From ad2d1a2603806c62b065273c76f3083ce2031701 Mon Sep 17 00:00:00 2001
From: Admin <admin@kalekber.cc>
Date: Sun, 5 Apr 2026 00:32:18 +0500
Subject: [PATCH] feat: stream chapter-name generation via SSE batching

Split chapter-name LLM requests into 100-chapter batches and stream
results back as SSE so large books (e.g. Shadow Slave: 2916 chapters)
never time out or truncate. Frontend shows live batch progress inline
and accumulates proposals as they arrive.
---
 backend/internal/backend/handlers_textgen.go  | 194 ++++++++----
 ui/src/routes/admin/image-gen/+page.server.ts |  41 ++-
 ui/src/routes/admin/image-gen/+page.svelte    | 258 +++++++++++++---
 ui/src/routes/admin/text-gen/+page.server.ts  |  37 ++-
 ui/src/routes/admin/text-gen/+page.svelte     | 283 +++++++++++++++---
 .../admin/text-gen/chapter-names/+server.ts   |  25 +-
 6 files changed, 660 insertions(+), 178 deletions(-)

diff --git a/backend/internal/backend/handlers_textgen.go b/backend/internal/backend/handlers_textgen.go
index 2c21536..c42dcd3 100644
--- a/backend/internal/backend/handlers_textgen.go
+++ b/backend/internal/backend/handlers_textgen.go
@@ -10,6 +10,10 @@ import (
 	"github.com/libnovel/backend/internal/domain"
 )
 
+// chapterNamesBatchSize is the number of chapters sent per LLM request.
+// Keeps output well within the 4096-token response limit (~30 tokens/title).
+const chapterNamesBatchSize = 100
+
 // handleAdminTextGenModels handles GET /api/admin/text-gen/models.
 // Returns the list of supported Cloudflare AI text generation models.
 func (s *Server) handleAdminTextGenModels(w http.ResponseWriter, r *http.Request) {
@@ -36,16 +40,6 @@ type textGenChapterNamesRequest struct {
 	MaxTokens int `json:"max_tokens"`
 }
 
-// textGenChapterNamesResponse is the JSON body returned by POST /api/admin/text-gen/chapter-names.
-type textGenChapterNamesResponse struct {
-	// Chapters is the list of proposed chapter titles, indexed by chapter number.
-	Chapters []proposedChapterTitle `json:"chapters"`
-	// Model is the model that was used.
-	Model string `json:"model"`
-	// RawResponse is the raw model output for debugging / manual editing.
-	RawResponse string `json:"raw_response"`
-}
-
 // proposedChapterTitle is a single chapter with its AI-proposed title.
 type proposedChapterTitle struct {
 	Number int `json:"number"`
@@ -55,12 +49,35 @@ type proposedChapterTitle struct {
 	NewTitle string `json:"new_title"`
 }
 
+// chapterNamesBatchEvent is one SSE event emitted per processed batch.
+type chapterNamesBatchEvent struct {
+	// Batch is the 1-based batch index.
+	Batch int `json:"batch"`
+	// TotalBatches is the total number of batches.
+	TotalBatches int `json:"total_batches"`
+	// ChaptersDone is the cumulative count of chapters processed so far.
+	ChaptersDone int `json:"chapters_done"`
+	// TotalChapters is the total chapter count for this book.
+	TotalChapters int `json:"total_chapters"`
+	// Model is the CF AI model used.
+	Model string `json:"model"`
+	// Chapters contains the proposed titles for this batch.
+	Chapters []proposedChapterTitle `json:"chapters"`
+	// Error is non-empty if this batch failed.
+	Error string `json:"error,omitempty"`
+	// Done is true on the final sentinel event (no Chapters).
+	Done bool `json:"done,omitempty"`
+}
+
 // handleAdminTextGenChapterNames handles POST /api/admin/text-gen/chapter-names.
 //
-// Reads all chapter titles for the given slug, sends them to the LLM with the
-// requested naming pattern, and returns proposed replacements. Does NOT persist
-// anything — the frontend shows a diff and the user must confirm via
-// POST /api/admin/text-gen/chapter-names/apply.
+// Splits all chapters into batches of chapterNamesBatchSize, sends each batch
+// to the LLM sequentially, and streams results back as Server-Sent Events so
+// the frontend can show live progress. Each SSE data line is a JSON-encoded
+// chapterNamesBatchEvent. The final event has Done=true.
+//
+// Does NOT persist anything — the frontend shows a diff and the user must
+// confirm via POST /api/admin/text-gen/chapter-names/apply.
 func (s *Server) handleAdminTextGenChapterNames(w http.ResponseWriter, r *http.Request) {
 	if s.deps.TextGen == nil {
 		jsonError(w, http.StatusServiceUnavailable, "text generation not configured (CFAI_ACCOUNT_ID/CFAI_API_TOKEN missing)")
@@ -92,11 +109,29 @@ func (s *Server) handleAdminTextGenChapterNames(w http.ResponseWriter, r *http.R
 		return
 	}
 
