Merge pull request 'feat: fruit overview with thumbnails and card layout (story #07)' (#7) from feature/07-improve-fruit-overview into main

Reviewed-on: #7

backend/cmd/server/router.go

@@ -39,6 +39,7 @@ func New(pool *pgxpool.Pool) *echo.Echo {
 	g.GET("/:id/images", fruits.ListImages)
 	g.POST("/:id/images", fruits.UploadImage, middleware.BodyLimit("5M"))
 	g.GET("/:id/images/:imageId", fruits.ServeImage)
+	g.GET("/:id/images/:imageId/thumbnail", fruits.ServeThumbnail)
 	g.DELETE("/:id/images/:imageId", fruits.DeleteImage)
 
 	// Publications (story #04)
@@ -68,7 +69,13 @@ func New(pool *pgxpool.Pool) *echo.Echo {
 	p.GET("/:id/fruit-images", pubs.ListFruitImages)
 	p.POST("/:id/fruit-images", pubs.UploadFruitImage, middleware.BodyLimit("5M"))
 	p.GET("/:id/fruit-images/:imgId", pubs.ServeFruitImage)
+	p.GET("/:id/fruit-images/:imgId/thumbnail", pubs.ServeFruitImageThumbnail)
 	p.DELETE("/:id/fruit-images/:imgId", pubs.DeleteFruitImage)
 
+	// Admin (story #07)
+	admin := handler.NewAdminHandler(fruitRepo, pubRepo)
+	adminGroup := api.Group("/admin")
+	adminGroup.POST("/backfill-thumbnails", admin.BackfillThumbnails)
+
 	return e
 }

backend/internal/domain/fruit.go

@@ -11,15 +11,16 @@ var FruitTypeAliases = map[string][]string{
 }
 
 type Fruit struct {
-	ID          int          `json:"id"`
-	Name        string       `json:"name"`
-	OSDBNumber  string       `json:"osdb_number"`
-	Comment     *string      `json:"comment"`
-	FruitType   string       `json:"fruit_type"`
-	Synonyms    []string     `json:"synonyms"`
-	Images      []FruitImage `json:"images"`
-	CreatedAt   time.Time    `json:"created_at"`
-	UpdatedAt   time.Time    `json:"updated_at"`
+	ID           int          `json:"id"`
+	Name         string       `json:"name"`
+	OSDBNumber   string       `json:"osdb_number"`
+	Comment      *string      `json:"comment"`
+	FruitType    string       `json:"fruit_type"`
+	Synonyms     []string     `json:"synonyms"`
+	Images       []FruitImage `json:"images"`
+	ThumbnailURL *string      `json:"thumbnail_url"`
+	CreatedAt    time.Time    `json:"created_at"`
+	UpdatedAt    time.Time    `json:"updated_at"`
 }
 
 type FruitImage struct {

backend/internal/handler/admin_handler.go

@@ -0,0 +1,44 @@
+package handler
+
+import (
+	"context"
+	"net/http"
+
+	"github.com/labstack/echo/v4"
+)
+
+type FruitBackfiller interface {
+	BackfillThumbnails(ctx context.Context) (int, error)
+}
+
+type PubBackfiller interface {
+	BackfillThumbnails(ctx context.Context) (int, error)
+}
+
+type AdminHandler struct {
+	fruitRepo FruitBackfiller
+	pubRepo   PubBackfiller
+}
+
+func NewAdminHandler(fruitRepo FruitBackfiller, pubRepo PubBackfiller) *AdminHandler {
+	return &AdminHandler{fruitRepo: fruitRepo, pubRepo: pubRepo}
+}
+
+func (h *AdminHandler) BackfillThumbnails(c echo.Context) error {
+	ctx := c.Request().Context()
+
+	fruitCount, err := h.fruitRepo.BackfillThumbnails(ctx)
+	if err != nil {
+		return c.JSON(http.StatusInternalServerError, map[string]string{"error": "backfill failed: " + err.Error()})
+	}
+
+	pubCount, err := h.pubRepo.BackfillThumbnails(ctx)
+	if err != nil {
+		return c.JSON(http.StatusInternalServerError, map[string]string{"error": "backfill failed: " + err.Error()})
+	}
+
+	return c.JSON(http.StatusOK, map[string]int{
+		"fruit_images_processed":       fruitCount,
+		"pub_fruit_images_processed":   pubCount,
+	})
+}

backend/internal/handler/fruit_handler.go

@@ -29,6 +29,7 @@ type FruitRepository interface {
 	ListImages(ctx context.Context, fruitID int) ([]domain.FruitImage, error)
 	AddImage(ctx context.Context, fruitID int, filename *string, data []byte, imageType string, title *string) (domain.FruitImage, error)
 	GetImageData(ctx context.Context, fruitID, imageID int) ([]byte, error)
+	GetThumbnailData(ctx context.Context, fruitID, imageID int) ([]byte, error)
 	DeleteImage(ctx context.Context, fruitID, imageID int) error
 }
 
