feat: delta/instant upload + frontend UI/UX polish

Bundles the backend+frontend delta-upload (content-dedup) feature with a
batch of frontend fixes from this session.

Upload / dedup:
- Client-hashed delta & instant upload (deltaUpload, hashWasm vendor shim)
- Backend dedup batch endpoint (dedup_service, dedup_handler, routes)
- session store owned-hash helpers; unit tests + upload-strategy bench

Frontend UI/UX:
- Colour file-type icons in grid/list (per-type tinted tiles + glyph hue)
- Robust thumbnail fallback; PDFs now show their type icon (backend
  generates no PDF thumbnails) instead of a blank tile
- Fix PDF preview: load via a same-origin blob: iframe — the API URL is
  blocked by the global X-Frame-Options: DENY in the browser's framed
  PDF viewer, matching the existing CSP `frame-src blob:` design
- Groups: localized virtual-group description (no DB schema-note leak),
  add nav.groups to the 15 missing locales, fix primary-button contrast
- Repoint --color-text-light → --color-on-accent (was faint grey on accent)
- Nudge the admin role badge off the user-menu header divider

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

frontend/src/lib/api/endpoints/deltaUpload.test.ts

@@ -0,0 +1,87 @@
+import { beforeEach, describe, expect, it, vi } from 'vitest';
+
+// vi.mock is hoisted; build the spies with vi.hoisted so the factories can use them.
+const { blake3Mock, byHashMock, batchMock } = vi.hoisted(() => ({
+	blake3Mock: vi.fn(),
+	byHashMock: vi.fn(),
+	batchMock: vi.fn()
+}));
+
+vi.mock('$lib/vendor/hashWasm', () => ({ blake3HexOfFile: blake3Mock }));
+vi.mock('$lib/api/endpoints/files', () => ({
+	createFileByHash: byHashMock,
+	dedupCheckBatch: batchMock
+}));
+
+import { DELTA_UPLOAD_MIN_SIZE, instantUploadOwned, resolveOwnedHashes } from './deltaUpload';
+
+const fakeFile = (size: number, name = 'x.bin') => ({ size, name }) as unknown as File;
+const hashOf = (name: string) => name.padEnd(64, '0');
+const MB = 1024 * 1024;
+
+describe('resolveOwnedHashes (batch check)', () => {
+	beforeEach(() => {
+		blake3Mock.mockReset();
+		batchMock.mockReset();
+		blake3Mock.mockImplementation((f: File) => Promise.resolve(hashOf(f.name)));
+	});
+
+	it('hits nothing when no files are in-band (empty / >= delta threshold)', async () => {
+		const owned = await resolveOwnedHashes([
+			fakeFile(0, 'empty'),
+			fakeFile(DELTA_UPLOAD_MIN_SIZE, 'big')
+		]);
+		expect(owned.size).toBe(0);
+		expect(blake3Mock).not.toHaveBeenCalled();
+		expect(batchMock).not.toHaveBeenCalled();
+	});
+
+	it('hashes in-band files and maps only the server-owned subset in ONE batch call', async () => {
+		const a = fakeFile(2 * MB, 'a');
+		const b = fakeFile(3 * MB, 'b');
+		batchMock.mockResolvedValue(new Set([hashOf('a')])); // server owns only "a"
+		const owned = await resolveOwnedHashes([a, b]);
+		expect(batchMock).toHaveBeenCalledTimes(1);
+		expect(batchMock).toHaveBeenCalledWith([hashOf('a'), hashOf('b')]);
+		expect(owned.get(a)).toBe(hashOf('a'));
+		expect(owned.has(b)).toBe(false);
+	});
+
+	it('falls back to an empty map when client-side hashing fails', async () => {
+		blake3Mock.mockRejectedValue(new Error('wasm down'));
+		const owned = await resolveOwnedHashes([fakeFile(2 * MB, 'a')]);
+		expect(owned.size).toBe(0);
+		expect(batchMock).not.toHaveBeenCalled();
+	});
+
+	it('falls back to an empty map when the batch request fails', async () => {
+		batchMock.mockRejectedValue(new Error('network'));
+		const owned = await resolveOwnedHashes([fakeFile(2 * MB, 'a')]);
+		expect(owned.size).toBe(0);
+	});
+});
+
+describe('instantUploadOwned (zero-byte create)', () => {
+	beforeEach(() => byHashMock.mockReset());
+
+	it('reports zero-byte success on 201', async () => {
+		byHashMock.mockResolvedValue({ ok: true, status: 201, data: { id: 'f1' } });
+		const r = await instantUploadOwned('folder', fakeFile(2 * MB, 'a'), hashOf('a'));
+		expect(r).toEqual({ ok: true, data: { id: 'f1' }, savedBytes: 2 * MB });
+		expect(byHashMock).toHaveBeenCalledWith('folder', 'a', hashOf('a'));
+	});
+
+	it('falls back (null) when the blob vanished (404)', async () => {
+		byHashMock.mockResolvedValue({ ok: false, status: 404 });
+		expect(await instantUploadOwned('folder', fakeFile(2 * MB), hashOf('a'))).toBeNull();
+	});
+
+	it('surfaces a quota error on 507', async () => {
+		byHashMock.mockResolvedValue({ ok: false, status: 507 });
+		expect(await instantUploadOwned('folder', fakeFile(2 * MB), hashOf('a'))).toEqual({
+			ok: false,
+			isQuotaError: true,
+			errorMsg: 'Storage quota exceeded'
+		});
+	});
+});

frontend/src/lib/api/endpoints/deltaUpload.ts

@@ -8,6 +8,8 @@
  * byte upload — delta is an optimization, never a gate.
  */
 import { getCsrfToken } from '$lib/api/csrf';
+import { createFileByHash, dedupCheckBatch } from '$lib/api/endpoints/files';
+import { blake3HexOfFile } from '$lib/vendor/hashWasm';
 
 /** Files smaller than this skip delta: the round-trips cost more than the bytes. */
 export const DELTA_UPLOAD_MIN_SIZE = 8 * 1024 * 1024;
@@ -128,3 +130,58 @@ export function tryDeltaUpload(
 		worker.postMessage({ file, folderId, name: file.name, csrfToken: getCsrfToken() || '' });
 	});
 }
+
+/**
+ * Create a file from a blob the caller already owns (`POST /api/files/by-hash`)
+ * — zero content bytes cross the wire. `hash` must come from a prior batch
+ * ownership check ([`resolveOwnedHashes`]). Resolves an answer with
+ * `savedBytes = file.size` on success, surfaces a 507 quota error, or resolves
+ * `null` to fall back to a normal upload (e.g. the blob was GC'd between the
+ * check and this create — rare).
+ */
+export async function instantUploadOwned(
+	folderId: string,
+	file: File,
+	hash: string
+): Promise<DeltaUploadAnswer | null> {
+	const res = await createFileByHash(folderId, file.name, hash);
+	if (res.ok) return { ok: true, data: res.data, savedBytes: file.size };
+	if (res.status === 507) {
+		return { ok: false, isQuotaError: true, errorMsg: 'Storage quota exceeded' };
+	}
+	return null;
+}
+
+/**
+ * Resolve which of `files` the server already owns, with a SINGLE batch round
+ * trip (the Dropbox-style "have you got these?" probe). Every file below the
+ * delta threshold is BLAKE3-hashed locally, the whole hash set is sent to
+ * `/api/dedup/check-batch`, and the owned subset is mapped back to `file → hash`
+ * so callers can instant-upload those (zero bytes) and upload the rest normally.
+ *
+ * Excludes empty files and files `>= DELTA_UPLOAD_MIN_SIZE` (the delta protocol
+ * dedups those itself). Resolves an empty map on any failure — hashing
+ * unavailable, request error — so uploads always proceed.
+ */
+export async function resolveOwnedHashes(files: File[]): Promise<Map<File, string>> {
+	const inBand = files.filter((f) => f.size > 0 && f.size < DELTA_UPLOAD_MIN_SIZE);
+	if (inBand.length === 0) return new Map();
+
+	const hashByFile = new Map<File, string>();
+	try {
+		for (const f of inBand) hashByFile.set(f, await blake3HexOfFile(f));
+	} catch {
+		return new Map(); // WASM/hashing unavailable → skip instant uploads
+	}
+
+	let owned: Set<string>;
+	try {
+		owned = await dedupCheckBatch([...new Set(hashByFile.values())]);
+	} catch {
+		return new Map();
+	}
+
+	const result = new Map<File, string>();
+	for (const [f, h] of hashByFile) if (owned.has(h)) result.set(f, h);
+	return result;
+}

frontend/src/lib/api/endpoints/files.ts

@@ -4,6 +4,46 @@ import { getCsrfHeaders } from '$lib/api/csrf';
 
 const JSON_HEADERS = { 'Content-Type': 'application/json' };
 
