Steve Degosserie 67f375860b feat: ✨ Performance-Based Validator Rewards and Inflation Scaling (#306) ... ## Summary Building on #304, this PR implements two complementary mechanisms to improve validator incentives and network performance: 1. **Performance-Based Validator Rewards** (session-level) 2. **Inflation Scaling** (era-level) ## Reward Model Comparison ### Old Model (main branch) vs New Model | Metric | Old Model (20 pts/block) | New Model (320 pts/block pool) | |--------|--------------------------|--------------------------------| | **Per Block** | Author: 20 pts, Others: 0 | Author: ~196 pts, Others: ~4 pts each | | **Formula** | Direct author reward | 60% authoring + 30% liveness + 10% base | | **Per Session** (600 blocks, 32 validators) | 12,000 total pts | 192,000 total pts | | **Per Validator/Session** (uniform) | ~375 pts | ~6,000 pts | | **Per Validator/Era** (6 sessions) | ~2,250 pts | ~36,000 pts | | **Offline Validator** | 0 pts | ~600 pts/session (base only) | | **Over-performer (150% blocks)** | 150% of fair share | Up to 130% reward (soft cap) | ### Key Differences - **Pool-based**: New model adds 320 points to a shared pool per block, distributed via formula - **Liveness rewarded**: 30% of rewards go to validators who are online (heartbeat OR block authorship) - **Base guarantee**: 10% ensures all active validators receive minimum rewards - **Soft cap**: Prevents extreme over-performance rewards (max 150% of fair share credited) ## Performance-Based Validator Rewards Introduces a **60/30/10 reward formula** that rewards validators based on their contribution during each session: - **60%** based on block production (with soft cap allowing up to 150% of fair share) - **30%** based on liveness (ImOnline heartbeat OR block authorship) - **10%** guaranteed base reward for all active validators ### Key Features - Tracks individual validator block authorship per session - Calculates fair share dynamically: `fair_share = total_blocks / total_validator_count` - Fair share uses **total** validator count (including whitelisted) since all validators occupy block slots - **Soft cap**: Over-performers can earn credit up to 150% of their fair share (configurable via `OperatorRewardsFairShareCap` at 50%) - With 60% BlockAuthoringWeight, this gives over-performers up to **30% bonus reward** - **BasePointsPerBlock**: Defines points added to pool per block produced (default: 320) - Integrates with SessionManager for automatic point awards at session end - Excludes whitelisted validators from rewards (but includes them in fair share calculation) - Slashing check disabled but hook retained for future use - Points accumulate across sessions within an era ### Dynamic Parameters (Governance-Adjustable) - `OperatorRewardsBlockAuthoringWeight`: Weight for block authoring (default: 60%) - `OperatorRewardsLivenessWeight`: Weight for liveness (default: 30%) - `OperatorRewardsFairShareCap`: Soft cap percentage above fair share (default: 50%) ## Inflation Scaling Implements **dynamic inflation scaling** that adjusts total inflation based on network block production: - **Minimum**: 20% of base inflation (network halt protection) - **Maximum**: 100% of base inflation (caps at expected blocks) - **Linear scaling** between minimum and maximum based on performance ### Scaling Examples - 0% blocks produced → 20% inflation (safety floor) - 50% blocks produced → 60% inflation - 100% blocks produced → 100% inflation - >100% blocks produced → capped at 100% ### Configuration - **ExpectedBlocksPerEra**: Computed as `SessionsPerEra × EpochDurationInBlocks` - **MinInflationPercent**: 20% - **MaxInflationPercent**: 100% ## Combined Effect These mechanisms work together to create a comprehensive incentive structure: 1. **Session rewards** encourage individual validator performance and uptime 2. **Era inflation scaling** incentivizes collective network health 3. **Minimum inflation floor** protects against network halt 4. **Soft cap** allows over-performers to earn up to 30% bonus while preventing extreme centralization ## Implementation