LayerX SettlementAnchor, LayerXVault, and Deployment Contracts

Overview

The LayerX contract suite is self-contained: production src/ has zero external imports. Safety primitives (ECDSA, EIP-712, SafeERC20, Governed, Pausable) are reimplemented in-house under src/lib. The two primary contracts are LayerXVault (reserve custody and settlement) and SettlementAnchor (immutable root log).

Foundry Configuration

Source: layerx/contracts/foundry.toml

Key	Value
`src`	`src`
`test`	`test`
`script`	`script`
`solc`	`0.8.27`
`evm_version`	`shanghai`
`optimizer`	`true` (200 runs)
`[rpc_endpoints].paxeer`	`${PAXEER_RPC_URL}`

forge-std is vendored under lib/ for tests only; production src/ never imports it.

Deployment Script

Source: layerx/contracts/script/Deploy.s.sol

Deploy.run reads environment variables, deploys SettlementAnchor first, then LayerXVault, and conditionally wires the anchor writer when the broadcaster matches the governor.

Environment variable	Role
`LAYERX_GOVERNOR`	Protocol root authority
`LAYERX_OPERATOR_ADDR`	Sequencer EVM key
`LAYERX_GUARDIAN`	Emergency pause authority
`LAYERX_USDL_ADDR`	USDL reserve token
`LAYERX_DEX_ROUTER`	Paxeer DEX router
`LAYERX_WRAPPED_NATIVE`	Wrapped native asset
`LAYERX_EXIT_DELAY`	Force-exit challenge window (seconds)

SettlementAnchor

Source: layerx/contracts/src/SettlementAnchor.sol

Minimal, append-only registry for settled batch Merkle roots. Never holds funds.

Properties

Property	Type	Description
`writer`	`address`	Authorized writer
`rootOf`	`mapping(bytes32 => bytes32)`	Anchored root per batch id
`anchored`	`mapping(bytes32 => bool)`	Idempotency flag

Methods

Method	Access	Description
`record(batchId, root, totalSettled, count, windowEnd)`	Writer	Anchor one batch root, emit `SettlementAnchored`
`setWriter(newWriter)`	Governor	Rotate authorized writer

Errors

NotWriter, AlreadyAnchored, ZeroRoot

Event

SettlementAnchored(batchId, root, totalSettled, count, windowEnd, anchoredAt)

LayerXVault

Source: layerx/contracts/src/LayerXVault.sol

On-chain custody and settlement contract. Holds the USDL reserve, mints USDX accounting against deposits, executes settlement payouts, and provides the unilateral force-exit escape hatch.

Constructor

Parameter	Type	Description
`usdl_`	`address`	Reserve asset (USDL)
`governor_`	`address`	Protocol root authority
`operator_`	`address`	Sequencer key
`guardian_`	`address`	Emergency pause
`anchor_`	`address`	SettlementAnchor contract
`dexRouter_`	`address`	PECOR DEX router
`wrappedNative_`	`address`	Wrapped native token
`exitDelay_`	`uint64`	Force-exit challenge window

Deposit methods

Method	Description
`depositUSDL(amount, did)`	Direct USDL deposit, mints USDX 1:1
`depositSwap(tokenIn, amountIn, amountOutMin, deadline, did)`	Swap allowlisted token to USDL, mint from realized output
`depositNative(amountOutMin, deadline, did)`	Wrap native PAX, swap to USDL, mint

All deposit paths measure token balance deltas before/after transfer (fee-on-transfer safe).

Settlement

settle(batch) anchors the root via SettlementAnchor.record, then pays batch recipients via SafeERC20.safeTransfer. Protected by reentrancy guard. Batch is idempotent via settledBatch[batchId].

Force-exit (L1 escape hatch)

Method	Description
`initiateExit(amount, epoch, operatorSig)`	Start exit using operator's co-signed balance proof (EIP-712)
`challengeExit(amount, epoch, operatorSig)`	Replace pending exit with strictly newer proof
`finalizeExit()`	Complete matured exit after `exitDelay`

Admin methods

setOperator, setGuardian, setDexRouter, setAnchor, setWrappedNative, setExitDelay, setMaxSettlementPerBatch, setSwapAllowed, pause, unpause

Key properties

Property	Type	Description
`usdl`	`IERC20`	Reserve token
`operator`	`address`	Settlement operator
`guardian`	`address`	Pause authority
`anchor`	`ISettlementAnchor`	Root log
`totalDeposited`	`uint256`	Cumulative USDL deposited
`totalSettledOut`	`uint256`	Cumulative USDL settled
`totalExited`	`uint256`	Cumulative USDL exited
`exitDelay`	`uint64`	Force-exit window
`maxSettlementPerBatch`	`uint256`	Per-batch cap (0 = uncapped)

In-House Safety Libraries

ECDSA (`src/lib/ECDSA.sol`)

secp256k1 signer recovery. Rejects high-s signatures, invalid v values, zero-address recovery.

EIP712 (`src/lib/EIP712.sol`)

Typed-data domain hashing. Domain separator cached at construction, re-derived on chain ID change (fork-safe).

SafeERC20 (`src/lib/SafeERC20.sol`)

Token-call wrapper. Tolerates no-boolean-return ERC-20 variants. forceApprove handles USDT-style reset-to-zero.

Governed (`src/lib/Governed.sol`)

Two-step governance handoff: transferGovernance + acceptGovernance.

Pausable (`src/lib/Pausable.sol`)

Emergency stop with _pause/_unpause and whenNotPaused/whenPaused modifiers.

Chain Bindings (Go side)

Source: layerx/internal/chain/bindings.go

Minimal inline ABI fragments for the contracts the sequencer touches:

ABI	Contract	Methods
`layerXVaultABI`	LayerXVault	`settle`, `reserveBalance`, `operator`, `settledBatch`, `exited` + `Deposit`/`Settled` events
`settlementAnchorABI`	SettlementAnchor	`rootOf`, `anchored`, `writer` + `SettlementAnchored` event
`erc20ABI`	IERC20	`balanceOf`, `decimals`
`pecorRouterABI`	IPECORRouter	`swapBestRoute`

PackSettle ABI-encodes a LayerXVault.settle(batch) call.

Paxeer Chain Integration

Source: layerx/internal/chain/settler.go, layerx/internal/chain/watcher.go, layerx/internal/chain/operator.go

The Settler submits settlement batches to the vault contract. The Watcher monitors Deposit events for chain-in crediting. The Operator manages the sequencer's on-chain transactions.