@@ -291,3 +292,20 @@ func (h *FruitHandler) DeleteImage(c echo.Context) error {
 	}
 	return c.NoContent(http.StatusNoContent)
 }
+
+func (h *FruitHandler) ServeThumbnail(c echo.Context) error {
+	fruitID, err := parseID(c, "id")
+	if err != nil {
+		return err
+	}
+	imageID, err := parseID(c, "imageId")
+	if err != nil {
+		return err
+	}
+	data, err := h.repo.GetThumbnailData(c.Request().Context(), fruitID, imageID)
+	if err != nil {
+		return mapRepoError(c, err)
+	}
+	contentType := http.DetectContentType(data)
+	return c.Blob(http.StatusOK, contentType, data)
+}

backend/internal/handler/fruit_handler_test.go

@@ -194,6 +194,14 @@ func (r *fakeRepo) GetImageData(_ context.Context, fruitID, imageID int) ([]byte
 	return r.imageData[imageID], nil
 }
 
+func (r *fakeRepo) GetThumbnailData(_ context.Context, fruitID, imageID int) ([]byte, error) {
+	img, ok := r.images[imageID]
+	if !ok || img.FruitID != fruitID {
+		return nil, handler.ErrNotFound
+	}
+	return r.imageData[imageID], nil
+}
+
 func (r *fakeRepo) DeleteImage(_ context.Context, fruitID, imageID int) error {
 	img, ok := r.images[imageID]
 	if !ok || img.FruitID != fruitID {

backend/internal/handler/publication_handler.go

@@ -42,6 +42,7 @@ type PublicationRepository interface {
 	ListFruitImages(ctx context.Context, pubID int) ([]domain.PublicationFruitImage, error)
 	AddFruitImage(ctx context.Context, pubID, fruitID int, filename *string, data []byte) (domain.PublicationFruitImage, error)
 	GetFruitImageData(ctx context.Context, pubID, imgID int) ([]byte, error)
+	GetFruitImageThumbnailData(ctx context.Context, pubID, imgID int) ([]byte, error)
 	DeleteFruitImage(ctx context.Context, pubID, imgID int) error
 
 	GetFruitDescriptions(ctx context.Context, fruitID int) ([]domain.PublicationDescription, error)
@@ -386,6 +387,23 @@ func (h *PublicationHandler) ServeFruitImage(c echo.Context) error {
 	return c.Blob(http.StatusOK, contentType, data)
 }
 
+func (h *PublicationHandler) ServeFruitImageThumbnail(c echo.Context) error {
+	pubID, err := parseID(c, "id")
+	if err != nil {
+		return err
+	}
+	imgID, err := parseID(c, "imgId")
+	if err != nil {
+		return err
+	}
+	data, err := h.repo.GetFruitImageThumbnailData(c.Request().Context(), pubID, imgID)
+	if err != nil {
+		return mapPubRepoError(c, err)
+	}
+	contentType := http.DetectContentType(data)
+	return c.Blob(http.StatusOK, contentType, data)
+}
+
 func (h *PublicationHandler) DeleteFruitImage(c echo.Context) error {
 	pubID, err := parseID(c, "id")
 	if err != nil {

backend/internal/handler/publication_handler_test.go

@@ -265,6 +265,14 @@ func (r *fakePubRepo) GetFruitImageData(_ context.Context, pubID, imgID int) ([]
 	return r.fruitImgData[imgID], nil
 }
 
