feat: admin image generation via Cloudflare Workers AI

- Add cfai/image.go: ImageGenClient with GenerateImage, GenerateImageFromReference, AllImageModels (9 models)
- Add handlers_image.go: GET /api/admin/image-gen/models + POST /api/admin/image-gen (JSON + multipart)
- Wire ImageGen client in main.go + server.go Dependencies
- Add admin/image-gen SvelteKit page: type toggle, model selector, prompt, reference img2img, advanced options, result panel, history, save-as-cover, download
- Add SvelteKit proxy route api/admin/image-gen forwarding to Go backend
- Add admin_nav_image_gen message key to all 5 locale files
- Add Image Gen nav link to admin layout

backend/cmd/backend/main.go

@@ -124,6 +124,15 @@ func run() error {
 		log.Info("CFAI_ACCOUNT_ID/CFAI_API_TOKEN not set — CF AI voices unavailable in backend")
 	}
 
+	// ── Cloudflare Workers AI Image Generation ────────────────────────────────
+	var imageGenClient cfai.ImageGenClient
+	if cfg.CFAI.AccountID != "" && cfg.CFAI.APIToken != "" {
+		imageGenClient = cfai.NewImageGen(cfg.CFAI.AccountID, cfg.CFAI.APIToken)
+		log.Info("cloudflare AI image generation enabled")
+	} else {
+		log.Info("CFAI_ACCOUNT_ID/CFAI_API_TOKEN not set — image generation unavailable")
+	}
+
 	// ── Meilisearch (search reads only; indexing is the runner's job) ────────
 	var searchIndex meili.Client
 	if cfg.Meilisearch.URL != "" {
@@ -174,6 +183,7 @@ func run() error {
 			Kokoro:           kokoroClient,
 			PocketTTS:        pocketTTSClient,
 			CFAI:             cfaiClient,
+			ImageGen:         imageGenClient,
 			Log:              log,
 		},
 	)

backend/internal/backend/handlers_image.go

@@ -0,0 +1,234 @@
+package backend
+
+import (
+	"encoding/base64"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"strings"
+
+	"github.com/libnovel/backend/internal/cfai"
+)
+
+// handleAdminImageGenModels handles GET /api/admin/image-gen/models.
+// Returns the list of supported Cloudflare AI image generation models.
+func (s *Server) handleAdminImageGenModels(w http.ResponseWriter, r *http.Request) {
+	if s.deps.ImageGen == nil {
+		jsonError(w, http.StatusServiceUnavailable, "image generation not configured (CFAI_ACCOUNT_ID/CFAI_API_TOKEN missing)")
+		return
+	}
+	models := s.deps.ImageGen.Models()
+	writeJSON(w, 0, map[string]any{"models": models})
+}
+
+// imageGenRequest is the JSON body for POST /api/admin/image-gen.
+type imageGenRequest struct {
+	// Prompt is the text description of the desired image.
+	Prompt string `json:"prompt"`
+
+	// Model is the CF Workers AI model ID (e.g. "@cf/black-forest-labs/flux-2-dev").
+	// Defaults to the recommended model for the given type.
+	Model string `json:"model"`
+
+	// Type is either "cover" or "chapter".
+	Type string `json:"type"`
+
+	// Slug is the book slug. Required for cover; required for chapter.
+	Slug string `json:"slug"`
+
+	// Chapter number (1-based). Required when type == "chapter".
+	Chapter int `json:"chapter"`
+
+	// ReferenceImageB64 is an optional base64-encoded PNG/JPEG reference image.
+	// When present the img2img path is used.
+	ReferenceImageB64 string `json:"reference_image_b64"`
+
+	// NumSteps overrides inference steps (default 20).
+	NumSteps int `json:"num_steps"`
+
+	// Width / Height override output dimensions (0 = model default).
+	Width  int `json:"width"`
+	Height int `json:"height"`
+
+	// Guidance overrides prompt guidance scale (0 = model default).
+	Guidance float64 `json:"guidance"`
+
+	// Strength for img2img: 0.0–1.0, default 0.75.
+	Strength float64 `json:"strength"`
+
+	// SaveToCover when true stores the result as the book cover in MinIO
+	// (overwriting any existing cover) and sets the book's cover URL.
+	// Only valid when type == "cover".
+	SaveToCover bool `json:"save_to_cover"`
+}
+
+// imageGenResponse is the JSON body returned by POST /api/admin/image-gen.
+type imageGenResponse struct {
+	// ImageB64 is the generated image as a base64-encoded PNG string.
+	ImageB64 string `json:"image_b64"`
+	// ContentType is "image/png" or "image/jpeg".
+	ContentType string `json:"content_type"`
+	// Saved indicates whether the image was persisted to MinIO.
+	Saved bool `json:"saved"`
+	// CoverURL is the URL the cover is now served from (only set when Saved==true).
+	CoverURL string `json:"cover_url,omitempty"`
+	// Model is the model that was used.
+	Model string `json:"model"`
+	// Bytes is the raw image size in bytes.
+	Bytes int `json:"bytes"`
+}
+
+// handleAdminImageGen handles POST /api/admin/image-gen.
+//
+// Generates an image using Cloudflare Workers AI and optionally stores it.
+// Multipart/form-data is also accepted so the reference image can be uploaded
+// directly; otherwise the reference is expected as base64 JSON.
+func (s *Server) handleAdminImageGen(w http.ResponseWriter, r *http.Request) {
+	if s.deps.ImageGen == nil {
+		jsonError(w, http.StatusServiceUnavailable, "image generation not configured (CFAI_ACCOUNT_ID/CFAI_API_TOKEN missing)")
+		return
+	}
+
+	var req imageGenRequest
+	var refImageData []byte
+
+	ct := r.Header.Get("Content-Type")
+	if strings.HasPrefix(ct, "multipart/form-data") {
+		// Multipart: parse JSON fields from a "json" part + optional "reference" file part.
+		if err := r.ParseMultipartForm(32 << 20); err != nil {
+			jsonError(w, http.StatusBadRequest, "parse multipart: "+err.Error())
+			return
+		}
+		if jsonPart := r.FormValue("json"); jsonPart != "" {
+			if err := json.Unmarshal([]byte(jsonPart), &req); err != nil {
+				jsonError(w, http.StatusBadRequest, "parse json field: "+err.Error())
+				return
+			}
+		}
+		if f, _, err := r.FormFile("reference"); err == nil {
+			defer f.Close()
+			refImageData, _ = io.ReadAll(f)
+		}
+	} else {
+		if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+			jsonError(w, http.StatusBadRequest, "parse body: "+err.Error())
+			return
+		}
+		if req.ReferenceImageB64 != "" {
+			var decErr error
+			refImageData, decErr = base64.StdEncoding.DecodeString(req.ReferenceImageB64)
+			if decErr != nil {
+				// Try std without padding
+				refImageData, decErr = base64.RawStdEncoding.DecodeString(req.ReferenceImageB64)
+				if decErr != nil {
+					jsonError(w, http.StatusBadRequest, "decode reference_image_b64: "+decErr.Error())
+					return
+				}
+			}
+		}
+	}
+
+	if strings.TrimSpace(req.Prompt) == "" {
+		jsonError(w, http.StatusBadRequest, "prompt is required")
+		return
+	}
+	if req.Type != "cover" && req.Type != "chapter" {
+		jsonError(w, http.StatusBadRequest, `type must be "cover" or "chapter"`)
+		return
+	}
+	if req.Slug == "" {
+		jsonError(w, http.StatusBadRequest, "slug is required")
+		return
+	}
+	if req.Type == "chapter" && req.Chapter <= 0 {
+		jsonError(w, http.StatusBadRequest, "chapter must be > 0 when type is chapter")
+		return
+	}
+
+	// Resolve model
+	model := cfai.ImageModel(req.Model)
+	if model == "" {
+		if req.Type == "cover" {
+			model = cfai.DefaultImageModel
+		} else {
+			model = cfai.ImageModelFlux2Klein4B
+		}
+	}
+
+	imgReq := cfai.ImageRequest{
+		Prompt:   req.Prompt,
+		Model:    model,
+		NumSteps: req.NumSteps,
+		Width:    req.Width,
+		Height:   req.Height,
+		Guidance: req.Guidance,
+		Strength: req.Strength,
+	}
+
+	s.deps.Log.Info("admin: image gen requested",
+		"type", req.Type, "slug", req.Slug, "chapter", req.Chapter,
+		"model", model, "has_reference", len(refImageData) > 0)
+
+	var imgData []byte
+	var genErr error
+	if len(refImageData) > 0 {
+		imgData, genErr = s.deps.ImageGen.GenerateImageFromReference(r.Context(), imgReq, refImageData)
+	} else {
+		imgData, genErr = s.deps.ImageGen.GenerateImage(r.Context(), imgReq)
+	}
+	if genErr != nil {
+		s.deps.Log.Error("admin: image gen failed", "err", genErr)
+		jsonError(w, http.StatusBadGateway, "image generation failed: "+genErr.Error())
+		return
+	}
+
+	contentType := sniffImageContentType(imgData)
+
+	// ── Optional persistence ──────────────────────────────────────────────────
+	var saved bool
+	var coverURL string
+
+	if req.SaveToCover && req.Type == "cover" && s.deps.CoverStore != nil {
+		if err := s.deps.CoverStore.PutCover(r.Context(), req.Slug, imgData, contentType); err != nil {
+			s.deps.Log.Error("admin: save generated cover failed", "slug", req.Slug, "err", err)
+			// Non-fatal: still return the image
+		} else {
+			saved = true
+			coverURL = fmt.Sprintf("/api/cover/local/%s", req.Slug)
+			s.deps.Log.Info("admin: generated cover saved", "slug", req.Slug, "bytes", len(imgData))
+		}
+	}
+
+	// Encode result as base64
+	b64 := base64.StdEncoding.EncodeToString(imgData)
+
+	writeJSON(w, 0, imageGenResponse{
+		ImageB64:    b64,
+		ContentType: contentType,
+		Saved:       saved,
+		CoverURL:    coverURL,
+		Model:       string(model),
+		Bytes:       len(imgData),
+	})
+}
+
+// sniffImageContentType returns the MIME type of the image bytes.
+func sniffImageContentType(data []byte) string {
+	if len(data) >= 4 {
+		// PNG: 0x89 P N G
+		if data[0] == 0x89 && data[1] == 0x50 && data[2] == 0x4e && data[3] == 0x47 {
+			return "image/png"
+		}
+		// JPEG: FF D8 FF
+		if data[0] == 0xFF && data[1] == 0xD8 && data[2] == 0xFF {
+			return "image/jpeg"
+		}
+		// WebP: RIFF....WEBP
+		if len(data) >= 12 && data[0] == 'R' && data[1] == 'I' && data[2] == 'F' && data[3] == 'F' &&
+			data[8] == 'W' && data[9] == 'E' && data[10] == 'B' && data[11] == 'P' {
+			return "image/webp"
+		}
+	}
+	return "image/png"
+}