-	// Build the prompt.
-	var chapterListSB strings.Builder
-	for _, ch := range chapters {
-		chapterListSB.WriteString(fmt.Sprintf("%d: %s\n", ch.Number, ch.Title))
+	model := cfai.TextModel(req.Model)
+	if model == "" {
+		model = cfai.DefaultTextModel
 	}
+	// 4096 tokens comfortably fits 100 chapter titles (~30 tokens each).
+	maxTokens := req.MaxTokens
+	if maxTokens <= 0 {
+		maxTokens = 4096
+	}
+
+	// Index existing titles for old/new diff.
+	existing := make(map[int]string, len(chapters))
+	for _, ch := range chapters {
+		existing[ch.Number] = ch.Title
+	}
+
+	// Partition chapters into batches.
+	batches := chunkChapters(chapters, chapterNamesBatchSize)
+	totalBatches := len(batches)
+
+	s.deps.Log.Info("admin: text-gen chapter-names requested",
+		"slug", req.Slug, "chapters", len(chapters),
+		"batches", totalBatches, "model", model, "max_tokens", maxTokens)
 
 	systemPrompt := `You are a chapter title editor for a web novel platform. ` +
 		`The user provides a list of chapter numbers with their current titles, ` +
@@ -111,64 +146,91 @@ func (s *Server) handleAdminTextGenChapterNames(w http.ResponseWriter, r *http.R
 		`5. Each element: {"number": <int>, "title": <string>}. ` +
 		`6. Output every chapter in the input list, in order. Do not skip any.`
 
-	userPrompt := fmt.Sprintf(
-		"Naming pattern: %s\n\nChapters:\n%s",
-		req.Pattern,
-		chapterListSB.String(),
-	)
+	// Switch to SSE before writing anything.
+	w.Header().Set("Content-Type", "text/event-stream")
+	w.Header().Set("Cache-Control", "no-cache")
+	w.Header().Set("X-Accel-Buffering", "no") // disable nginx/caddy buffering
+	flusher, canFlush := w.(http.Flusher)
 
-	model := cfai.TextModel(req.Model)
-	if model == "" {
-		model = cfai.DefaultTextModel
+	sseWrite := func(evt chapterNamesBatchEvent) {
+		b, _ := json.Marshal(evt)
+		fmt.Fprintf(w, "data: %s\n\n", b)
+		if canFlush {
+			flusher.Flush()
+		}
 	}
 
-	// Default to 4096 tokens so large chapter lists are not truncated.
-	maxTokens := req.MaxTokens
-	if maxTokens <= 0 {
-		maxTokens = 4096
-	}
+	chaptersDone := 0
+	for i, batch := range batches {
+		if r.Context().Err() != nil {
+			return // client disconnected
+		}
 
-	s.deps.Log.Info("admin: text-gen chapter-names requested",
-		"slug", req.Slug, "chapters", len(chapters), "model", model, "max_tokens", maxTokens)
+		var chapterListSB strings.Builder
+		for _, ch := range batch {
+			chapterListSB.WriteString(fmt.Sprintf("%d: %s\n", ch.Number, ch.Title))
+		}
+		userPrompt := fmt.Sprintf("Naming pattern: %s\n\nChapters:\n%s", req.Pattern, chapterListSB.String())
 
-	raw, genErr := s.deps.TextGen.Generate(r.Context(), cfai.TextRequest{
-		Model: model,
-		Messages: []cfai.TextMessage{
-			{Role: "system", Content: systemPrompt},
-			{Role: "user", Content: userPrompt},
-		},
-		MaxTokens: maxTokens,
-	})
-	if genErr != nil {
-		s.deps.Log.Error("admin: text-gen chapter-names failed", "err", genErr)
-		jsonError(w, http.StatusBadGateway, "text generation failed: "+genErr.Error())
-		return
-	}
+		raw, genErr := s.deps.TextGen.Generate(r.Context(), cfai.TextRequest{
+			Model: model,
+			Messages: []cfai.TextMessage{
+				{Role: "system", Content: systemPrompt},
+				{Role: "user", Content: userPrompt},
+			},
+			MaxTokens: maxTokens,
+		})
+		if genErr != nil {
+			s.deps.Log.Error("admin: text-gen chapter-names batch failed",
+				"batch", i+1, "err", genErr)
+			sseWrite(chapterNamesBatchEvent{
+				Batch:         i + 1,
+				TotalBatches:  totalBatches,
+				ChaptersDone:  chaptersDone,
+				TotalChapters: len(chapters),
+				Model:         string(model),
+				Error:         genErr.Error(),
+			})
+			continue
+		}
 
-	// Parse the JSON array from the model response.
-	proposed := parseChapterTitlesJSON(raw)
+		proposed := parseChapterTitlesJSON(raw)
+		result := make([]proposedChapterTitle, 0, len(proposed))
+		for _, p := range proposed {
+			result = append(result, proposedChapterTitle{
+				Number:   p.Number,
+				OldTitle: existing[p.Number],
+				NewTitle: p.Title,
+			})
+		}
+		chaptersDone += len(batch)
 
-	// Build the response: merge proposed titles with old titles.
-	// Index existing chapters by number for O(1) lookup.
-	existing := make(map[int]string, len(chapters))
-	for _, ch := range chapters {
-		existing[ch.Number] = ch.Title
-	}
-
-	result := make([]proposedChapterTitle, 0, len(proposed))
-	for _, p := range proposed {
-		result = append(result, proposedChapterTitle{
-			Number:   p.Number,
-			OldTitle: existing[p.Number],
-			NewTitle: p.Title,
+		sseWrite(chapterNamesBatchEvent{
+			Batch:         i + 1,
+			TotalBatches:  totalBatches,
+			ChaptersDone:  chaptersDone,
+			TotalChapters: len(chapters),
+			Model:         string(model),
+			Chapters:      result,
 		})
 	}
 