+func (r *fakePubRepo) GetFruitImageThumbnailData(_ context.Context, pubID, imgID int) ([]byte, error) {
+	img, ok := r.fruitImages[imgID]
+	if !ok || img.PublicationID != pubID {
+		return nil, handler.ErrNotFound
+	}
+	return r.fruitImgData[imgID], nil
+}
+
 func (r *fakePubRepo) DeleteFruitImage(_ context.Context, pubID, imgID int) error {
 	img, ok := r.fruitImages[imgID]
 	if !ok || img.PublicationID != pubID {

backend/internal/imaging/crop.go

@@ -0,0 +1,137 @@
+package imaging
+
+import (
+	"bytes"
+	"image"
+	"image/color"
+	"image/draw"
+	"image/jpeg"
+	_ "image/png"
+)
+
+const (
+	bgThreshold = 10
+	padding     = 5
+	maxDim      = 300
+)
+
+// CropToContent auto-crops src to the bounding box of non-background pixels,
+// adds padding, scales to fit within maxDim×maxDim, and re-encodes as JPEG.
+// Returns the original bytes unchanged if decoding fails.
+func CropToContent(src []byte) ([]byte, error) {
+	img, _, err := image.Decode(bytes.NewReader(src))
+	if err != nil {
+		return src, nil
+	}
+
+	bounds := img.Bounds()
+	if bounds.Dx() == 0 || bounds.Dy() == 0 {
+		return src, nil
+	}
+
+	bgColor := img.At(bounds.Min.X, bounds.Min.Y)
+
+	minX, minY, maxX, maxY := findContentBounds(img, bgColor, bounds)
+	if minX > maxX || minY > maxY {
+		return src, nil
+	}
+
+	minX = max(bounds.Min.X, minX-padding)
+	minY = max(bounds.Min.Y, minY-padding)
+	maxX = min(bounds.Max.X-1, maxX+padding)
+	maxY = min(bounds.Max.Y-1, maxY+padding)
+
+	cropRect := image.Rect(minX, minY, maxX+1, maxY+1)
+	cropped := cropImage(img, cropRect)
+	scaled := scaleDown(cropped)
+
+	var buf bytes.Buffer
+	if err := jpeg.Encode(&buf, scaled, &jpeg.Options{Quality: 85}); err != nil {
+		return src, nil
+	}
+	return buf.Bytes(), nil
+}
+
+func findContentBounds(img image.Image, bg color.Color, bounds image.Rectangle) (minX, minY, maxX, maxY int) {
+	minX = bounds.Max.X
+	minY = bounds.Max.Y
+	maxX = bounds.Min.X - 1
+	maxY = bounds.Min.Y - 1
+
+	for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
+		for x := bounds.Min.X; x < bounds.Max.X; x++ {
+			if channelDiff(img.At(x, y), bg) > bgThreshold {
+				if x < minX {
+					minX = x
+				}
+				if y < minY {
+					minY = y
+				}
+				if x > maxX {
+					maxX = x
+				}
+				if y > maxY {
+					maxY = y
+				}
+			}
+		}
+	}
+	return
+}
+
+func channelDiff(c1, c2 color.Color) int {
+	r1, g1, b1, _ := c1.RGBA()
+	r2, g2, b2, _ := c2.RGBA()
+	dr := abs(int(r1>>8) - int(r2>>8))
+	dg := abs(int(g1>>8) - int(g2>>8))
+	db := abs(int(b1>>8) - int(b2>>8))
+	return max(dr, max(dg, db))
+}
+
+func abs(x int) int {
+	if x < 0 {
+		return -x
+	}
+	return x
+}
+
+type subImager interface {
+	SubImage(r image.Rectangle) image.Image
+}
+
+func cropImage(img image.Image, rect image.Rectangle) image.Image {
+	if si, ok := img.(subImager); ok {
+		return si.SubImage(rect)
+	}
+	dst := image.NewRGBA(image.Rect(0, 0, rect.Dx(), rect.Dy()))
+	draw.Draw(dst, dst.Bounds(), img, rect.Min, draw.Src)
+	return dst
+}
+
+func scaleDown(img image.Image) image.Image {
+	bounds := img.Bounds()
+	w, h := bounds.Dx(), bounds.Dy()
+	if w <= maxDim && h <= maxDim {
+		return img
+	}
+
+	scaleW := float64(maxDim) / float64(w)
+	scaleH := float64(maxDim) / float64(h)
+	scale := scaleW
+	if scaleH < scale {
+		scale = scaleH
+	}
+
+	newW := max(1, int(float64(w)*scale))
+	newH := max(1, int(float64(h)*scale))
+
+	dst := image.NewRGBA(image.Rect(0, 0, newW, newH))
+	for y := 0; y < newH; y++ {
+		for x := 0; x < newW; x++ {
+			srcX := bounds.Min.X + int(float64(x)/scale)
+			srcY := bounds.Min.Y + int(float64(y)/scale)
+			dst.Set(x, y, img.At(srcX, srcY))
+		}
+	}
+	return dst
+}

