feat: reading view modes — progress bar, paginated, spacing, width, focus

Five new reader settings (persisted in localStorage as reader_layout_v1):

- Read mode: Scroll (default) vs Pages — paginated mode splits content
  into viewport-height pages, navigate with tap left/right, arrow keys,
  or Prev/Next buttons. Recalculates on content change.

- Line spacing: Tight (1.55) / Normal (1.85) / Loose (2.2) via
  --reading-line-height CSS var on :root.

- Reading width: Narrow (58ch) / Normal (72ch) / Wide (90ch) via
  --reading-max-width CSS var on :root.

- Paragraph style: Spaced (default) vs Indented (text-indent: 2em,
  tight margin — book-like feel).

- Focus mode: hides audio player, language switcher, bottom nav and
  comments so only the text remains.

Scroll progress bar: thin 2px brand-colored bar fixed at top of
viewport in scroll mode, fills as you read through the chapter.

All options added to the floating settings gear panel.

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

ui/src/app.css

@@ -106,12 +106,14 @@ html {
 :root {
 	--reading-font: system-ui, -apple-system, sans-serif;
 	--reading-size: 1.05rem;
+	--reading-line-height: 1.85;
+	--reading-max-width: 72ch;
 }
 
 /* ── Chapter prose ─────────────────────────────────────────────────── */
 .prose-chapter {
-	max-width: 72ch;
-	line-height: 1.85;
+	max-width: var(--reading-max-width, 72ch);
+	line-height: var(--reading-line-height, 1.85);
 	font-family: var(--reading-font);
 	font-size: var(--reading-size);
 	color: var(--color-muted);
@@ -134,6 +136,12 @@ html {
 	margin-bottom: 1.2em;
 }
 
+/* Indented paragraph style — book-like, no gap, indent instead */
+.prose-chapter.para-indented p {
+	text-indent: 2em;
+	margin-bottom: 0.35em;
+}
+
 .prose-chapter em {
 	color: var(--color-muted);
 }
@@ -147,6 +155,31 @@ html {
 	margin: 2em 0;
 }
 
+/* ── Reading progress bar ───────────────────────────────────────────── */
+.reading-progress {
+	position: fixed;
+	top: 0;
+	left: 0;
+	height: 2px;
+	z-index: 100;
+	background: var(--color-brand);
+	pointer-events: none;
+	transition: width 0.1s linear;
+}
+
+/* ── Paginated reader ───────────────────────────────────────────────── */
+.paginated-container {
+	overflow: hidden;
+	cursor: pointer;
+	user-select: none;
+	-webkit-user-select: none;
+}
+
+.paginated-container .prose-chapter {
+	transition: transform 0.25s cubic-bezier(0.4, 0, 0.2, 1);
+	will-change: transform;
+}
+
 /* ── Hide scrollbars (used on horizontal carousels) ────────────────── */
 .scrollbar-none {
 	scrollbar-width: none;       /* Firefox */

ui/src/routes/books/[slug]/chapters/[n]/+page.svelte

@@ -1,5 +1,6 @@
 <script lang="ts">
 	import { onMount, untrack, getContext } from 'svelte';
+	import { browser } from '$app/environment';
 	import { goto } from '$app/navigation';
 	import { page } from '$app/state';
 	import AudioPlayer from '$lib/components/AudioPlayer.svelte';
@@ -56,7 +57,114 @@
 		if (settingsCtx) settingsCtx.fontSize = v;
 	}
 
