diff --git a/frontend/src/lib/components/file/PreviewLightbox.svelte b/frontend/src/lib/components/file/PreviewLightbox.svelte
deleted file mode 100644
index fc0a526..0000000
--- a/frontend/src/lib/components/file/PreviewLightbox.svelte
+++ /dev/null
@@ -1,252 +0,0 @@
-<script lang="ts">
-	import { get } from 'svelte/store';
-	import { untrack } from 'svelte';
-	import { authStore } from '$lib/stores/auth';
-	import type { File } from '$lib/api/types';
-
-	interface Props {
-		/** Files to page through (e.g. a duplicate cluster). */
-		files: File[];
-		/** Id to open first. */
-		startId: string;
-		onClose: () => void;
-	}
-
-	let { files, startId, onClose }: Props = $props();
-
-	// Resolve the starting index once. The lightbox is remounted on each open, so
-	// the props are effectively init-only — untrack acknowledges that read.
-	let index = $state(untrack(() => Math.max(0, files.findIndex((f) => f.id === startId))));
-	let src = $state<string | null>(null);
-	let failed = $state(false);
-
-	let current = $derived(files[index]);
-	let hasPrev = $derived(index > 0);
-	let hasNext = $derived(index < files.length - 1);
-
-	// Load the full preview — the same image the single-file viewer shows, so the
-	// user can actually tell duplicates apart instead of squinting at thumbnails.
-	// Auth-gated, rendered from a blob; re-runs when the index changes.
-	$effect(() => {
-		const f = files[index];
-		if (!f) return;
-		const token = get(authStore).accessToken;
-		let objectUrl: string | null = null;
-		let cancelled = false;
-		src = null;
-		failed = false;
-
-		fetch(`/api/v1/files/${f.id}/preview`, {
-			headers: token ? { Authorization: `Bearer ${token}` } : {}
-		})
-			.then((res) => (res.ok ? res.blob() : null))
-			.then((blob) => {
-				if (cancelled || !blob) {
-					if (!cancelled) failed = true;
-					return;
-				}
-				objectUrl = URL.createObjectURL(blob);
-				src = objectUrl;
-			})
-			.catch(() => {
-				if (!cancelled) failed = true;
-			});
-
-		return () => {
-			cancelled = true;
-			if (objectUrl) URL.revokeObjectURL(objectUrl);
-		};
-	});
-
-	function prev() {
-		if (hasPrev) index -= 1;
-	}
-	function next() {
-		if (hasNext) index += 1;
-	}
-
-	function onKeydown(e: KeyboardEvent) {
-		if (e.key === 'Escape') onClose();
-		else if (e.key === 'ArrowLeft') prev();
-		else if (e.key === 'ArrowRight') next();
-	}
-</script>
-
-<svelte:window onkeydown={onKeydown} />
-
-<!-- Close only when the backdrop itself is clicked (not the image or controls);
-     Escape and the × button close from anywhere. -->
-<!-- svelte-ignore a11y_click_events_have_key_events -->
-<div
-	class="backdrop"
-	role="dialog"
-	aria-modal="true"
-	aria-label="Enlarged preview"
-	tabindex="-1"
-	onclick={(e) => {
-		if (e.target === e.currentTarget) onClose();
-	}}
->
-	<button class="close" onclick={onClose} aria-label="Close">
-		<svg width="22" height="22" viewBox="0 0 22 22" fill="none" aria-hidden="true">
-			<path
-				d="M6 6l10 10M16 6L6 16"
-				stroke="currentColor"
-				stroke-width="2"
-				stroke-linecap="round"
-			/>
-		</svg>
-	</button>
-
-	<div class="stage">
-		{#if src}
-			<img class="img" {src} alt={current?.original_name ?? ''} />
-		{:else if failed}
-			<div class="ph failed">Failed to load preview</div>
-		{:else}
-			<div class="ph loading">Loading…</div>
-		{/if}
-
-		{#if hasPrev}
-			<button class="nav prev" onclick={prev} aria-label="Previous">
