Solana mainnet · classic SPL USDC
Gas recovery, explained
This Solana extension evolved from the original Borrow Gas lending-shaped interface. It is not a loan: a user-authorized fixed route exchanges USDC for useful SOL, beginning with 0 SOL and no approval transaction.
One atomic route transaction
The supported transaction uses the pinned classic USDC route and performs USDC → temporary WSOL → SOL close, then repays the sponsor. The swap, unwrap/close, user output and sponsor repayment are one atomic transaction. The sponsor advances fee and rent; successful execution recovers the agreed rent and reimbursement from the route economics.
- Validate the fixed mainnet mint, route accounts, owner source account, expiry and minimum output.
- Create and initialize only the validated temporary WSOL account.
- Swap the exact requested USDC, close WSOL to the owner, and repay the sponsor.
The public demo uses the fixed classic USDC route. It does not accept arbitrary swap instructions, tokens, recipients, fee payers or priority fees.
Two wallet modes, exact signatures
Demo mode uses a server-controlled demo wallet after its balance, lease and cap checks. Real-wallet mode asks the user wallet to sign the exact prepared legacy transaction; the backend never receives the user’s private key and never asks the wallet to call sendTransaction. Both modes use the same constrained route and public operation/recovery states.
Operator-only refill is separate from the public swap: it is a capped, durable funding workflow for the fixed demo wallet, not part of the atomic user transaction. Reset is not a public endpoint.
Limits and evidence
The Solana extension has an independent cumulative sponsor ceiling of 50,000,000 lamports (0.05 SOL), including fee and rent outlays. Recovery does not replenish that budget. Amounts, accounts, blockhash expiry and route state are checked before signing or broadcast.
Verified on mainnet: the demo wallet started with 0 SOL, spent 0.25 USDC and received 0.002514415 SOL. The sponsor recovered its advanced rent and 0.00001 SOL transaction fee; the temporary account closed. Inspect the transaction.
Local cloned-pool tests also cover an exact-amount refill and a deliberately failed swap: token balances remain unchanged, although a failed transaction can still charge a fee. This prototype has not received an external security audit.