+/**
+ * Instant upload: materialise a file from a blob the caller **already owns**,
+ * by its whole-file BLAKE3 — zero content bytes cross the wire. Returns the HTTP
+ * status so the caller can fall back to a plain upload on 404 (hash not owned).
+ * Scoped to the caller's own content server-side (no cross-user probing).
+ */
+export async function createFileByHash(
+	folderId: string,
+	name: string,
+	hash: string
+): Promise<{ ok: boolean; status: number; data?: unknown }> {
+	const res = await apiFetch('/api/files/by-hash', {
+		method: 'POST',
+		credentials: 'same-origin',
+		headers: { ...JSON_HEADERS, ...getCsrfHeaders() },
+		body: JSON.stringify({ name, folder_id: folderId, hash })
+	});
+	const data = res.ok ? await res.json().catch(() => undefined) : undefined;
+	return { ok: res.ok, status: res.status, data };
+}
+
+/**
+ * Batch dedup check: given candidate whole-file BLAKE3 hashes, return the set
+ * the caller **already owns** — in a single round trip. Drives instant uploads:
+ * a file whose hash is in the set can be created with zero content bytes.
+ * Resolves an empty set on any failure, so the caller just uploads everything.
+ */
+export async function dedupCheckBatch(hashes: string[]): Promise<Set<string>> {
+	if (hashes.length === 0) return new Set();
+	const res = await apiFetch('/api/dedup/check-batch', {
+		method: 'POST',
+		credentials: 'same-origin',
+		headers: { ...JSON_HEADERS, ...getCsrfHeaders() },
+		body: JSON.stringify({ hashes })
+	});
+	if (!res.ok) return new Set();
+	const data = (await res.json().catch(() => null)) as { owned?: string[] } | null;
+	return new Set(data?.owned ?? []);
+}
+
 export async function uploadFile(folderId: string | null, file: File): Promise<void> {
 	const form = new FormData();
 	if (folderId) form.append('folder_id', folderId);

frontend/src/lib/api/endpoints/groups.ts

@@ -22,6 +22,17 @@ const VIRTUAL_NAME_KEYS: Record<string, string> = {
 	[INTERNAL_GROUP_ID]: 'groups.virtual_internal_name'
 };
 
+/**
+ * Map of well-known virtual-group UUIDs → i18n key for a human-readable
+ * description. Virtual groups are server-seeded and their `description` column
+ * holds developer/schema notes (e.g. the Internal group's "…no rows in
+ * subject_group_members."), which must never reach end users — so virtual
+ * groups display a localized blurb instead of their raw `description`.
+ */
+const VIRTUAL_DESC_KEYS: Record<string, string> = {
+	[INTERNAL_GROUP_ID]: 'groups.virtual_internal_explanation'
+};
+
 export interface GroupItem {
 	id: string;
 	name: string;
@@ -87,6 +98,20 @@ export function groupDisplayName(group: GroupItem): string {
 	return group.name;
 }
 
+/**
+ * Human-readable description for a group row. Virtual groups render a localized
+ * blurb (via the well-known UUID mapping) so their internal DB schema notes
+ * never leak to the UI; a virtual group without a mapped key shows nothing.
+ * User-defined groups display their raw `description` verbatim.
+ */
+export function groupDescription(group: GroupItem): string | null {
+	if (group.is_virtual) {
+		const key = VIRTUAL_DESC_KEYS[group.id];
+		return key ? t(key, group.name) : null;
+	}
+	return group.description ?? null;
+}
+
 /**
  * Pick the icon registry name for a group avatar. Virtual (system-wide)
  * groups use `people-roof`; user-defined groups use `user-group`. Ported from

frontend/src/lib/api/endpoints/uploadStrategies.bench.test.ts

@@ -0,0 +1,129 @@
+/**
+ * Benchmark: upload-dedup strategies compared.
+ *
+ *   BASELINE  — no instant upload: every file's bytes are sent.
+ *   PER-FILE  — instant upload probed one file at a time (a by-hash request per
+ *               file; a miss costs an extra round trip before the plain upload).
+ *   BATCH     — Dropbox-style: hash every file, ONE `/api/dedup/check-batch`
+ *               request, then instant-upload the owned ones and send the rest.
+ *
+ * It's an analytic model (round trips × RTT + bytes / bandwidth + hashing
+ * time), not a live transfer — the point is to compare the strategies' network
+ * cost. Run it to see the table:
+ *   npm run test:unit -- uploadStrategies
+ */
+import { describe, expect, it } from 'vitest';
+
+interface Cost {
+	roundTrips: number;
+	mbSent: number;
+	mbHashed: number;
+	seconds: number;
+}
+interface Scenario {
+	name: string;
+	files: number;
+	sizeMB: number;
+	ownedFrac: number;
+	rttMs: number;
+	mbps: number;
+}
+
+/** BLAKE3 + file read throughput on a typical client (MB/s). */
+const HASH_MBPS = 1500;
+
+function cost(roundTrips: number, mbSent: number, mbHashed: number, s: Scenario): Cost {
+	const linkMBps = s.mbps / 8;
+	const seconds = roundTrips * (s.rttMs / 1000) + mbSent / linkMBps + mbHashed / HASH_MBPS;
+	return { roundTrips, mbSent, mbHashed, seconds };
+}
+
+function baseline(s: Scenario): Cost {
+	return cost(s.files, s.files * s.sizeMB, 0, s);
+}
+function perFile(s: Scenario): Cost {
+	const owned = Math.round(s.files * s.ownedFrac);
+	const miss = s.files - owned;
+	// owned → 1 by-hash create; miss → by-hash 404 + plain upload. Every file hashed.
+	return cost(owned + miss * 2, miss * s.sizeMB, s.files * s.sizeMB, s);
+}
+function batch(s: Scenario): Cost {
+	const owned = Math.round(s.files * s.ownedFrac);
+	const miss = s.files - owned;
+	// 1 batch check + owned creates + miss uploads. Every file hashed.
+	return cost(1 + owned + miss, miss * s.sizeMB, s.files * s.sizeMB, s);
+}
+
+const SCENARIOS: Scenario[] = [
+	{
+		name: '200×4MB · 50% re-upload · home (40ms/50Mbps)',
+		files: 200,
+		sizeMB: 4,
+		ownedFrac: 0.5,
+		rttMs: 40,
+		mbps: 50
+	},
+	{
+		name: '200×4MB · ALL new · home (40ms/50Mbps)',
+		files: 200,
+		sizeMB: 4,
+		ownedFrac: 0,
+		rttMs: 40,
+		mbps: 50
+	},
+	{
+		name: '200×4MB · ALL owned (re-sync) · home',
+		files: 200,
+		sizeMB: 4,
+		ownedFrac: 1,
+		rttMs: 40,
+		mbps: 50
+	},
+	{
+		name: '1000×0.5MB · 30% owned · WAN (80ms/100Mbps)',
+		files: 1000,
+		sizeMB: 0.5,
+		ownedFrac: 0.3,
+		rttMs: 80,
+		mbps: 100
+	}
+];
+
+describe('upload-dedup strategies', () => {
+	it('batch never sends more bytes than baseline and matches per-file dedup', () => {
+		const rows: string[] = [];
+		rows.push('');
+		rows.push('╔══ Upload-dedup strategies — analytic cost model ══════════════════════════');
+		for (const s of SCENARIOS) {
+			const b = baseline(s);
+			const p = perFile(s);
+			const z = batch(s);
+			const line = (tag: string, c: Cost) =>
+				`║ ${tag.padEnd(9)} │ RT ${String(c.roundTrips).padStart(4)} │ sent ${c.mbSent
+					.toFixed(0)
+					.padStart(4)} MB │ ~${c.seconds.toFixed(1).padStart(6)} s`;
+			rows.push(`╟─ ${s.name}`);
+			rows.push(line('baseline', b));
+			rows.push(line('per-file', p));
+			rows.push(line('BATCH', z));
+			const vsBase = (1 - z.seconds / b.seconds) * 100;
+			const rtVsPerFile = p.roundTrips - z.roundTrips;
+			rows.push(
+				`║   → BATCH: ${vsBase.toFixed(0)}% faster than baseline · ${rtVsPerFile} fewer round trips than per-file`
+			);
+
+			// Invariants the strategies must satisfy:
+			expect(z.mbSent).toBe(p.mbSent); // batch and per-file dedup identically
+			expect(z.mbSent).toBeLessThanOrEqual(b.mbSent); // never worse than baseline on bytes
+			// When there's anything to dedup, batch is clearly faster than baseline.
+			// (With NOTHING owned, batch pays hashing + one check for no payoff — a
+			// small, honest overhead the table shows.)
+			if (s.ownedFrac > 0) expect(z.seconds).toBeLessThan(b.seconds);
+			// Batch collapses the N per-file probes into one check: for any miss it
+			// strictly wins on round trips (and is at most +1 in the all-owned case).
+			if (s.ownedFrac < 1) expect(z.roundTrips).toBeLessThan(p.roundTrips);
+		}
+		rows.push('╚═══════════════════════════════════════════════════════════════════════════');
+		console.log(rows.join('\n'));
+	});
+});