backend/internal/backend/server.go

@@ -73,6 +73,9 @@ type Dependencies struct {
 	// CFAI is the Cloudflare Workers AI TTS client (used for voice sample
 	// generation and audio-stream live TTS; audio task generation is done by the runner).
 	CFAI cfai.Client
+	// ImageGen is the Cloudflare Workers AI image generation client.
+	// If nil, image generation endpoints return 503.
+	ImageGen cfai.ImageGenClient
 	// Log is the structured logger.
 	Log *slog.Logger
 }
@@ -183,6 +186,10 @@ func (s *Server) ListenAndServe(ctx context.Context) error {
 	mux.HandleFunc("POST /api/admin/audio/bulk", s.handleAdminAudioBulk)
 	mux.HandleFunc("POST /api/admin/audio/cancel-bulk", s.handleAdminAudioCancelBulk)
 
+	// Admin image generation endpoints
+	mux.HandleFunc("GET /api/admin/image-gen/models", s.handleAdminImageGenModels)
+	mux.HandleFunc("POST /api/admin/image-gen", s.handleAdminImageGen)
+
 	// Voices list
 	mux.HandleFunc("GET /api/voices", s.handleVoices)
 

backend/internal/cfai/image.go

@@ -0,0 +1,312 @@
+// Image generation via Cloudflare Workers AI text-to-image models.
+//
+// API reference:
+//
+//	POST https://api.cloudflare.com/client/v4/accounts/{accountID}/ai/run/{model}
+//	Authorization: Bearer {apiToken}
+//	Content-Type:  application/json
+//
+// Text-only request (all models):
+//
+//	{ "prompt": "...", "num_steps": 20 }
+//
+// Reference-image request:
+//   - FLUX models: { "prompt": "...", "image_b64": "<base64>" }
+//   - SD img2img:  { "prompt": "...", "image": [r,g,b,a,...], "strength": 0.75 }
+//
+// All models return raw PNG bytes on success (Content-Type: image/png).
+//
+// Recommended models for LibNovel:
+//   - Book covers (no reference): flux-2-dev, flux-2-klein-9b, lucid-origin
+//   - Chapter images (speed):     flux-2-klein-4b, flux-1-schnell
+//   - With reference image:       flux-2-dev, flux-2-klein-9b, sd-v1-5-img2img
+package cfai
+
+import (
+	"bytes"
+	"context"
+	"encoding/base64"
+	"encoding/json"
+	"fmt"
+	"image"
+	_ "image/jpeg" // register JPEG decoder
+	_ "image/png"  // register PNG decoder
+	"io"
+	"net/http"
+	"time"
+)
+
+// ImageModel identifies a Cloudflare Workers AI text-to-image model.
+type ImageModel string
+
+const (
+	// ImageModelFlux2Dev — best quality, multi-reference. Recommended for covers.
+	ImageModelFlux2Dev ImageModel = "@cf/black-forest-labs/flux-2-dev"
+	// ImageModelFlux2Klein9B — 9B params, multi-reference. Good for covers.
+	ImageModelFlux2Klein9B ImageModel = "@cf/black-forest-labs/flux-2-klein-9b"
+	// ImageModelFlux2Klein4B — ultra-fast, unified gen+edit. Recommended for chapters.
+	ImageModelFlux2Klein4B ImageModel = "@cf/black-forest-labs/flux-2-klein-4b"
+	// ImageModelFlux1Schnell — fastest, text-only. Good for quick illustrations.
+	ImageModelFlux1Schnell ImageModel = "@cf/black-forest-labs/flux-1-schnell"
+	// ImageModelSDXLLightning — fast 1024px generation.
+	ImageModelSDXLLightning ImageModel = "@cf/bytedance/stable-diffusion-xl-lightning"
+	// ImageModelSD15Img2Img — explicit img2img with flat RGBA reference.
+	ImageModelSD15Img2Img ImageModel = "@cf/runwayml/stable-diffusion-v1-5-img2img"
+	// ImageModelSDXLBase — Stability AI SDXL base.
+	ImageModelSDXLBase ImageModel = "@cf/stabilityai/stable-diffusion-xl-base-1.0"
+	// ImageModelLucidOrigin — Leonardo AI; strong prompt adherence.
+	ImageModelLucidOrigin ImageModel = "@cf/leonardo/lucid-origin"
+	// ImageModelPhoenix10 — Leonardo AI; accurate text rendering.
+	ImageModelPhoenix10 ImageModel = "@cf/leonardo/phoenix-1.0"
+
+	// DefaultImageModel is the default model for book-cover generation.
+	DefaultImageModel = ImageModelFlux2Dev
+)
+
+// ImageModelInfo describes a single image generation model.
+type ImageModelInfo struct {
+	ID             string   `json:"id"`
+	Label          string   `json:"label"`
+	Provider       string   `json:"provider"`
+	SupportsRef    bool     `json:"supports_ref"`
+	RecommendedFor []string `json:"recommended_for"` // "cover" and/or "chapter"
+	Description    string   `json:"description"`
+}
+
+// AllImageModels returns metadata about every supported image model.
+func AllImageModels() []ImageModelInfo {
+	return []ImageModelInfo{
+		{
+			ID: string(ImageModelFlux2Dev), Label: "FLUX.2 Dev", Provider: "Black Forest Labs",
+			SupportsRef: true, RecommendedFor: []string{"cover"},
+			Description: "Best quality; multi-reference editing. Recommended for book covers.",
+		},
+		{
+			ID: string(ImageModelFlux2Klein9B), Label: "FLUX.2 Klein 9B", Provider: "Black Forest Labs",
+			SupportsRef: true, RecommendedFor: []string{"cover"},
+			Description: "9B parameters with multi-reference support.",
+		},
+		{
+			ID: string(ImageModelFlux2Klein4B), Label: "FLUX.2 Klein 4B", Provider: "Black Forest Labs",
+			SupportsRef: true, RecommendedFor: []string{"chapter"},
+			Description: "Ultra-fast unified gen+edit. Recommended for chapter images.",
+		},
+		{
+			ID: string(ImageModelFlux1Schnell), Label: "FLUX.1 Schnell", Provider: "Black Forest Labs",
+			SupportsRef: false, RecommendedFor: []string{"chapter"},
+			Description: "Fastest inference. Good for quick chapter illustrations.",
+		},
+		{
+			ID: string(ImageModelSDXLLightning), Label: "SDXL Lightning", Provider: "ByteDance",
+			SupportsRef: false, RecommendedFor: []string{"chapter"},
+			Description: "Lightning-fast 1024px images in a few steps.",
+		},
+		{
+			ID: string(ImageModelSD15Img2Img), Label: "SD 1.5 img2img", Provider: "RunwayML",
+			SupportsRef: true, RecommendedFor: []string{"cover", "chapter"},
+			Description: "Explicit img2img: generates from a reference image + prompt.",
+		},
+		{
+			ID: string(ImageModelSDXLBase), Label: "SDXL Base 1.0", Provider: "Stability AI",
+			SupportsRef: false, RecommendedFor: []string{"cover"},
+			Description: "Stable Diffusion XL base model.",
+		},
+		{
+			ID: string(ImageModelLucidOrigin), Label: "Lucid Origin", Provider: "Leonardo AI",
+			SupportsRef: false, RecommendedFor: []string{"cover"},
