Orders

Orders rest on-chain in the pair's orders mapping and are matched in sequencer batches. Every user has one net position per market (a position bucket); orders modify it.

Order types

TypePriced byTriggerNotes
Marketoracle ± maxSlippageBp—slippage cap 5%; 12-block (~3 s) lifetime; 1 active per user; rejected while the oracle is stale
LimitlimitPrice—the only post-only-capable type
StopLimitlimitPricearms at triggerPricelimit must be on the fillable side of the trigger (buy: limit ≥ trigger)
TakeProfitlimitPrice—position-reducing only: opposite direction, size ≤ position, 1 per position, never expires
StopLossoracle ± maxSlippageBparms at triggerPricesame restrictions as TakeProfit

Stops are trigger-gated against the batch's settlement oracle price, not a sequencer-chosen price — a sequencer cannot arm a stop early. Buy stops fire at price ≥ trigger, sell stops at ≤ (inclusive).

Creation rules

  • Minimum order notional $5, with one exemption: an exact full-close of your position is always allowed.
  • Initial-margin check at creation covers worst-case exposure: your position plus all resting orders in whichever direction is worse — including the flip case. Under a stale oracle the requirement doubles.
  • Anti-DoS caps: ≤ 100 active Limit+StopLimit orders per user, 1 active Market order, 1 TakeProfit + 1 StopLoss per position. These bound both the sequencer's calldata and the exposure-tally iteration cost.
  • Lifetimes are stamped in Arbitrum L2 blocks: minimum ~3 s (12 blocks), maximum ~1 year; market orders always ~3 s; TP/SL never expire.
  • Every order can carry an integrator address that earns a referral fee on fills.

Cancellation & cleanup

  • cancelOrders(orderIds[], …) — creator-only, up to 200 per call.
  • Expired limit orders are swept lazily during creation, withdrawal, and the getUserActiveLimitOrders query (the matching walk merely skips them); sweeps emit the same OrderUpdated(Canceled) event.
  • The matching engine auto-cancels orders in four situations: a fill that would fail the owner's margin check, a self-match (newer order cancels), a post-only order that would take instead of make, and a resting TP/SL left oversized after a fill shrinks or flips the position. Auto-cancellation is what makes omission challenges sound — every walked order ends in a provable terminal state.

Order lifecycle

createOrder ──► resting ──┬─► filled          (matchBatch, full or partial fills)
                          ├─► canceled        (user, auto-cancel, lazy sweep)
                          └─► expired         (block-stamped lifetime passes)

filledBlock / canceledBlock stamps plus creationBlock ≤ observationBlock liveness rules are exactly what omission challenges replay — see Sequencers & Fraud Proofs.