test(recipes): verify null preview is stored when compressor returns null

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

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

@@ -604,4 +604,30 @@ class RecipeServiceTest {
 
         assertThat(result).isEmpty();
     }
+
+    @Test
+    void createRecipeShouldStoreNullPreviewWhenCompressorReturnsNull() {
+        var household = testHousehold();
+        when(householdRepository.findById(HOUSEHOLD_ID)).thenReturn(Optional.of(household));
+        when(imageCompressor.compressToPreview(any())).thenReturn(null);
+        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", "data:image/jpeg;base64,abc",
+                List.of(), List.of(), List.of());
+
+        RecipeDetailResponse result = recipeService.createRecipe(HOUSEHOLD_ID, request);
+
+        assertThat(result.id()).isNotNull();
+        // verify the recipe was saved without a preview (compressor returned null)
+        verify(recipeRepository).save(argThat(r -> r.getHeroImagePreview() == null));
+    }
 }