frontend/src/lib/components/FileViewer.svelte

@@ -40,9 +40,14 @@
 	let canEdit = $state(false);
 	/** Image zoom factor (1 = fit). */
 	let zoom = $state(1);
-	/** PDF embed fallback engaged when the <object> stays blank ~2s. */
+	/** Object URL for the fetched PDF blob. The PDF is rendered from a same-origin
-	let pdfFallback = $state(false);
+	 *  blob: in an <iframe> (allowed by CSP `frame-src blob:`) rather than from its
-	let pdfObjectEl = $state<HTMLObjectElement | null>(null);
+	 *  API URL directly — that response carries the global `X-Frame-Options: DENY`
+	 *  + `frame-ancestors 'none'`, which the browser's framed PDF viewer honours,
+	 *  so an embedded API URL renders as a broken-document icon. A blob has no
+	 *  response headers, so it sidesteps the framing block. */
+	let pdfUrl = $state<string | null>(null);
+	let pdfError = $state(false);
 
 	function isImage(f: FileItem): boolean {
 		const m = (f.mime_type ?? '').toLowerCase();
@@ -72,7 +77,7 @@
 		open = false;
 		textContent = '';
 		zoom = 1;
-		pdfFallback = false;
+		pdfError = false;
 		onrefresh?.();
 	}
 
@@ -94,7 +99,6 @@
 		const f = file;
 		canEdit = false;
 		zoom = 1;
-		pdfFallback = false;
 		const k = kindOf(f);
 
 		// Office docs (WOPI-editable, non-image) open straight in the editor
@@ -119,21 +123,25 @@
 				.finally(() => (textLoading = false));
 		}
 
-		// PDF blank-render guard: if the <object> shows nothing after ~2s,
+		// Fetch the PDF as a same-origin blob and view it via an object URL (see
-		// fall back to an <embed> (some browsers refuse <object> for PDFs).
+		// `pdfUrl`). The cleanup revokes the URL when the file changes or the
+		// viewer closes; a stale response (newer file opened mid-fetch) is dropped.
 		if (k === 'pdf') {
-			const timer = setTimeout(() => {
+			pdfError = false;
-				const el = pdfObjectEl;
+			pdfUrl = null;
-				let blank = false;
+			let objectUrl: string | null = null;
-				try {
+			apiFetch(fileInlineUrl(f.id), { credentials: 'same-origin' })
-					const doc = el?.contentDocument;
+				.then((r) => (r.ok ? r.blob() : Promise.reject(new Error(`HTTP ${r.status}`))))
-					blank = !doc || doc.body?.innerHTML === '';
+				.then((blob) => {
-				} catch {
+					if (file !== f || !open) return;
-					blank = false; // cross-origin: assume it rendered
+					objectUrl = URL.createObjectURL(blob);
-				}
+					pdfUrl = objectUrl;
-				if (blank) pdfFallback = true;
+				})
-			}, 2000);
+				.catch(() => (pdfError = true));
-			return () => clearTimeout(timer);
+			return () => {
+				if (objectUrl) URL.revokeObjectURL(objectUrl);
+				pdfUrl = null;
+			};
 		}
 	});
 </script>
@@ -220,18 +228,15 @@
 				{:else if kind === 'audio'}
 					<audio class="fv__audio" src={fileInlineUrl(file.id)} controls></audio>
 				{:else if kind === 'pdf'}
-					{#if pdfFallback}
+					{#if pdfError}
-						<embed class="fv__pdf" src={fileInlineUrl(file.id)} type="application/pdf" />
+						<div class="fv__status fv__status--center">
-					{:else}
+							<Icon name="file" class="fv__big-icon" />
-						<object
-							bind:this={pdfObjectEl}
-							class="fv__pdf"
-							data={fileInlineUrl(file.id)}
-							type="application/pdf"
-							title={file.name}
-						>
 							<p>{t('files.preview_failed', 'Could not load preview.')}</p>
-						</object>
+						</div>
+					{:else if pdfUrl}
+						<iframe class="fv__pdf" src={pdfUrl} title={file.name}></iframe>
+					{:else}
+						<p class="fv__status">{t('common.loading', 'Loading…')}</p>
 					{/if}
 				{:else if kind === 'text'}
 					{#if textLoading}

frontend/src/lib/components/ResourceList.svelte

@@ -59,7 +59,7 @@
 	import { t } from '$lib/i18n/index.svelte';
 	import { files as filesStore } from '$lib/stores/files.svelte';
 	import { formatBytes } from '$lib/utils/format';
-	import { formatDate, iconNameFromClass } from '$lib/utils/display';
+	import { formatDate, iconNameFromClass, fileIconKindClass } from '$lib/utils/display';
 	import { gridColumns } from '$lib/utils/grid';
 
 	interface Props {
@@ -301,6 +301,7 @@
 </script>
 
 {#snippet row(entry: ResourceEntry)}
+	{@const iconName = entry.kind === 'folder' ? 'folder' : iconNameFromClass(entry.iconClass)}
 	<!-- svelte-ignore a11y_no_noninteractive_tabindex -->
 	<div
 		class="file-item"
@@ -323,8 +324,8 @@
 			</div>
 		{/if}
 		<div class="name-cell">
-			<span class="file-icon">
+			<span class="file-icon {fileIconKindClass(iconName)}">
-				<Icon name={entry.kind === 'folder' ? 'folder' : iconNameFromClass(entry.iconClass)} />
+				<Icon name={iconName} />
 			</span>
 			<span class="name-cell__text">{entry.name}</span>
 		</div>