-	// Translation state
+	// ── Layout / reading-view prefs (localStorage) ──────────────────────────────
+	type ReadMode    = 'scroll' | 'paginated';
+	type LineSpacing = 'compact' | 'normal' | 'relaxed';
+	type ReadWidth   = 'narrow' | 'normal' | 'wide';
+	type ParaStyle   = 'spaced' | 'indented';
+
+	interface LayoutPrefs {
+		readMode:    ReadMode;
+		lineSpacing: LineSpacing;
+		readWidth:   ReadWidth;
+		paraStyle:   ParaStyle;
+		focusMode:   boolean;
+	}
+
+	const LAYOUT_KEY = 'reader_layout_v1';
+	const LINE_HEIGHTS: Record<LineSpacing, number> = { compact: 1.55, normal: 1.85, relaxed: 2.2 };
+	const READ_WIDTHS:  Record<ReadWidth,   string>  = { narrow: '58ch', normal: '72ch', wide: 'min(90ch, 100%)' };
+	const DEFAULT_LAYOUT: LayoutPrefs = { readMode: 'scroll', lineSpacing: 'normal', readWidth: 'normal', paraStyle: 'spaced', focusMode: false };
+
+	function loadLayout(): LayoutPrefs {
+		if (!browser) return DEFAULT_LAYOUT;
+		try {
+			const raw = localStorage.getItem(LAYOUT_KEY);
+			if (raw) return { ...DEFAULT_LAYOUT, ...JSON.parse(raw) as Partial<LayoutPrefs> };
+		} catch { /* ignore */ }
+		return DEFAULT_LAYOUT;
+	}
+
+	let layout = $state<LayoutPrefs>(loadLayout());
+
+	function setLayout<K extends keyof LayoutPrefs>(key: K, value: LayoutPrefs[K]) {
+		layout = { ...layout, [key]: value };
+		if (browser) localStorage.setItem(LAYOUT_KEY, JSON.stringify(layout));
+	}
+
+	// Apply reading CSS vars whenever layout changes
+	$effect(() => {
+		if (!browser) return;
+		document.documentElement.style.setProperty('--reading-line-height', String(LINE_HEIGHTS[layout.lineSpacing]));
+		document.documentElement.style.setProperty('--reading-max-width', READ_WIDTHS[layout.readWidth]);
+	});
+
+	// ── Scroll progress bar ──────────────────────────────────────────────────────
+	let scrollProgress = $state(0);
+
+	$effect(() => {
+		if (!browser || layout.readMode === 'paginated') { scrollProgress = 0; return; }
+		function onScroll() {
+			const el = document.documentElement;
+			const max = el.scrollHeight - el.clientHeight;
+			scrollProgress = max > 0 ? el.scrollTop / max : 0;
+		}
+		window.addEventListener('scroll', onScroll, { passive: true });
+		return () => window.removeEventListener('scroll', onScroll);
+	});
+
+	// ── Paginated mode ───────────────────────────────────────────────────────────
+	let pageIndex = $state(0);
+	let totalPages = $state(1);
+	let paginatedContainerEl = $state<HTMLDivElement | null>(null);
+	let paginatedContentEl   = $state<HTMLDivElement | null>(null);
+	let containerH = $state(0);
+
+	$effect(() => {
+		if (layout.readMode !== 'paginated') { pageIndex = 0; totalPages = 1; return; }
+		// Re-run when html changes or container is bound
+		void html; void paginatedContainerEl; void paginatedContentEl;
+		requestAnimationFrame(() => {
+			if (!paginatedContainerEl || !paginatedContentEl) return;
+			const h = paginatedContainerEl.clientHeight;
+			if (h > 0) {
+				containerH = h;
+				totalPages = Math.max(1, Math.ceil(paginatedContentEl.scrollHeight / h));
+				pageIndex = Math.min(pageIndex, totalPages - 1);
+			}
+		});
+	});
+
+	// Reset page index when chapter changes
+	$effect(() => { void data.chapter.number; pageIndex = 0; });
+
+	function handlePaginatedClick(e: MouseEvent) {
+		const rect = (e.currentTarget as HTMLElement).getBoundingClientRect();
+		if (e.clientX - rect.left > rect.width / 2) {
+			if (pageIndex < totalPages - 1) pageIndex++;
+		} else {
+			if (pageIndex > 0) pageIndex--;
+		}
+	}
+
+	// Keyboard nav for paginated mode
+	$effect(() => {
+		if (!browser) return;
+		function onKey(e: KeyboardEvent) {
+			if (layout.readMode !== 'paginated') return;
+			if (e.key === 'ArrowRight' || e.key === 'PageDown' || e.key === ' ') {
+				e.preventDefault();
+				if (pageIndex < totalPages - 1) pageIndex++;
+			} else if (e.key === 'ArrowLeft' || e.key === 'PageUp') {
+				e.preventDefault();
+				if (pageIndex > 0) pageIndex--;
+			}
+		}
+		window.addEventListener('keydown', onKey);
+		return () => window.removeEventListener('keydown', onKey);
+	});
+
+	// ── Translation state
 	const SUPPORTED_LANGS = [
 		{ code: 'ru', label: 'RU' },
 		{ code: 'id', label: 'ID' },
@@ -189,6 +297,11 @@
 	<title>{data.chapter.title || m.reader_chapter_n({ n: String(data.chapter.number) })} — {data.book.title} — libnovel</title>
 </svelte:head>
 
+<!-- Reading progress bar (scroll mode) -->
+{#if layout.readMode === 'scroll'}
+<div class="reading-progress" style="width: {scrollProgress * 100}%"></div>
+{/if}
+
 <!-- Top nav -->
 <div class="flex items-center justify-between mb-6 gap-4">
 	<a
@@ -235,8 +348,8 @@
 	{/if}
 </div>
 