-	writeJSON(w, 0, textGenChapterNamesResponse{
-		Chapters:    result,
-		Model:       string(model),
-		RawResponse: raw,
-	})
+	// Final sentinel event.
+	sseWrite(chapterNamesBatchEvent{Done: true, TotalChapters: len(chapters), Model: string(model)})
+}
+
+// chunkChapters splits a chapter slice into batches of at most size n.
+func chunkChapters(chapters []domain.ChapterInfo, n int) [][]domain.ChapterInfo {
+	var batches [][]domain.ChapterInfo
+	for len(chapters) > 0 {
+		end := n
+		if end > len(chapters) {
+			end = len(chapters)
+		}
+		batches = append(batches, chapters[:end])
+		chapters = chapters[end:]
+	}
+	return batches
 }
 
 // parseChapterTitlesJSON extracts the JSON array from a model response.
diff --git a/ui/src/routes/admin/image-gen/+page.server.ts b/ui/src/routes/admin/image-gen/+page.server.ts
index b44793d..da09808 100644
--- a/ui/src/routes/admin/image-gen/+page.server.ts
+++ b/ui/src/routes/admin/image-gen/+page.server.ts
@@ -1,6 +1,7 @@
 import type { PageServerLoad } from './$types';
 import { backendFetch } from '$lib/server/scraper';
 import { log } from '$lib/server/logger';
+import { listBooks } from '$lib/server/pocketbase';
 
 export interface ImageModelInfo {
 	id: string;
@@ -11,18 +12,36 @@ export interface ImageModelInfo {
 	description: string;
 }
 
+export interface BookSummary {
+	slug: string;
+	title: string;
+	summary: string;
+	cover: 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[] };
+	const [modelsResult, books] = await Promise.allSettled([
+		(async () => {
+			const res = await backendFetch('/api/admin/image-gen/models');
+			if (!res.ok) throw new Error(`status ${res.status}`);
+			const data = await res.json();
+			return (data.models ?? []) as ImageModelInfo[];
+		})(),
+		listBooks()
+	]);
+
+	if (modelsResult.status === 'rejected') {
+		log.warn('admin/image-gen', 'failed to load models', { err: String(modelsResult.reason) });
 	}
+
+	return {
+		models: modelsResult.status === 'fulfilled' ? modelsResult.value : ([] as ImageModelInfo[]),
+		books: (books.status === 'fulfilled' ? books.value : []).map((b) => ({
+			slug: b.slug,
+			title: b.title,
+			summary: b.summary ?? '',
+			cover: b.cover ?? ''
+		})) as BookSummary[]
+	};
 };
diff --git a/ui/src/routes/admin/image-gen/+page.svelte b/ui/src/routes/admin/image-gen/+page.svelte
index 1ab9b9d..49d1089 100644
--- a/ui/src/routes/admin/image-gen/+page.svelte
+++ b/ui/src/routes/admin/image-gen/+page.svelte
@@ -1,26 +1,120 @@
 <script lang="ts">
+	import { browser } from '$app/environment';
 	import type { PageData } from './$types';
-	import type { ImageModelInfo } from './+page.server';
+	import type { ImageModelInfo, BookSummary } from './+page.server';
 
 	let { data }: { data: PageData } = $props();
 
 	// ── Form state ───────────────────────────────────────────────────────────────
 	type ImageType = 'cover' | 'chapter';
+
+	const CONFIG_KEY = 'admin_image_gen_config_v1';
+
+	interface SavedConfig {
+		selectedModel: string;
+		numSteps: number;
+		guidance: number;
+		strength: number;
+		width: number;
+		height: number;
+		showAdvanced: boolean;
+	}
+
+	function loadConfig(): Partial<SavedConfig> {
+		if (!browser) return {};
+		try {
+			const raw = localStorage.getItem(CONFIG_KEY);
+			return raw ? (JSON.parse(raw) as Partial<SavedConfig>) : {};
+		} catch { return {}; }
+	}
+
+	function saveConfig() {
+		if (!browser) return;
+		const cfg: SavedConfig = { selectedModel, numSteps, guidance, strength, width, height, showAdvanced };
+		localStorage.setItem(CONFIG_KEY, JSON.stringify(cfg));
+	}
+
+	const saved = loadConfig();
+
 	let imageType = $state<ImageType>('cover');
 	let slug = $state('');
 	let chapter = $state<number>(1);
-	let selectedModel = $state('');
+	let selectedModel = $state(saved.selectedModel ?? '');
 	let prompt = $state('');
 	let referenceFile = $state<File | null>(null);
 	let referencePreviewUrl = $state('');
+	let useCoverAsRef = $state(false);
 
 	// 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);
+	let showAdvanced = $state(saved.showAdvanced ?? false);
+	let numSteps = $state(saved.numSteps ?? 20);
+	let guidance = $state(saved.guidance ?? 7.5);
+	let strength = $state(saved.strength ?? 0.75);
+	let width = $state(saved.width ?? 1024);
+	let height = $state(saved.height ?? 1024);
+
+	// Persist config on change
+	$effect(() => {
+		void selectedModel; void numSteps; void guidance; void strength;
+		void width; void height; void showAdvanced;
+		saveConfig();
+	});
+
+	// ── Book autocomplete ────────────────────────────────────────────────────────
+	const books = data.books as BookSummary[];
+	let slugInput = $state('');
+	let slugFocused = $state(false);
+	let selectedBook = $state<BookSummary | null>(null);
+
+	let bookSuggestions = $derived(
+		slugInput.trim().length === 0
+			? []
+			: books
+				.filter((b) =>
+					b.slug.includes(slugInput.toLowerCase()) ||
+					b.title.toLowerCase().includes(slugInput.toLowerCase())
+				)
+				.slice(0, 8)
+	);
+
+	function selectBook(b: BookSummary) {
+		selectedBook = b;
+		slug = b.slug;
+		slugInput = b.slug;
+		slugFocused = false;
+		// Reset cover-as-ref if no cover
+		if (!b.cover) useCoverAsRef = false;
+	}
+
+	function onSlugInput() {
+		slug = slugInput;
+		// If user edits away from selected book slug, deselect
+		if (selectedBook && slugInput !== selectedBook.slug) {
+			selectedBook = null;
+			useCoverAsRef = false;
+		}
+	}
+
+	// When useCoverAsRef toggled on, load the book cover as reference
+	$effect(() => {
+		if (!browser) return;
+		if (!useCoverAsRef || !selectedBook?.cover) {
+			if (useCoverAsRef) useCoverAsRef = false;
+			return;
+		}
+		// Fetch the cover image and set as referenceFile
+		(async () => {
+			try {
+				const res = await fetch(selectedBook!.cover);
+				const blob = await res.blob();
+				const ext = blob.type === 'image/jpeg' ? 'jpg' : blob.type === 'image/webp' ? 'webp' : 'png';
+				const file = new File([blob], `${selectedBook!.slug}-cover.${ext}`, { type: blob.type });
+				handleReferenceFile(file);
+			} catch {
+				useCoverAsRef = false;
+			}
+		})();
+	});
 
