SIMD-0249: Delay commission updates

proposals/0249-delay-commission-updates.md

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+---
+simd: '0249'
+title: Delay Commission Updates
+authors: Justin Starry (Anza)
+category: Standard
+type: Core
+status: Review
+created: 2025-02-18
+feature: (fill in with feature key and github tracking issues once accepted)
+---
+
+## Summary
+
+Allow validators to update their commission values without restriction but delay
+those commission changes for at least one full epoch.
+
+## Motivation
+
+Stake delegators should have time to re-delegate their stake in response to
+validator commission rate changes.
+
+## New Terminology
+
+NA
+
+## Detailed Design
+
+- During inflation reward distribution for an epoch `E`, use the commission rate
+set in the vote account state at the beginning of the epoch `E - 1` when
+calculating validator commissions. This is the same vote account state used to
+calculate the leader schedule for epoch `E` so it must already be available
+in-protocol. The only exception is inflation reward distribution for epoch `E ==
+0`. In that case, use the commission rate set by vote accounts in the genesis
+config.
+
+- Update the core vote program to no longer restrict commission updates in any way.
+
+## Alternatives Considered
+
+An alternative approach is to track recent commission values over the past few
+epochs in the vote account state. This bookkeeping increases state size
+requirements of the vote account for each type of commission set by a validator.
+
+## Impact
+
+- Validators will need to wait at least one full epoch before their commission
+updates are applied.
+
+- Stake delegators will have at least one full epoch to react to commission
+updates.
+
+## Security Considerations
+
+NA
+
+## Drawbacks *(Optional)*
+
+Why should we not do this?
+
+## Backwards Compatibility *(Optional)*
+
+No backwards compatibility issues. Commission updates will be less restrictive.