-				<svg width="20" height="20" viewBox="0 0 20 20" fill="none" aria-hidden="true">
-					<path
-						d="M12 4L6 10L12 16"
-						stroke="currentColor"
-						stroke-width="2"
-						stroke-linecap="round"
-						stroke-linejoin="round"
-					/>
-				</svg>
-			</button>
-		{/if}
-		{#if hasNext}
-			<button class="nav next" onclick={next} aria-label="Next">
-				<svg width="20" height="20" viewBox="0 0 20 20" fill="none" aria-hidden="true">
-					<path
-						d="M8 4L14 10L8 16"
-						stroke="currentColor"
-						stroke-width="2"
-						stroke-linecap="round"
-						stroke-linejoin="round"
-					/>
-				</svg>
-			</button>
-		{/if}
-	</div>
-
-	<div class="caption">
-		<span class="name" title={current?.original_name ?? ''}>{current?.original_name ?? '—'}</span>
-		<span class="pos">{index + 1} / {files.length}</span>
-	</div>
-</div>
-
-<style>
-	.backdrop {
-		position: fixed;
-		inset: 0;
-		z-index: 100;
-		display: flex;
-		flex-direction: column;
-		align-items: center;
-		justify-content: center;
-		gap: 10px;
-		padding: 16px;
-		background-color: rgba(0, 0, 0, 0.88);
-	}
-
-	.close {
-		position: absolute;
-		top: 12px;
-		right: 12px;
-		width: 38px;
-		height: 38px;
-		display: flex;
-		align-items: center;
-		justify-content: center;
-		border-radius: 50%;
-		border: none;
-		background-color: rgba(0, 0, 0, 0.5);
-		color: #fff;
-		cursor: pointer;
-	}
-	.close:hover {
-		background-color: rgba(0, 0, 0, 0.8);
-	}
-
-	.stage {
-		position: relative;
-		display: flex;
-		align-items: center;
-		justify-content: center;
-		max-width: 100%;
-		min-height: 0;
-		flex: 1;
-	}
-
-	.img {
-		max-width: 100%;
-		max-height: 100%;
-		object-fit: contain;
-		display: block;
-		border-radius: 6px;
-	}
-
-	.ph {
-		display: flex;
-		align-items: center;
-		justify-content: center;
-		min-width: 220px;
-		min-height: 220px;
-		color: var(--color-text-muted);
-		font-size: 0.9rem;
-	}
-	.ph.failed {
-		color: var(--color-danger);
-	}
-
-	.nav {
-		position: absolute;
-		top: 50%;
-		transform: translateY(-50%);
-		width: 44px;
-		height: 44px;
-		border-radius: 50%;
-		border: none;
-		background-color: rgba(0, 0, 0, 0.55);
-		color: #fff;
-		display: flex;
-		align-items: center;
-		justify-content: center;
-		cursor: pointer;
-		transition: background-color 0.15s;
-	}
-	.nav:hover {
-		background-color: rgba(0, 0, 0, 0.85);
-	}
-	.nav.prev {
-		left: 8px;
-	}
-	.nav.next {
-		right: 8px;
-	}
-
-	.caption {
-		display: flex;
-		align-items: center;
-		gap: 10px;
-		max-width: 100%;
-		color: var(--color-text-primary);
-		font-size: 0.85rem;
-		flex-shrink: 0;
-	}
-	.caption .name {
-		overflow: hidden;
-		text-overflow: ellipsis;
-		white-space: nowrap;
-	}
-	.caption .pos {
-		color: var(--color-text-muted);
-		flex-shrink: 0;
-	}
-</style>
diff --git a/frontend/src/routes/files/duplicates/+page.svelte b/frontend/src/routes/files/duplicates/+page.svelte
index 0e91fd4..3b6eeed 100644
--- a/frontend/src/routes/files/duplicates/+page.svelte
+++ b/frontend/src/routes/files/duplicates/+page.svelte
@@ -4,7 +4,7 @@
 	import { getDuplicates, dismissDuplicate } from '$lib/api/duplicates';
 	import Thumb from '$lib/components/file/Thumb.svelte';
 	import DuplicateMergeDialog from '$lib/components/file/DuplicateMergeDialog.svelte';
-	import PreviewLightbox from '$lib/components/file/PreviewLightbox.svelte';
+	import FileViewer from '$lib/components/file/FileViewer.svelte';
 	import type { File } from '$lib/api/types';
 
