You fund a budget from your main account, set a period length, a per-period limit, an expiry and a rollover policy, then name up to 16 delegates. The LayerX kernel checks every spend against the remaining period allowance and the funded balance before any transfer settles. A spend over the allowance returns -713 and one over the balance returns -714. Close the budget and the remainder returns to you.

What it does

A budget holds funds in a dedicated budget account with a per-period limit, a period length, an expiry and a rollover policy. The owner funds it from their main account, and either the owner or a named delegate spends from it. Every spend is checked in the LayerX kernel against both the remaining period allowance and the funded balance before any transfer settles. Closing or revoking a budget returns whatever is left to the owner and freezes the limit at what has already been spent.

Key capabilities

• Seven activities: create, fund, amend, add delegate, remove delegate, spend, close.
• Per-period limit with a period length, an expiry and a rollover policy.
• Rollover NONE drops unspent allowance; CAPPED carries it forward up to a carry cap.
• Up to 16 named delegates per budget; only the owner or a named delegate may spend.
• Amend changes the limit, carry cap, expiry and rollover policy without moving funds.
• Close or revoke drains the remaining balance back to the funding account.

Differentiators

The limit is enforced on the settlement path: a spend above the period allowance returns -713, and one above the funded balance returns -714, instead of settling. The period roll is applied both at the start of an epoch and again at each spend, so crossing a period boundary needs no separate transaction.

Outcomes

• Agents cannot spend past the period allowance, even with wrong code
• Unspent allowance lapses or carries forward up to a set cap
• Closing or revoking a budget drains the balance back to you

Technical notes

• Activity types 0x00030001 to 0x00030007; the module requires protocol_version == 3.
• LX_BUDGET_STORE_CAPACITY = 128 budgets, LX_BUDGET_MAX_DELEGATES = 16.
• Payload sizes: create 211 bytes (251 at encoding version 2), fund 50 (58 at version 2), amend 75, delegate 66, spend 82, close 42.
• Periods are measured in milliseconds against the batch timestamp. A record is rejected with a zero limit, a zero period length, an expiry at or before the period start, or a non-zero carry cap under rollover NONE.
• Error codes: BUDGET_PERIOD_CAP (-701), BUDGET_ALLOWANCE_EXCEEDED (-713), INSUFFICIENT_BUDGET_FUNDS (-714), UNAUTHORIZED_DELEGATE (-715), BUDGET_REVOKED (-716).
• Not yet implemented: no drawdown, error-rate or quality-drop stop rule exists anywhere in the code. Per-counterparty ceilings exist only in the layerx-agentd limiter, which is daemon-enforced and marked as bypassable by not going through the daemon. The kernel's delegate capability, which carries a per-recipient and per-spend ceiling, is not reachable through a budget activity type. The agent SDK exposes budget.create, budget.fund, budget.list, budget.reconciliation and budget.revoke; spend, amend and delegate changes are not in its operation list. The human-plane spend view is still blocked on canonical protocol budget state.

import { Client, type IdempotentMutation } from "layerx-sdk";

const budget: IdempotentMutation<{ limit: bigint; enforcement: "ProtocolBudget" }> = {
  requestId: 1n,
  key: idempotencyKey,
  bodyDigest,
  operation: { limit: 500000000000000000000n, enforcement: "ProtocolBudget" },
};

await client.call("budget.create", budget);

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