Depth you can gate.

In a constant-function pool, an arbitrageur who spots a stale price can drain the full depth in one block. The LP eats the loss — LVR — while the arb keeps the spread. The status quo for deciding who gets depth is a gas race, JIT liquidity, or a private RFQ desk. None of those pay the LP for the capacity they are giving away.

Each epoch, total eligible reserves are split by a fixed ratio λ (here, 25% active). The active side is tradable this epoch. The passive side stays locked until refresh — it cannot be reached by splitting an order across blocks in the same epoch.

On refresh, active reserves are recomputed from the new total, every un-consumed cadence slot is burned, and a fresh capacity budget is minted for the new epoch. Scarcity is real: capacity you don't use, you lose. That expiry is the honesty of the instrument — a slot is a time-slice, not equity.

Three checks run before any swap touches the pool:

1. 1

   require slot ≥ size

   The caller (or router payer) must hold a cadence slot for the current epoch with capacity ≥ trade size.

2. 2

   burn / lock the notional

   The consumed capacity is burned from the slot — capacity is single-use per epoch.

3. 3

   fill against active only

   The swap executes against active reserves. Passive is untouchable, full stop.

Every reject is public and indexed — the hook refusing a trade is the venue doing its job. Three paths, all demonstrated live in the console:

• No cadence slot

  beforeSwap reverted: trader holds no cadence slot for this epoch.

• Oversize vs slot

  beforeSwap reverted: trade size exceeds cadence slot capacity for this epoch.

• Passive unlock attempt

  beforeSwap reverted: order split would reach passive reserves in the same block.

• Bad reveal

  beforeSwap reverted: reveal(size, salt) does not hash to the committed H.

• Unsafe withdraw

  withdraw reverted: it would orphan active capacity already sold this epoch.

• Epoch expired

  slot id not current epoch — unused cadence slots expire worthless at refresh.