Sharing & P2P sync

Kalta supports two ways to keep multiple people in sync: cloud-based sharing of a warehouse (invite-link flow through our backend) and peer-to-peer sync between two nearby iPhones over Bluetooth and WiFi (no internet needed).

Most households use cloud sharing as the default. P2P is there for offline scenarios or as a privacy-focused alternative.

Cloud-based sharing (invite links)

A warehouse can be shared with other Kalta users. When you share, everyone who joins has read and write access to that warehouse: they can add and edit items, rename boxes, and mark things as opened. Only the owner can delete a warehouse or remove members.

Generating an invite

1. Open the warehouse → Settings tab.
2. Tap Invite.
3. Kalta generates a link valid for 7 days. You’ll see the iOS share sheet.
4. Send the link however you like — iMessage, email, WhatsApp, AirDrop, Signal, any app on your phone.

Accepting an invite

On the recipient’s side:

1. Open the link on their iPhone.
2. If Kalta is installed → it opens directly. If not → App Store opens to Kalta’s page; after install, the link is remembered and processed on first launch.
3. The recipient signs in with Apple (if they haven’t already).
4. Kalta shows the warehouse preview. Tap Accept.
5. The warehouse appears in their dashboard. It’s now shared.

Member management

Inside the shared warehouse → Settings → Members:

• See all people who have access, with their display name.
• Owners can remove members — swipe left on a member → Remove. Access is revoked immediately.
• A removed member can be re-invited later with a new link.

Safety tips

• Only share invite links with people you trust. There’s no email verification or approval flow — whoever opens the link can accept.
• Invite links expire after 7 days but are active for anyone during that window. If a link goes to the wrong person, the fastest fix is to generate a fresh one (the old one doesn’t auto-revoke, but it only works once). Then remove the wrong person from the Members list if they accepted.
• Removed members can no longer see the warehouse after removal, but any data they viewed or exported while active is theirs to keep — we cannot retroactively revoke what they already saw.

Who sees what

All members see:

• All boxes, items, notes, and photos in the warehouse.
• Other members’ display names.
• Inventory history (who added/changed what, if you had multiple members active at once).

Nobody outside the warehouse membership can see any of this — not other Kalta users, not us (well, we host the data but only you and members can read it via the app).

P2P sync (two nearby iPhones)

P2P sync lets two iPhones running Kalta exchange inventory data directly over Bluetooth and WiFi using Apple’s MultipeerConnectivity framework. No internet is required.

When to use P2P

• Offline locations — cabin without WiFi, remote shelter, underground basement.
• Initial setup — want to clone your inventory to a second device quickly.
• Privacy preference — you don’t want your sync traffic to pass through any server, including ours.

For day-to-day household use, cloud sharing is simpler — changes sync automatically in the background. P2P is a manual, on-demand transfer.

How to start a P2P sync

Both devices must have Kalta open on the P2P Sync screen at the same time.

1. Open Kalta → Settings → P2P Sync (or from a warehouse’s Settings tab).
2. Tap Start searching on both devices.
3. The other device’s name appears in the list.
4. On one device, tap the peer → Connect.
5. The other device shows a connection confirmation → tap Accept.
6. Once connected, tap Sync now on either device to start the exchange.

Review and accept

Once you tap Sync now, both devices exchange their data and show a review screen:

• A banner at the top: “Changes from {peer name}”.
• A list of every change the peer’s data would make to your local copy: items added, item fields modified (quantity, notes, expiry, …) shown as a red “before” / green “after” diff, just like the pending changes screen.
• Any conflicts (you and the peer edited the same field with different values) are flagged in the same list with a warning icon.

At the bottom: Reject or Accept.

Both devices must independently tap Accept before any change is written to either local database. If either side taps Reject — or one of you closes the screen / the connection drops — the sync is canceled and nothing is saved on either side.

After both peers accept, each device applies the other’s bundle to its local data. Conflicts (if any) get logged so you can resolve them later in Settings → Conflicts.

What’s exchanged

Both devices send each other a JSON bundle of their local data: warehouses, boxes, items, members, custom products, inventory sessions. The receiving side merges it using a per-field merge with baseline awareness: a field is considered a conflict only when both sides edited it concurrently to different values. If you and the peer edited different fields on the same item, both edits are kept — no conflict.

Encryption

The MultipeerConnectivity session is TLS-encrypted end-to-end by Apple’s framework — nobody in between (e.g., a passer-by on the same WiFi) can read the payload.

Conflict resolution

Real conflicts (both sides edited the same field) get added to Settings → Conflicts after the sync completes. There you pick the correct value per field, the same flow as for cloud sync conflicts.

Troubleshooting P2P

• Both Bluetooth and WiFi radios must be on on both devices. Despite the feature name suggesting “Bluetooth sync”, iOS’s MultipeerConnectivity framework uses both: WiFi (via AWDL, the same protocol as AirDrop) for peer discovery and fast transfer, Bluetooth as a fallback. Without WiFi radio on, devices won’t find each other.
• Your WiFi does not need to be connected to any internet — just the radio must be active. Airplane mode with WiFi and Bluetooth manually re-enabled works perfectly.
• Make sure neither device is in Low Power Mode — it aggressively disables peer scanning.
• The P2P Sync screen has to stay open on both devices for them to see each other. Don’t background the app during sync.
• If they don’t see each other after 30 seconds, force-close Kalta on both devices and retry.
• Verify the device name shown in the peer list matches the device you intend to pair with. P2P is for trusted devices (family, your own second iPhone) — don’t connect to random peers.

Which should you use?

For most households: cloud share with your partner once, forget about it. Use P2P only when you actually need it.

What’s next

• If you haven’t set up notifications yet, read Expiry & reminders.
• For the printing side of boxes (labels, Brother printers), see Printing QR labels.