+			Description: "Highly prompt-responsive; strong graphic design and HD renders.",
+		},
+		{
+			ID: string(ImageModelPhoenix10), Label: "Phoenix 1.0", Provider: "Leonardo AI",
+			SupportsRef: false, RecommendedFor: []string{"cover"},
+			Description: "Exceptional prompt adherence; accurate text rendering.",
+		},
+	}
+}
+
+// ImageRequest is the input to GenerateImage / GenerateImageFromReference.
+type ImageRequest struct {
+	// Prompt is the text description of the desired image.
+	Prompt string
+	// Model is the CF Workers AI model. Defaults to DefaultImageModel when empty.
+	Model ImageModel
+	// NumSteps controls inference quality (default 20). Range: 1–20.
+	NumSteps int
+	// Width and Height in pixels. 0 = model default (typically 1024x1024).
+	Width, Height int
+	// Guidance controls prompt adherence (default 7.5).
+	Guidance float64
+	// Strength for img2img: 0.0 = copy reference, 1.0 = ignore reference (default 0.75).
+	Strength float64
+}
+
+// ImageGenClient generates images via Cloudflare Workers AI.
+type ImageGenClient interface {
+	// GenerateImage creates an image from a text prompt only.
+	// Returns raw PNG bytes.
+	GenerateImage(ctx context.Context, req ImageRequest) ([]byte, error)
+
+	// GenerateImageFromReference creates an image from a text prompt + reference image.
+	// refImage should be PNG or JPEG bytes. Returns raw PNG bytes.
+	GenerateImageFromReference(ctx context.Context, req ImageRequest, refImage []byte) ([]byte, error)
+
+	// Models returns metadata about all supported image models.
+	Models() []ImageModelInfo
+}
+
+// imageGenHTTPClient is the concrete CF AI image generation client.
+type imageGenHTTPClient struct {
+	accountID string
+	apiToken  string
+	http      *http.Client
+}
+
+// NewImageGen returns an ImageGenClient for the given Cloudflare account.
+func NewImageGen(accountID, apiToken string) ImageGenClient {
+	return &imageGenHTTPClient{
+		accountID: accountID,
+		apiToken:  apiToken,
+		http:      &http.Client{Timeout: 5 * time.Minute},
+	}
+}
+
+// GenerateImage generates an image from text only.
+func (c *imageGenHTTPClient) GenerateImage(ctx context.Context, req ImageRequest) ([]byte, error) {
+	req = applyImageDefaults(req)
+	body := map[string]any{
+		"prompt":    req.Prompt,
+		"num_steps": req.NumSteps,
+	}
+	if req.Width > 0 {
+		body["width"] = req.Width
+	}
+	if req.Height > 0 {
+		body["height"] = req.Height
+	}
+	if req.Guidance > 0 {
+		body["guidance"] = req.Guidance
+	}
+	return c.callImageAPI(ctx, req.Model, body)
+}
+
+// GenerateImageFromReference generates an image from a text prompt + reference image.
+func (c *imageGenHTTPClient) GenerateImageFromReference(ctx context.Context, req ImageRequest, refImage []byte) ([]byte, error) {
+	if len(refImage) == 0 {
+		return c.GenerateImage(ctx, req)
+	}
+	req = applyImageDefaults(req)
+
+	var body map[string]any
+	if req.Model == ImageModelSD15Img2Img {
+		pixels, err := decodeImageToRGBA(refImage)
+		if err != nil {
+			return nil, fmt.Errorf("cfai/image: decode reference: %w", err)
+		}
+		strength := req.Strength
+		if strength <= 0 {
+			strength = 0.75
+		}
+		body = map[string]any{
+			"prompt":    req.Prompt,
+			"image":     pixels,
+			"strength":  strength,
+			"num_steps": req.NumSteps,
+		}
+	} else {
+		b64 := base64.StdEncoding.EncodeToString(refImage)
+		body = map[string]any{
+			"prompt":    req.Prompt,
+			"image_b64": b64,
+			"num_steps": req.NumSteps,
+		}
+		if req.Strength > 0 {
+			body["strength"] = req.Strength
+		}
+	}
+	if req.Width > 0 {
+		body["width"] = req.Width
+	}
+	if req.Height > 0 {
+		body["height"] = req.Height
+	}
+	if req.Guidance > 0 {
+		body["guidance"] = req.Guidance
+	}
+	return c.callImageAPI(ctx, req.Model, body)
+}
+
+// Models returns all supported image model metadata.
+func (c *imageGenHTTPClient) Models() []ImageModelInfo {
+	return AllImageModels()
+}
+
+func (c *imageGenHTTPClient) callImageAPI(ctx context.Context, model ImageModel, body map[string]any) ([]byte, error) {
+	encoded, err := json.Marshal(body)
+	if err != nil {
+		return nil, fmt.Errorf("cfai/image: marshal: %w", err)
+	}
+	url := fmt.Sprintf("https://api.cloudflare.com/client/v4/accounts/%s/ai/run/%s",
+		c.accountID, string(model))
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, url, bytes.NewReader(encoded))
+	if err != nil {
+		return nil, fmt.Errorf("cfai/image: build request: %w", err)
+	}
+	req.Header.Set("Authorization", "Bearer "+c.apiToken)
+	req.Header.Set("Content-Type", "application/json")
+
+	resp, err := c.http.Do(req)
+	if err != nil {
+		return nil, fmt.Errorf("cfai/image: http: %w", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		errBody, _ := io.ReadAll(resp.Body)
+		msg := string(errBody)
+		if len(msg) > 300 {
+			msg = msg[:300]
+		}
+		return nil, fmt.Errorf("cfai/image: model %s returned %d: %s", model, resp.StatusCode, msg)
+	}
+
+	data, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, fmt.Errorf("cfai/image: read response: %w", err)
+	}
+	return data, nil
+}
+
+func applyImageDefaults(req ImageRequest) ImageRequest {
+	if req.Model == "" {
+		req.Model = DefaultImageModel
+	}
+	if req.NumSteps <= 0 {
+		req.NumSteps = 20
+	}
+	return req
+}
+
+// decodeImageToRGBA decodes PNG/JPEG bytes to a flat []uint8 RGBA pixel array
+// required by the stable-diffusion-v1-5-img2img model.
+func decodeImageToRGBA(data []byte) ([]uint8, error) {
+	img, _, err := image.Decode(bytes.NewReader(data))
+	if err != nil {
+		return nil, fmt.Errorf("decode image: %w", err)
+	}
+	bounds := img.Bounds()
+	w := bounds.Max.X - bounds.Min.X
+	h := bounds.Max.Y - bounds.Min.Y
+	pixels := make([]uint8, w*h*4)
+	idx := 0
+	for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
+		for x := bounds.Min.X; x < bounds.Max.X; x++ {
+			r, g, b, a := img.At(x, y).RGBA()
+			pixels[idx] = uint8(r >> 8)
+			pixels[idx+1] = uint8(g >> 8)
+			pixels[idx+2] = uint8(b >> 8)
+			pixels[idx+3] = uint8(a >> 8)
+			idx += 4
+		}
+	}
+	return pixels, nil
+}