frontend/src/lib/stores/session.svelte.test.ts

@@ -0,0 +1,45 @@
+import { beforeEach, describe, expect, it, vi } from 'vitest';
+import type { User } from '$lib/api/types';
+
+// `vi.mock` is hoisted above imports, so the spy it references must be created
+// with `vi.hoisted` (a plain top-level const isn't initialised yet when the
+// factory runs).
+const { fetchMeMock } = vi.hoisted(() => ({ fetchMeMock: vi.fn() }));
+
+vi.mock('$lib/api/endpoints/auth', () => ({
+	fetchMe: () => fetchMeMock(),
+	tryRefresh: vi.fn(async () => false)
+}));
+
+import { session } from './session.svelte';
+
+const userWithUsage = (used: number) => ({ storage_used_bytes: used }) as unknown as User;
+
+describe('session.refresh', () => {
+	beforeEach(() => {
+		fetchMeMock.mockReset();
+		session.reset();
+	});
+
+	it('pulls the fresh storage usage into the reactive user (upload/delete sync)', async () => {
+		fetchMeMock.mockResolvedValue(userWithUsage(2048));
+		await session.refresh();
+		expect(session.user?.storage_used_bytes).toBe(2048);
+	});
+
+	it('leaves the current user intact when the probe returns null', async () => {
+		fetchMeMock.mockResolvedValue(userWithUsage(2048));
+		await session.refresh();
+		fetchMeMock.mockResolvedValue(null);
+		await session.refresh();
+		expect(session.user?.storage_used_bytes).toBe(2048);
+	});
+
+	it('leaves the current user intact when the probe throws', async () => {
+		fetchMeMock.mockResolvedValue(userWithUsage(2048));
+		await session.refresh();
+		fetchMeMock.mockRejectedValue(new Error('network'));
+		await session.refresh();
+		expect(session.user?.storage_used_bytes).toBe(2048);
+	});
+});

frontend/src/lib/stores/session.svelte.ts

@@ -40,6 +40,22 @@ class SessionStore {
 		return this.user;
 	}
 
+	/**
+	 * Re-fetch the authenticated user from the server, bypassing the one-shot
+	 * `load()` cache. Call after operations that change server-side user state —
+	 * chiefly storage usage after uploads / deletes — so the UI reflects the new
+	 * `storage_used_bytes` instead of the value cached at login. A transient
+	 * failure leaves the current user untouched (never logs the UI out).
+	 */
+	async refresh(): Promise<void> {
+		try {
+			const me = await fetchMe();
+			if (me) this.user = me;
+		} catch {
+			/* keep the existing user on a transient /api/auth/me failure */
+		}
+	}
+
 	/**
 	 * Resolve the caller's default personal drive's root folder — the landing
 	 * point for `/files` and the `/` redirect. Externals (grant-only) have no

frontend/src/lib/styles/base/variables.css

@@ -236,7 +236,11 @@
     --color-text-gray: var(--color-text-muted);
     --color-text-medium: var(--color-text-muted);
     --color-text-faint2: var(--color-text-faint);
-    --color-text-light: var(--color-text-faint);
+    /* "Light" = light-coloured (near-white) text for accent/dark fills, NOT a
+     * faint tier. Every consumer is a primary button (background: --color-primary),
+     * so this must resolve to the on-accent foreground, not muted grey — which
+     * rendered muddy and failed contrast on the orange accent. */
+    --color-text-light: var(--color-on-accent);
     --color-text-placeholder: var(--color-text-faint);
 
     /* Accent (orange) — mostly mode-agnostic. */
@@ -644,6 +648,24 @@
     /* Status badge — gray/disabled */
     --color-badge-gray: #d1d5db;
 
+    /* File-type glyph colours — one vivid hue per broad file family, used by the
+     * .file-icon--* buckets (resourceList.css) so the grid/list type icons read
+     * as colourful tiles instead of flat monochrome. Tile tints are derived from
+     * these with color-mix(), so only the foreground hue lives here. Dark-mode
+     * shades are lightened for contrast against the dark tile fill. */
+    --file-kind-folder: light-dark(#3b82f6, #60a5fa);
+    --file-kind-pdf: light-dark(#ef4444, #f87171);
+    --file-kind-doc: light-dark(#2563eb, #60a5fa);
+    --file-kind-sheet: light-dark(#16a34a, #4ade80);
+    --file-kind-slides: light-dark(#ea580c, #fb923c);
+    --file-kind-archive: light-dark(#d97706, #fbbf24);
+    --file-kind-code: light-dark(#7c3aed, #a78bfa);
+    --file-kind-image: light-dark(#0891b2, #22d3ee);
+    --file-kind-video: light-dark(#c026d3, #e879f9);
+    --file-kind-audio: light-dark(#db2777, #f472b6);
+    --file-kind-text: light-dark(#475569, #94a3b8);
+    --file-kind-generic: light-dark(#64748b, #94a3b8);
+
     /* (Removed: the legacy dark-mode badge tokens that lived here had zero
      * consumers — the light-dark() badge tokens above are the single source.) */
 

frontend/src/lib/styles/ported/resourceList.css

@@ -43,6 +43,69 @@
     pointer-events: none;
 }
 
+/* ── File-type colours ───────────────────────────────────────
+   Each bucket sets a local --fk (the foreground hue, from the
+   --file-kind-* tokens). The glyph takes --fk directly and the tile
+   fill/ring derive soft tints from it with color-mix(), so the icons read
+   as colourful tiles instead of flat monochrome. Adding a bucket is a
+   single custom-property line; the consuming rules never change. */
+.file-icon {
+    --fk: var(--file-kind-generic);
+}
+
+.file-icon--folder {
+    --fk: var(--file-kind-folder);
+}
+
+.file-icon--pdf {
+    --fk: var(--file-kind-pdf);
+}
+
+.file-icon--doc {
+    --fk: var(--file-kind-doc);
+}
+
+.file-icon--sheet {
+    --fk: var(--file-kind-sheet);
+}
+
+.file-icon--slides {
+    --fk: var(--file-kind-slides);
+}
+
+.file-icon--archive {
+    --fk: var(--file-kind-archive);
+}
+
+.file-icon--code {
+    --fk: var(--file-kind-code);
+}
+
+.file-icon--image {
+    --fk: var(--file-kind-image);
+}
+
+.file-icon--video {
+    --fk: var(--file-kind-video);
+}
+
+.file-icon--audio {
+    --fk: var(--file-kind-audio);
+}
+
+.file-icon--text {
+    --fk: var(--file-kind-text);
+}
+
+.file-icon--generic {
+    --fk: var(--file-kind-generic);
+}
+
+.file-icon > i,
+.file-icon > svg {
+    color: var(--fk);
+}
+
 /* ── Item states ─────────────────────────────────────────── */
 
 .file-item {
@@ -355,9 +418,10 @@
     align-items: center;
     justify-content: center;
     border-radius: var(--radius-lg);
-    /* Hairline inner ring — consistent with the grid thumbnails so light
+    /* Soft type-tinted tile + matching hairline ring so the row glyph reads as
-       previews don't bleed into the row. */
+       a colourful chip (and light previews don't bleed into the row). */
-    box-shadow: inset 0 0 0 1px var(--color-border);
+    background: color-mix(in srgb, var(--fk) 12%, transparent);
+    box-shadow: inset 0 0 0 1px color-mix(in srgb, var(--fk) 22%, var(--color-border));
     font-size: var(--text-md);
     margin-bottom: 0;
     flex-shrink: 0;
@@ -859,9 +923,11 @@
     height: auto;
     aspect-ratio: 4 / 3;
     border-radius: var(--radius-lg);
-    background: var(--color-bg-input);
+    /* Soft type-tinted fill + matching hairline ring (a thumbnail, when
-    /* Hairline inner ring so light thumbnails don't bleed into the card. */
+       present, covers both edge-to-edge). Gives non-preview files a modern
-    box-shadow: inset 0 0 0 1px var(--color-border);
+       colourful tile keyed to their type instead of a flat grey panel. */
+    background: color-mix(in srgb, var(--fk) 9%, var(--color-bg-input));
+    box-shadow: inset 0 0 0 1px color-mix(in srgb, var(--fk) 22%, var(--color-border));
     margin: 0 0 var(--space-3);
     font-size: 30px;
 }

frontend/src/lib/styles/ported/userMenu.css

@@ -262,7 +262,7 @@
 }
 
 .user-menu-role-badge {
-    padding: 0 var(--space-5) var(--space-1);
+    padding: var(--space-2) var(--space-5) var(--space-1);
 }
 
 .role-badge {

frontend/src/lib/utils/display.ts

@@ -12,6 +12,50 @@ export function iconNameFromClass(iconClass: string | undefined | null): string
 	return token ? token.slice(3) : 'file';
 }
 