 	// ── Generation state ─────────────────────────────────────────────────────────
 	let generating = $state(false);
@@ -52,16 +146,10 @@
 	// ── 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 coverModels = $derived(models.filter((m) => m.recommended_for.includes('cover')));
+	let chapterModels = $derived(models.filter((m) => m.recommended_for.includes('chapter')));
 	let otherModels = $derived(
-		filteredModels.filter(
+		models.filter(
 			(m) => !m.recommended_for.includes('cover') && !m.recommended_for.includes('chapter')
 		)
 	);
@@ -74,12 +162,10 @@
 		}
 	});
 
-	// Reset model selection when type changes if current selection no longer fits
 	$effect(() => {
-		void imageType; // track
+		void imageType;
 		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;
@@ -90,14 +176,21 @@
 	// ── 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.`
+			? `Book cover for "${slugInput || 'untitled novel'}", a fantasy adventure novel. Epic scene with dramatic lighting, professional book cover art, cinematic composition, highly detailed, 4K.`
+			: `Illustration for chapter ${chapter} of "${slugInput || 'untitled novel'}". Dramatic moment, vivid colors, anime-inspired style, detailed background, cinematic lighting.`
 	);
 
 	function applyTemplate() {
 		prompt = promptTemplate;
 	}
 
+	function injectDescription() {
+		const desc = selectedBook?.summary?.trim();
+		if (!desc) return;
+		const snippet = desc.length > 300 ? desc.slice(0, 300) + '…' : desc;
+		prompt = prompt ? `${prompt}\n\nBook description: ${snippet}` : `Book description: ${snippet}`;
+	}
+
 	// ── Reference image handling ─────────────────────────────────────────────────
 	let dragOver = $state(false);
 
@@ -110,17 +203,22 @@
 	function onFileInput(e: Event) {
 		const input = e.target as HTMLInputElement;
 		handleReferenceFile(input.files?.[0] ?? null);
+		useCoverAsRef = false;
 	}
 
 	function onDrop(e: DragEvent) {
 		e.preventDefault();
 		dragOver = false;
 		const file = e.dataTransfer?.files[0];
-		if (file && file.type.startsWith('image/')) handleReferenceFile(file);
+		if (file && file.type.startsWith('image/')) {
+			handleReferenceFile(file);
+			useCoverAsRef = false;
+		}
 	}
 
 	function clearReference() {
 		handleReferenceFile(null);
+		useCoverAsRef = false;
 		const input = document.getElementById('ref-file-input') as HTMLInputElement | null;
 		if (input) input.value = '';
 	}
@@ -219,7 +317,6 @@
 		saveSuccess = false;
 
 		try {
-			// Extract the raw base64 from the data URL (data:<mime>;base64,<b64>)
 			const b64 = result.imageSrc.split(',')[1];
 			const res = await fetch('/api/admin/image-gen/save-cover', {
 				method: 'POST',
@@ -308,13 +405,63 @@
 					<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)"
-					/>
+					<!-- Autocomplete wrapper -->
+					<div class="relative">
+						<input
+							id="slug-input"
+							type="text"
+							bind:value={slugInput}
+							oninput={onSlugInput}
+							onfocus={() => (slugFocused = true)}
+							onblur={() => setTimeout(() => { slugFocused = false; }, 150)}
+							placeholder="e.g. shadow-slave"
+							autocomplete="off"
+							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)"
+						/>
+						{#if slugFocused && bookSuggestions.length > 0}
+							<ul class="absolute z-50 top-full left-0 right-0 mt-1 bg-(--color-surface-2) border border-(--color-border) rounded-lg shadow-xl overflow-hidden max-h-56 overflow-y-auto">
+								{#each bookSuggestions as b}
+									<!-- svelte-ignore a11y_click_events_have_key_events a11y_interactive_supports_focus -->
+									<li
+										role="option"
+										aria-selected={selectedBook?.slug === b.slug}
+										onmousedown={() => selectBook(b)}
+										class="flex items-center gap-3 px-3 py-2 cursor-pointer hover:bg-(--color-surface-3) transition-colors"
+									>
+										{#if b.cover}
+											<img src={b.cover} alt="" class="w-8 h-10 object-cover rounded shrink-0" />
+										{:else}
+											<div class="w-8 h-10 rounded bg-(--color-surface-3) shrink-0"></div>
+										{/if}
+										<div class="min-w-0">
+											<p class="text-sm text-(--color-text) truncate">{b.title}</p>
+											<p class="text-xs text-(--color-muted) truncate font-mono">{b.slug}</p>
+										</div>
+									</li>
+								{/each}
+							</ul>
+						{/if}
+					</div>
+					<!-- Book info pill when a book is selected -->
+					{#if selectedBook}
+						<div class="flex items-center gap-2 mt-1">
+							<span class="text-xs text-(--color-success) flex items-center gap-1">
+								<svg class="w-3 h-3" fill="currentColor" viewBox="0 0 20 20">
+									<path fill-rule="evenodd" d="M16.707 5.293a1 1 0 010 1.414l-8 8a1 1 0 01-1.414 0l-4-4a1 1 0 011.414-1.414L8 12.586l7.293-7.293a1 1 0 011.414 0z" clip-rule="evenodd"/>
+								</svg>
+								{selectedBook.title}
+							</span>
+							{#if selectedBook.summary}
+								<button
+									onclick={injectDescription}
+									class="text-xs text-(--color-brand) hover:text-(--color-brand-dim) transition-colors"
+									title="Append book description to prompt"
+								>
+									+ inject description
+								</button>
+							{/if}
+						</div>
+					{/if}
 				</div>
 
