Sponsored transactions

Every transaction against the privacy pool pays a pool fee, charged by the pool contract itself and read live from get_fee_amount. It is not set by strk20.run and we cannot waive it. What we can do is pay it for you, and for your first three transactions we do.

What "sponsored" actually means

A sponsored transaction is submitted by our relayer instead of by your account. The relayer signs it, its own approve covers the pool fee, and its wallet pays the Starknet gas. Your account still proves the transaction — the proof is built in your browser from your key, and the relayer cannot compose one for you — but the bill lands on us.

The practical consequence is the one worth knowing: a sponsored transaction needs no public STRK in your account at all. A freshly registered account holding nothing but a shielded starting balance can still send, swap, bet or vote, because none of those cost it anything public.

What the three cover

Your registration takes the first one automatically — that is the transaction that puts your account in the pool, and it happens before you have any way to pay for it yourself.

The other two are yours to spend, and the review screen asks before it spends one:

They work on any pool transaction: sending, unshielding, swapping, bridging, backing a market, creating one, funding a house, delegating, voting, and buying into a launch.

Creating a House, opening a proposal and launching a token are a slightly different shape — they are direct calls rather than pool transactions, so there is no pool fee on them at all, only Starknet gas. The same toggle appears, and turning it on spends a covered transaction to have us pay that gas. Left off, your own account pays it, which is the ordinary case.

Why shielding is not on that list

Shielding is a deposit, and a deposit pulls funds from whoever submits the transaction. If our relayer submitted your shield, our STRK would go into the pool — in a note owned by you. That is not a sponsored transaction, it is a gift, and it is a different thing with different limits.

So a shield is always sent by your own account, which means it always pays its own pool fee and gas out of your public STRK. The review screen says so rather than showing a toggle that cannot work.

We do hand out a starting balance separately — a small shielded note, sent and proved by the relayer with its own key, once per account. That is the gift; the three transactions are the sponsorship. They are metered apart and neither draws down the other.

When they run out

Nothing breaks. Your account keeps working exactly as before, and each transaction pays the pool fee from your own balance like any other. The review screen stops offering the toggle and says which of the two situations you are in.

The limits, stated

• Three per account, once. Not three per day — they do not come back at midnight.
• The starting balance and the public drip are also once, per account. Separate from the three, metered separately, and neither renews.
• Everything metered per connection is a lifetime allocation too. A network that has used its share does not get a fresh one tomorrow. These ceilings are set high enough that shared internet connections — an office, a campus, a mobile carrier — are not mistaken for one person.
• A shared daily budget bounds what the relayer will pay for across everyone in a UTC day. This is the one thing here that does reset: it is a limit on our spending for a day, not a rule about you. When it is spent, sponsorship pauses until 00:00 UTC and self-paid transactions carry on.
• A reverted transaction gives the unit back. The relayer reads the receipt itself and refunds what a failure cost you. It never takes a client's word for it.
• A relayer low on funds refuses rather than half-pays. It stops signing below twice the live pool fee, and the app falls back to offering you the self-paid path.