CIP-31: updates according to the implemention

cips/cip-031.md

@@ -1,4 +1,3 @@
-
 | cip            | 31                                                                                                                      |
 |----------------|-------------------------------------------------------------------------------------------------------------------------|
 | title          | Incorporate staking rewards into vesting account schedules                                                              |
@@ -17,7 +16,7 @@
 
 *Note: in the software lockup accounts are referred to vesting accounts, for this document we will refer to them as lockup accounts.*
 
-This CIP proposes integrating staking rewards directly into lockup accounts. When a lockup account receives rewards from staking, the system adds the reward amount to the lockup balance and recalculates the daily unlock rate over the remaining lockup period. This mechanism ensures that reward tokens remain subject to an account’s existing lockup constraints while still providing incentive to secure the network through staking.
+This CIP proposes integrating staking rewards directly into lockup accounts. When a lockup account receives rewards from staking, the system adds the reward amount to the lockup balance and recalculates the daily unlock rate over the remaining lockup period. This mechanism ensures that reward tokens remain subject to an account's existing lockup constraints while still providing incentive to secure the network through staking.
 
 ## Motivation
 
@@ -66,49 +65,76 @@ By integrating staking rewards directly into the lockup schedule, this proposal
    - Unlocked & Unstaked
    - Unlocked & Staked
 
-4. **Mathematical Model & Example:**
-   For a lockup schedule of 100 tokens over 365 days (≈0.274 tokens/day), once 30% of the tokens have unlocked, claiming a reward of about 0.657 tokens immediately unlocks 30% (≈0.197 tokens) while the remaining 70% (≈0.460 tokens) is added to the locked balance. This brings the locked amount to roughly 70.460 tokens, which will continue unlocking over the remaining 70% of the period (approximately 255.5 days), yielding an updated daily unlock rate of about 0.276 tokens/day.
+4. **Example Implementations:**
 
-    *NOTE: reward calculation is arbitrary, it is not based on Celestia's inflation.*
+### Continuous Vesting Accounts
 
-5. **Error Handling:**
-   - Ensure sufficient balance checks before processing rewards.
-   - Validate that the lockup period is still active.
-   - Separate commission transfers from reward lockup updates.
+   Consider a lockup schedule initially granting 100 tokens over 365 days (unlocking ≈0.274 tokens/day). Assume 30% of the lockup period has passed (109.5 days), meaning 30 tokens have already unlocked, and 70 tokens remain locked.
 
-### Module Interaction
+   If the account holder claims a staking reward of 0.657 tokens at this point:
 
-The following sequence summarizes the module interactions:
+   1. The reward is added to the *original* vesting amount: `New Total Original Amount = 100 + 0.657 = 100.657 tokens`.
+   2. The system recalculates the amount that *should* be unlocked after 30% of the period based on this new total: `Target Unlocked Amount = 0.30 * 100.657 = 30.1971 tokens`.
+   3. The difference between the target unlocked amount and the amount already unlocked is made available immediately: `Immediate Unlock = 30.1971 - 30 = 0.1971 tokens`. This represents 30% of the claimed reward (0.30 * 0.657).
+   4. The total amount now unlocked is 30.1971 tokens.
+   5. The remaining locked amount is recalculated: `New Remaining Locked = 100.657 (New Total) - 30.1971 (New Unlocked) = 70.4599 tokens`.
+   6. This new remaining locked amount (70.4599 tokens) will unlock over the remaining 70% of the period (255.5 days).
+   7. The daily unlock rate for the remainder of the period increases slightly: `New Daily Rate = 70.4599 / 255.5 ≈ 0.2758 tokens/day`.
 
-```mermaid
-sequenceDiagram
-participant DM as Distribution Module
-participant AK as Account Keeper
-participant LM as Lockup Module
-participant BM as Bank Module
+   A portion of the reward corresponding to the elapsed vesting duration (30% in this case) unlocks immediately, while the rest (70%) is added to the future vesting schedule.
 
-DM->>AK: Get Receiving Account
-AK-->>DM: Return Account
+### Delayed Vesting Accounts
 
-rect rgb(0, 0, 139)
-  Note over DM: Account Type Check
-  DM->>DM: Is Lockup Account?
-end
+   For a `DelayedVestingAccount`, the entire principal vests at a single point in the future (`EndTime`).
+   Consider an account set up with 1000 tokens scheduled to unlock entirely after 730 days (2 years).
+   Assume at day 200, the account holder claims a staking reward of 50 tokens.
 
-alt Is Lockup Account
-   DM->>LM: Get Lockup Type
-   DM->>LM: Calculate New Lockup Schedule
-   LM->>LM: Update Lockup Parameters
-   LM->>BM: Update Account Balance
-   LM-->>DM: Return Success
-else Not Lockup Account
-  DM->>BM: Process Normal Reward Transfer
-end
+   1. The reward is added to the `OriginalVesting` amount tracked by the account: `New Total Original Amount = 1000 + 50 = 1050 tokens`.
+   2. Unlike continuous vesting, no portion of this reward unlocks immediately, regardless of the time elapsed.
+   3. The account continues to hold 0 unlocked tokens.
+   4. When the `EndTime` (day 730) is reached, the *entire* 1050 tokens (original 1000 + 50 reward) unlock at once.
 