-<!-- Language switcher (not shown for preview chapters) -->
-{#if !data.isPreview}
+<!-- Language switcher (not shown for preview chapters or focus mode) -->
+{#if !data.isPreview && !layout.focusMode}
 <div class="flex items-center gap-2 mb-6 flex-wrap">
 	<span class="text-(--color-muted) text-xs">Read in:</span>
 
@@ -292,8 +405,8 @@
 </div>
 {/if}
 
-<!-- Audio player -->
-{#if !data.isPreview}
+<!-- Audio player (hidden in focus mode) -->
+{#if !data.isPreview && !layout.focusMode}
 {#if !page.data.user}
 	<!-- Unauthenticated: sign-in prompt -->
 	<div class="mb-6 px-4 py-3 rounded-lg bg-(--color-surface-2) border border-(--color-border) flex items-center justify-between gap-4">
@@ -353,13 +466,66 @@
 	<div class="text-(--color-muted) text-center py-16">
 		<p>{fetchError || m.reader_audio_error()}</p>
 	</div>
+{:else if layout.readMode === 'paginated'}
+	<!-- ── Paginated reader ─────────────────────────────────────────────── -->
+	<!-- svelte-ignore a11y_click_events_have_key_events a11y_no_static_element_interactions -->
+	<div
+		bind:this={paginatedContainerEl}
+		class="paginated-container mt-8"
+		style="height: {layout.focusMode ? 'calc(100svh - 8rem)' : 'calc(100svh - 26rem)'};"
+		onclick={handlePaginatedClick}
+	>
+		<div
+			bind:this={paginatedContentEl}
+			class="prose-chapter {layout.paraStyle === 'indented' ? 'para-indented' : ''}"
+			style="transform: translateY({containerH > 0 ? -(pageIndex * containerH) : 0}px);"
+		>
+			{@html html}
+		</div>
+	</div>
+
+	<!-- Page indicator + nav -->
+	<div class="flex items-center justify-between mt-4 select-none">
+		<button
+			type="button"
+			onclick={() => { if (pageIndex > 0) pageIndex--; }}
+			disabled={pageIndex === 0}
+			class="flex items-center gap-1.5 px-3 py-1.5 rounded-lg bg-(--color-surface-2) border border-(--color-border) text-sm text-(--color-muted) hover:text-(--color-text) disabled:opacity-30 transition-colors"
+		>
+			<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="M15 19l-7-7 7-7"/>
+			</svg>
+			Prev
+		</button>
+
+		<span class="text-sm text-(--color-muted) tabular-nums">
+			{pageIndex + 1} <span class="opacity-40">/</span> {totalPages}
+		</span>
+
+		<button
+			type="button"
+			onclick={() => { if (pageIndex < totalPages - 1) pageIndex++; }}
+			disabled={pageIndex === totalPages - 1}
+			class="flex items-center gap-1.5 px-3 py-1.5 rounded-lg bg-(--color-surface-2) border border-(--color-border) text-sm text-(--color-muted) hover:text-(--color-text) disabled:opacity-30 transition-colors"
+		>
+			Next
+			<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="M9 5l7 7-7 7"/>
+			</svg>
+		</button>
+	</div>
+
+	<!-- Tap hint -->
+	<p class="text-center text-xs text-(--color-muted)/40 mt-2">Tap left/right · Arrow keys · Space</p>
 {:else}
-	<div class="prose-chapter mt-8">
+	<!-- ── Scroll reader ────────────────────────────────────────────────── -->
+	<div class="prose-chapter mt-8 {layout.paraStyle === 'indented' ? 'para-indented' : ''}">
 		{@html html}
 	</div>
 {/if}
 
-<!-- Bottom nav -->
+<!-- Bottom nav + comments (hidden in paginated focus mode) -->
+{#if !(layout.focusMode && layout.readMode === 'paginated')}
 <div class="flex justify-between mt-12 pt-6 border-t border-(--color-border) gap-4">
 	{#if data.prev}
 		<a
@@ -381,7 +547,6 @@
 	{/if}
 </div>
 
-<!-- Chapter comments -->
 <div class="mt-12">
 	<CommentsSection
 		slug={data.book.slug}
@@ -390,6 +555,7 @@
 		currentUserId={page.data.user?.id ?? ''}
 	/>
 </div>
+{/if}
 
 <!-- ── Floating reader settings ─────────────────────────────────────────── -->
 {#if settingsCtx}
@@ -480,6 +646,95 @@
 		</div>
 	</div>
 
