A week ago a whale sold its FlatEarth and PEPE, swept it into USDCx and bridged out to Ethereum. We said the same door swings both ways and we were building the return. Now it works, and this morning it worked with real money on mainnet.
The first crossing, with receipts
A fresh passkey wallet named eth-judge. 13 USDC sent from MetaMask on Ethereum at 14:35 UTC. Circle attested the deposit and Stacks minted 13 USDCx into the wallet at 14:56. The pre-signed swap then cleared on Bitflow and the wallet ended the trip holding 16,438 sats of sBTC. Nobody typed a seed phrase, nobody held STX for gas, and nobody was asked to trust us in the middle.
Every hop is public: the deposit on Ethereum, the USDCx mint on Stacks, and the swap into sBTC. As far as we know it is the first time anyone has gone from USDC on Ethereum to self-custodied Bitcoin on Stacks in one flow, with a passkey and no seed phrase.
Honest note: the first swap attempt aborted because the wallet tried to pay its 20-sat sBTC gas before it owned any sBTC. We fixed it in minutes, the keeper replayed the same signature, and it cleared. That is the point of pre-signed intents: a failed broadcast costs you nothing and needs nothing from you.
No seed phrase. FaceID and a USDC transfer.
Create a wallet with FaceID. The key lives in your phone's secure hardware; there is nothing to write down and nothing to lose. Open MetaMask, send USDC, confirm once. A few minutes later the dollars land in your wallet as USDCx and swap themselves to sBTC, Bitcoin on Stacks, with no further taps. You signed that swap upfront with your passkey; our keeper broadcasts it the moment the funds arrive.
While your dollars are in transit you can watch them: the deposit page shows each hop live, sent on Ethereum, minted on Stacks, swapped to sBTC, with a retry button if anything ever stalls. Smooth criminal UX.
What's under it
- Circle's xReserve bridge carries the dollars from Ethereum to Stacks, the same rail the whale used to leave.
- Bitflow's DLMM swaps USDCx to sBTC, the deepest direct market for the pair.
- A passkey smart wallet on Stacks holds the result. Your keys, your phone, no custodian.
- Everything is on-chain and verifiable: the wallet, the swap, the routing.
Fund a wallet from Ethereum or read the full post on fak.fun. None of this is financial advice. It is a road, not a recommendation.