backend/internal/imaging/crop_test.go

@@ -0,0 +1,153 @@
+package imaging_test
+
+import (
+	"bytes"
+	"image"
+	"image/color"
+	"image/jpeg"
+	"image/png"
+	"testing"
+
+	"osdb/internal/imaging"
+)
+
+func makeWhitePNG(w, h int) []byte {
+	img := image.NewRGBA(image.Rect(0, 0, w, h))
+	for y := 0; y < h; y++ {
+		for x := 0; x < w; x++ {
+			img.Set(x, y, color.White)
+		}
+	}
+	var buf bytes.Buffer
+	_ = png.Encode(&buf, img)
+	return buf.Bytes()
+}
+
+func makeContentPNG(w, h, contentX, contentY, contentW, contentH int) []byte {
+	img := image.NewRGBA(image.Rect(0, 0, w, h))
+	for y := 0; y < h; y++ {
+		for x := 0; x < w; x++ {
+			img.Set(x, y, color.White)
+		}
+	}
+	for y := contentY; y < contentY+contentH; y++ {
+		for x := contentX; x < contentX+contentW; x++ {
+			img.Set(x, y, color.RGBA{R: 100, G: 50, B: 30, A: 255})
+		}
+	}
+	var buf bytes.Buffer
+	_ = png.Encode(&buf, img)
+	return buf.Bytes()
+}
+
+func imageDims(data []byte) (int, int) {
+	img, _, err := image.Decode(bytes.NewReader(data))
+	if err != nil {
+		return 0, 0
+	}
+	b := img.Bounds()
+	return b.Dx(), b.Dy()
+}
+
+func TestCropToContent_InvalidData(t *testing.T) {
+	result, err := imaging.CropToContent([]byte("not an image"))
+	if err != nil {
+		t.Fatalf("expected no error, got %v", err)
+	}
+	if !bytes.Equal(result, []byte("not an image")) {
+		t.Error("expected original bytes returned on decode failure")
+	}
+}
+
+func TestCropToContent_AllBackground(t *testing.T) {
+	src := makeWhitePNG(100, 100)
+	result, err := imaging.CropToContent(src)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if len(result) == 0 {
+		t.Error("expected non-empty result")
+	}
+}
+
+func TestCropToContent_CropsToContent(t *testing.T) {
+	// 200x200 white image with a 20x20 content block at (80,80)
+	src := makeContentPNG(200, 200, 80, 80, 20, 20)
+	result, err := imaging.CropToContent(src)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	w, h := imageDims(result)
+	if w >= 200 || h >= 200 {
+		t.Errorf("expected smaller result, got %dx%d", w, h)
+	}
+}
+
+func TestCropToContent_PreservesContentWithPadding(t *testing.T) {
+	// 200x200 white image with a 30x30 red block at (85,85)
+	src := makeContentPNG(200, 200, 85, 85, 30, 30)
+	result, err := imaging.CropToContent(src)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	// Result should be smaller than original but include padding
+	w, h := imageDims(result)
+	if w == 0 || h == 0 {
+		t.Error("expected valid image dimensions")
+	}
+	if w >= 200 || h >= 200 {
+		t.Errorf("expected crop, got %dx%d", w, h)
+	}
+}
+
+func TestCropToContent_ScalesDownLargeImage(t *testing.T) {
+	// 600x600 image with content filling most of it
+	src := makeContentPNG(600, 600, 10, 10, 580, 580)
+	result, err := imaging.CropToContent(src)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	w, h := imageDims(result)
+	if w > 300 || h > 300 {
+		t.Errorf("expected scale-down to ≤300, got %dx%d", w, h)
+	}
+}
+
+func TestCropToContent_ReturnsJPEG(t *testing.T) {
+	src := makeContentPNG(100, 100, 20, 20, 60, 60)
+	result, err := imaging.CropToContent(src)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	// JPEG magic bytes: FF D8 FF
+	if len(result) < 3 || result[0] != 0xFF || result[1] != 0xD8 {
+		// Check if we got back original (all-background case returns src)
+		if !bytes.Equal(result, src) {
+			t.Error("expected JPEG output")
+		}
+	}
+}
+
+func TestCropToContent_JPEGInput(t *testing.T) {
+	// Create a JPEG input
+	img := image.NewRGBA(image.Rect(0, 0, 100, 100))
+	for y := 0; y < 100; y++ {
+		for x := 0; x < 100; x++ {
+			if x > 20 && x < 80 && y > 20 && y < 80 {
+				img.Set(x, y, color.RGBA{R: 200, G: 100, B: 50, A: 255})
+			} else {
+				img.Set(x, y, color.White)
+			}
+		}
+	}
+	var buf bytes.Buffer
+	_ = jpeg.Encode(&buf, img, nil)
+
+	result, err := imaging.CropToContent(buf.Bytes())
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if len(result) == 0 {
+		t.Error("expected non-empty result")
+	}
+}

