
+		expect(screen.getByText('Chicken Tikka')).toBeTruthy();
+		expect(screen.getByText('Chicken Curry')).toBeTruthy();
 	});
 
 	it('renders nothing when warnings is empty', () => {
-		render(VarietyWarningCards, { props: { warnings: [] } });
+		render(VarietyWarningCards, { props: { warnings: [], weekStart: '2026-04-07' } });
 		expect(screen.queryAllByTestId('warning-card').length).toBe(0);
 	});
 });

frontend/src/lib/recipes/RecipeCard.svelte

@@ -23,8 +23,8 @@
 			data-testid="image-area"
 			class="w-full overflow-hidden {compact ? 'h-[64px]' : 'h-[100px]'}"
 		>
-			{#if recipe.heroImageUrl}
+			{#if recipe.heroImagePreview}
-				<img src={recipe.heroImageUrl} alt={recipe.name} class="w-full h-full object-cover" />
+				<img src={recipe.heroImagePreview} alt={recipe.name} class="w-full h-full object-cover" />
 			{:else}
 				<div
 					data-testid="image-placeholder"

frontend/src/lib/recipes/RecipeCard.test.ts

@@ -8,7 +8,7 @@ const mockRecipe = {
 	name: 'Spaghetti Bolognese',
 	cookTimeMin: 30,
 	effort: 'Easy',
-	heroImageUrl: undefined
+	heroImagePreview: undefined
 };
 
 describe('RecipeCard', () => {
@@ -27,18 +27,18 @@ describe('RecipeCard', () => {
 		expect(screen.getByText(/easy/i)).toBeInTheDocument();
 	});
 
-	it('shows placeholder when no heroImageUrl', () => {
+	it('shows placeholder when no heroImagePreview', () => {
-		render(RecipeCard, { props: { recipe: { ...mockRecipe, heroImageUrl: undefined } } });
+		render(RecipeCard, { props: { recipe: { ...mockRecipe, heroImagePreview: undefined } } });
 		expect(screen.queryByRole('img')).not.toBeInTheDocument();
 		expect(document.querySelector('[data-testid="image-placeholder"]')).toBeInTheDocument();
 	});
 
-	it('shows image when heroImageUrl is provided', () => {
+	it('shows image when heroImagePreview is provided', () => {
 		render(RecipeCard, {
-			props: { recipe: { ...mockRecipe, heroImageUrl: '/uploads/test.jpg' } }
+			props: { recipe: { ...mockRecipe, heroImagePreview: 'data:image/jpeg;base64,abc' } }
 		});
 		const img = screen.getByRole('img');
-		expect(img).toHaveAttribute('src', '/uploads/test.jpg');
+		expect(img).toHaveAttribute('src', 'data:image/jpeg;base64,abc');
 		expect(img).toHaveAttribute('alt', 'Spaghetti Bolognese');
 	});
 

frontend/src/lib/recipes/RecipeForm.svelte

@@ -61,10 +61,19 @@
 	);
 	let steps = $state(initial?.steps.map((s) => s.instruction) ?? ['']);
 	let heroImageUrl = $state<string | null>(initial?.heroImageUrl ?? null);
+	let imageError = $state<string | null>(null);
+
+	const MAX_IMAGE_BYTES = 5 * 1024 * 1024;
 
 	function handleImageChange(e: Event) {
 		const file = (e.currentTarget as HTMLInputElement).files?.[0];
 		if (!file) return;
+		if (file.size > MAX_IMAGE_BYTES) {
+			imageError = 'Datei zu groß. Maximal 5 MB erlaubt.';
+			(e.currentTarget as HTMLInputElement).value = '';
+			return;
+		}
+		imageError = null;
 		const reader = new FileReader();
 		reader.onload = () => {
 			heroImageUrl = reader.result as string;
@@ -196,6 +205,11 @@
 					/>
 					{heroImageUrl ? 'Bild ändern' : 'Bild hochladen'}
 				</label>
+				{#if imageError}
+					<p class="mt-[6px] text-[12px] text-[var(--color-error)]">{imageError}</p>
+				{:else}
+					<p class="mt-[6px] text-[11px] text-[var(--color-text-muted)]">Max. 5 MB</p>
+				{/if}
 				<input type="hidden" name="heroImageUrl" value={heroImageUrl ?? ''} />
 			</div>
 