+/**
+ * Coarse colour bucket for a resolved icon name (see {@link iconNameFromClass}).
+ * One hue per broad file family so the grid/list glyphs render in type-specific
+ * colours instead of a flat monochrome. Each bucket is backed by a
+ * `--file-kind-*` token (variables.css) and consumed via the `.file-icon--*`
+ * modifier classes (resourceList.css).
+ */
+export function fileIconKind(iconName: string): string {
+	switch (iconName) {
+		case 'folder':
+		case 'folder-open':
+			return 'folder';
+		case 'file-pdf':
+			return 'pdf';
+		case 'file-word':
+			return 'doc';
+		case 'file-excel':
+			return 'sheet';
+		case 'file-powerpoint':
+			return 'slides';
+		case 'file-archive':
+		case 'file-zipper':
+			return 'archive';
+		case 'file-code':
+			return 'code';
+		case 'file-image':
+			return 'image';
+		case 'file-video':
+			return 'video';
+		case 'file-audio':
+			return 'audio';
+		case 'file-alt':
+		case 'file-lines':
+			return 'text';
+		default:
+			return 'generic';
+	}
+}
+
+/** `.file-icon` colour-bucket modifier class for a resolved icon name. */
+export function fileIconKindClass(iconName: string): string {
+	return `file-icon--${fileIconKind(iconName)}`;
+}
+
 /** Format a timestamp (epoch seconds/ms or ISO-8601 string) as a local date. */
 export function formatDate(value: number | string | null | undefined): string {
 	if (value === null || value === undefined) return '';

frontend/src/lib/vendor/hashWasm.ts

@@ -0,0 +1,46 @@
+/**
+ * Lazy loader + minimal typing for the vendored OxiCloud hash WASM
+ * (`/vendors/hash-wasm/oxicloud_hash_wasm.js`) — the same BLAKE3 crate the
+ * server and the delta worker use. Loaded on the main thread to compute a
+ * small file's whole-file BLAKE3 for instant ("by-hash") upload; large files
+ * hash off-thread inside the delta worker instead.
+ */
+
+interface HashWasmModule {
+	/** wasm-bindgen init; resolves once the `.wasm` is instantiated. */
+	default: () => Promise<unknown>;
+	/** One-shot BLAKE3 of a buffer → 64-char lowercase hex. */
+	blake3Hex: (data: Uint8Array) => string;
+}
+
+const WASM_GLUE_URL = '/vendors/hash-wasm/oxicloud_hash_wasm.js';
+
+let modPromise: Promise<HashWasmModule> | null = null;
+
+function load(): Promise<HashWasmModule> {
+	if (!modPromise) {
+		modPromise = (async () => {
+			// Runtime URL of a vendored asset (not a project module) — keep Vite
+			// from trying to resolve/bundle it, exactly like the delta worker does.
+			const mod = (await import(/* @vite-ignore */ WASM_GLUE_URL)) as unknown as HashWasmModule;
+			await mod.default();
+			return mod;
+		})().catch((err) => {
+			modPromise = null; // let a later call retry after a transient failure
+			throw err;
+		});
+	}
+	return modPromise;
+}
+
+/**
+ * Whole-file BLAKE3 (64-char lowercase hex) of `file`. Matches the server's
+ * `file_hash` (BLAKE3 over the whole content), so it can be handed to
+ * `/api/files/by-hash`. Reads the file fully into memory — intended for small
+ * files only.
+ */
+export async function blake3HexOfFile(file: File): Promise<string> {
+	const mod = await load();
+	const bytes = new Uint8Array(await file.arrayBuffer());
+	return mod.blake3Hex(bytes);
+}

frontend/src/routes/files/[...path]/+page.svelte

@@ -26,11 +26,14 @@
 		fileThumbnailUrl,
 		moveFile,
 		renameFile,
-		uploadFile,
 		uploadFileWithProgress
 	} from '$lib/api/endpoints/files';
 	import { folderZipUrl } from '$lib/api/endpoints/folders';
-	import { tryDeltaUpload } from '$lib/api/endpoints/deltaUpload';
+	import {
+		instantUploadOwned,
+		resolveOwnedHashes,
+		tryDeltaUpload
+	} from '$lib/api/endpoints/deltaUpload';
 	import { addFavorite, removeFavorite } from '$lib/api/endpoints/favorites';
 	import { canEditWithWopi, getEditorUrlWithFallback } from '$lib/api/endpoints/wopi';
 	import { addTracks, createPlaylist, listPlaylists } from '$lib/api/endpoints/music';
@@ -56,7 +59,7 @@
 		typeLabel
 	} from '$lib/stores/files.svelte';
 	import { formatBytes } from '$lib/utils/format';
-	import { formatDate, iconNameFromClass } from '$lib/utils/display';
+	import { formatDate, iconNameFromClass, fileIconKindClass } from '$lib/utils/display';
 	import { gridColumns } from '$lib/utils/grid';
 
 	// File preview and the WOPI editor are heavy and only appear on demand, so
@@ -286,6 +289,39 @@
 		}
 	}
 
+	/**
+	 * Upload one file through the best available path, returning the bytes saved
+	 * by deduplication (0 when the body was sent in full). Order:
+	 *   1. Instant by-hash upload — zero bytes when `ownedHash` is set (the batch
+	 *      check found the server already has this exact blob).
+	 *   2. Delta upload — sub-file CDC dedup for large files (>= 8 MB).
+	 *   3. Plain byte upload — fallback when neither applies.
+	 * Throws on a hard failure (e.g. quota).
+	 */
+	async function uploadOneFile(
+		folderId: string | null,
+		file: File,
+		report: (frac: number) => void,
+		ownedHash: string | null
+	): Promise<number> {
+		const dedup =
+			(ownedHash && folderId ? await instantUploadOwned(folderId, file, ownedHash) : null) ??
+			(await tryDeltaUpload(file, folderId, (pct) => report(pct / 100)));
+		if (dedup) {
+			if (!dedup.ok) throw new Error(dedup.errorMsg ?? 'upload failed');
+			return dedup.savedBytes ?? 0;
+		}
+		await uploadFileWithProgress(folderId, file, report);
+		return 0;
+	}
+
+	/** Final bell message for a finished upload, noting deduplicated bytes. */
+	function uploadDoneMessage(savedBytes: number): string {
+		if (savedBytes <= 0) return t('files.uploaded', 'Upload complete');
+		const mb = (savedBytes / (1024 * 1024)).toFixed(1);
+		return t('files.uploaded_saved', { mb }, `Upload complete — ${mb} MB deduplicated`);
+	}
+
 	/**
 	 * Upload a batch of files into the current folder, reporting aggregate
 	 * progress through a single bell notification with a progress bar.
@@ -301,32 +337,23 @@
 		const nid = ui.startProgress(label(0));
 		let savedBytes = 0;
 		try {
+			// One batch round trip: which of these files does the server already
+			// have? Owned ones upload as zero bytes; the rest go delta/plain.
+			const owned = await resolveOwnedHashes(files);
 			for (let i = 0; i < files.length; i++) {
 				const report = (frac: number) => {
 					const base = i / total;
 					const step = Number.isNaN(frac) ? 0 : frac / total;
 					ui.updateProgress(nid, Math.round((base + step) * 100), label(i));
 				};
-				// Delta upload for large files (dedup); transparently falls back.
+				savedBytes += await uploadOneFile(currentId, files[i], report, owned.get(files[i]) ?? null);
-				const delta = await tryDeltaUpload(files[i], currentId, (pct) => report(pct / 100));
-				if (delta) {
-					if (!delta.ok) throw new Error(delta.errorMsg ?? 'upload failed');
-					savedBytes += delta.savedBytes ?? 0;
-				} else {
-					await uploadFileWithProgress(currentId, files[i], report);
-				}
 				ui.updateProgress(nid, Math.round(((i + 1) / total) * 100), label(i + 1));
 			}
-			const done =
+			ui.finishProgress(nid, uploadDoneMessage(savedBytes), 'success');
-				savedBytes > 0
-					? t(
-							'files.uploaded_saved',
-							{ mb: (savedBytes / (1024 * 1024)).toFixed(1) },
-							`Upload complete — ${(savedBytes / (1024 * 1024)).toFixed(1)} MB deduplicated`
-						)
-					: t('files.uploaded', 'Upload complete');
-			ui.finishProgress(nid, done, 'success');
 			await reload();
+			// Storage usage changed server-side — pull the fresh figure so the
+			// "Almacenamiento" bar moves off its login value instead of 0%.
+			void session.refresh();
 		} catch (err) {
 			ui.finishProgress(nid, errorMessage(err), 'error');
 		} finally {
@@ -430,6 +457,7 @@
 			if (kind === 'file') await deleteFile(id);
 			else await deleteFolder(id);
 			await reload();
+			void session.refresh();
 		} catch (e) {
 			errorToast(e);
 		}
@@ -480,16 +508,16 @@
 	});
 
