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feat: implement compute_weak_subjectivity_period for Gloas (EIP-8061) #9625

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feat: implement compute_weak_subjectivity_period for Gloas (EIP-8061) #9625

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d90efb6
feat: implement compute_weak_subjectivity_period for Gloas (EIP-8061)
markolazic01 Jul 9, 2026
526ff7c
Merge branch 'unstable' into feat/gloas-weak-subjectivity
markolazic01 Jul 9, 2026
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17 changes: 17 additions & 0 deletions packages/state-transition/src/util/validator.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -128,6 +128,23 @@ export function getConsolidationChurnLimit(fork: ForkSeq, epochCtx: EpochCache):
return getBalanceChurnLimitFromCache(epochCtx) - getActivationExitChurnLimit(epochCtx);
}

// NOTE: duplicates the quotient/min choices in get{Exit,Activation,Consolidation}ChurnLimit.
export function getGloasChurnLimits(
config: ChainForkConfig,
totalActiveBalanceIncrements: number
): {exit: number; activation: number; consolidation: number} {
const exit = getBalanceChurnLimit(
totalActiveBalanceIncrements,
config.CHURN_LIMIT_QUOTIENT_GLOAS,
config.MIN_PER_EPOCH_CHURN_LIMIT_ELECTRA
);
return {
exit,
activation: Math.min(config.MAX_PER_EPOCH_ACTIVATION_CHURN_LIMIT_GLOAS, exit),
consolidation: getBalanceChurnLimit(totalActiveBalanceIncrements, config.CONSOLIDATION_CHURN_LIMIT_QUOTIENT, 0),
};
}

export function getMaxEffectiveBalance(withdrawalCredentials: Uint8Array): number {
// Compounding withdrawal credential only available since Electra
if (hasCompoundingWithdrawalCredential(withdrawalCredentials)) {
Expand Down
83 changes: 61 additions & 22 deletions packages/state-transition/src/util/weakSubjectivity.ts
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Original file line number Diff line number Diff line change
@@ -1,10 +1,12 @@
import {BeaconConfig, ChainForkConfig} from "@lodestar/config";
import {
EFFECTIVE_BALANCE_INCREMENT,
ForkSeq,
MAX_DEPOSITS,
MAX_EFFECTIVE_BALANCE,
SLOTS_PER_EPOCH,
isForkPostElectra,
isForkPostGloas,
} from "@lodestar/params";
import {Epoch, Root, ssz} from "@lodestar/types";
import {Checkpoint} from "@lodestar/types/phase0";
Expand All @@ -14,10 +16,14 @@ import {BeaconStateAllForks, CachedBeaconStateAllForks} from "../types.js";
import {computeCheckpointEpochAtStateSlot, computeEpochAtSlot, getCurrentEpoch} from "./epoch.js";
import {getCurrentSlot} from "./slot.js";
import {
getActivationChurnLimit,
getActiveValidatorIndices,
getBalanceChurnLimit,
getBalanceChurnLimitFromCache,
getChurnLimit,
getConsolidationChurnLimit,
getExitChurnLimit,
getGloasChurnLimits,
} from "./validator.js";

export const ETH_TO_GWEI = 10 ** 9;
Expand Down Expand Up @@ -49,18 +55,26 @@ export function computeWeakSubjectivityPeriodCachedState(
const activeValidatorCount = state.epochCtx.currentShuffling.activeIndices.length;
const fork = config.getForkName(state.slot);

return isForkPostElectra(fork)
? computeWeakSubjectivityPeriodFromConstituentsElectra(
return isForkPostGloas(fork)
? computeWeakSubjectivityPeriodFromConstituentsGloas(
state.epochCtx.totalActiveBalanceIncrements,
getBalanceChurnLimitFromCache(state.epochCtx),
getExitChurnLimit(state.epochCtx),
getActivationChurnLimit(state.epochCtx),
getConsolidationChurnLimit(ForkSeq.gloas, state.epochCtx),
config.MIN_VALIDATOR_WITHDRAWABILITY_DELAY
)
: computeWeakSubjectivityPeriodFromConstituentsPhase0(
activeValidatorCount,
state.epochCtx.totalActiveBalanceIncrements,
getChurnLimit(config, activeValidatorCount),
config.MIN_VALIDATOR_WITHDRAWABILITY_DELAY
);
: isForkPostElectra(fork)
? computeWeakSubjectivityPeriodFromConstituentsElectra(
state.epochCtx.totalActiveBalanceIncrements,
getBalanceChurnLimitFromCache(state.epochCtx),
config.MIN_VALIDATOR_WITHDRAWABILITY_DELAY
)
: computeWeakSubjectivityPeriodFromConstituentsPhase0(
activeValidatorCount,
state.epochCtx.totalActiveBalanceIncrements,
getChurnLimit(config, activeValidatorCount),
config.MIN_VALIDATOR_WITHDRAWABILITY_DELAY
);
}

