commitment-vault

A savings commitment device with real stakes. You commit to save target of a token by deadline. Hit the target and wait until the deadline → withdraw everything, penalty-free. Bail early, or fall short at the deadline → you can still get your money out, but a penaltyBps cut goes to a beneficiary you chose up front (a friend, a cause, or an "anti-charity" you'd hate to fund). The looming penalty is the motivator — StickK/Beeminder on-chain. MIT.

Flow

• createGoal(token, target, deadline, penaltyBps, beneficiary, initialDeposit) — open a goal (penalty capped at 50%). Funds credited actual-received (fee-on-transfer-safe).
• deposit(id, amount) — add toward the target (anyone can top up; it's the owner's to withdraw).
• withdraw(id) — owner-only, once. Penalty-free only if balance >= target and the deadline has passed; otherwise penaltyBps of the balance goes to the beneficiary and the rest to the owner.
• quoteWithdraw(id) / isSuccess(id) — preview the split / check the penalty-free state.

Invariant (fuzzed, fail_on_revert=true, non-hollow)

• Solvency — the vault's balance always equals the sum of every un-withdrawn goal's balance, across any sequence of create / deposit / withdraw / warp (12,800 calls, 0 reverts). A withdrawal splits exactly into toOwner + penalty == balance — no dust created or lost. Mutation-checked (paying the owner the full balance, skipping the penalty, fails the penalty tests); reentrancy-safe (terminal state set before transfers, CEI + nonReentrant).

Trust model (honest)

• Only the goal owner (subject to the rules) and their chosen beneficiary ever receive funds. No admin, no fees, no path to another goal's money.
• The commitment is self-imposed and self-enforcing — the contract can't check whether you actually did the real-world thing; it enforces the on-chain saving target and the penalty. Choose a beneficiary that genuinely motivates you. Standard ERC-20 assumed. Unaudited reference implementation.

forge test   # 13 tests: success/early/missed withdrawals, conservation, isolation, reentrancy, solvency invariant