feat: add spec of mint manager

specs/glossary.md

@@ -26,7 +26,6 @@
   - [Priority Gas Auction](#priority-gas-auction)
 - [Sequencing](#sequencing)
   - [Sequencer](#sequencer)
-  - [Maximal Extractable Value](#maximal-extractable-value)
   - [Sequencing Window](#sequencing-window)
   - [Sequencing Epoch](#sequencing-epoch)
   - [L1 Origin](#l1-origin)

specs/protocol/deposits.md

@@ -17,6 +17,7 @@
   - [L1 Attributes Depositor Account](#l1-attributes-depositor-account)
   - [L1 Attributes Predeployed Contract](#l1-attributes-predeployed-contract)
     - [L1 Attributes Predeployed Contract: Reference Implementation](#l1-attributes-predeployed-contract-reference-implementation)
+    - [Mint Token](#mint-token)
 - [User-Deposited Transactions](#user-deposited-transactions)
   - [Deposit Contract](#deposit-contract)
     - [Address Aliasing](#address-aliasing)
@@ -305,6 +306,11 @@ After running `pnpm build` in the `packages/contracts` directory, the bytecode t
 file will be located in the `deployedBytecode` field of the build artifacts file at
 `/packages/contracts/artifacts/contracts/L2/L1Block.sol/L1Block.json`.
 
+#### Mint Token
+
+After storing all attributes of the L1 block, call the mint function of the MintManager contract to mint tokens. 
+See [MintManager](./mint-manager.md) specification.
+
 ## User-Deposited Transactions
 
 [user-deposited]: #user-deposited-transactions

specs/protocol/mint-manager.md

@@ -0,0 +1,108 @@
+# MintManager
+
+<!-- START doctoc generated TOC please keep comment here to allow auto update -->
+<!-- DON'T EDIT THIS SECTION, INSTEAD RE-RUN doctoc TO UPDATE -->
+
+- [Overview](#overview)
+- [Activation](#activation)
+- [Calculating Minting Amount](#calculating-minting-amount)
+- [Initial Minting](#initial-minting)
+- [Distribution](#distribution)
+
+<!-- END doctoc generated TOC please keep comment here to allow auto update -->
+
+<!-- All glossary references in this file. -->
+
+[g-deposited]: ../glossary.md#deposited-transaction
+[g-l1-attr-deposit]: ../glossary.md#l1-attributes-deposited-transaction
+[g-l1-attr-predeploy]: glossary.md#l1-attributes-predeployed-contract
+[g-eoa]: ../glossary.md#eoa
+
+## Overview
+
+The `GovernanceToken` of Kroma is minted every block by the `MintManager` contract on L2 and distributed to recipients.
+`MintManager` is a predeployed contract on L2 at address `0x4200000000000000000000000000000000000070`.
+
+In the [L1 Attributes Deposited Transaction][g-l1-attr-deposit], the [L1 Attributes Predeployed Contract][g-l1-attr-predeploy] calls the mint function of the MintManager contract to mint tokens. 
+
+> Note that the mint function of the MintManager contract can only called by the
+[L1 Attributes Predeployed Contract][g-l1-attr-predeploy]
+
+## Activation
+
+The mint function is activated from a specific L2 block number, 
+which is recorded in an immutable variable named `MINT_ACTIVATED_BLOCK`.
+If the mint function is called before the activation block number, nothing will happen (it will not revert).
+
+## Calculating Minting Amount
+
+The amount of `GovernanceToken` minted per block decreases periodically.
+The amount to be minted is calculated by repeatedly applying decay based on the current block number for a
+certain number of epochs.
+An epoch can be calculated by dividing the current block number by `SLIDING_WINDOW_BLOCKS` value.
+
+Only up to 8 decimal places are considered for the minting amount.
+
+```python
+def get_mint_amount_per_block(block_number):
+    epoch = (block_number - 1) // SLIDING_WINDOW + 1
+    offset = (block_number - 1) % SLIDING_WINDOW + 1
+
+    mint_amount = INIT_MINT_PER_BLOCK
+    for i in range(1, epoch):
+        mint_amount = (mint_amount * DECAYING_FACTOR) // DECAYING_DENOMINATOR
+        mint_amount = mint_amount // FLOOR_UNIT * FLOOR_UNIT
+
+    return mint_amount
+```
+
+- `SLIDING_WINDOW_BLOCKS`: The period (in blocks) which the mint amount decreases.
+- `INIT_MINT_PER_BLOCK`: The amount minted per block during the first epoch.
+- `DECAYING_FACTOR`: The ratio by which the mint amount decreases from the previous period.
+- `DECAYING_DENOMINATOR`: The denominator of the decaying factor. This value is `10^5`.
+- `FLOOR_UNIT`: The unit for rounding down decimal places. Since the decimal places for `GovernanceToken` are 18,
+  and the mint amount is considered up to 8 decimal places, this value is `10^10`
+
+## Initial Minting
+
+Mints the amount of tokens that should have been minted from the genesis block to the current block.
+This function operates only if it has never been minted through the MintManager contract before.
+
+```python
+def initial_mint_amount(block_number):
+    amount = 0
+    mint_per_block = INIT_MINT_PER_BLOCK
+    epoch = (block_number - 1) // SLIDING_WINDOW + 1
+    offset = (block_number - 1) % SLIDING_WINDOW + 1
+
+    for i in range(1, epoch):
+        amount = amount + mint_per_block * SLIDING_WINDOW
+        mint_per_block = (mint_per_block * DECAYING_FACTOR) // DECAYING_DENOMINATOR
+        mint_per_block = (mint_per_block // FLOOR_UNIT) * FLOOR_UNIT
+
+    if offset > 0:
+        amount = amount + mint_per_block * offset
+
+    return amount
+```
+
+## Distribution
+
+After deploying the MintManager contract, the recipient addresses and their respective share percentages
+are set during initialization.
+The minted amount for the current block is then distributed to the configured addresses.
+
+```python
+mint_amount_per_block = get_mint_amount_per_block(block_number)
+
+for i in range(len(recipients)):
+    recipient = recipients[i]
+    shares = shares[i]
+    amount = mint_amount_per_block * shares / SHARE_DENOMINATOR
+
+    governance_token_mint(recipient, amount)
+
+last_minted_block = block_number
+```
+
+- `SHARE_DENOMINATOR`: The denominator of the share. This value is `10^5`.

specs/protocol/validator.md

@@ -4,6 +4,7 @@
 <!-- DON'T EDIT THIS SECTION, INSTEAD RE-RUN doctoc TO UPDATE -->
 **Table of Contents**
 
+- [Overview](#overview)
 - [Submitting L2 Output Commitments](#submitting-l2-output-commitments)
 - [L2 Output Commitment Construction](#l2-output-commitment-construction)
   - [Output Payload(Version 0)](#output-payloadversion-0)