+	<!-- Divider -->
+	<div class="border-t border-(--color-border)"></div>
+
+	<!-- Read mode -->
+	<div class="space-y-2">
+		<p class="text-xs text-(--color-muted)">Read mode</p>
+		<div class="flex gap-1.5">
+			{#each ([['scroll', 'Scroll'], ['paginated', 'Pages']] as const) as [mode, label]}
+				<button
+					type="button"
+					onclick={() => setLayout('readMode', mode)}
+					class="flex-1 py-1.5 rounded-lg border text-xs font-medium transition-colors
+						{layout.readMode === mode
+							? 'border-(--color-brand) bg-(--color-brand)/10 text-(--color-brand)'
+							: 'border-(--color-border) bg-(--color-surface-3) text-(--color-muted) hover:border-(--color-brand)/50 hover:text-(--color-text)'}"
+					aria-pressed={layout.readMode === mode}
+				>{label}</button>
+			{/each}
+		</div>
+	</div>
+
+	<!-- Line spacing -->
+	<div class="space-y-2">
+		<p class="text-xs text-(--color-muted)">Line spacing</p>
+		<div class="flex gap-1.5">
+			{#each ([['compact', 'Tight'], ['normal', 'Normal'], ['relaxed', 'Loose']] as const) as [s, label]}
+				<button
+					type="button"
+					onclick={() => setLayout('lineSpacing', s)}
+					class="flex-1 py-1.5 rounded-lg border text-xs font-medium transition-colors
+						{layout.lineSpacing === s
+							? 'border-(--color-brand) bg-(--color-brand)/10 text-(--color-brand)'
+							: 'border-(--color-border) bg-(--color-surface-3) text-(--color-muted) hover:border-(--color-brand)/50 hover:text-(--color-text)'}"
+					aria-pressed={layout.lineSpacing === s}
+				>{label}</button>
+			{/each}
+		</div>
+	</div>
+
+	<!-- Reading width -->
+	<div class="space-y-2">
+		<p class="text-xs text-(--color-muted)">Width</p>
+		<div class="flex gap-1.5">
+			{#each ([['narrow', 'Narrow'], ['normal', 'Normal'], ['wide', 'Wide']] as const) as [w, label]}
+				<button
+					type="button"
+					onclick={() => setLayout('readWidth', w)}
+					class="flex-1 py-1.5 rounded-lg border text-xs font-medium transition-colors
+						{layout.readWidth === w
+							? 'border-(--color-brand) bg-(--color-brand)/10 text-(--color-brand)'
+							: 'border-(--color-border) bg-(--color-surface-3) text-(--color-muted) hover:border-(--color-brand)/50 hover:text-(--color-text)'}"
+					aria-pressed={layout.readWidth === w}
+				>{label}</button>
+			{/each}
+		</div>
+	</div>
+
+	<!-- Paragraph style -->
+	<div class="space-y-2">
+		<p class="text-xs text-(--color-muted)">Paragraphs</p>
+		<div class="flex gap-1.5">
+			{#each ([['spaced', 'Spaced'], ['indented', 'Indented']] as const) as [s, label]}
+				<button
+					type="button"
+					onclick={() => setLayout('paraStyle', s)}
+					class="flex-1 py-1.5 rounded-lg border text-xs font-medium transition-colors
+						{layout.paraStyle === s
+							? 'border-(--color-brand) bg-(--color-brand)/10 text-(--color-brand)'
+							: 'border-(--color-border) bg-(--color-surface-3) text-(--color-muted) hover:border-(--color-brand)/50 hover:text-(--color-text)'}"
+					aria-pressed={layout.paraStyle === s}
+				>{label}</button>
+			{/each}
+		</div>
+	</div>
+
+	<!-- Focus mode -->
+	<button
+		type="button"
+		onclick={() => setLayout('focusMode', !layout.focusMode)}
+		class="w-full flex items-center justify-between py-2 px-3 rounded-lg border text-xs font-medium transition-colors
+			{layout.focusMode
+				? 'border-(--color-brand) bg-(--color-brand)/10 text-(--color-brand)'
+				: 'border-(--color-border) bg-(--color-surface-3) text-(--color-muted) hover:border-(--color-brand)/50 hover:text-(--color-text)'}"
+		aria-pressed={layout.focusMode}
+	>
+		<span>Focus mode</span>
+		<span class="opacity-60 text-xs">{layout.focusMode ? 'On — audio & nav hidden' : 'Off'}</span>
+	</button>
+
 	<p class="text-xs text-(--color-muted)/60 text-center">Changes save automatically</p>
 </div>
 {/if}