Mint Module

Source: paxeer-network/modules/mint/

Overview

The mint module creates new PAX tokens according to a predefined schedule. It enables scheduled token release structures that distribute tokens over time. The goal is to reach a deflationary state where no more inflation occurs and the network relies solely on transaction fees.

Minting occurs daily (UTC), incentivizing users to stake tokens for longer durations to earn rewards.

Minting Mechanism

The mint module operates on a daily distribution model:

A total_mint_amount is defined for a period between start_date and end_date
Each day, the module calculates daily_mint_amount = remaining_mint_amount / days_remaining
Tokens are minted and sent to the fee_collector account
The distribution module distributes collected fees to stakers

Example

If total_mint_amount = 1,000,000 tokens and the period is 100 days:

Initial daily mint: 1,000,000 / 100 = 10,000 tokens/day
After 50 days: 500,000 remaining / 50 days = 10,000 tokens/day (unchanged if no downtime)
If the chain was down for 1 day at day 50: 500,000 remaining / 49 days = 10,204 tokens/day (adjusted)

Network outages automatically adjust the daily rate to meet the total mint amount by the end date.

State

Minter

The minter stores current inflation state:

type Minter struct {
    StartDate           string  // The day where the mint begins
    EndDate             string  // The day where the mint ends
    Denom               string  // Denom for the coins minted (default uhpx)
    TotalMintAmount     uint64  // Total amount to be minted
    RemainingMintAmount uint64  // Remaining amount to be minted
    LastMintAmount      uint64  // Last amount minted (usually from the day before)
    LastMintDate        string  // Last day minted
    LastMintHeight      uint64  // The height of the last mint
}

Query the current minter:

paxd q mint minter

Params

Parameters define the minting schedule:

type Params struct {
    MintDenom            string                   // Type of coin to mint
    TokenReleaseSchedule []ScheduledTokenRelease  // List of token release schedules
}

type ScheduledTokenRelease struct {
    StartDate          string  // The day where the mint begins
    EndDate            string  // The day where the mint ends
    TokenReleaseAmount uint64  // Total amount to be minted
}

Multiple release schedules can be defined, allowing sequential minting periods.

Begin-Block

At the end of each epoch (default 60s), the mint module:

Checks if it's the minting start date
Calculates the daily mint amount
Mints tokens to the fee_collector account
Updates LastMintAmount, LastMintDate, and RemainingMintAmount

Epoch hooks trigger the minting check. See Epoch module for how epochs work.

Governance

Update Minter Proposal

The minter can be updated via governance to change the mint schedule:

{
  "title": "Update Minter",
  "description": "Adjust mint schedule",
  "minter": {
    "start_date": "2023-10-05",
    "end_date": "2023-11-22",
    "denom": "uhpx",
    "total_mint_amount": 100000
  }
}

Submit the proposal:

paxd tx gov submit-proposal update-minter ./minter_prop.json \
  --deposit 20pax --from admin -b block -y \
  --gas 200000 --fees 2000uhpx

Before the proposal:

> paxd q mint minter
denom: uhpx
end_date: "2023-04-30"
last_mint_amount: "333333333333"
last_mint_date: "2023-04-27"
last_mint_height: "0"
remaining_mint_amount: "666666666666"
start_date: "2023-04-27"
total_mint_amount: "999999999999"

After the proposal passes:

> paxd q mint minter
denom: uhpx
end_date: "2023-11-22"
last_mint_amount: "0"
last_mint_date: ""
last_mint_height: "0"
remaining_mint_amount: "0"
start_date: "2023-10-05"
total_mint_amount: "100000"

Update Params Proposal

Parameters can be updated to define new token release schedules:

{
  "title": "Param Change Proposal",
  "description": "Update token release schedule",
  "changes": [
    {
      "subspace": "mint",
      "key": "MintDenom",
      "value": "uhpx"
    },
    {
      "subspace": "mint",
      "key": "TokenReleaseSchedule",
      "value": [
        {
          "token_release_amount": 500,
          "start_date": "2023-10-01",
          "end_date": "2023-10-30"
        },
        {
          "token_release_amount": 1000,
          "start_date": "2023-11-01",
          "end_date": "2023-11-30"
        }
      ]
    }
  ]
}

Submit:

paxd tx gov submit-proposal param-change ./param_change_prop.json \
  --from admin -b block -y --gas 200000 --fees 200000uhpx

Note: Changes to total_mint_amount or remaining_mint_amount after the start date do not affect tokens already minted.

Events

Mint Event

Emitted on each successful mint:

mint_date: Date of the mint
mint_epoch: Epoch number when the mint occurred
amount: Amount minted

Metrics

The mint module emits a pax_mint_coins{denom} Prometheus metric on each successful mint event.

Next Steps

Epoch Module

Oracle Module