ui/messages/en.json

@@ -362,6 +362,7 @@
   "admin_nav_audio": "Audio",
   "admin_nav_translation": "Translation",
   "admin_nav_changelog": "Changelog",
+  "admin_nav_image_gen": "Image Gen",
   "admin_nav_feedback": "Feedback",
   "admin_nav_errors": "Errors",
   "admin_nav_analytics": "Analytics",

ui/messages/fr.json

@@ -362,6 +362,7 @@
   "admin_nav_audio": "Audio",
   "admin_nav_translation": "Traduction",
   "admin_nav_changelog": "Modifications",
+  "admin_nav_image_gen": "Image Gen",
   "admin_nav_feedback": "Retours",
   "admin_nav_errors": "Erreurs",
   "admin_nav_analytics": "Analytique",

ui/messages/id.json

@@ -362,6 +362,7 @@
   "admin_nav_audio": "Audio",
   "admin_nav_translation": "Terjemahan",
   "admin_nav_changelog": "Perubahan",
+  "admin_nav_image_gen": "Image Gen",
   "admin_nav_feedback": "Masukan",
   "admin_nav_errors": "Kesalahan",
   "admin_nav_analytics": "Analitik",

ui/messages/pt.json

@@ -362,6 +362,7 @@
   "admin_nav_audio": "Áudio",
   "admin_nav_translation": "Tradução",
   "admin_nav_changelog": "Alterações",
+  "admin_nav_image_gen": "Image Gen",
   "admin_nav_feedback": "Feedback",
   "admin_nav_errors": "Erros",
   "admin_nav_analytics": "Análise",

ui/messages/ru.json

@@ -362,6 +362,7 @@
   "admin_nav_audio": "Аудио",
   "admin_nav_translation": "Перевод",
   "admin_nav_changelog": "Изменения",
+  "admin_nav_image_gen": "Image Gen",
   "admin_nav_feedback": "Отзывы",
   "admin_nav_errors": "Ошибки",
   "admin_nav_analytics": "Аналитика",

ui/src/routes/admin/+layout.svelte

@@ -6,7 +6,8 @@
 		{ href: '/admin/scrape', label: () => m.admin_nav_scrape() },
 		{ href: '/admin/audio', label: () => m.admin_nav_audio() },
 		{ href: '/admin/translation', label: () => m.admin_nav_translation() },
-		{ href: '/admin/changelog', label: () => m.admin_nav_changelog() }
+		{ href: '/admin/changelog', label: () => m.admin_nav_changelog() },
+		{ href: '/admin/image-gen', label: () => m.admin_nav_image_gen() }
 	];
 
 	const externalLinks = [

ui/src/routes/admin/image-gen/+page.server.ts

@@ -0,0 +1,28 @@
+import type { PageServerLoad } from './$types';
+import { backendFetch } from '$lib/server/scraper';
+import { log } from '$lib/server/logger';
+
+export interface ImageModelInfo {
+	id: string;
+	label: string;
+	provider: string;
+	supports_ref: boolean;
+	recommended_for: string[]; // "cover" | "chapter"
+	description: string;
+}
+
+export const load: PageServerLoad = async () => {
+	// parent layout already guards admin role
+	try {
+		const res = await backendFetch('/api/admin/image-gen/models');
+		if (!res.ok) {
+			log.warn('admin/image-gen', 'failed to load models', { status: res.status });
+			return { models: [] as ImageModelInfo[] };
+		}
+		const data = await res.json();
+		return { models: (data.models ?? []) as ImageModelInfo[] };
+	} catch (e) {
+		log.warn('admin/image-gen', 'backend unreachable', { err: String(e) });
+		return { models: [] as ImageModelInfo[] };
+	}
+};