 				{#if imageType === 'chapter'}
@@ -385,12 +532,22 @@
 					<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 class="flex items-center gap-3">
+						{#if selectedBook?.summary}
+							<button
+								onclick={injectDescription}
+								class="text-xs text-(--color-brand) hover:text-(--color-brand-dim) transition-colors"
+							>
+								Inject description
+							</button>
+						{/if}
+						<button
+							onclick={applyTemplate}
+							class="text-xs text-(--color-muted) hover:text-(--color-text) transition-colors"
+						>
+							Use template
+						</button>
+					</div>
 				</div>
 				<textarea
 					id="prompt-input"
@@ -403,9 +560,26 @@
 
 			<!-- 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>
+				<div class="flex items-center justify-between">
+					<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 selectedBook?.cover && selectedModelInfo?.supports_ref}
+						<label class="flex items-center gap-1.5 cursor-pointer select-none">
+							<div
+								role="checkbox"
+								aria-checked={useCoverAsRef}
+								tabindex="0"
+								onkeydown={(e) => { if (e.key === ' ' || e.key === 'Enter') useCoverAsRef = !useCoverAsRef; }}
+								onclick={() => (useCoverAsRef = !useCoverAsRef)}
+								class="w-8 h-4 rounded-full transition-colors relative {useCoverAsRef ? 'bg-(--color-brand)' : 'bg-(--color-surface-3)'}"
+							>
+								<span class="absolute top-0.5 left-0.5 w-3 h-3 rounded-full bg-white transition-transform {useCoverAsRef ? 'translate-x-4' : ''}"></span>
+							</div>
+							<span class="text-xs text-(--color-muted)">Use book cover</span>
+						</label>
+					{/if}
+				</div>
 				{#if referenceFile && referencePreviewUrl}
 					<div class="flex items-start gap-3 p-3 bg-(--color-surface-2) rounded-lg border border-(--color-border)">
 						<img
@@ -416,6 +590,9 @@
 						<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>
+							{#if useCoverAsRef}
+								<p class="text-xs text-(--color-brand)">Current book cover</p>
+							{/if}
 						</div>
 						<button
 							onclick={clearReference}
@@ -530,7 +707,6 @@
 					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" />
diff --git a/ui/src/routes/admin/text-gen/+page.server.ts b/ui/src/routes/admin/text-gen/+page.server.ts
index 8a3459e..165f5ac 100644
--- a/ui/src/routes/admin/text-gen/+page.server.ts
+++ b/ui/src/routes/admin/text-gen/+page.server.ts
@@ -1,6 +1,12 @@
 import type { PageServerLoad } from './$types';
 import { backendFetch } from '$lib/server/scraper';
 import { log } from '$lib/server/logger';
+import { listBooks } from '$lib/server/pocketbase';
+
+export interface BookSummary {
+	slug: string;
+	title: string;
+}
 
 export interface TextModelInfo {
 	id: string;
@@ -12,16 +18,25 @@ export interface TextModelInfo {
 
 export const load: PageServerLoad = async () => {
 	// Parent layout already guards admin role.
-	try {
-		const res = await backendFetch('/api/admin/text-gen/models');
-		if (!res.ok) {
-			log.warn('admin/text-gen', 'failed to load models', { status: res.status });
-			return { models: [] as TextModelInfo[] };
-		}
-		const data = await res.json();
-		return { models: (data.models ?? []) as TextModelInfo[] };
-	} catch (e) {
-		log.warn('admin/text-gen', 'backend unreachable', { err: String(e) });
-		return { models: [] as TextModelInfo[] };
+	const [modelsResult, books] = await Promise.allSettled([
+		(async () => {
+			const res = await backendFetch('/api/admin/text-gen/models');
+			if (!res.ok) throw new Error(`status ${res.status}`);
+			const data = await res.json();
+			return (data.models ?? []) as TextModelInfo[];
+		})(),
+		listBooks()
+	]);
+
+	if (modelsResult.status === 'rejected') {
+		log.warn('admin/text-gen', 'failed to load models', { err: String(modelsResult.reason) });
 	}
+
+	return {
+		models: modelsResult.status === 'fulfilled' ? modelsResult.value : ([] as TextModelInfo[]),
+		books: (books.status === 'fulfilled' ? books.value : []).map((b) => ({
+			slug: b.slug,
+			title: b.title
+		})) as BookSummary[]
+	};
 };
diff --git a/ui/src/routes/admin/text-gen/+page.svelte b/ui/src/routes/admin/text-gen/+page.svelte
index 35f617c..6fa95d5 100644
--- a/ui/src/routes/admin/text-gen/+page.svelte
+++ b/ui/src/routes/admin/text-gen/+page.svelte
@@ -1,26 +1,82 @@
 <script lang="ts">
+	import { browser } from '$app/environment';
 	import type { PageData } from './$types';
-	import type { TextModelInfo } from './+page.server';
+	import type { TextModelInfo, BookSummary } from './+page.server';
 