Details ### Pallet Changes - Add `BlocksAuthoredInSession` storage for per-validator tracking - Add `BlocksProducedInEra` storage for total network tracking (cleaned up with HistoryDepth) - Add `note_block_author()` function called on block production - Add `award_session_performance_points()` function with configurable 60/30/10 formula - Add `calculate_scaled_inflation()` function for era-level scaling - Update `on_era_end()` to use scaled inflation - Integrate with SessionManager via wrapper types - Defensive weight validation: proportionally scales if sum > 100% ### Configuration Parameters - `ValidatorSet`: Provides active validator list - `LivenessCheck`: Uses `ImOnline::is_online()` (heartbeat OR block authorship) - `SlashingCheck`: Integration with slashing pallet (currently disabled) - `BasePointsPerBlock`: Points added to pool per block (default: 320) - `BlockAuthoringWeight`: Dynamic parameter (60%) - `LivenessWeight`: Dynamic parameter (30%) - `FairShareCap`: Dynamic parameter (50%) - `ExpectedBlocksPerEra`: Computed from session/epoch config - `MinInflationPercent`: 20% - `MaxInflationPercent`: 100% ### Runtime Updates - Full configuration added to mainnet, testnet, and stagenet runtimes - Dynamic parameters added to `runtime_params.rs` for governance control - Uses `prod_or_fast!()` macro for environment-specific parameters - `ValidatorIsOnline` uses `ImOnline::is_online()` for accurate liveness detection ## Testing - **76 tests passing** ✅ - Comprehensive coverage of both mechanisms ### Test Coverage - Inflation scaling at 0%, 25%, 50%, 75%, 100%, >100% blocks - Session performance with 60/30/10 formula - Fair share calculations with soft cap (150%) - Whitelisted validator exclusion from rewards (with correct fair share using total count) - Total points verification (sum of individual = total) - Whitelisted over-producer scenarios - Overflow protection (large block counts, near-u32::MAX) - End-to-end session to era flow - MockLivenessCheck mirrors ImOnline behavior (block authorship = online) - Multiple eras with different performance levels - Edge cases (zero participation, single validator, large numbers) - BlocksProducedInEra cleanup on era start ## ⚠️ Breaking Changes ⚠️ ### Reward Distribution Previously, rewards were distributed equally among all validators regardless of their contribution. Now: - **Performance-based**: Validators earn rewards proportional to their block production (60%), liveness (30%), and a guaranteed base (10%) - **Pool-based**: `BasePointsPerBlock` defines points added to pool per block (320), distributed via formula - **Fair share uses total validators**: Ensures non-whitelisted aren't penalized for whitelisted validators' block slots - **Soft cap**: Block production rewards allow up to 150% of fair share (50% cap = 30% bonus with 60% weight) - **Slashing check disabled**: Hook retained for future use, but currently not applied ### Inflation Mechanism Previously, the full calculated inflation was minted each era. Now: - **Scaled by performance**: Total inflation scales between 20%-100% based on actual blocks produced vs expected - **Safety floor**: Even with zero blocks, 20% of inflation is still minted to prevent complete halt - **Network incentive**: Collective block production directly impacts total rewards available ### Pallet Configuration The `pallet-external-validators-rewards` Config now requires additional types: - `BlockAuthoringWeight`, `LivenessWeight`, `FairShareCap` for reward formula - `ValidatorSet`, `LivenessCheck`, `SlashingCheck` for validator tracking - `ExpectedBlocksPerEra`, `MinInflationPercent`, `MaxInflationPercent` for inflation scaling --------- Co-authored-by: Claude <noreply@anthropic.com> Co-authored-by: Ahmad Kaouk <56095276+ahmadkaouk@users.noreply.github.com>		2025-12-16 16:27:03 +01:00
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src	feat: ✨ Performance-Based Validator Rewards and Inflation Scaling (#306)	2025-12-16 16:27:03 +01:00
Cargo.toml	feat: set slashing mode in genesis config (#264)	2025-10-29 18:24:49 +02:00