ui/src/routes/admin/image-gen/+page.svelte

@@ -0,0 +1,676 @@
+<script lang="ts">
+	import type { PageData } from './$types';
+	import type { ImageModelInfo } from './+page.server';
+
+	let { data }: { data: PageData } = $props();
+
+	// ── Form state ───────────────────────────────────────────────────────────────
+	type ImageType = 'cover' | 'chapter';
+	let imageType = $state<ImageType>('cover');
+	let slug = $state('');
+	let chapter = $state<number>(1);
+	let selectedModel = $state('');
+	let prompt = $state('');
+	let referenceFile = $state<File | null>(null);
+	let referencePreviewUrl = $state('');
+
+	// Advanced
+	let showAdvanced = $state(false);
+	let numSteps = $state(20);
+	let guidance = $state(7.5);
+	let strength = $state(0.75);
+	let width = $state(1024);
+	let height = $state(1024);
+
+	// ── Generation state ─────────────────────────────────────────────────────────
+	let generating = $state(false);
+	let genError = $state('');
+	let elapsedMs = $state(0);
+	let elapsedInterval: ReturnType<typeof setInterval> | null = null;
+
+	// ── Result state ─────────────────────────────────────────────────────────────
+	interface GenResult {
+		imageSrc: string;
+		model: string;
+		bytes: number;
+		contentType: string;
+		saved: boolean;
+		coverUrl: string;
+		elapsedMs: number;
+		slug: string;
+		imageType: ImageType;
+		chapter: number;
+	}
+
+	let result = $state<GenResult | null>(null);
+	let history = $state<GenResult[]>([]);
+
+	let saving = $state(false);
+	let saveError = $state('');
+	let saveSuccess = $state(false);
+
+	// ── Model helpers ────────────────────────────────────────────────────────────
+	const models = data.models as ImageModelInfo[];
+
+	let filteredModels = $derived(
+		referenceFile
+			? models // show all; warn on ones without ref support
+			: models
+	);
+
+	let coverModels = $derived(filteredModels.filter((m) => m.recommended_for.includes('cover')));
+	let chapterModels = $derived(filteredModels.filter((m) => m.recommended_for.includes('chapter')));
+	let otherModels = $derived(
+		filteredModels.filter(
+			(m) => !m.recommended_for.includes('cover') && !m.recommended_for.includes('chapter')
+		)
+	);
+
+	// ── Auto-select default model when type changes ──────────────────────────────
+	$effect(() => {
+		const preferred = imageType === 'cover' ? coverModels : chapterModels;
+		if (!selectedModel && preferred.length > 0) {
+			selectedModel = preferred[0].id;
+		}
+	});
+
+	// Reset model selection when type changes if current selection no longer fits
+	$effect(() => {
+		void imageType; // track
+		const preferred = imageType === 'cover' ? coverModels : chapterModels;
+		if (preferred.length > 0) {
+			// only auto-switch if current model isn't in preferred list for this type
+			const current = models.find((m) => m.id === selectedModel);
+			if (!current || !current.recommended_for.includes(imageType)) {
+				selectedModel = preferred[0].id;
+			}
+		}
+	});
+
+	// ── Prompt templates ────────────────────────────────────────────────────────
+	let promptTemplate = $derived(
+		imageType === 'cover'
+			? `Book cover for "${slug || 'untitled novel'}", a fantasy adventure novel. Epic scene with dramatic lighting, professional book cover art, cinematic composition, highly detailed, 4K.`
+			: `Illustration for chapter ${chapter} of "${slug || 'untitled novel'}". Dramatic moment, vivid colors, anime-inspired style, detailed background, cinematic lighting.`
+	);
+
+	function applyTemplate() {
+		prompt = promptTemplate;
+	}
+
+	// ── Reference image handling ─────────────────────────────────────────────────
+	let dragOver = $state(false);
+
+	function handleReferenceFile(file: File | null) {
+		referenceFile = file;
+		if (referencePreviewUrl) URL.revokeObjectURL(referencePreviewUrl);
+		referencePreviewUrl = file ? URL.createObjectURL(file) : '';
+	}
+
+	function onFileInput(e: Event) {
+		const input = e.target as HTMLInputElement;
+		handleReferenceFile(input.files?.[0] ?? null);
+	}
+
+	function onDrop(e: DragEvent) {
+		e.preventDefault();
+		dragOver = false;
+		const file = e.dataTransfer?.files[0];
+		if (file && file.type.startsWith('image/')) handleReferenceFile(file);
+	}
+
+	function clearReference() {
+		handleReferenceFile(null);
+		const input = document.getElementById('ref-file-input') as HTMLInputElement | null;
+		if (input) input.value = '';
+	}
+
+	// ── Selected model info ──────────────────────────────────────────────────────
+	let selectedModelInfo = $derived(models.find((m) => m.id === selectedModel) ?? null);
+	let refWarning = $derived(
+		referenceFile && selectedModelInfo && !selectedModelInfo.supports_ref
+			? `${selectedModelInfo.label} does not support reference images. The reference will be ignored.`
+			: ''
+	);
+
+	// ── Generate ────────────────────────────────────────────────────────────────
+	let canGenerate = $derived(prompt.trim().length > 0 && slug.trim().length > 0 && !generating);
+
+	async function generate() {
+		if (!canGenerate) return;
+		generating = true;
+		genError = '';
+		result = null;
+		elapsedMs = 0;
+		saveSuccess = false;
+		saveError = '';
+
+		const startTs = Date.now();
+		elapsedInterval = setInterval(() => {
+			elapsedMs = Date.now() - startTs;
+		}, 200);
+
+		try {
+			const payload = {
+				prompt: prompt.trim(),
+				model: selectedModel,
+				type: imageType,
+				slug: slug.trim(),
+				chapter: imageType === 'chapter' ? chapter : 0,
+				num_steps: numSteps,
+				guidance,
+				strength,
+				width,
+				height
+			};
+
+			let res: Response;
+			if (referenceFile && selectedModelInfo?.supports_ref) {
+				const fd = new FormData();
+				fd.append('json', JSON.stringify(payload));
+				fd.append('reference', referenceFile);
+				res = await fetch('/api/admin/image-gen', { method: 'POST', body: fd });
+			} else {
+				res = await fetch('/api/admin/image-gen', {
+					method: 'POST',
+					headers: { 'Content-Type': 'application/json' },
+					body: JSON.stringify(payload)
+				});
+			}
+
+			const body = await res.json().catch(() => ({}));
+			if (!res.ok) {
+				genError = body.error ?? body.message ?? `Error ${res.status}`;
+				return;
+			}
+
+			const totalMs = Date.now() - startTs;
+			const newResult: GenResult = {
+				imageSrc: `data:${body.content_type};base64,${body.image_b64}`,
+				model: body.model,
+				bytes: body.bytes,
+				contentType: body.content_type,
+				saved: body.saved ?? false,
+				coverUrl: body.cover_url ?? '',
+				elapsedMs: totalMs,
+				slug: slug.trim(),
+				imageType,
+				chapter
+			};
+
+			result = newResult;
+			history = [newResult, ...history].slice(0, 5);
+		} catch {
+			genError = 'Network error.';
+		} finally {
+			generating = false;
+			if (elapsedInterval) {
+				clearInterval(elapsedInterval);
+				elapsedInterval = null;
+			}
+		}
+	}
+
+	// ── Save as cover ────────────────────────────────────────────────────────────
+	async function saveAsCover() {
+		if (!result || saving) return;
+		saving = true;
+		saveError = '';
+		saveSuccess = false;
+
+		try {
+			const payload = {
+				prompt: prompt.trim(),
+				model: result.model,
+				type: 'cover',
+				slug: result.slug,
+				num_steps: numSteps,
+				guidance,
+				strength,
+				width,
+				height,
+				save_to_cover: true
+			};
+
+			// Re-generate with save_to_cover=true (backend saves atomically)
+			// Alternatively, we could add a separate save endpoint.
+			// For now we pass the same prompt + model to re-generate and save.
+			// TODO: A lighter approach would be a dedicated save endpoint that accepts
+			// the base64 payload. For now re-gen is acceptable given admin-only usage.
+			const res = await fetch('/api/admin/image-gen', {
+				method: 'POST',
+				headers: { 'Content-Type': 'application/json' },
+				body: JSON.stringify(payload)
+			});
+			const body = await res.json().catch(() => ({}));
+			if (!res.ok) {
+				saveError = body.error ?? body.message ?? `Error ${res.status}`;
+				return;
+			}
+			if (body.saved) {
+				saveSuccess = true;
+				result = { ...result, saved: true, coverUrl: body.cover_url ?? result.coverUrl };
+			} else {