 	/**
-	 * Whether the server can render a thumbnail preview for this file. Images and
+	 * Whether the server can render a thumbnail preview for this file. Only images
-	 * videos always have one; PDFs (and other thumbnail-capable docs) do too, so
+	 * and videos have server-side thumbnails (see `ThumbnailService::is_supported_image`
-	 * surface those rather than a generic icon. A failed <img> load falls back to
+	 * plus client-uploaded video frames); the backend does NOT rasterise PDFs or
-	 * the icon via onerror, so being permissive here is safe.
+	 * documents, so claiming it could left their tiles blank (the doomed <img>
+	 * 404s and `onerror` hides it). Non-thumbnail files fall back to their colour
+	 * type icon, which renders underneath the <img> regardless.
 	 */
 	function canThumbnail(file: FileItem): boolean {
 		const m = file.mime_type ?? '';
-		if (m.startsWith('image/') || m.startsWith('video/')) return true;
+		return m.startsWith('image/') || m.startsWith('video/');
-		if (m === 'application/pdf') return true;
-		return /\.pdf$/i.test(file.name);
 	}
 
 	// ── Multi-select + batch ────────────────────────────────────────────────
@@ -690,6 +718,7 @@
 		}
 		clearSelection();
 		await reload();
+		void session.refresh();
 	}
 
 	// ── Drag-to-move ─────────────────────────────────────────────────────────
@@ -955,6 +984,13 @@
 	async function uploadTree(entries: { file: File; relativePath: string }[]) {
 		if (entries.length === 0) return;
 		uploading = true;
+		const total = entries.length;
+		const label = (done: number) =>
+			t('files.uploading_n', { done, total }, `Uploading ${done}/${total} files…`);
+		// Same bell progress notification as uploadBatch, so folder uploads show
+		// live progress + a final result instead of staying silent until the end.
+		const nid = ui.startProgress(label(0));
+		let savedBytes = 0;
 		try {
 			// Map each relative directory path to its created folder id; '' = current.
 			const dirIds = new Map<string, string | null>([['', currentId]]);
@@ -969,16 +1005,31 @@
 				return created.id;
 			}
 
-			for (const { file, relativePath } of entries) {
+			// One batch round trip for the whole tree: which files does the server
+			// already have? Owned ones upload as zero bytes.
+			const owned = await resolveOwnedHashes(entries.map((e) => e.file));
+			for (let i = 0; i < entries.length; i++) {
+				const { file, relativePath } = entries[i];
 				const segs = relativePath.split('/');
 				segs.pop(); // drop the filename, keep the directory trail
 				const dirId = await ensureDir(segs.join('/'));
-				await uploadFile(dirId, file);
+				savedBytes += await uploadOneFile(
+					dirId,
+					file,
+					(frac) => {
+						const base = i / total;
+						const step = Number.isNaN(frac) ? 0 : frac / total;
+						ui.updateProgress(nid, Math.round((base + step) * 100), label(i));
+					},
+					owned.get(file) ?? null
+				);
+				ui.updateProgress(nid, Math.round(((i + 1) / total) * 100), label(i + 1));
 			}
-			ui.notify(t('files.uploaded', 'Upload complete'), 'success');
+			ui.finishProgress(nid, uploadDoneMessage(savedBytes), 'success');
 			await reload();
+			void session.refresh();
 		} catch (err) {
-			errorToast(err);
+			ui.finishProgress(nid, errorMessage(err), 'error');
 		} finally {
 			uploading = false;
 		}
@@ -1458,7 +1509,7 @@
 			/>
 		</div>
 		<div class="name-cell">
-			<div class="file-icon"><Icon name="folder" /></div>
+			<div class="file-icon file-icon--folder"><Icon name="folder" /></div>
 			<span title={folder.name}>{folder.name}</span>
 			{#if favoriteIds.has(folder.id)}<div
 					class="item-badge item-badge--fav"
@@ -1538,6 +1589,7 @@
 {/snippet}
 
 {#snippet fileRow(file: FileItem)}
+	{@const iconName = iconNameFromClass(file.icon_class)}
 	<div
 		class="file-item"
 		class:selected={selected.has(file.id)}
@@ -1564,7 +1616,10 @@
 			/>
 		</div>
 		<div class="name-cell">
-			<div class="file-icon">
+			<div class="file-icon {fileIconKindClass(iconName)}">
+				<!-- Colour type icon is always rendered; a successful thumbnail covers it
+				     edge-to-edge, and a failed one (onerror hides the <img>) reveals it. -->
+				<Icon name={iconName} />
 				{#if canThumbnail(file)}
 					<img
 						class="file-thumb"
@@ -1573,8 +1628,6 @@
 						loading="lazy"
 						onerror={(e) => ((e.currentTarget as HTMLImageElement).style.display = 'none')}
 					/>
-				{:else}
-					<Icon name={iconNameFromClass(file.icon_class)} />
 				{/if}
 			</div>
 			<span title={file.name}>{file.name}</span>

frontend/src/routes/groups/+page.svelte

@@ -6,6 +6,7 @@
 		addUserMember,
 		createGroup,
 		deleteGroup,
+		groupDescription,
 		groupDisplayName,
 		groupIconName,
 		INTERNAL_GROUP_ID,
@@ -243,6 +244,7 @@
 	{:else}
 		<ul class="list">
 			{#each groups as g (g.id)}
+				{@const description = groupDescription(g)}
 				<li class="group">
 					<div class="group__row">
 						<button class="group__name" onclick={() => expand(g)}>
@@ -254,7 +256,7 @@
 											>{t('groups.virtual_badge', 'System')}</span
 										>{/if}
 								</span>
-								{#if g.description}<span class="muted">{g.description}</span>{/if}
+								{#if description}<span class="muted">{description}</span>{/if}
 								{#if !g.is_virtual && g.member_count != null}
 									<span class="muted">{memberCountLabel(g.member_count)}</span>
 								{/if}

frontend/src/routes/search/+page.svelte

@@ -10,7 +10,7 @@
 	import { t } from '$lib/i18n/index.svelte';
 	import { files as filesStore } from '$lib/stores/files.svelte';
 	import { formatBytes } from '$lib/utils/format';
-	import { formatDate, iconNameFromClass } from '$lib/utils/display';
+	import { formatDate, iconNameFromClass, fileIconKindClass } from '$lib/utils/display';
 
 	const query = $derived(page.url.searchParams.get('q') ?? '');
 