-BM-->>DM: Return Status
+   The claimed rewards simply increase the total balance that will become available at the predefined unlock date.
 
+### Periodic Vesting Accounts
 
-```
+Periodic account creation will be removed, and update schedule will be a noop
+
+### Permanent Vesting Accounts
+
+Permanent account creation will be removed, and update schedule will be a noop
+
+### Module Interaction
+
+The following sequence summarizes the module interactions:
+
+  ```mermaid
+  sequenceDiagram
+  participant DM as Distribution Module
+  participant AK as Account Keeper
+  participant LM as Lockup Module
+  participant BM as Bank Module
+
+  DM->>AK: Get Receiving Account
+  AK-->>DM: Return Account
+
+  rect rgb(0, 0, 139)
+    Note over DM: Account Type Check
+    DM->>DM: Is Lockup Account?
+  end
+
+  alt Is Lockup Account
+    DM->>LM: Get Lockup Type
+    DM->>LM: Calculate New Lockup Schedule
+    LM->>LM: Update Lockup Parameters
+    LM->>BM: Update Account Balance
+    LM-->>DM: Return Success
+  else Not Lockup Account
+    DM->>BM: Process Normal Reward Transfer
+  end
+
+  BM-->>DM: Return Status
+  ```
 
 ### Commission Cap
 
@@ -122,23 +148,59 @@ When upgrading to v4 we propose introducing a migration that will set the Parame
 
 # Backwards Compatibility
 
-All existing lockup accounts will be subject to the locking system. This change will take effect in v4, since this is a larger upgrade there is not a need for backwards compatible systems.
+The continuous and delayed vesting account types will be updated to implement CIP-31. Specifically, they will implement the `UpdateSchedule` function so that the original vesting amount can account for staking rewards. The periodic and permanent account types will not support CIP-31. They will be disallowed from being created.
 
 # Test Cases
 
 The implementation should include test cases covering:
 
 - **Basic Reward Claim:**
   - Claim rewards multiple times and verify that the lockup schedule updates correctly.
-- **Redelegation with Rewards:**
-  - Ensure the hook triggers before redelegation and that rewards are claimed and added to lockup.
-- **Unbonding with Rewards:**
-  - Verify that the lockup schedule is updated correctly prior to unbonding.
 - **Validator Commission Path:**
   - Confirm that commission rewards are processed normally (non-locked) while staking rewards are added to the lockup schedule.
 
 # Reference Implementation
 
+The `VestingAccount` interface will be updated to account for an UpdateSchedule method which includes the amount to update the schedule with and the blocktime at which it occured. We must pass in the blocktime in order to understand if the account is fully vested or not.
+
+```diff
+// VestingAccount defines an account type that vests coins via a vesting schedule.
+type VestingAccount interface {
+	sdk.AccountI
+
+	// LockedCoins returns the set of coins that are not spendable (i.e. locked),
+	// defined as the vesting coins that are not delegated.
+	//
+	// To get spendable coins of a vesting account, first the total balance must
+	// be retrieved and the locked tokens can be subtracted from the total balance.
+	// Note, the spendable balance can be negative.
+	LockedCoins(blockTime time.Time) sdk.Coins
+
+	// TrackDelegation performs internal vesting accounting necessary when
+	// delegating from a vesting account. It accepts the current block time, the
+	// delegation amount and balance of all coins whose denomination exists in
+	// the account's original vesting balance.
+	TrackDelegation(blockTime time.Time, balance, amount sdk.Coins)
+
+	// TrackUndelegation performs internal vesting accounting necessary when a
+	// vesting account performs an undelegation.
+	TrackUndelegation(amount sdk.Coins)
+
+	GetVestedCoins(blockTime time.Time) sdk.Coins
+	GetVestingCoins(blockTime time.Time) sdk.Coins
+
+	GetStartTime() int64
+	GetEndTime() int64
+
+	GetOriginalVesting() sdk.Coins
+	GetDelegatedFree() sdk.Coins
+	GetDelegatedVesting() sdk.Coins
+
++ // UpdateSchedule updates the original vesting amount for the account.
++	UpdateSchedule(blockTime time.Time, amount sdk.Coins) error
+}
+```
+
 A reference implementation will be provided in the Celestia codebase under the distribution and lockup modules. It includes the modifications to the reward claim functions, the new lockup schedule recalculation logic, and updated tests demonstrating correct behavior for all outlined paths. The PR can be found at <https://github.com/01builders/cosmos-sdk/pull/10>.
 
 # Security Considerations