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What the app cannot do

More honest than leaving it out. None of this is a fault waiting to be fixed — these are the other side of working without a server.

Double redemption is detectable, not preventable​

Two counters without a connection can redeem the same class. Without a central machine to ask both, there is no other way.

What the app does instead: it shows the contradiction once the entries come together, with both records. The balance is charged exactly once — a contradiction never gives a class away and never costs two.

The damage per incident is one yoga class. In exchange there is no server.

Whoever knows an address can read along​

The underlying database has write permissions but no read permissions. Anyone who knows a database's address and can reach a device holding it can read it in full.

In practice: your pass accounts live with you and on your studio's devices, and none of those addresses is distributed. But that is a matter of distribution, not an enforced barrier.

Spelled out in full in the privacy analysis.

Nothing on the device is encrypted​

Anyone who picks up an unlocked studio device reads everything on it. No passkey needed.

For the iPad at the front desk that is the realistic way to get at data — not the network. A lock screen and device encryption matter more here than anything the app could do.

Some connections do not come together over a distance​

Some internet connections do not let two devices reach each other directly. There are helper servers for that; the app deliberately uses none, because they would see the traffic. In the studio, on the same network, the case does not arise.

No deletion in the real sense​

Entries are appended, never overwritten — which is why the numbers add up. A pass can be voided, but its history stays readable.

So there is no finished procedure for a GDPR erasure request yet. That is open, and recorded as open in the repository.

There is nobody to fall back on​

No provider, no password reset, no recovery. Which is why:

  • a second device in the studio, from the start
  • export regularly
  • keep passkeys where they are synchronised