pakt

Custody is genuinely on-chain: the vault is a token account owned by the deal PDA, payouts go only to the recorded seller and buyer, there is no admin instruction, and the server only relays unsigned transactions. It stops short of the top because the deployer key still held upgrade authority at submission, so the authors could still change every rule.

The flow is fully implemented across program, CLI, GUI and server with 94 measured test cases including security refusals, which supports A and B over C's 4. But the required PDF deck and video of at most 3 minutes were not submitted, no devnet transaction signature or explorer link appears in the pack, and the automated check reached only the faucet, never the claimed live app.

The target user is named precisely, people paying strangers a few hundred to a few thousand zloty outside buyer-protection platforms, with a cost table against Vinted, OLX, Allegro and Escrow.com and a substantive answer to why a database cannot do it: an administrator can be begged or bribed, the program cannot. The honest payoff-matrix analysis, including that the honest side loses more in a standoff, strengthens the framing.

The Anchor program is soundly engineered, with terms pinned by hash at take, checked arithmetic, a vault-shortfall guard, permissionless release and refund on two silence clocks, and typed errors, so it is deployable beyond the demo. A's 9.3 overshoots the median because real limits remain: upgrade authority is still active, a dispute freezes funds indefinitely, and deposits lock twice the item value with no fiat ramp.

The double-deposit core is borrowed and self-admitted from Solidity's Safe Remote Purchase and Particl MAD, so it is beyond a renamed tutorial but not a new mechanism. The additions A and B substantiate in code, partial settlement as a dispute exit, anyone-callable release and refund, on-chain track records, a simulate-the-refusal panel, are real, which does not support C's 5.