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PSM Keeper Setup

Guide to running the PSM-focused keeper for maintenance operations.

Overview​

The PSM Keeper performs three maintenance operations on the kss-lite-psm:

OperationFunctionPurpose
Fillfill()Mint pre-minted KUSD into PSM for liquidity
Trimtrim()Burn excess KUSD from PSM
Chugchug()Collect accumulated fees to Vow

How PSM Maintenance Works​

┌───────────────────────────────────────────────────────────────┐
│                    PSM Keeper Operations                       │
├───────────────────────────────────────────────────────────────┤
│                                                                │
│   rush() > 0        gush() > 0        cut() > minAmount       │
│       │                 │                    │                 │
│       ▼                 ▼                    ▼                 │
│   ┌────────┐       ┌────────┐          ┌────────┐             │
│   │  fill  │       │  trim  │          │  chug  │             │
│   │        │       │        │          │        │             │
│   └────────┘       └────────┘          └────────┘             │
│   Mint KUSD        Burn KUSD           Send fees              │
│   into PSM         from PSM            to Vow                 │
│                                                                │
└───────────────────────────────────────────────────────────────┘

Installation​

cd KUSD/psm-keeper
npm install
cp .env.example .env

Configuration​

# Network
RPC_URL=https://testnetrpc.kalychain.io/rpc
CHAIN_ID=3889

# Wallet
PRIVATE_KEY=your_private_key

# Contracts
PSM_ADDRESS=0xF61448725934d38b7fF94f9162AEed729486de35

# Settings
POLL_INTERVAL_MS=30000
MIN_CHUG_AMOUNT=100000000000000000000  # 100 KUSD in wei
MAX_GAS_PRICE=50000000000              # 50 Gwei
GAS_LIMIT=500000
GAS_PRICE=21000000000                  # 21 Gwei

Running​

# Development
npm run dev

# Production
npm run build
npm start

PSM Status Checks​

The keeper calls these view functions to check status:

FunctionReturnsTriggers
rush()KUSD that can be filledfill() when > 0
gush()KUSD that can be trimmedtrim() when > 0
cut()Fees that can be chuggedchug() when > minAmount

Operation Details​

fill() — Mint KUSD Liquidity​

Called when there's room to mint more KUSD into the PSM:

  • Limited by buf (buffer) parameter
  • Limited by debt ceiling (line)
  • Limited by global debt ceiling (Line)

trim() — Burn Excess KUSD​

Called when there's more KUSD than needed:

  • Reduces system debt
  • Triggered after buyGem operations

chug() — Collect Fees​

Called to move accumulated swap fees to the Vow:

  • Only called when fees exceed threshold
  • Fees come from tin and tout on swaps

Gas Considerations​

The keeper checks gas price before executing:

if (currentGasPrice > this.config.maxGasPrice) {
    logger.warn('Gas price too high, skipping');
    return { success: false };
}

Monitoring​

Check logs for operation status:

npm start | grep -E "(fill|trim|chug)"