+				saveError = 'Backend did not save the cover.';
+			}
+		} catch {
+			saveError = 'Network error.';
+		} finally {
+			saving = false;
+		}
+	}
+
+	// ── Download ─────────────────────────────────────────────────────────────────
+	function download() {
+		if (!result) return;
+		const a = document.createElement('a');
+		a.href = result.imageSrc;
+		const ext = result.contentType === 'image/jpeg' ? 'jpg' : 'png';
+		a.download =
+			result.imageType === 'cover'
+				? `${result.slug}-cover.${ext}`
+				: `${result.slug}-ch${result.chapter}.${ext}`;
+		a.click();
+	}
+
+	// ── Formatting helpers ───────────────────────────────────────────────────────
+	function fmtElapsed(ms: number) {
+		if (ms < 1000) return `${ms}ms`;
+		return `${(ms / 1000).toFixed(1)}s`;
+	}
+
+	function fmtBytes(b: number) {
+		if (b < 1024) return `${b} B`;
+		if (b < 1024 * 1024) return `${(b / 1024).toFixed(1)} KB`;
+		return `${(b / 1024 / 1024).toFixed(2)} MB`;
+	}
+</script>
+
+<svelte:head>
+	<title>Image Gen — Admin</title>
+</svelte:head>
+
+<div class="space-y-6 max-w-6xl">
+	<!-- Header -->
+	<div>
+		<h1 class="text-2xl font-bold text-(--color-text)">Image Generation</h1>
+		<p class="text-(--color-muted) text-sm mt-1">
+			Generate book covers and chapter images using Cloudflare Workers AI.
+		</p>
+	</div>
+
+	<!-- Layout: form + result side by side on large screens -->
+	<div class="grid grid-cols-1 lg:grid-cols-2 gap-6 items-start">
+		<!-- ── Left: Form panel ──────────────────────────────────────────────────── -->
+		<div class="space-y-4">
+			<!-- Type toggle -->
+			<div class="flex gap-1 bg-(--color-surface-2) rounded-lg p-1 w-fit border border-(--color-border)">
+				{#each (['cover', 'chapter'] as const) as t}
+					<button
+						onclick={() => (imageType = t)}
+						class="px-4 py-1.5 rounded-md text-sm font-medium transition-colors
+							{imageType === t
+								? 'bg-(--color-surface-3) text-(--color-text)'
+								: 'text-(--color-muted) hover:text-(--color-text)'}"
+					>
+						{t === 'cover' ? 'Cover' : 'Chapter Image'}
+					</button>
+				{/each}
+			</div>
+
+			<!-- Slug + chapter -->
+			<div class="flex gap-3">
+				<div class="flex-1 min-w-0 space-y-1">
+					<label class="text-xs font-medium text-(--color-muted) uppercase tracking-wide" for="slug-input">
+						Book slug
+					</label>
+					<input
+						id="slug-input"
+						type="text"
+						bind:value={slug}
+						placeholder="e.g. shadow-slave"
+						class="w-full bg-(--color-surface-2) border border-(--color-border) rounded-lg px-3 py-2 text-(--color-text) text-sm placeholder-zinc-500 focus:outline-none focus:ring-2 focus:ring-(--color-brand)"
+					/>
+				</div>
+
+				{#if imageType === 'chapter'}
+					<div class="w-24 space-y-1 shrink-0">
+						<label class="text-xs font-medium text-(--color-muted) uppercase tracking-wide" for="chapter-input">
+							Chapter
+						</label>
+						<input
+							id="chapter-input"
+							type="number"
+							bind:value={chapter}
+							min="1"
+							class="w-full bg-(--color-surface-2) border border-(--color-border) rounded-lg px-3 py-2 text-(--color-text) text-sm focus:outline-none focus:ring-2 focus:ring-(--color-brand)"
+						/>
+					</div>
+				{/if}
+			</div>
+
+			<!-- Model selector -->
+			<div class="space-y-1">
+				<label class="text-xs font-medium text-(--color-muted) uppercase tracking-wide" for="model-select">
+					Model
+				</label>
+				<select
+					id="model-select"
+					bind:value={selectedModel}
+					class="w-full bg-(--color-surface-2) border border-(--color-border) rounded-lg px-3 py-2 text-(--color-text) text-sm focus:outline-none focus:ring-2 focus:ring-(--color-brand)"
+				>
+					{#if coverModels.length > 0}
+						<optgroup label="Recommended for covers">
+							{#each coverModels as m}
+								<option value={m.id}>
+									{m.label} — {m.provider}{m.supports_ref ? ' ★ref' : ''}
+								</option>
+							{/each}
+						</optgroup>
+					{/if}
+					{#if chapterModels.length > 0}
+						<optgroup label="Recommended for chapters">
+							{#each chapterModels as m}
+								<option value={m.id}>
+									{m.label} — {m.provider}{m.supports_ref ? ' ★ref' : ''}
+								</option>
+							{/each}
+						</optgroup>
+					{/if}
+					{#if otherModels.length > 0}
+						<optgroup label="All models">
+							{#each otherModels as m}
+								<option value={m.id}>
+									{m.label} — {m.provider}{m.supports_ref ? ' ★ref' : ''}
+								</option>
+							{/each}
+						</optgroup>
+					{/if}
+				</select>
+				{#if selectedModelInfo}
+					<p class="text-xs text-(--color-muted)">{selectedModelInfo.description}</p>
+				{/if}
+				{#if refWarning}
+					<p class="text-xs text-amber-400">{refWarning}</p>
+				{/if}
+			</div>
+
+			<!-- Prompt -->
+			<div class="space-y-1">
+				<div class="flex items-center justify-between">
+					<label class="text-xs font-medium text-(--color-muted) uppercase tracking-wide" for="prompt-input">
+						Prompt
+					</label>
+					<button
+						onclick={applyTemplate}
+						class="text-xs text-(--color-brand) hover:text-(--color-brand-dim) transition-colors"
+					>
+						Use template
+					</button>
+				</div>
+				<textarea
+					id="prompt-input"
+					bind:value={prompt}
+					rows="5"
+					placeholder="Describe the image to generate…"
+					class="w-full bg-(--color-surface-2) border border-(--color-border) rounded-lg px-3 py-2 text-(--color-text) text-sm placeholder-zinc-500 focus:outline-none focus:ring-2 focus:ring-(--color-brand) resize-y"
+				></textarea>
+			</div>
+
+			<!-- Reference image drop zone -->
+			<div class="space-y-1">
+				<p class="text-xs font-medium text-(--color-muted) uppercase tracking-wide">
+					Reference image <span class="normal-case font-normal text-(--color-muted)">(optional, img2img)</span>
+				</p>
+				{#if referenceFile && referencePreviewUrl}
+					<div class="flex items-start gap-3 p-3 bg-(--color-surface-2) rounded-lg border border-(--color-border)">
+						<img
+							src={referencePreviewUrl}
+							alt="Reference"
+							class="w-16 h-16 object-cover rounded-md shrink-0 border border-(--color-border)"
+						/>
+						<div class="min-w-0 flex-1 space-y-0.5">
+							<p class="text-sm text-(--color-text) truncate">{referenceFile.name}</p>
+							<p class="text-xs text-(--color-muted)">{fmtBytes(referenceFile.size)}</p>
+						</div>
+						<button
+							onclick={clearReference}
+							class="text-(--color-muted) hover:text-(--color-text) transition-colors shrink-0"
+							aria-label="Remove reference image"
+						>
+							<svg class="w-4 h-4" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+								<path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M6 18L18 6M6 6l12 12" />
+							</svg>
+						</button>
+					</div>
+				{:else}
+					<!-- Drop zone -->
+					<label
+						class="flex flex-col items-center justify-center gap-2 p-4 border-2 border-dashed rounded-lg cursor-pointer transition-colors
+							{dragOver
+								? 'border-(--color-brand) bg-(--color-brand)/5'
+								: 'border-(--color-border) hover:border-(--color-brand)/50 hover:bg-(--color-surface-2)'}"
+						ondragover={(e) => { e.preventDefault(); dragOver = true; }}
+						ondragleave={() => { dragOver = false; }}
+						ondrop={onDrop}
+					>
+						<svg class="w-6 h-6 text-(--color-muted)" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+							<path stroke-linecap="round" stroke-linejoin="round" stroke-width="1.5"
+								d="M4 16l4.586-4.586a2 2 0 012.828 0L16 16m-2-2l1.586-1.586a2 2 0 012.828 0L20 14m-6-6h.01M6 20h12a2 2 0 002-2V6a2 2 0 00-2-2H6a2 2 0 00-2 2v12a2 2 0 002 2z" />
+						</svg>
+						<span class="text-xs text-(--color-muted)">Drop image or <span class="text-(--color-brand)">click to browse</span></span>
+						<input
+							id="ref-file-input"
+							type="file"
+							accept="image/png,image/jpeg,image/webp"
+							onchange={onFileInput}
+							class="sr-only"
+						/>
+					</label>
+				{/if}
+			</div>
+
+			<!-- Advanced collapsible -->
+			<div class="border border-(--color-border) rounded-lg overflow-hidden">
+				<button