backend/internal/repository/fruit_repo.go

@@ -12,6 +12,7 @@ import (
 
 	"osdb/internal/domain"
 	"osdb/internal/handler"
+	"osdb/internal/imaging"
 )
 
 type FruitRepo struct {
@@ -26,6 +27,10 @@ func imageURL(fruitID, imageID int) string {
 	return fmt.Sprintf("/api/v1/fruits/%d/images/%d", fruitID, imageID)
 }
 
+func thumbnailURL(fruitID, imageID int) string {
+	return fmt.Sprintf("/api/v1/fruits/%d/images/%d/thumbnail", fruitID, imageID)
+}
+
 func mapPgError(err error) error {
 	var pgErr *pgconn.PgError
 	if errors.As(err, &pgErr) && pgErr.Code == "23505" {
@@ -56,7 +61,14 @@ func (r *FruitRepo) List(ctx context.Context, limit, offset int, name string, ty
 	}
 
 	rows, err := r.pool.Query(ctx,
-		`SELECT DISTINCT f.id, f.name, f.osdb_number, f.comment, f.fruit_type, f.created_at, f.updated_at
+		`SELECT DISTINCT f.id, f.name, f.osdb_number, f.comment, f.fruit_type, f.created_at, f.updated_at,
+		        COALESCE((SELECT array_agg(fs2.synonym ORDER BY fs2.id) FROM fruit_synonyms fs2 WHERE fs2.fruit_id = f.id), '{}') AS synonyms,
+		        COALESCE(
+		          (SELECT '/api/v1/fruits/' || f.id || '/images/' || fi.id || '/thumbnail'
+		           FROM fruit_images fi WHERE fi.fruit_id = f.id AND fi.image_type = 'fruit' ORDER BY fi.id LIMIT 1),
+		          (SELECT '/api/v1/publications/' || pfi.publication_id || '/fruit-images/' || pfi.id || '/thumbnail'
+		           FROM publication_fruit_images pfi WHERE pfi.fruit_id = f.id ORDER BY pfi.id LIMIT 1)
+		        ) AS thumbnail_url
 		 FROM fruits f
 		 LEFT JOIN fruit_synonyms fs ON fs.fruit_id = f.id
 		 WHERE ($1 = '' OR f.name ILIKE '%' || $1 || '%' ESCAPE '\' OR fs.synonym ILIKE '%' || $1 || '%' ESCAPE '\')
@@ -71,10 +83,13 @@ func (r *FruitRepo) List(ctx context.Context, limit, offset int, name string, ty
 	fruits := []domain.Fruit{}
 	for rows.Next() {
 		var f domain.Fruit
-		if err := rows.Scan(&f.ID, &f.Name, &f.OSDBNumber, &f.Comment, &f.FruitType, &f.CreatedAt, &f.UpdatedAt); err != nil {
+		if err := rows.Scan(&f.ID, &f.Name, &f.OSDBNumber, &f.Comment, &f.FruitType, &f.CreatedAt, &f.UpdatedAt,
+			&f.Synonyms, &f.ThumbnailURL); err != nil {
 			return nil, 0, err
 		}
-		f.Synonyms = []string{}
+		if f.Synonyms == nil {
+			f.Synonyms = []string{}
+		}
 		f.Images = []domain.FruitImage{}
 		fruits = append(fruits, f)
 	}
@@ -264,7 +279,6 @@ func (r *FruitRepo) ListImages(ctx context.Context, fruitID int) ([]domain.Fruit
 }
 
 func (r *FruitRepo) AddImage(ctx context.Context, fruitID int, filename *string, data []byte, imageType string, title *string) (domain.FruitImage, error) {
-	// verify fruit exists
 	var exists bool
 	if err := r.pool.QueryRow(ctx, `SELECT EXISTS(SELECT 1 FROM fruits WHERE id=$1)`, fruitID).Scan(&exists); err != nil {
 		return domain.FruitImage{}, err
@@ -273,12 +287,14 @@ func (r *FruitRepo) AddImage(ctx context.Context, fruitID int, filename *string,
 		return domain.FruitImage{}, handler.ErrNotFound
 	}
 