@@ -265,7 +265,7 @@
 					onkeydown={(e) => e.key === 'Enter' && openFolder(folder)}
 				>
 					<div class="name-cell">
-						<span class="file-icon"><Icon name="folder" /></span>
+						<span class="file-icon file-icon--folder"><Icon name="folder" /></span>
 						<span>{folder.name}</span>
 					</div>
 					<div class="path-cell">{folder.path}</div>
@@ -283,7 +283,9 @@
 					onkeydown={(e) => e.key === 'Enter' && openFile(file)}
 				>
 					<div class="name-cell">
-						<span class="file-icon"><Icon name={iconNameFromClass(file.icon_class)} /></span>
+						<span class="file-icon {fileIconKindClass(iconNameFromClass(file.icon_class))}"
+							><Icon name={iconNameFromClass(file.icon_class)} /></span
+						>
 						<span>{file.name}</span>
 					</div>
 					<div class="path-cell">{file.path}</div>

frontend/static/locales/ar.json

@@ -52,7 +52,8 @@
     "trash": "سلة المهملات",
     "sharedwithme": "مشتركة معي",
     "profile": "الملف الشخصي",
-    "shared_with_me": "مشتركة معي"
+    "shared_with_me": "مشتركة معي",
+    "groups": "المجموعات"
   },
   "photos": {
     "empty_state": "لا توجد صور بعد",

frontend/static/locales/de.json

@@ -52,7 +52,8 @@
     "trash": "Papierkorb",
     "sharedwithme": "Mit mir geteilt",
     "profile": "Profil",
-    "shared_with_me": "Mit mir geteilt"
+    "shared_with_me": "Mit mir geteilt",
+    "groups": "Gruppen"
   },
   "photos": {
     "empty_state": "Noch keine Fotos",

frontend/static/locales/es.json

@@ -52,7 +52,8 @@
     "trash": "Papelera",
     "sharedwithme": "Compartidos conmigo",
     "profile": "Perfil",
-    "shared_with_me": "Compartidos conmigo"
+    "shared_with_me": "Compartidos conmigo",
+    "groups": "Grupos"
   },
   "photos": {
     "empty_state": "Aún no hay fotos",
@@ -365,7 +366,8 @@
     "new_folder": "Nueva carpeta",
     "share": "Compartir",
     "view": "Ver",
-    "selected_count": "{{count}} seleccionados"
+    "selected_count": "{{count}} seleccionados",
+    "uploaded_saved": "Subida completa — {{mb}} MB deduplicados"
   },
   "dialogs": {
     "rename_folder": "Renombrar carpeta",

frontend/static/locales/fa.json

@@ -52,7 +52,8 @@
     "trash": "سطل زباله",
     "sharedwithme": "به اشتراک‌گذاشته شده با من",
     "profile": "پروفایل",
-    "shared_with_me": "به اشتراک‌گذاشته شده با من"
+    "shared_with_me": "به اشتراک‌گذاشته شده با من",
+    "groups": "گروه‌ها"
   },
   "photos": {
     "empty_state": "هنوز عکسی نیست",

frontend/static/locales/fr.json

@@ -52,7 +52,8 @@
     "trash": "Corbeille",
     "sharedwithme": "Partages avec moi",
     "profile": "Profil",
-    "shared_with_me": "Partages avec moi"
+    "shared_with_me": "Partages avec moi",
+    "groups": "Groupes"
   },
   "photos": {
     "empty_state": "Pas encore de photos",

frontend/static/locales/hi.json

@@ -52,7 +52,8 @@
     "trash": "रद्दी",
     "sharedwithme": "मेरे साथ साझा किए गए",
     "profile": "प्रोफ़ाइल",
-    "shared_with_me": "मेरे साथ साझा किए गए"
+    "shared_with_me": "मेरे साथ साझा किए गए",
+    "groups": "समूह"
   },
   "photos": {
     "empty_state": "अभी कोई फ़ोटो नहीं",

frontend/static/locales/it.json

@@ -52,7 +52,8 @@
     "trash": "Cestino",
     "sharedwithme": "Condivisi con me",
     "profile": "Profilo",
-    "shared_with_me": "Condivisi con me"
+    "shared_with_me": "Condivisi con me",
+    "groups": "Gruppi"
   },
   "photos": {
     "empty_state": "Nessuna foto ancora",

frontend/static/locales/ja.json

@@ -52,7 +52,8 @@
     "trash": "ゴミ箱",
     "sharedwithme": "自分と共有",
     "profile": "プロフィール",
-    "shared_with_me": "自分と共有"
+    "shared_with_me": "自分と共有",
+    "groups": "グループ"
   },
   "photos": {
     "empty_state": "写真はまだありません",

frontend/static/locales/ko.json

@@ -52,7 +52,8 @@
     "trash": "휴지통",
     "sharedwithme": "나와 공유됨",
     "profile": "프로필",
-    "shared_with_me": "나와 공유됨"
+    "shared_with_me": "나와 공유됨",
+    "groups": "그룹"
   },
   "photos": {
     "empty_state": "아직 사진이 없습니다",

frontend/static/locales/nl.json

@@ -52,7 +52,8 @@
     "trash": "Prullenbak",
     "sharedwithme": "Gedeeld met mij",
     "profile": "Profiel",
-    "shared_with_me": "Gedeeld met mij"
+    "shared_with_me": "Gedeeld met mij",
+    "groups": "Groepen"
   },
   "photos": {
     "empty_state": "Nog geen foto's",

frontend/static/locales/pl.json

@@ -52,7 +52,8 @@
     "trash": "Kosz",
     "sharedwithme": "Udostępnione dla mnie",
     "profile": "Profil",
-    "shared_with_me": "Udostępnione dla mnie"
+    "shared_with_me": "Udostępnione dla mnie",
+    "groups": "Grupy"
   },
   "photos": {
     "empty_state": "Brak zdjęć",

frontend/static/locales/pt.json

@@ -52,7 +52,8 @@
     "trash": "Lixeira",
     "sharedwithme": "Compartilhados comigo",
     "profile": "Perfil",
-    "shared_with_me": "Compartilhados comigo"
+    "shared_with_me": "Compartilhados comigo",
+    "groups": "Grupos"
   },
   "photos": {
     "empty_state": "Nenhuma foto ainda",

frontend/static/locales/ru.json

@@ -52,7 +52,8 @@
     "trash": "Корзина",
     "sharedwithme": "Доступно мне",
     "profile": "Профиль",
-    "shared_with_me": "Доступно мне"
+    "shared_with_me": "Доступно мне",
+    "groups": "Группы"
   },
   "photos": {
     "empty_state": "Фотографий пока нет",

frontend/static/locales/zh-TW.json

@@ -52,7 +52,8 @@
     "trash": "回收站",
     "sharedwithme": "與我共享",
     "profile": "個人資料",
-    "shared_with_me": "與我共享"
+    "shared_with_me": "與我共享",
+    "groups": "群組"
   },
   "photos": {
     "empty_state": "還沒有照片",

frontend/static/locales/zh.json

@@ -52,7 +52,8 @@
     "trash": "回收站",
     "sharedwithme": "与我共享",
     "profile": "个人资料",
-    "shared_with_me": "与我共享"
+    "shared_with_me": "与我共享",
+    "groups": "群组"
   },
   "photos": {
     "empty_state": "还没有照片",

src/infrastructure/services/dedup_service.rs

@@ -1075,6 +1075,33 @@ impl DedupService {
         .unwrap_or(false)
     }
 
+    /// Batch variant of [`Self::user_owns_blob_reference`]: given candidate
+    /// hashes, return the subset the user already references — in ONE query
+    /// (backed by `idx_files_blob_hash`). Lets a client hash a whole upload set
+    /// and learn which files it can skip with a single round trip instead of
+    /// one probe per file.
+    ///
+    /// User-scoped, exactly like the single check: only the caller's own blobs
+    /// are returned, so it cannot probe whether *other* users hold a blob.
+    pub async fn user_owned_blob_references(
+        &self,
+        hashes: &[String],
+        user_id: &str,
+    ) -> Vec<String> {
+        if hashes.is_empty() {
+            return Vec::new();
+        }
+        sqlx::query_scalar::<_, String>(
+            "SELECT DISTINCT blob_hash FROM storage.files \
+             WHERE blob_hash = ANY($1) AND user_id = $2::uuid",
+        )
+        .bind(hashes)
+        .bind(user_id)
+        .fetch_all(self.pool.as_ref())
+        .await
+        .unwrap_or_default()
+    }
+
     /// Get metadata for a blob (manifest-aware with legacy fallback).
     pub async fn get_blob_metadata(&self, hash: &str) -> Option<BlobMetadataDto> {
         // Check manifest first

src/interfaces/api/handlers/dedup_handler.rs

@@ -1,10 +1,10 @@
 use axum::{
     body::Body,
-    extract::{Multipart, Path, State},
+    extract::{Json, Multipart, Path, State},
     http::{Response, StatusCode, header},
     response::IntoResponse,
 };
-use serde::Serialize;
+use serde::{Deserialize, Serialize};
 use utoipa::ToSchema;
 
 use crate::common::di::AppState;
@@ -15,6 +15,17 @@ use std::sync::Arc;
 /// Global application state for dependency injection
 type GlobalState = Arc<AppState>;
 
