The refill — how a machine earns and burns

Every cabinet has a REFILL PRESSURE gauge: a bar that fills as the machine earns, and a promise about what happens when it's full — the machine buys its own coin back and burns it. This page explains exactly what fills that bar, in which currency, and why.

Where a machine's earnings come from

Every swap in a cabinet's pool pays a small fee, and the floor's fee plumbing delivers all of a pool's fees in one currency: the coin the cabinet is paired with (fees collected in other coins are auto-converted on the way — we verified this on-chain, in both trade directions). So each machine earns exactly one thing:

• Every cabinet trades against WETH, the mother included — one pair for the whole floor, so no cabinet has to read another cabinet's pool to know what it earned. The floor counts what it earns in sats, so a bar means the same thing in a month as it does today.
• The bar's full mark is 50 basis points of that pool's own depth, read live from the pool every pass — a deep pool has a higher bar than a thin one, and no number is typed anywhere. (It used to be a fixed setting, and when the floor's pair changed the setting did not: the mother's bar read "24 sats" against a real target of 645,900. A live read cannot go stale.)
• A pool earns only what is in it. A cabinet's pool holds its coin and WETH, so those are the only two things its fees can arrive as. Your ETH still gets there — the router wraps and routes it — but by the time it reaches the pool it is the pair.

(Until 09-04 the mother traded against Bitcoin and every other cabinet traded against COIN-OP, which is why older screenshots show two currencies and a change machine between them. One pair replaced both.)

One machine, one currency, one gauge. No hidden streams.

What fills the bar

The bar fills with the machine's pair currency — the coin it will spend on its own buyback. The floor has one pair, so this reads the same for every machine, the mother included: the pot holds WETH, and the floor counts it in sats — shown in sats against a sats target.

The numbers are live on-chain balances, never estimates: the bar is the pot's own balance, read from the chain on every pass.

The target scales with the machine. The bar's target is the larger of a published minimum and 0.5% of the pool's own depth on the pay side, read live from the pool: a bigger pool needs a bigger refill to move it, and the minimum keeps a tiny pool from firing dust. The cabinet page shows the live target — the same number the keeper fires on.

"Ready to burn" — the line under the bar

Sometimes the pot ends up holding the machine's own coin — for example when an expired prize round's unclaimed coins are swept back to REFILL. Those don't need to be bought — they're the very thing the buyback exists to acquire. They wait under the bar as "+ X in the pot, ready to burn" and burn together with the bought-back coins when the bar fills.

One rule with no exceptions: the machine never sells its own coin. Its own coin has exactly one exit from the pot, and it's the furnace.

When the bar fills

• Mother machine: the pot's WETH (counted in sats) market-buys COIN-OP in its own pool → everything burns.
• Every other cabinet: the pot holds the cabinet's own pay currency — WETH, the floor's one pair — and buys the cabinet's coin in one hop through its own pool → everything burns.

Note what happens to the WETH a refill spends: it isn't burned — it lands inside the cabinet's own pool as depth, like any buy. So one refill firing does two things at once: the cabinet's coin burns (supply down), and its pool ends up deeper on the pay side (depth up).

A quiet machine still fires

A bar that never fills would be a machine that never burns, so the keeper keeps a weekly heartbeat: if seven days pass since a machine's last refill and its pot holds at least one twentieth of its target, it fires anyway — with whatever the pot holds. The burn is smaller than a full bar's, and it is the same transaction: a market buy from the machine's own pot, then the furnace.

The mother's burn of 09-27 was a heartbeat: seven days to the minute after the full bar of 09-20, on a quiet floor, with about a third of a bar in the pot. Below the twentieth, the machine waits: a burn of dust would cost more gas than it eats.

Every burn feeds the COINS EATEN counter. The floor eats; the float shrinks.