 	const LIMIT = 20;
@@ -35,9 +35,10 @@
 	let mergeKeep = $state<File | null>(null);
 	let mergeDiscard = $state<File | null>(null);
 
-	// Enlarged-preview lightbox: thumbnails are too small to tell near-duplicates
-	// apart, so a zoom opens the full preview and pages across the cluster.
-	let lightbox = $state<{ files: File[]; startId: string } | null>(null);
+	// Full viewer (same as the files page): thumbnails are too small to compare,
+	// and dedup decisions need date / tags / EXIF, so the zoom opens the real
+	// viewer and pages across the cluster's files.
+	let viewer = $state<{ key: number; files: File[]; id: string } | null>(null);
 
 	$effect(() => {
 		if (!initialLoaded && !loading) void load();
@@ -103,8 +104,36 @@
 		}
 	}
 
-	function openLightbox(c: Cluster, startId: string) {
-		lightbox = { files: c.files, startId };
+	function openViewer(c: Cluster, id: string) {
+		viewer = { key: c.key, files: c.files, id };
+	}
+
+	// Prev/next within the cluster currently open in the viewer.
+	let viewerPrevId = $derived.by(() => {
+		const v = viewer;
+		if (!v) return null;
+		const i = v.files.findIndex((f) => f.id === v.id);
+		return i > 0 ? (v.files[i - 1]?.id ?? null) : null;
+	});
+	let viewerNextId = $derived.by(() => {
+		const v = viewer;
+		if (!v) return null;
+		const i = v.files.findIndex((f) => f.id === v.id);
+		return i >= 0 && i < v.files.length - 1 ? (v.files[i + 1]?.id ?? null) : null;
+	});
+
+	function viewerNavigate(id: string) {
+		if (viewer) viewer = { ...viewer, id };
+	}
+
+	// Mirror a review toggle made inside the viewer back into the cluster list and
+	// the viewer's own navigation snapshot so both stay consistent.
+	function onViewerReviewChange(id: string, needsReview: boolean) {
+		const apply = (f: File) => (f.id === id ? { ...f, needs_review: needsReview } : f);
+		clusters = clusters.map((c) =>
+			c.key === viewer?.key ? { ...c, files: c.files.map(apply) } : c
+		);
+		if (viewer) viewer = { ...viewer, files: viewer.files.map(apply) };
 	}
 
 	function openMerge(c: Cluster, other: File) {
@@ -216,10 +245,10 @@
 									class="zoom"
 									onclick={(e) => {
 										e.stopPropagation();
-										openLightbox(c, f.id);
+										openViewer(c, f.id);
 									}}
-									aria-label="Enlarge preview"
-									title="Enlarge preview"
+									aria-label="Open in viewer"
+									title="Open in viewer"
 								>
 									<svg width="15" height="15" viewBox="0 0 15 15" fill="none" aria-hidden="true">
 										<circle cx="6.5" cy="6.5" r="4.5" stroke="currentColor" stroke-width="1.5" />
@@ -268,12 +297,17 @@
 	</main>
 </div>
 
-{#if lightbox}
-	<PreviewLightbox
-		files={lightbox.files}
-		startId={lightbox.startId}
-		onClose={() => (lightbox = null)}
-	/>
+{#if viewer}
+	<div class="viewer-overlay">
+		<FileViewer
+			fileId={viewer.id}
+			prevId={viewerPrevId}
+			nextId={viewerNextId}
+			onNavigate={viewerNavigate}
+			onClose={() => (viewer = null)}
+			onReviewChange={onViewerReviewChange}
+		/>
+	</div>
 {/if}
 
 {#if mergeKeep && mergeDiscard}
@@ -493,4 +527,14 @@
 		color: var(--color-text-muted);
 		font-size: 0.9rem;
 	}
+
+	/* Full-screen overlay for the file viewer, mirroring the files page. */
+	.viewer-overlay {
+		position: fixed;
+		inset: 0;
+		z-index: 200;
+		background-color: var(--color-bg-primary);
+		overflow-y: auto;
+		overscroll-behavior: contain;
+	}
 </style>