+/// Upper bound on hashes accepted in one batch ownership check — keeps a single
+/// request from pinning the DB with a pathologically large `ANY(...)` array.
+/// ~10k covers any realistic folder upload; clients fall back to plain uploads
+/// for whatever doesn't fit.
+const MAX_BATCH_HASHES: usize = 10_000;
+
+/// A well-formed BLAKE3 hash is 64 hex characters.
+fn is_valid_blob_hash(hash: &str) -> bool {
+    hash.len() == 64 && hash.chars().all(|c| c.is_ascii_hexdigit())
+}
+
 /// Response for hash check endpoint
 #[derive(Debug, Serialize, ToSchema)]
 pub struct HashCheckResponse {
@@ -32,6 +43,20 @@ pub struct HashCheckResponse {
     pub ref_count: Option<u32>,
 }
 
+/// Request body for the batch hash-ownership check (`POST /api/dedup/check-batch`).
+#[derive(Debug, Deserialize, ToSchema)]
+pub struct HashBatchRequest {
+    /// Candidate BLAKE3 hashes (64 hex chars each) to test for ownership.
+    pub hashes: Vec<String>,
+}
+
+/// Response for the batch hash-ownership check.
+#[derive(Debug, Serialize, ToSchema)]
+pub struct HashBatchResponse {
+    /// The subset of the submitted `hashes` the authenticated user already owns.
+    pub owned: Vec<String>,
+}
+
 /// Response for upload with dedup endpoint
 #[derive(Debug, Serialize, ToSchema)]
 pub struct DedupUploadResponse {
@@ -98,7 +123,7 @@ impl DedupHandler {
         let dedup = &state.core.dedup_service;
 
         // Validate hash format (BLAKE3 = 64 hex chars)
-        if hash.len() != 64 || !hash.chars().all(|c| c.is_ascii_hexdigit()) {
+        if !is_valid_blob_hash(&hash) {
             return Response::builder()
                 .status(StatusCode::BAD_REQUEST)
                 .header(header::CONTENT_TYPE, "application/json")
@@ -152,6 +177,52 @@ impl DedupHandler {
         }
     }
 
+    /// Batch variant of [`Self::check_hash_impl`]: return the subset of the
+    /// submitted hashes the authenticated user already owns, in one round trip.
+    /// Lets a client hash a whole upload set up front and learn which files it
+    /// can skip with ONE request instead of one probe per file.
+    ///
+    /// User-scoped (anti-enumeration): only the caller's own blobs are echoed
+    /// back — never reveals whether other users hold a blob. Malformed hashes
+    /// are silently dropped (they can't be owned anyway).
+    ///
+    /// POST /api/dedup/check-batch
+    pub(super) async fn check_hashes_batch_impl(
+        State(state): State<GlobalState>,
+        auth_user: AuthUser,
+        Json(request): Json<HashBatchRequest>,
+    ) -> impl IntoResponse {
+        if request.hashes.len() > MAX_BATCH_HASHES {
+            return Response::builder()
+                .status(StatusCode::BAD_REQUEST)
+                .header(header::CONTENT_TYPE, "application/json")
+                .body(Body::from(r#"{"error": "Too many hashes in one batch"}"#))
+                .unwrap()
+                .into_response();
+        }
+
+        let valid: Vec<String> = request
+            .hashes
+            .into_iter()
+            .filter(|h| is_valid_blob_hash(h))
+            .collect();
+
+        let owned = state
+            .core
+            .dedup_service
+            .user_owned_blob_references(&valid, &auth_user.id.to_string())
+            .await;
+
+        Response::builder()
+            .status(StatusCode::OK)
+            .header(header::CONTENT_TYPE, "application/json")
+            .body(Body::from(
+                serde_json::to_string(&HashBatchResponse { owned }).unwrap(),
+            ))
+            .unwrap()
+            .into_response()
+    }
+
     /// Upload content with automatic deduplication (streaming).
     ///
     /// Streams the multipart field straight into the CDC chunk store —
@@ -313,7 +384,7 @@ impl DedupHandler {
         let dedup = &state.core.dedup_service;
 
         // Validate hash format
-        if hash.len() != 64 || !hash.chars().all(|c| c.is_ascii_hexdigit()) {
+        if !is_valid_blob_hash(&hash) {
             return Response::builder()
                 .status(StatusCode::BAD_REQUEST)
                 .header(header::CONTENT_TYPE, "application/json")
@@ -472,6 +543,25 @@ pub async fn check_hash(
     DedupHandler::check_hash_impl(state, auth_user, path).await
 }
 
+#[utoipa::path(
+    post,
+    path = "/api/dedup/check-batch",
+    request_body = HashBatchRequest,
+    responses(
+        (status = 200, description = "The subset of the submitted hashes the caller already owns", body = HashBatchResponse),
+        (status = 400, description = "Too many hashes in one batch"),
+    ),
+    tag = "dedup",
+    security(("bearerAuth" = []))
+)]
+pub async fn check_hashes_batch(
+    state: State<GlobalState>,
+    auth_user: AuthUser,
+    body: Json<HashBatchRequest>,
+) -> impl IntoResponse {
+    DedupHandler::check_hashes_batch_impl(state, auth_user, body).await
+}
+
 #[utoipa::path(
     post,
     path = "/api/dedup/upload",
@@ -751,4 +841,30 @@ mod tests {
         assert_eq!(parsed["bytes_saved"], 2048);
         assert_eq!(parsed["ref_count"], 3);
     }
+
+    #[test]
+    fn valid_blob_hash_accepts_64_hex_only() {
+        assert!(is_valid_blob_hash(&"abcdef0123456789".repeat(4))); // 64 hex chars
+        assert!(!is_valid_blob_hash(&"a".repeat(63))); // too short
+        assert!(!is_valid_blob_hash(&"a".repeat(65))); // too long
+        assert!(!is_valid_blob_hash(&"g".repeat(64))); // non-hex
+        assert!(!is_valid_blob_hash("")); // empty
+    }
+
+    #[test]
+    fn hash_batch_request_deserializes() {
+        let req: HashBatchRequest = serde_json::from_str(r#"{"hashes":["aa","bb"]}"#).unwrap();
+        assert_eq!(req.hashes, vec!["aa".to_string(), "bb".to_string()]);
+    }
+
+    #[test]
+    fn hash_batch_response_serializes_owned_subset() {
+        let r = HashBatchResponse {
+            owned: vec!["a".repeat(64), "b".repeat(64)],
+        };
+        let parsed: serde_json::Value =
+            serde_json::from_str(&serde_json::to_string(&r).unwrap()).unwrap();
+        assert_eq!(parsed["owned"].as_array().unwrap().len(), 2);
+        assert_eq!(parsed["owned"][0], "a".repeat(64));
+    }
 }

src/interfaces/api/routes.rs

@@ -391,10 +391,11 @@ pub fn create_api_routes(app_state: &Arc<AppState>) -> Router<Arc<AppState>> {
     // All handlers are free functions — see dedup_handler.rs for why
     // #[utoipa::path] cannot be applied to DedupHandler impl methods directly.
     use super::handlers::dedup_handler::{
-        check_hash, get_blob, get_stats, recalculate_stats, upload_with_dedup,
+        check_hash, check_hashes_batch, get_blob, get_stats, recalculate_stats, upload_with_dedup,
     };
     let dedup_router = Router::new()
         .route("/check/{hash}", get(check_hash))
+        .route("/check-batch", post(check_hashes_batch))
         .route("/upload", post(upload_with_dedup))
         .route("/stats", get(get_stats))
         .route("/blob/{hash}", get(get_blob))