 	let { data }: { data: PageData } = $props();
 
 	const models = data.models as TextModelInfo[];
+	const books = data.books as BookSummary[];
+
+	// ── Config persistence ───────────────────────────────────────────────────────
+	const CONFIG_KEY = 'admin_text_gen_config_v1';
+
+	interface SavedConfig {
+		selectedModel: string;
+		activeTab: 'chapters' | 'description';
+		chPattern: string;
+		dInstructions: string;
+	}
+
+	function loadConfig(): Partial<SavedConfig> {
+		if (!browser) return {};
+		try {
+			const raw = localStorage.getItem(CONFIG_KEY);
+			return raw ? (JSON.parse(raw) as Partial<SavedConfig>) : {};
+		} catch { return {}; }
+	}
+
+	function saveConfig() {
+		if (!browser) return;
+		const cfg: SavedConfig = { selectedModel, activeTab, chPattern, dInstructions };
+		localStorage.setItem(CONFIG_KEY, JSON.stringify(cfg));
+	}
+
+	const saved = loadConfig();
 
 	// ── Shared ────────────────────────────────────────────────────────────────────
 	type ActiveTab = 'chapters' | 'description';
-	let activeTab = $state<ActiveTab>('chapters');
-	let selectedModel = $state(models[0]?.id ?? '');
+	let activeTab = $state<ActiveTab>(saved.activeTab ?? 'chapters');
+	let selectedModel = $state(saved.selectedModel ?? (models[0]?.id ?? ''));
 
 	let selectedModelInfo = $derived(models.find((m) => m.id === selectedModel) ?? null);
 
+	$effect(() => { void selectedModel; void activeTab; void chPattern; void dInstructions; saveConfig(); });
+
 	function fmtCtx(n: number) {
 		if (n >= 1000) return `${(n / 1000).toFixed(0)}k ctx`;
 		return `${n} ctx`;
 	}
 
+	// ── Book autocomplete (shared component logic) ───────────────────────────────
+	function makeBookAC() {
+		let inputVal = $state('');
+		let focused = $state(false);
+
+		const suggestions = $derived(
+			inputVal.trim().length === 0
+				? []
+				: books
+					.filter((b) =>
+						b.slug.includes(inputVal.toLowerCase()) ||
+						b.title.toLowerCase().includes(inputVal.toLowerCase())
+					)
+					.slice(0, 8)
+		);
+
+		return {
+			get inputVal() { return inputVal; },
+			set inputVal(v: string) { inputVal = v; },
+			get focused() { return focused; },
+			set focused(v: boolean) { focused = v; },
+			get suggestions() { return suggestions; }
+		};
+	}
+
 	// ── Chapter names state ───────────────────────────────────────────────────────
+	let chAC = makeBookAC();
 	let chSlug = $state('');
-	let chPattern = $state('Chapter {n}: {scene}');
+	let chPattern = $state(saved.chPattern ?? 'Chapter {n}: {scene}');
 	let chGenerating = $state(false);
 	let chError = $state('');
 
@@ -28,13 +84,13 @@
 		number: number;
 		old_title: string;
 		new_title: string;
-		// editable copy
 		edited: string;
 	}
 	let chProposals = $state<ProposedChapter[]>([]);
-	let chRawResponse = $state('');
 	let chUsedModel = $state('');
-	let chShowRaw = $state(false);
+
+	let chBatchProgress = $state('');
+	let chBatchWarnings = $state<string[]>([]);
 
 	let chApplying = $state(false);
 	let chApplyError = $state('');
@@ -43,11 +99,24 @@
 	let chCanGenerate = $derived(chSlug.trim().length > 0 && chPattern.trim().length > 0 && !chGenerating);
 	let chCanApply = $derived(chProposals.length > 0 && !chApplying);
 
+	function selectChBook(b: BookSummary) {
+		chSlug = b.slug;
+		chAC.inputVal = b.slug;
+		chAC.focused = false;
+	}
+
+	function onChSlugInput() {
+		chSlug = chAC.inputVal;
+	}
+
 	async function generateChapterNames() {
 		if (!chCanGenerate) return;
 		chGenerating = true;
 		chError = '';
 		chProposals = [];
+		chUsedModel = '';
+		chBatchProgress = '';
+		chBatchWarnings = [];
 		chApplySuccess = false;
 		chApplyError = '';
 