+	thumbnailData, _ := imaging.CropToContent(data)
+
 	var img domain.FruitImage
 	err := r.pool.QueryRow(ctx,
-		`INSERT INTO fruit_images (fruit_id, filename, data, image_type, title)
-		 VALUES ($1, $2, $3, $4, $5)
+		`INSERT INTO fruit_images (fruit_id, filename, data, thumbnail_data, image_type, title)
+		 VALUES ($1, $2, $3, $4, $5, $6)
 		 RETURNING id, fruit_id, filename, image_type, title, created_at`,
-		fruitID, filename, data, imageType, title).
+		fruitID, filename, data, thumbnailData, imageType, title).
 		Scan(&img.ID, &img.FruitID, &img.Filename, &img.ImageType, &img.Title, &img.CreatedAt)
 	if err != nil {
 		return domain.FruitImage{}, err
@@ -300,6 +316,24 @@ func (r *FruitRepo) GetImageData(ctx context.Context, fruitID, imageID int) ([]b
 	return data, nil
 }
 
+// GetThumbnailData returns thumbnail_data if present, falls back to data.
+func (r *FruitRepo) GetThumbnailData(ctx context.Context, fruitID, imageID int) ([]byte, error) {
+	var thumbnailData, data []byte
+	err := r.pool.QueryRow(ctx,
+		`SELECT thumbnail_data, data FROM fruit_images WHERE id=$1 AND fruit_id=$2`, imageID, fruitID).
+		Scan(&thumbnailData, &data)
+	if errors.Is(err, pgx.ErrNoRows) {
+		return nil, handler.ErrNotFound
+	}
+	if err != nil {
+		return nil, err
+	}
+	if len(thumbnailData) > 0 {
+		return thumbnailData, nil
+	}
+	return data, nil
+}
+
 func (r *FruitRepo) DeleteImage(ctx context.Context, fruitID, imageID int) error {
 	tag, err := r.pool.Exec(ctx, `DELETE FROM fruit_images WHERE id=$1 AND fruit_id=$2`, imageID, fruitID)
 	if err != nil {
@@ -310,3 +344,40 @@ func (r *FruitRepo) DeleteImage(ctx context.Context, fruitID, imageID int) error
 	}
 	return nil
 }
+
+// BackfillThumbnails generates thumbnail_data for all fruit_images rows missing it.
+// Returns count of rows processed.
+func (r *FruitRepo) BackfillThumbnails(ctx context.Context) (int, error) {
+	rows, err := r.pool.Query(ctx, `SELECT id, fruit_id, data FROM fruit_images WHERE thumbnail_data IS NULL`)
+	if err != nil {
+		return 0, err
+	}
+	defer rows.Close()
+
+	type row struct {
+		id, fruitID int
+		data        []byte
+	}
+	var pending []row
+	for rows.Next() {
+		var rw row
+		if err := rows.Scan(&rw.id, &rw.fruitID, &rw.data); err != nil {
+			return 0, err
+		}
+		pending = append(pending, rw)
+	}
+	if err := rows.Err(); err != nil {
+		return 0, err
+	}
+
+	count := 0
+	for _, rw := range pending {
+		thumb, _ := imaging.CropToContent(rw.data)
+		if _, err := r.pool.Exec(ctx,
+			`UPDATE fruit_images SET thumbnail_data=$1 WHERE id=$2`, thumb, rw.id); err != nil {
+			return count, err
+		}
+		count++
+	}
+	return count, nil
+}

backend/internal/repository/publication_repo.go

@@ -10,6 +10,7 @@ import (
 
 	"osdb/internal/domain"
 	"osdb/internal/handler"
+	"osdb/internal/imaging"
 )
 