frontend/src/lib/recipes/RecipeForm.test.ts

@@ -29,7 +29,7 @@ const editProps = {
 		name: 'Spaghetti Bolognese',
 		serves: 4,
 		cookTimeMin: 30,
-		effort: 'Medium',
+		effort: 'medium',
 		heroImageUrl: undefined as string | undefined,
 		ingredients: [
 			{ name: 'Spaghetti', quantity: 200, unit: 'g' }
@@ -162,4 +162,31 @@ describe('RecipeForm', () => {
 		render(RecipeForm, { props: emptyProps });
 		expect(screen.queryByRole('alert')).not.toBeInTheDocument();
 	});
+
+	it('shows Max. 5 MB hint below upload button', () => {
+		render(RecipeForm, { props: emptyProps });
+		expect(screen.getByText('Max. 5 MB')).toBeInTheDocument();
+	});
+
+	it('shows error when selected file exceeds 5 MB', async () => {
+		const user = userEvent.setup();
+		render(RecipeForm, { props: emptyProps });
+
+		const oversizedFile = new File(['x'.repeat(6 * 1024 * 1024)], 'big.jpg', { type: 'image/jpeg' });
+		const fileInput = document.querySelector('input[type="file"]') as HTMLInputElement;
+		await user.upload(fileInput, oversizedFile);
+
+		expect(screen.getByText(/datei zu groß/i)).toBeInTheDocument();
+	});
+
+	it('does not show file size error for file within 5 MB', async () => {
+		const user = userEvent.setup();
+		render(RecipeForm, { props: emptyProps });
+
+		const okFile = new File(['x'.repeat(1 * 1024 * 1024)], 'small.jpg', { type: 'image/jpeg' });
+		const fileInput = document.querySelector('input[type="file"]') as HTMLInputElement;
+		await user.upload(fileInput, okFile);
+
+		expect(screen.queryByText(/datei zu groß/i)).not.toBeInTheDocument();
+	});
 });

frontend/src/lib/recipes/types.ts

@@ -3,7 +3,7 @@ export type RecipeSummary = {
 	name: string;
 	cookTimeMin?: number;
 	effort?: string;
-	heroImageUrl?: string;
+	heroImagePreview?: string;
 };
 
 export type Tag = {

frontend/src/routes/(app)/recipes/+page.server.ts

@@ -20,7 +20,7 @@ export const load: PageServerLoad = async ({ fetch }) => {
 					name: r.name!,
 					cookTimeMin: r.cookTimeMin,
 					effort: r.effort,
-					heroImageUrl: r.heroImageUrl
+					heroImagePreview: r.heroImagePreview
 				}));
 
 	const activePlan =

frontend/src/routes/(app)/recipes/[id]/edit/+page.server.ts

@@ -72,15 +72,15 @@ export const actions: Actions = {
 			params: { path: { id: params.id } },
 			body: {
 				name: name.trim(),
-				serves: serves ? Number(serves) || undefined : undefined,
+				serves: serves ? Number(serves) || null : null,
-				cookTimeMin: cookTimeMin ? Number(cookTimeMin) || undefined : undefined,
+				cookTimeMin: cookTimeMin ? Number(cookTimeMin) || null : null,
 				effort,
 				heroImageUrl,
 				ingredients: (parsedIngredients as { name: string; quantity: string; unit: string }[])
-					.filter((ing) => ing.name?.trim())
+					.filter((ing) => ing.name?.trim() && Number(ing.quantity) > 0)
 					.map((ing, i) => ({
 						newIngredientName: ing.name.trim(),
-						quantity: Number(ing.quantity) || 0,
+						quantity: Number(ing.quantity),
 						unit: ing.unit || '',
 						sortOrder: i
 					})),

frontend/src/routes/(app)/recipes/[id]/edit/page.server.test.ts

@@ -178,6 +178,19 @@ describe('edit recipe page — update action', () => {
 		}));
 	});
 
+	it('sends null for serves and cookTimeMin when fields are blank', async () => {
+		mockPut.mockResolvedValue({ error: undefined });
+		const fd = makeFormData({ serves: '', cookTimeMin: '' });
+		await actions.update({
+			request: { formData: async () => fd },
+			fetch: vi.fn(),
+			params: { id: 'r1' }
+		} as any).catch(() => {});
+		const body = mockPut.mock.calls[0][1].body;
+		expect(body.serves).toBeNull();
+		expect(body.cookTimeMin).toBeNull();
+	});
+
 	it('sends heroImageUrl in PUT body when provided', async () => {
 		mockPut.mockResolvedValue({ error: undefined });
 		const fd = makeFormData({ heroImageUrl: 'data:image/jpeg;base64,abc123' });
@@ -204,6 +217,25 @@ describe('edit recipe page — update action', () => {
 		}));
 	});
 