@@ -61,20 +130,77 @@
 					model: selectedModel
 				})
 			});
-			const body = await res.json().catch(() => ({}));
+
+			// Non-SSE error response (e.g. 400/404/502 before streaming started).
 			if (!res.ok) {
+				const body = await res.json().catch(() => ({}));
 				chError = body.error ?? body.message ?? `Error ${res.status}`;
 				return;
 			}
-			chProposals = ((body.chapters ?? []) as { number: number; old_title: string; new_title: string }[]).map(
-				(p) => ({ ...p, edited: p.new_title })
-			);
-			chRawResponse = body.raw_response ?? '';
-			chUsedModel = body.model ?? '';
-			// If backend returned chapters:[] but we have a raw response, the model
-			// output was unparseable (likely truncated). Treat it as an error.
-			if (chProposals.length === 0 && chRawResponse.trim().length > 0) {
-				chError = 'Model response could not be parsed (output may be truncated). Raw response shown below.';
+
+			// Stream SSE events line by line.
+			const reader = res.body!.getReader();
+			const decoder = new TextDecoder();
+			let buffer = '';
+
+			outer: while (true) {
+				const { value, done } = await reader.read();
+				if (done) break;
+				buffer += decoder.decode(value, { stream: true });
+
+				// Process all complete SSE messages in the buffer.
+				const lines = buffer.split('\n');
+				buffer = lines.pop() ?? ''; // keep incomplete last line
+
+				for (const line of lines) {
+					if (!line.startsWith('data: ')) continue;
+					const payload = line.slice(6).trim();
+					if (!payload) continue;
+
+					let evt: {
+						batch?: number;
+						total_batches?: number;
+						chapters_done?: number;
+						total_chapters?: number;
+						model?: string;
+						chapters?: { number: number; old_title: string; new_title: string }[];
+						error?: string;
+						done?: boolean;
+					};
+					try {
+						evt = JSON.parse(payload);
+					} catch {
+						continue;
+					}
+
+					if (evt.done) {
+						chBatchProgress = `Done — ${evt.total_chapters ?? chProposals.length} chapters`;
+						chGenerating = false;
+						break outer;
+					}
+
+					if (evt.model) chUsedModel = evt.model;
+
+					if (evt.error) {
+						chBatchWarnings = [
+							...chBatchWarnings,
+							`Batch ${evt.batch}/${evt.total_batches} failed: ${evt.error}`
+						];
+					} else if (evt.chapters) {
+						const incoming = (evt.chapters as { number: number; old_title: string; new_title: string }[]).map(
+							(p) => ({ ...p, edited: p.new_title })
+						);
+						chProposals = [...chProposals, ...incoming];
+					}
+
+					if (evt.batch != null && evt.total_batches != null) {
+						chBatchProgress = `Batch ${evt.batch}/${evt.total_batches} · ${evt.chapters_done ?? chProposals.length}/${evt.total_chapters ?? '?'} chapters`;
+					}
+				}
+			}
+
+			if (chProposals.length === 0 && chBatchWarnings.length === 0) {
+				chError = 'No proposals returned. The model may have failed to parse the chapters.';
 			}
 		} catch {
 			chError = 'Network error.';
@@ -112,8 +238,9 @@
 	}
 
 	// ── Description state ─────────────────────────────────────────────────────────
+	let dAC = makeBookAC();
 	let dSlug = $state('');
-	let dInstructions = $state('');
+	let dInstructions = $state(saved.dInstructions ?? '');
 	let dGenerating = $state(false);
 	let dError = $state('');
 
@@ -128,6 +255,16 @@
 	let dCanGenerate = $derived(dSlug.trim().length > 0 && !dGenerating);
 	let dCanApply = $derived(dNewDesc.trim().length > 0 && !dApplying);
 
+	function selectDBook(b: BookSummary) {
+		dSlug = b.slug;
+		dAC.inputVal = b.slug;
+		dAC.focused = false;
+	}
+
+	function onDSlugInput() {
+		dSlug = dAC.inputVal;
+	}
+
 	async function generateDescription() {
 		if (!dCanGenerate) return;
 		dGenerating = true;
@@ -247,13 +384,37 @@
 					<label class="text-xs font-medium text-(--color-muted) uppercase tracking-wide" for="ch-slug">
 						Book slug
 					</label>
-					<input
-						id="ch-slug"
-						type="text"
-						bind:value={chSlug}
-						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 class="relative">
+						<input
+							id="ch-slug"
+							type="text"
+							bind:value={chAC.inputVal}
+							oninput={onChSlugInput}
+							onfocus={() => (chAC.focused = true)}
+							onblur={() => setTimeout(() => { chAC.focused = false; }, 150)}
+							placeholder="e.g. shadow-slave"
+							autocomplete="off"
+							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)"
+						/>
+						{#if chAC.focused && chAC.suggestions.length > 0}
+							<ul class="absolute z-50 top-full left-0 right-0 mt-1 bg-(--color-surface-2) border border-(--color-border) rounded-lg shadow-xl overflow-hidden max-h-56 overflow-y-auto">
+								{#each chAC.suggestions as b}
+									<!-- svelte-ignore a11y_click_events_have_key_events a11y_interactive_supports_focus -->
+									<li
+										role="option"
+										aria-selected={chSlug === b.slug}
+										onmousedown={() => selectChBook(b)}
+										class="flex items-center gap-3 px-3 py-2 cursor-pointer hover:bg-(--color-surface-3) transition-colors"
+									>
+										<div class="min-w-0">
+											<p class="text-sm text-(--color-text) truncate">{b.title}</p>
+											<p class="text-xs text-(--color-muted) font-mono">{b.slug}</p>
+										</div>
+									</li>
+								{/each}
+							</ul>
+						{/if}
+					</div>
 				</div>
 
 				<div class="space-y-1">
@@ -292,9 +453,6 @@
 
 				{#if chError}
 					<p class="text-sm text-(--color-danger) bg-(--color-danger)/10 rounded-lg px-3 py-2">{chError}</p>
-					{#if chRawResponse}
-						<pre class="text-xs bg-(--color-surface-2) border border-(--color-border) rounded-lg p-3 overflow-auto max-h-48 text-(--color-muted) whitespace-pre-wrap break-words">{chRawResponse}</pre>
-					{/if}
 				{/if}
 			</div>
 
