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Clearing Price

Each matching interval is a uniform-price batch auction. Crossing orders in the batch settle at one clearing price, subject to every order’s limit and the market’s oracle circuit-breaker policy.

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Selection

The matcher considers eligible bid and ask price levels, chooses the price that maximizes executable volume, and applies deterministic tie-breaking. A zero-limit market ask can execute at any positive clearing price, but it is not itself a price candidate. FIFO priority is preserved within a price level. A bid is eligible only when the clearing price is at or below its price_limit. An ask is eligible only when the price is at or above its limit; an ask limit of zero accepts any positive clearing price. IOC, FOK, AON, and minimum-fill rules further constrain executable volume.

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Oracle circuit breaker

The matcher reads the configured oracle reference and refuses candidate prices outside the market’s circuit-breaker bounds. This protects against a stale or pathological book clearing arbitrarily far from the reference. Oracle updates are authenticated and replay-ordered, and their signed publish time must remain fresh. An unhealthy oracle pauses new placement, modification, and matching for markets bound to that feed without blocking healthy markets, cancellation, or settlement recovery. This is an attested matching-policy guarantee. The settlement circuit does not receive the oracle observation or re-run the limit book, so clients rely on verifying the expected matcher image for oracle-band, limit, FIFO, and tie-breaking correctness.

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What settlement proves

VALID_MATCH_BATCH binds every active match to the on-chain market mints and price_scale, then proves:
with a constrained remainder. It also proves conservation, the exact configured fee, and deterministic ownership of user and protocol outputs. The price and amount stay private even though their arithmetic is checked. This division matters: attestation answers “did the expected matcher select a fair eligible price?”; zero knowledge answers “does this private result conserve the configured assets at exactly that scaled arithmetic?”

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Trader implications

  • price_limit is a worst acceptable bound, not a requested execution price.
  • Every match in the batch receives the same clearing price.
  • There is no maker/taker fee role, although supply and demand can still produce price improvement relative to one side’s limit.
  • Use a capped IOC for an immediate marketable order. A market ask may use zero; a bid must always carry a positive cap.
See Order Types and Privacy & Attestation.