Show HN: FitVow – a smart contract that fines me if I miss weekly fitness goals
fitvow.pedroaugusto.devFitVow is my personal commitment-device experiment: I lock funds in a smart contract for 12 weeks, define weekly fitness goals, and if I miss a week a penalty becomes enforceable.
Enforcement is permissionless: anyone can call the contract and a portion of the penalty is paid to the caller; the rest goes to a charity (Giveth).
Weekly activity data comes from my smartwatch (via Samsung Health / Health Connect), synced by an Android app that publishes the weekly activity on-chain.
The site is mostly a viewer for on-chain state. Full write-up / architecture / security notes in the first comment. Author here: I built this because I kept finding ways to “renegotiate with myself” on weeks I didn’t feel like training. I wanted a commitment device with real consequences and no trusted referee — just code and incentives. Write-up / architecture / threat model: https://pedrooaugusto.github.io/blog/posts/making-missed-wor... Current run parameters: - Network: Arbitrum (Ethereum L2) - Duration: 12 weeks (Jan 19 → Apr 13) - Total stake: ~$235 (0.075 ETH) - Penalty per failed week: ~$19 (0.00625 ETH) How enforcement works: - If a week fails, anyone can call enforceAgreement() and receive a share of the penalty; the rest goes to the Giveth charity. - There’s also a Chainlink Automation backstop so “nobody enforced” can’t become an escape hatch. If automation is the first to enforce a missed week, there’s no caller to reward, so 100% of the fine goes to Giveth. I’d love feedback on: 1) where you’d try to cheat this, 2) what would make it more verifiable/auditable to you.