 type PublicationRepo struct {
@@ -332,12 +333,15 @@ func (r *PublicationRepo) AddFruitImage(ctx context.Context, pubID, fruitID int,
 	if err := r.requirePublication(ctx, pubID); err != nil {
 		return domain.PublicationFruitImage{}, err
 	}
+
+	thumbnailData, _ := imaging.CropToContent(data)
+
 	var img domain.PublicationFruitImage
 	err := r.pool.QueryRow(ctx,
-		`INSERT INTO publication_fruit_images (publication_id, fruit_id, filename, data, image_type)
-		 VALUES ($1, $2, $3, $4, 'fruit')
+		`INSERT INTO publication_fruit_images (publication_id, fruit_id, filename, data, thumbnail_data, image_type)
+		 VALUES ($1, $2, $3, $4, $5, 'fruit')
 		 RETURNING id, publication_id, fruit_id, filename, image_type, created_at`,
-		pubID, fruitID, filename, data).
+		pubID, fruitID, filename, data, thumbnailData).
 		Scan(&img.ID, &img.PublicationID, &img.FruitID, &img.Filename, &img.ImageType, &img.CreatedAt)
 	if err != nil {
 		return domain.PublicationFruitImage{}, err
@@ -357,6 +361,24 @@ func (r *PublicationRepo) GetFruitImageData(ctx context.Context, pubID, imgID in
 	return data, err
 }
 
+// GetFruitImageThumbnailData returns thumbnail_data if present, falls back to data.
+func (r *PublicationRepo) GetFruitImageThumbnailData(ctx context.Context, pubID, imgID int) ([]byte, error) {
+	var thumbnailData, data []byte
+	err := r.pool.QueryRow(ctx,
+		`SELECT thumbnail_data, data FROM publication_fruit_images WHERE id=$1 AND publication_id=$2`,
+		imgID, pubID).Scan(&thumbnailData, &data)
+	if errors.Is(err, pgx.ErrNoRows) {
+		return nil, handler.ErrNotFound
+	}
+	if err != nil {
+		return nil, err
+	}
+	if len(thumbnailData) > 0 {
+		return thumbnailData, nil
+	}
+	return data, nil
+}
+
 func (r *PublicationRepo) DeleteFruitImage(ctx context.Context, pubID, imgID int) error {
 	tag, err := r.pool.Exec(ctx,
 		`DELETE FROM publication_fruit_images WHERE id=$1 AND publication_id=$2`, imgID, pubID)
@@ -426,3 +448,41 @@ func (r *PublicationRepo) requirePublication(ctx context.Context, pubID int) err
 	}
 	return nil
 }
+
+// BackfillThumbnails generates thumbnail_data for all publication_fruit_images rows missing it.
+// Returns count of rows processed.
+func (r *PublicationRepo) BackfillThumbnails(ctx context.Context) (int, error) {
+	rows, err := r.pool.Query(ctx,
+		`SELECT id, data FROM publication_fruit_images WHERE thumbnail_data IS NULL`)
+	if err != nil {
+		return 0, err
+	}
+	defer rows.Close()
+
+	type row struct {
+		id   int
+		data []byte
+	}
+	var pending []row
+	for rows.Next() {
+		var rw row
+		if err := rows.Scan(&rw.id, &rw.data); err != nil {
+			return 0, err
+		}
+		pending = append(pending, rw)
+	}
+	if err := rows.Err(); err != nil {
+		return 0, err
+	}
+
+	count := 0
+	for _, rw := range pending {
+		thumb, _ := imaging.CropToContent(rw.data)
+		if _, err := r.pool.Exec(ctx,
+			`UPDATE publication_fruit_images SET thumbnail_data=$1 WHERE id=$2`, thumb, rw.id); err != nil {
+			return count, err
+		}
+		count++
+	}
+	return count, nil
+}

backend/migrations/000004_add_thumbnails.down.sql

@@ -0,0 +1,2 @@
+ALTER TABLE fruit_images DROP COLUMN thumbnail_data;
+ALTER TABLE publication_fruit_images DROP COLUMN thumbnail_data;

backend/migrations/000004_add_thumbnails.up.sql

@@ -0,0 +1,2 @@
+ALTER TABLE fruit_images ADD COLUMN thumbnail_data BYTEA;
+ALTER TABLE publication_fruit_images ADD COLUMN thumbnail_data BYTEA;

frontend/src/api/fruits.ts

@@ -38,6 +38,7 @@ export interface Fruit {
   fruit_type: string
   synonyms: string[]
   images: FruitImage[]
+  thumbnail_url: string | null
   created_at: string
   updated_at: string
 }

