How Kizuna Settlement Works on Solana

How Kizuna Settlement Works

Settlement is the moment when a verified payment approval becomes a completed financial transaction. In Kizuna, settlement is the second step of the two-phase verify/settle flow. Once the x402 facilitator has created a reservation during verify, settlement executes the actual fund movement.

Kizuna settles on Solana for its sub-second finality, low transaction costs, and high throughput. Every settlement emits an exactly-once billable event — the atomic unit of Kizuna's commercial model.

The Verify/Settle Two-Phase Flow

The flow begins when a client SDK calls verify. The facilitator validates protocol inputs, resolves the agent's lane, and forwards the request to the Kizuna kernel. If the kernel approves, the facilitator creates a reservation in the appropriate pool and returns a signed approval envelope.

The client then calls settle with the reservation ID. The facilitator validates the reservation and decision envelope, then executes settlement:

• Enterprise lane: consumes locked prefund from the mandate account
• Crypto-fast lane: creates debt against the isolated collateral pool
• On-chain settlement executes via Solana programs
• Exactly-once billable event is emitted and recorded

Settlement on Solana

Solana provides the execution layer for Kizuna settlement. The protocol's Solana programs handle fund transfers, state updates, and event emission. Key advantages of Solana for settlement include:

Enterprise Settlement Mechanics

For enterprise lane settlements, the flow consumes locked prefund. When an enterprise agent onboards, its operator deposits funds into a mandate account with spending limits. Each settlement deducts from this prefund balance. When the balance runs low, the operator replenishes it.

This model provides clear audit trails: every settlement is traceable to a specific mandate, amount, and timestamp. There is no credit risk — funds are locked before any agent can spend them.

Crypto-Fast Settlement Mechanics

Crypto-fast settlements create debt against collateral. The agent posts collateral into an isolated pool before making requests. Each settlement creates a debt position within that pool, subject to LTV caps and health factor enforcement.

If the health factor drops below threshold, the kernel restricts new settlements until the agent repays debt or adds collateral. This isolation ensures that one agent's risk cannot affect others.

Exactly-Once Billable Events

Every Kizuna settlement emits exactly one billable event. This is enforced at the protocol level — duplicate settlements are rejected, and partial settlements are not possible. The billable event is the foundation of Kizuna's commercial model and audit system.

Billable events include the settlement amount, lane, agent identity, reservation ID, and timestamp. They are indexed and queryable through the companion API for billing, reconciliation, and compliance reporting.