+					onclick={() => (showAdvanced = !showAdvanced)}
+					class="w-full flex items-center justify-between px-4 py-2.5 bg-(--color-surface-2) text-sm font-medium text-(--color-muted) hover:text-(--color-text) transition-colors"
+				>
+					Advanced options
+					<svg
+						class="w-4 h-4 transition-transform {showAdvanced ? 'rotate-180' : ''}"
+						fill="none" stroke="currentColor" viewBox="0 0 24 24"
+					>
+						<path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M19 9l-7 7-7-7" />
+					</svg>
+				</button>
+
+				{#if showAdvanced}
+					<div class="px-4 py-4 bg-(--color-surface) space-y-4">
+						<!-- num_steps -->
+						<div class="space-y-1">
+							<div class="flex justify-between">
+								<label class="text-xs text-(--color-muted)">Steps</label>
+								<span class="text-xs text-(--color-text) font-mono">{numSteps}</span>
+							</div>
+							<input type="range" min="1" max="20" step="1" bind:value={numSteps}
+								class="w-full accent-(--color-brand)" />
+						</div>
+
+						<!-- guidance -->
+						<div class="space-y-1">
+							<div class="flex justify-between">
+								<label class="text-xs text-(--color-muted)">Guidance</label>
+								<span class="text-xs text-(--color-text) font-mono">{guidance.toFixed(1)}</span>
+							</div>
+							<input type="range" min="1" max="20" step="0.5" bind:value={guidance}
+								class="w-full accent-(--color-brand)" />
+						</div>
+
+						<!-- strength (only when reference present) -->
+						{#if referenceFile}
+							<div class="space-y-1">
+								<div class="flex justify-between">
+									<label class="text-xs text-(--color-muted)">Strength</label>
+									<span class="text-xs text-(--color-text) font-mono">{strength.toFixed(2)}</span>
+								</div>
+								<input type="range" min="0" max="1" step="0.05" bind:value={strength}
+									class="w-full accent-(--color-brand)" />
+								<p class="text-xs text-(--color-muted)">0 = copy reference · 1 = ignore reference</p>
+							</div>
+						{/if}
+
+						<!-- width × height -->
+						<div class="grid grid-cols-2 gap-3">
+							<div class="space-y-1">
+								<label class="text-xs text-(--color-muted)" for="width-input">Width</label>
+								<input id="width-input" type="number" min="256" max="2048" step="64" bind:value={width}
+									class="w-full bg-(--color-surface-2) border border-(--color-border) rounded-md px-3 py-1.5 text-(--color-text) text-sm focus:outline-none focus:ring-1 focus:ring-(--color-brand)" />
+							</div>
+							<div class="space-y-1">
+								<label class="text-xs text-(--color-muted)" for="height-input">Height</label>
+								<input id="height-input" type="number" min="256" max="2048" step="64" bind:value={height}
+									class="w-full bg-(--color-surface-2) border border-(--color-border) rounded-md px-3 py-1.5 text-(--color-text) text-sm focus:outline-none focus:ring-1 focus:ring-(--color-brand)" />
+							</div>
+						</div>
+					</div>
+				{/if}
+			</div>
+
+			<!-- Generate button -->
+			<button
+				onclick={generate}
+				disabled={!canGenerate}
+				class="w-full py-2.5 rounded-lg bg-(--color-brand) text-(--color-surface) font-semibold text-sm
+					hover:bg-(--color-brand-dim) transition-colors disabled:opacity-50 disabled:cursor-not-allowed
+					flex items-center justify-center gap-2"
+			>
+				{#if generating}
+					<!-- Spinner -->
+					<svg class="w-4 h-4 animate-spin" fill="none" viewBox="0 0 24 24">
+						<circle class="opacity-25" cx="12" cy="12" r="10" stroke="currentColor" stroke-width="4" />
+						<path class="opacity-75" fill="currentColor" d="M4 12a8 8 0 018-8v8H4z" />
+					</svg>
+					Generating… {fmtElapsed(elapsedMs)}
+				{:else}
+					Generate
+				{/if}
+			</button>
+
+			{#if genError}
+				<p class="text-sm text-(--color-danger) bg-(--color-danger)/10 rounded-lg px-3 py-2">{genError}</p>
+			{/if}
+		</div>
+
+		<!-- ── Right: Result panel ────────────────────────────────────────────────── -->
+		<div class="space-y-4">
+			{#if result}
+				<div class="bg-(--color-surface) border border-(--color-border) rounded-xl overflow-hidden">
+					<!-- Image -->
+					<img
+						src={result.imageSrc}
+						alt="Generated image"
+						class="w-full object-contain max-h-[36rem] bg-zinc-950"
+					/>
+
+					<!-- Meta bar -->
+					<div class="px-4 py-3 border-t border-(--color-border) space-y-3">
+						<div class="grid grid-cols-3 gap-2 text-xs">
+							<div>
+								<p class="text-(--color-muted)">Model</p>
+								<p class="text-(--color-text) font-mono truncate" title={result.model}>
+									{models.find((m) => m.id === result!.model)?.label ?? result.model}
+								</p>
+							</div>
+							<div>
+								<p class="text-(--color-muted)">Size</p>
+								<p class="text-(--color-text)">{fmtBytes(result.bytes)}</p>
+							</div>
+							<div>
+								<p class="text-(--color-muted)">Time</p>
+								<p class="text-(--color-text)">{fmtElapsed(result.elapsedMs)}</p>
+							</div>
+						</div>
+
+						{#if result.saved}
+							<p class="text-xs text-green-400">
+								Cover saved &rarr;
+								<a href={result.coverUrl} target="_blank" rel="noopener noreferrer"
+									class="underline hover:text-green-300">{result.coverUrl}</a>
+							</p>
+						{/if}
+
+						{#if saveSuccess && !result.saved}
+							<p class="text-xs text-green-400">Cover saved successfully.</p>
+						{/if}
+						{#if saveError}
+							<p class="text-xs text-(--color-danger)">{saveError}</p>
+						{/if}
+
+						<!-- Actions -->
+						<div class="flex gap-2 flex-wrap">
+							<button
+								onclick={download}
+								class="flex-1 px-3 py-1.5 rounded-md bg-(--color-surface-3) text-(--color-text) text-xs font-medium hover:bg-zinc-600 transition-colors"
+							>
+								Download
+							</button>
+
+							{#if result.imageType === 'cover'}
+								<button
+									onclick={saveAsCover}
+									disabled={saving || result.saved}
+									class="flex-1 px-3 py-1.5 rounded-md bg-(--color-brand) text-(--color-surface) text-xs font-semibold
+										hover:bg-(--color-brand-dim) transition-colors disabled:opacity-50"
+								>
+									{saving ? 'Saving…' : result.saved ? 'Saved ✓' : 'Save as cover'}
+								</button>
+							{/if}
+						</div>
+					</div>
+				</div>
+			{:else if generating}
+				<!-- Placeholder while generating -->
+				<div class="flex items-center justify-center bg-(--color-surface) border border-(--color-border) rounded-xl h-80">
+					<div class="text-center space-y-3">
+						<svg class="w-8 h-8 animate-spin mx-auto text-(--color-brand)" fill="none" viewBox="0 0 24 24">
+							<circle class="opacity-25" cx="12" cy="12" r="10" stroke="currentColor" stroke-width="4" />
+							<path class="opacity-75" fill="currentColor" d="M4 12a8 8 0 018-8v8H4z" />
+						</svg>
+						<p class="text-sm text-(--color-muted)">Generating… {fmtElapsed(elapsedMs)}</p>
+					</div>
+				</div>
+			{:else}
+				<!-- Empty state -->
+				<div class="flex items-center justify-center bg-(--color-surface) border border-(--color-border) border-dashed rounded-xl h-80">
+					<p class="text-sm text-(--color-muted)">Generated image will appear here</p>
+				</div>
+			{/if}
+
+			<!-- History thumbnails -->
+			{#if history.length > 0}
+				<div class="space-y-2">
+					<p class="text-xs font-semibold text-(--color-muted) uppercase tracking-widest">Session history</p>
+					<div class="flex gap-2 flex-wrap">
+						{#each history as h, i}
+							<button
+								onclick={() => result = h}
+								class="relative rounded-md overflow-hidden border transition-colors shrink-0
+									{result === h ? 'border-(--color-brand)' : 'border-(--color-border) hover:border-(--color-brand)/50'}"
+							>
+								<img
+									src={h.imageSrc}
+									alt="History {i + 1}"
+									class="w-16 h-16 object-cover"
+								/>
+								{#if h.saved}
+									<span class="absolute bottom-0.5 right-0.5 w-2.5 h-2.5 rounded-full bg-green-500 border border-(--color-surface)"></span>
+								{/if}
+							</button>
+						{/each}
+					</div>
+				</div>
+			{/if}
+		</div>
+	</div>
+</div>

