PartyB Open Facet

Where PartyA submits an intent expressing their desire to open an options position, PartyB uses this facet to act on it — locking it to signal intent to fill, filling it to actually open the trade, or handling cancellation requests from PartyA.

Key Concepts:

• Lock: Before filling an intent, PartyB must first lock it. Locking moves the intent from PENDING to LOCKED and prevents any other PartyB from acting on it during that window.

• Unlock: If PartyB locks an intent but decides not to fill it (or can't), they release it back to PENDING so other PartyBs can pick it up. If the deadline has passed by the time they unlock, the intent transitions to EXPIRED instead.

• Partial Fill: PartyB can fill less than the full requested quantity. When this happens, the library automatically creates a new residual open intent for the unfilled portion, so PartyA's remaining exposure stays in the market.

• Residual Intent: The new intent created after a partial fill mirrors the original but with the remaining quantity. It immediately emits a SendOpenIntent event so other solvers can index it just like a fresh intent.

• CANCEL_PENDING: If PartyA requests cancellation while their intent is locked, it moves to CANCEL_PENDING. acceptCancelOpenIntent() is PartyB's acknowledgement, fully cancelling it.

• onlyPartyB: The lockOpenIntent() function is restricted to registered PartyB addresses — only recognized market makers can lock intents.

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Overview

The full PartyB open-side flow for a typical trade looks like this:

1. PartyA submits an open intent via PartyAOpenFacet.sendOpenIntent() — it sits PENDING

2. PartyB spots the intent and locks it via lockOpenIntent(), moving it to LOCKED

3. PartyB fills the intent via fillOpenIntent() at a price at least as favorable as PartyA's — a new Trade is created

4. If the fill is partial, a residual open intent is automatically created for the unfilled quantity

5. If PartyB locked the intent but can't fill it, they release it with unlockOpenIntent()

6. If PartyA requested cancellation while the intent was locked, PartyB processes it via acceptCancelOpenIntent()

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lockOpenIntent()

Reserves an open intent for PartyB to fill. Once locked, no other PartyB can act on the intent. This gives the locking PartyB an exclusive window to prepare and submit their fill.

Function Signature:

function lockOpenIntent(uint256 intentId) external whenPartyNotPaused(msg.sender) onlyPartyB(msg.sender);

Parameters:

• intentId: The unique identifier of the open intent to lock. Must currently be in PENDING state.

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unlockOpenIntent()

Releases a previously locked intent back to an available state. Only the PartyB that locked it can unlock it. The resulting state depends on whether the intent's deadline has passed:

• If the deadline has not passed → intent returns to PENDING, available for any eligible PartyB to lock again

• If the deadline has passed → intent moves to EXPIRED instead

Function Signature:

function unlockOpenIntent(uint256 intentId) external whenPartyNotPaused(msg.sender);

Parameters:

• intentId: The unique identifier of the locked open intent to release.

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acceptCancelOpenIntent()

Accepts a pending cancellation request from PartyA. When PartyA calls cancelOpenIntent() while an intent is locked, it can't cancel immediately — instead it moves to CANCEL_PENDING. This function is how the locking PartyB acknowledges that and finalises the cancellation.

Function Signature:

function acceptCancelOpenIntent(uint256 intentId) external whenPartyNotPaused(msg.sender);

Parameters:

• intentId: The unique identifier of the open intent in CANCEL_PENDING state.

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fillOpenIntent()

Opens a trade by filling a locked open intent. This is the core action — it creates a new Trade record between PartyA and PartyB at the agreed price. PartyB can fill the full requested quantity or a partial amount. If partial, a residual intent is automatically created for the remainder.

Function Signature:

function fillOpenIntent(
    uint256 intentId,
    uint256 quantity,
    uint256 price
) external whenPartyNotPaused(msg.sender);

Parameters:

• intentId: The unique identifier of the locked open intent to fill.

• quantity: The amount to fill. Must be greater than zero and no more than the remaining unfilled quantity on the intent.

• price: The price at which PartyB is opening the trade. Must be at least as favorable to PartyA as the price they specified in the intent — the library enforces this check.