+	it('filters out ingredients with quantity <= 0 before PUT', async () => {
+		mockPut.mockResolvedValue({ error: undefined });
+		const fd = makeFormData({
+			ingredientsJson: JSON.stringify([
+				{ name: 'Spaghetti', quantity: 200, unit: 'g' },
+				{ name: 'Salt', quantity: 0, unit: 'tsp' },
+				{ name: 'Pepper', quantity: -1, unit: 'tsp' }
+			])
+		});
+		await actions.update({
+			request: { formData: async () => fd },
+			fetch: vi.fn(),
+			params: { id: 'r1' }
+		} as any).catch(() => {});
+		const body = mockPut.mock.calls[0][1].body;
+		expect(body.ingredients).toHaveLength(1);
+		expect(body.ingredients[0].newIngredientName).toBe('Spaghetti');
+	});
+
 	it('returns fail(500) when API returns error', async () => {
 		mockPut.mockResolvedValue({ error: { status: 500 } });
 		const result = await actions.update({

frontend/src/routes/(app)/recipes/new/+page.server.ts

@@ -44,15 +44,15 @@ export const actions: Actions = {
 		const { error: apiError } = await api.POST('/v1/recipes', {
 			body: {
 				name: name.trim(),
-				serves: serves ? Number(serves) || undefined : undefined,
+				serves: serves ? Number(serves) || null : null,
-				cookTimeMin: cookTimeMin ? Number(cookTimeMin) || undefined : undefined,
+				cookTimeMin: cookTimeMin ? Number(cookTimeMin) || null : null,
 				effort,
 				heroImageUrl,
 				ingredients: (parsedIngredients as { name: string; quantity: string; unit: string }[])
-					.filter((ing) => ing.name?.trim())
+					.filter((ing) => ing.name?.trim() && Number(ing.quantity) > 0)
 					.map((ing, i) => ({
 						newIngredientName: ing.name.trim(),
-						quantity: Number(ing.quantity) || 0,
+						quantity: Number(ing.quantity),
 						unit: ing.unit || '',
 						sortOrder: i
 					})),

frontend/src/routes/(app)/recipes/new/page.server.test.ts

@@ -145,6 +145,15 @@ describe('new recipe page — create action', () => {
 		expect(mockPost).toHaveBeenCalledWith('/v1/recipes', expect.objectContaining({ body: expect.objectContaining({ name: 'Test Rezept', effort: 'easy' }) }));
 	});
 
+	it('sends null for serves and cookTimeMin when fields are blank', async () => {
+		mockPost.mockResolvedValue({ error: undefined });
+		const fd = makeFormData({ serves: '', cookTimeMin: '' });
+		await actions.create({ request: { formData: async () => fd }, fetch: vi.fn() } as any).catch(() => {});
+		const body = mockPost.mock.calls[0][1].body;
+		expect(body.serves).toBeNull();
+		expect(body.cookTimeMin).toBeNull();
+	});
+
 	it('sends heroImageUrl in POST body when provided', async () => {
 		mockPost.mockResolvedValue({ error: undefined });
 		const fd = makeFormData({ heroImageUrl: 'data:image/jpeg;base64,abc123' });
@@ -163,6 +172,23 @@ describe('new recipe page — create action', () => {
 		}));
 	});
 
+	it('filters out ingredients with quantity <= 0 before POST', async () => {
+		mockPost.mockResolvedValue({ error: undefined });
+		const fd = makeFormData({
+			ingredientsJson: JSON.stringify([
+				{ name: 'Spaghetti', quantity: 200, unit: 'g' },
+				{ name: 'Salt', quantity: 0, unit: 'tsp' },
+				{ name: 'Pepper', quantity: -1, unit: 'tsp' }
+			])
+		});
+		await actions.create({ request: { formData: async () => fd }, fetch: vi.fn() } as any).catch(
+			() => {}
+		);
+		const body = mockPost.mock.calls[0][1].body;
+		expect(body.ingredients).toHaveLength(1);
+		expect(body.ingredients[0].newIngredientName).toBe('Spaghetti');
+	});
+
 	it('returns fail(500) when API returns error', async () => {
 		mockPost.mockResolvedValue({ error: { status: 500 } });
 		const result = await actions.create({

frontend/src/routes/(app)/recipes/page.test.ts

@@ -5,9 +5,9 @@ import Page from './+page.svelte';
 
 const mockData = {
 	recipes: [
-		{ id: 'r1', name: 'Spaghetti Bolognese', cookTimeMin: 30, effort: 'Easy' },
+		{ id: 'r1', name: 'Spaghetti Bolognese', cookTimeMin: 30, effort: 'easy' },
-		{ id: 'r2', name: 'Chicken Curry', cookTimeMin: 45, effort: 'Medium' },
+		{ id: 'r2', name: 'Chicken Curry', cookTimeMin: 45, effort: 'medium' },
-		{ id: 'r3', name: 'Gemüsesuppe', cookTimeMin: 20, effort: 'Easy' }
+		{ id: 'r3', name: 'Gemüsesuppe', cookTimeMin: 20, effort: 'easy' }
 	],
 	activePlan: null
 };