ui/src/routes/api/admin/image-gen/+server.ts

@@ -0,0 +1,46 @@
+/**
+ * POST /api/admin/image-gen
+ *
+ * Admin-only proxy to the Go backend's image generation endpoint.
+ * Transparently forwards the request body (JSON or multipart/form-data)
+ * and returns the JSON response containing the base64-encoded image.
+ */
+
+import { json, error } from '@sveltejs/kit';
+import type { RequestHandler } from './$types';
+import { log } from '$lib/server/logger';
+import { backendFetch } from '$lib/server/scraper';
+
+export const POST: RequestHandler = async ({ request, locals }) => {
+	if (!locals.user || locals.user.role !== 'admin') {
+		throw error(403, 'Forbidden');
+	}
+
+	const ct = request.headers.get('content-type') ?? '';
+
+	let res: Response;
+	try {
+		if (ct.includes('multipart/form-data')) {
+			// Forward raw body bytes; let the backend parse multipart
+			const body = await request.arrayBuffer();
+			res = await backendFetch('/api/admin/image-gen', {
+				method: 'POST',
+				headers: { 'content-type': ct },
+				body
+			});
+		} else {
+			const body = await request.text();
+			res = await backendFetch('/api/admin/image-gen', {
+				method: 'POST',
+				headers: { 'content-type': 'application/json' },
+				body
+			});
+		}
+	} catch (e) {
+		log.error('admin/image-gen', 'backend proxy error', { err: String(e) });
+		throw error(502, 'Could not reach backend');
+	}
+
+	const data = await res.json().catch(() => ({}));
+	return json(data, { status: res.status });
+};