How verification works

Fitr is built to be cheat-resistant, not cheat-proof. Here is exactly what is checked, by whom, and what you are trusting.

1. Your phone counts the reps

On-device pose AI finds 33 body points in each camera frame and counts a rep only when your joints move through the full range (for example, elbows past 90° on a push-up). Half reps are shown as “not counted”. This runs entirely on your phone.

2. For staked workouts, Fitr's server checks again

When money is on the line, your phone also sends the skeleton points (never video) to Fitr's verification server while you work out. The server:

• re-counts every rep itself with the same counting engine, so it never takes your phone's word for it;
• gives you live challenges at random moments, such as “raise your right hand”, that a pre-recorded video can't know in advance;
• checks the movement is physically plausible: bone lengths stay constant, joints don't teleport, the pace is human;
• checks timing against its own clock, and rejects a session that was already submitted.

Only when all of that passes does the server mark your day complete on-chain.

3. The blockchain enforces the money rules

Your stake sits in an on-chain vault program on Solana, not with Fitr. The program enforces the deadlines, one commitment per wallet per day, the payout math (your stake back plus a pro-rata share of forfeited stakes, minus a 5% fee taken only from forfeits) and no double claims. Fitr can't move your stake to itself, and if a day is voided everyone is refunded.

What you are trusting

The blockchain can't see your workout, so you trust Fitr's server to judge it fairly: to mark you complete when you did the work, and not to mark anyone complete who didn't. Each decision carries a fingerprint of the session it judged, so it can be audited.

No camera-based system is impossible to fool. A determined cheater with a modified app or a convincing body double might get through. The checks above are there to make that hard, slow and not worth the stake.