@@ -309,16 +467,25 @@
 									<span class="normal-case font-normal">· {chUsedModel.split('/').pop()}</span>
 								{/if}
 							</p>
-							<button
-								onclick={() => (chShowRaw = !chShowRaw)}
-								class="text-xs text-(--color-muted) hover:text-(--color-text) transition-colors"
-							>
-								{chShowRaw ? 'Hide raw' : 'Show raw'}
-							</button>
+							{#if chBatchProgress}
+								<span class="text-xs text-(--color-muted) flex items-center gap-1.5">
+									{#if chGenerating}
+										<svg class="w-3 h-3 animate-spin shrink-0" 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>
+									{/if}
+									{chBatchProgress}
+								</span>
+							{/if}
 						</div>
 
-						{#if chShowRaw}
-							<pre class="text-xs bg-(--color-surface-2) border border-(--color-border) rounded-lg p-3 overflow-auto max-h-40 text-(--color-muted)">{chRawResponse}</pre>
+						{#if chBatchWarnings.length > 0}
+							<div class="space-y-1">
+								{#each chBatchWarnings as w}
+									<p class="text-xs text-amber-400 bg-amber-400/10 rounded-lg px-3 py-2">{w}</p>
+								{/each}
+							</div>
 						{/if}
 
 						<div class="max-h-[28rem] overflow-y-auto space-y-2 pr-1">
@@ -349,7 +516,7 @@
 								{chApplying ? 'Saving…' : chApplySuccess ? 'Saved ✓' : `Apply ${chProposals.length} titles`}
 							</button>
 							<button
-								onclick={() => { chProposals = []; chRawResponse = ''; chApplySuccess = false; }}
+								onclick={() => { chProposals = []; chBatchProgress = ''; chBatchWarnings = []; chApplySuccess = false; }}
 								class="px-4 py-2 rounded-lg bg-(--color-surface-2) text-(--color-muted) text-sm
 									hover:text-(--color-text) transition-colors border border-(--color-border)"
 							>
@@ -373,7 +540,9 @@
 								<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 chapter titles…</p>
+							<p class="text-sm text-(--color-muted)">
+								{chBatchProgress || 'Generating chapter titles…'}
+							</p>
 						</div>
 					</div>
 				{:else}
@@ -394,13 +563,37 @@
 					<label class="text-xs font-medium text-(--color-muted) uppercase tracking-wide" for="d-slug">
 						Book slug
 					</label>
-					<input
-						id="d-slug"
-						type="text"
-						bind:value={dSlug}
-						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 class="relative">
+						<input
+							id="d-slug"
+							type="text"
+							bind:value={dAC.inputVal}
+							oninput={onDSlugInput}
+							onfocus={() => (dAC.focused = true)}
+							onblur={() => setTimeout(() => { dAC.focused = false; }, 150)}
+							placeholder="e.g. shadow-slave"
+							autocomplete="off"
+							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)"
+						/>
+						{#if dAC.focused && dAC.suggestions.length > 0}
+							<ul class="absolute z-50 top-full left-0 right-0 mt-1 bg-(--color-surface-2) border border-(--color-border) rounded-lg shadow-xl overflow-hidden max-h-56 overflow-y-auto">
+								{#each dAC.suggestions as b}
+									<!-- svelte-ignore a11y_click_events_have_key_events a11y_interactive_supports_focus -->
+									<li
+										role="option"
+										aria-selected={dSlug === b.slug}
+										onmousedown={() => selectDBook(b)}
+										class="flex items-center gap-3 px-3 py-2 cursor-pointer hover:bg-(--color-surface-3) transition-colors"
+									>
+										<div class="min-w-0">
+											<p class="text-sm text-(--color-text) truncate">{b.title}</p>
+											<p class="text-xs text-(--color-muted) font-mono">{b.slug}</p>
+										</div>
+									</li>
+								{/each}
+							</ul>
+						{/if}
+					</div>
 				</div>
 
 				<div class="space-y-1">
diff --git a/ui/src/routes/api/admin/text-gen/chapter-names/+server.ts b/ui/src/routes/api/admin/text-gen/chapter-names/+server.ts
index 29a92fa..55221b3 100644
--- a/ui/src/routes/api/admin/text-gen/chapter-names/+server.ts
+++ b/ui/src/routes/api/admin/text-gen/chapter-names/+server.ts
@@ -2,10 +2,11 @@
  * POST /api/admin/text-gen/chapter-names
  *
  * Admin-only proxy to the Go backend's chapter-name generation endpoint.
- * Returns AI-proposed chapter titles; does NOT persist anything.
+ * The backend streams SSE events; this handler pipes the stream through
+ * directly so the browser can consume it without buffering.
  */
 
-import { json, error } from '@sveltejs/kit';
+import { error } from '@sveltejs/kit';
 import type { RequestHandler } from './$types';
 import { log } from '$lib/server/logger';
 import { backendFetch } from '$lib/server/scraper';
@@ -28,6 +29,22 @@ export const POST: RequestHandler = async ({ request, locals }) => {
 		throw error(502, 'Could not reach backend');
 	}
 
-	const data = await res.json().catch(() => ({}));
-	return json(data, { status: res.status });
+	// Non-2xx: the backend returned a JSON error before switching to SSE.
+	if (!res.ok) {
+		const data = await res.json().catch(() => ({}));
+		return new Response(JSON.stringify(data), {
+			status: res.status,
+			headers: { 'Content-Type': 'application/json' }
+		});
+	}
+
+	// Pipe the SSE stream straight through — do not buffer.
+	return new Response(res.body, {
+		status: 200,
+		headers: {
+			'Content-Type': 'text/event-stream',
+			'Cache-Control': 'no-cache',
+			'X-Accel-Buffering': 'no'
+		}
+	});
 };