Ordering & Inclusion

Order sequencing is deterministic, derived from the Continuum sequencing layer.

Continuum Sequence

Every order receives a globally unique sequence number:

continuum_sequence = (tick_number << 32) | sequence_in_tick

• tick_number — Block height from Continuum (VDF-proven)

• sequence_in_tick — Position within that tick (0-indexed)

This replaces timestamp-based ordering to ensure all nodes process orders identically.

Order Structure

TickOrder {
    order_id: OrderId,
    market_id: MarketId,
    account_id: AccountId,
    side: Side,                    // Buy | Sell
    price: i64,
    quantity: u64,

    // Sequencing
    tick_number: u64,
    sequence_in_tick: u64,
    continuum_sequence: u64,       // PRIMARY KEY

    // Perpetuals
    leverage: Option<u64>,
    position_effect: Option<PositionEffect>,  // Open | Close
    reduce_only: bool,
    margin_mode: Option<MarginMode>,          // Cross | Isolated
    liquidation: bool,             // System-generated liquidation
}

Inclusion Rules

1. Zero-quantity rejection — Orders with quantity == 0 are rejected at insertion

2. Margin validation — Orders must pass reserve_margin_for_order() before inclusion

3. Signature verification — All orders are Ed25519-signed; invalid signatures rejected

Priority Queue Processing

Orders are processed via a binary min-heap keyed by continuum_sequence:

price_updates → triggers → regular_orders → liquidations

Within each category, earlier sequences execute first (FIFO from Continuum).

Cancellation Handling

Cancellations use the same continuum_sequence ordering:

TickCancellation {
    order_id: OrderId,
    continuum_sequence: u64,
}

Cancels are processed in sequence order alongside new orders, ensuring deterministic interleaving.

---