PolicyBuilder

The PolicyBuilder provides a fluent (chainable) API for constructing policies. It validates your configuration at build time and produces a well-formed Policy object.

Basic Usage

import { PolicyBuilder } from "@policy-kit/sdk";
import { parseEther } from "viem";

const policy = new PolicyBuilder("treasury-guard")
  .allowTargets(["0xUniswapRouter", "0xAavePool"])
  .maxValue(parseEther("5"))
  .spendLimit("0xUSDC", parseEther("50000"), 86400)
  .cooldown(300)
  .maxSlippageBps(50)
  .requireSimulation(true)
  .setFailMode("closed")
  .build();

Constructor

new PolicyBuilder(id: string)

Parameter	Type	Description
`id`	`string`	A unique, human-readable identifier for the policy

Tier 1 Methods (Stateless On-Chain)

`.allowTargets(addresses)`

Whitelist contract addresses. Only transactions to these addresses will be allowed.

builder.allowTargets([
  "0x68b3465833fb72A70ecDF485E0e4C7bD8665Fc45",
  "0x7d2768dE32b0b80b7a3454c06BdAc94A69DDc7A9",
]);

Parameter	Type	Description
`addresses`	`Address[]`	Array of allowed contract addresses

Returns: PolicyBuilder (for chaining)

`.denyTargets(addresses)`

Blacklist contract addresses. Transactions to these addresses will be blocked.

builder.denyTargets(["0xKnownMalicious"]);

Parameter	Type	Description
`addresses`	`Address[]`	Array of denied contract addresses

Returns: PolicyBuilder (for chaining)

`.allowSelectors(selectors)`

Whitelist function selectors. Only calls to these functions will be allowed.

builder.allowSelectors([
  "0x38ed1739", // swapExactTokensForTokens
  "0x7ff36ab5", // swapExactETHForTokens
]);

Parameter	Type	Description
`selectors`	`Hex[]`	Array of 4-byte function selectors

Returns: PolicyBuilder (for chaining)

`.denySelectors(selectors)`

Blacklist function selectors.

builder.denySelectors([
  "0x095ea7b3", // approve
]);

Parameter	Type	Description
`selectors`	`Hex[]`	Array of 4-byte function selectors

Returns: PolicyBuilder (for chaining)

`.maxValue(wei)`

Set a maximum ETH value per transaction.

builder.maxValue(parseEther("10")); // 10 ETH

Parameter	Type	Description
`wei`	`bigint`	Maximum value in wei

Returns: PolicyBuilder (for chaining)

Tier 2 Methods (Stateful On-Chain)

`.spendLimit(token, amount, windowSeconds)`

Set a spending limit for a specific ERC-20 token within a rolling time window.

builder.spendLimit(
  "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48", // USDC
  parseUnits("50000", 6), // 50,000 USDC
  86400 // 24 hours
);

Parameter	Type	Description
`token`	`Address`	ERC-20 token contract address
`amount`	`bigint`	Maximum spend amount in token decimals
`windowSeconds`	`number`	Rolling time window in seconds

Returns: PolicyBuilder (for chaining)

`.cooldown(seconds)`

Enforce a minimum time between transactions.

builder.cooldown(300); // 5 minutes

Parameter	Type	Description
`seconds`	`number`	Minimum seconds between transactions

Returns: PolicyBuilder (for chaining)

Tier 3 Methods (Off-Chain)

`.maxSlippageBps(bps)`

Set maximum acceptable slippage for swap transactions.

builder.maxSlippageBps(50); // 0.5%

Parameter	Type	Description
`bps`	`number`	Maximum slippage in basis points (1 bps = 0.01%)

Returns: PolicyBuilder (for chaining)

`.requireSimulation(enabled)`

Require that the transaction succeeds when simulated.

builder.requireSimulation(true);

Parameter	Type	Description
`enabled`	`boolean`	Whether simulation is required

Returns: PolicyBuilder (for chaining)

`.customRule(config)`

Add a custom off-chain rule with IPFS-hosted logic.

builder.customRule({
  name: "check-oracle-price",
  description: "Verify price against oracle bounds",
  cid: "QmCustomRuleLogicCID",
  params: {
    oracle: "0xChainlinkPriceFeed",
    maxDeviation: 500,
  },
});

Parameter	Type	Description
`config.name`	`string`	Human-readable rule name
`config.description`	`string`	Description of what the rule checks
`config.cid`	`string`	IPFS CID of the rule logic
`config.params`	`Record<string, unknown>`	Parameters passed to the rule logic

Returns: PolicyBuilder (for chaining)

Configuration Methods

`.setFailMode(mode)`

Set the fail mode for off-chain rule evaluation.

builder.setFailMode("closed");

Parameter	Type	Description
`mode`	`"closed" \| "open"`	Fail mode

Returns: PolicyBuilder (for chaining)

Build

`.build()`

Validate and build the policy.

const policy: Policy = builder.build();

Returns: Policy Throws: ValidationError if the policy configuration is invalid. Validation checks include:

At least one rule is defined
Rule parameters are within valid ranges
Addresses are valid checksummed hex
Selectors are exactly 4 bytes
Spend limit amounts are positive
Cooldown and window values are positive integers

SDK Overview PolicyKit Client