frontend/src/components/FruitCard.vue

@@ -0,0 +1,31 @@
+<script setup lang="ts">
+import { RouterLink } from 'vue-router'
+import type { Fruit } from '../api/fruits'
+
+defineProps<{ fruit: Fruit }>()
+</script>
+
+<template>
+  <RouterLink
+    :to="`/fruits/${fruit.id}`"
+    class="block bg-white border border-gray-200 rounded-lg overflow-hidden hover:shadow-md transition-shadow"
+  >
+    <div class="aspect-[4/3] bg-gray-100 flex items-center justify-center overflow-hidden">
+      <img
+        v-if="fruit.thumbnail_url"
+        :src="fruit.thumbnail_url"
+        :alt="fruit.name"
+        class="max-w-full max-h-full object-contain"
+      />
+      <span v-else class="text-gray-300 text-4xl select-none">🌿</span>
+    </div>
+    <div class="p-3">
+      <p class="font-semibold text-gray-900 truncate">{{ fruit.name }}</p>
+      <p class="text-xs text-gray-500 mt-0.5">{{ fruit.osdb_number }}</p>
+      <p class="text-xs text-green-700 mt-0.5">{{ fruit.fruit_type }}</p>
+      <p v-if="fruit.synonyms.length" class="text-xs text-gray-400 mt-1 truncate">
+        {{ fruit.synonyms.join(', ') }}
+      </p>
+    </div>
+  </RouterLink>
+</template>

frontend/src/stores/fruitStore.test.ts

@@ -11,6 +11,7 @@ const makeFruit = (id: number, name = 'Boskop'): Fruit => ({
   fruit_type: 'Apfelsorten',
   synonyms: [],
   images: [],
+  thumbnail_url: null,
   created_at: '2024-01-01T00:00:00Z',
   updated_at: '2024-01-01T00:00:00Z',
 })

frontend/src/views/FruitList.vue

@@ -2,6 +2,7 @@
 import { onMounted, onUnmounted, computed, ref } from 'vue'
 import { RouterLink } from 'vue-router'
 import { useFruitStore } from '../stores/fruitStore'
+import FruitCard from '../components/FruitCard.vue'
 
 const SEARCH_TYPES = [
   { label: '(Alle)', value: '' },
@@ -105,35 +106,15 @@ function onTypeChange() {
     <div v-if="store.loading" class="text-gray-500">Wird geladen...</div>
     <div v-else-if="store.error" class="text-red-600">{{ store.error }}</div>
     <div v-else>
-      <table class="w-full border-collapse border border-gray-200 rounded">
-        <thead class="bg-gray-50">
-          <tr>
-            <th class="border border-gray-200 px-4 py-2 text-left text-sm font-medium text-gray-700">Name</th>
-            <th class="border border-gray-200 px-4 py-2 text-left text-sm font-medium text-gray-700">OSDB-Kürzel</th>
-            <th class="border border-gray-200 px-4 py-2 text-left text-sm font-medium text-gray-700">Typ</th>
-          </tr>
-        </thead>
-        <tbody>
-          <tr v-if="store.fruits.length === 0">
-            <td colspan="3" class="border border-gray-200 px-4 py-8 text-center text-gray-400">
-              Keine Früchte vorhanden.
-            </td>
-          </tr>
-          <tr
-            v-for="fruit in store.fruits"
-            :key="fruit.id"
-            class="hover:bg-gray-50 cursor-pointer"
-          >
-            <td class="border border-gray-200 px-4 py-2">
-              <RouterLink :to="`/fruits/${fruit.id}`" class="text-green-700 hover:underline">
-                {{ fruit.name }}
-              </RouterLink>
-            </td>
-            <td class="border border-gray-200 px-4 py-2 text-sm text-gray-600">{{ fruit.osdb_number }}</td>
-            <td class="border border-gray-200 px-4 py-2 text-sm text-gray-600">{{ fruit.fruit_type }}</td>
-          </tr>
-        </tbody>
-      </table>
+      <div v-if="store.fruits.length === 0" class="text-center text-gray-400 py-16">
+        Keine Früchte vorhanden.
+      </div>
+      <div
+        v-else
+        class="grid grid-cols-2 sm:grid-cols-3 md:grid-cols-4 lg:grid-cols-5 gap-4"
+      >
+        <FruitCard v-for="fruit in store.fruits" :key="fruit.id" :fruit="fruit" />
+      </div>
 
       <div class="flex items-center justify-between mt-4 text-sm text-gray-600">
         <span>{{ store.total }} Früchte gesamt</span>