Working offline

Manga Vault keeps your collection accessible offline and queues your changes to sync when you reconnect. A handful of features need a connection; everything you’ve already loaded keeps working.

What works offline

Browsing your Library — Your full collection, including cover art (cached after first viewing) and any series-level data the app has previously synced.
Adding volumes by manual entry — You can fill in a manual entry without a connection. Scanning a barcode requires a connection (see below).
Reading progress tracking — Mark as Reading, log pages, mark Completed. All local.
Shelves — Create, edit, delete shelves; assign volumes to them.
Filtering, sorting, searching — All Library operations against your existing collection are local.
Manga detail pages for owned volumes — Tap any volume in your Library to see its details (already cached locally).
Settings and preferences — Change theme, dark mode, etc.

What doesn’t work offline

Scanning a barcode — The lookup hits our cloud catalog. Without a connection, you’ll see a network error. (Manual entry still works.)
Opening a series detail page you haven’t visited before — Series details are fetched on demand from our server. Once loaded, the data caches locally.
Searching the broader catalog (Browse tab → search) — Goes through our search endpoint.
Cloud sync — Pending changes queue up; nothing syncs until you reconnect.
Friend interactions — Adding friends, viewing friend profiles, comparison data.
Push notifications — None received until reconnected.
Cover art for new volumes — If a volume’s cover hasn’t been cached locally, you’ll see a placeholder until you have a connection.

What happens when you make changes offline

Every change to your library is stored locally as a pending change:

The change applies to your local view immediately.
The change is saved to your phone’s storage (durable — survives app restart).

When you reconnect, all pending changes sync to the cloud. Order is preserved (changes apply in the order you made them).

What if I’m offline for days?

That’s fine. Pending changes accumulate. When you reconnect:

All your changes sync (in order).
The catalog snapshot updates with anything new since your last sync.
Friend data refreshes.

A long offline period might result in a longer-than-usual first sync, but it’ll catch up.

Conflict scenarios

If you’ve been offline and made a change on Device A, while online on Device B you make a different change to the same volume:

The most recent change (by timestamp) generally wins.
For shelves, both changes are merged (union semantics).
Deletions take precedence (a deleted volume stays deleted).

This rarely causes issues in practice unless you’re heavily using two devices simultaneously.

How to know if you’re offline

Pull-to-refresh fails or shows a network error.
Friend profiles say “Unable to load.”
Scanning a new barcode shows a network error.

Manga Vault doesn’t show a persistent “Offline” indicator — we don’t want to be alarmist. Instead, the app keeps working with what’s already loaded and queues changes.

Battery and data usage

When there are no pending changes and your catalog is up to date, sync uses minimal data. When changes are queued and you reconnect, sync runs and uses bandwidth proportional to the changes.

In airplane mode or limited connectivity:

App opens fast (no sync wait).
Your existing collection is fully accessible.
Library edits queue to sync later.

Tips for offline use

Pre-cache cover art. Browse your collection in grid view while online to ensure covers are cached.
Pre-sync before traveling. Open the app, pull-to-refresh, and let everything sync (including the catalog snapshot) before you fly or go off-grid.
Visit any series you’ll want to view offline. Series detail data is fetched on demand. Tap a series once while online and it’ll load instantly later, even offline.

Sync resumes automatically

There’s no “go online” button. As soon as your device gets a connection, Manga Vault detects it and starts syncing pending changes. You don’t need to do anything.