/**
Expand All @@ -80,22 +94,32 @@ export function computeWeakSubjectivityPeriod(config: ChainForkConfig, state: Be
totalActiveBalanceIncrements = 1;
}

return isForkPostElectra(fork)
? computeWeakSubjectivityPeriodFromConstituentsElectra(
const churnLimitsGloas = getGloasChurnLimits(config, totalActiveBalanceIncrements);

return isForkPostGloas(fork)
? computeWeakSubjectivityPeriodFromConstituentsGloas(
totalActiveBalanceIncrements,
getBalanceChurnLimit(
totalActiveBalanceIncrements,
config.CHURN_LIMIT_QUOTIENT,
config.MIN_PER_EPOCH_CHURN_LIMIT_ELECTRA
),
churnLimitsGloas.exit,
churnLimitsGloas.activation,
churnLimitsGloas.consolidation,
config.MIN_VALIDATOR_WITHDRAWABILITY_DELAY
)
: computeWeakSubjectivityPeriodFromConstituentsPhase0(
activeIndices.length,
totalActiveBalanceIncrements,
getChurnLimit(config, activeIndices.length),
config.MIN_VALIDATOR_WITHDRAWABILITY_DELAY
);
: isForkPostElectra(fork)
? computeWeakSubjectivityPeriodFromConstituentsElectra(
totalActiveBalanceIncrements,
getBalanceChurnLimit(
totalActiveBalanceIncrements,
config.CHURN_LIMIT_QUOTIENT,
config.MIN_PER_EPOCH_CHURN_LIMIT_ELECTRA
),
config.MIN_VALIDATOR_WITHDRAWABILITY_DELAY
)
: computeWeakSubjectivityPeriodFromConstituentsPhase0(
activeIndices.length,
totalActiveBalanceIncrements,
getChurnLimit(config, activeIndices.length),
config.MIN_VALIDATOR_WITHDRAWABILITY_DELAY
);
Comment on lines +97 to +122

@gemini-code-assist gemini-code-assist Bot Jul 9, 2026

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medium

Currently, getGloasChurnLimits is called unconditionally, even for pre-Gloas forks. If Gloas configuration parameters (like CHURN_LIMIT_QUOTIENT_GLOAS) are not defined or initialized on older forks or certain networks, this will result in NaN values being computed and passed around, which is unnecessary and potentially error-prone. Moving this calculation inside the isForkPostGloas(fork) conditional block ensures it is only executed when actually needed.

  if (isForkPostGloas(fork)) {
    const churnLimitsGloas = getGloasChurnLimits(config, totalActiveBalanceIncrements);
    return computeWeakSubjectivityPeriodFromConstituentsGloas(
      totalActiveBalanceIncrements,
      churnLimitsGloas.exit,
      churnLimitsGloas.activation,
      churnLimitsGloas.consolidation,
      config.MIN_VALIDATOR_WITHDRAWABILITY_DELAY
    );
  }

  return isForkPostElectra(fork)
    ? computeWeakSubjectivityPeriodFromConstituentsElectra(
        totalActiveBalanceIncrements,
        getBalanceChurnLimit(
          totalActiveBalanceIncrements,
          config.CHURN_LIMIT_QUOTIENT,
          config.MIN_PER_EPOCH_CHURN_LIMIT_ELECTRA
        ),
        config.MIN_VALIDATOR_WITHDRAWABILITY_DELAY
      )
    : computeWeakSubjectivityPeriodFromConstituentsPhase0(
        activeIndices.length,
        totalActiveBalanceIncrements,
        getChurnLimit(config, activeIndices.length),
        config.MIN_VALIDATOR_WITHDRAWABILITY_DELAY
      );

@markolazic01 markolazic01 Jul 9, 2026

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Noted this in the PR desc, it is not perfect but it is imo harmless and much more readable as is.
Willing to change this if needed ofc.

}

export function computeWeakSubjectivityPeriodFromConstituentsPhase0(
Expand Down Expand Up @@ -142,6 +166,21 @@ export function computeWeakSubjectivityPeriodFromConstituentsElectra(
return minWithdrawabilityDelay + epochsForValidatorSetChurn;
}

export function computeWeakSubjectivityPeriodFromConstituentsGloas(
totalBalanceByIncrement: number,
exitChurnLimit: number,
activationChurnLimit: number,
consolidationChurnLimit: number,
minWithdrawabilityDelay: number
): number {
// Keep t as increment for now. Multiply final result by EFFECTIVE_BALANCE_INCREMENT
const t = totalBalanceByIncrement;
const delta = Math.floor((2 * exitChurnLimit) / 3) + Math.floor(activationChurnLimit / 3) + consolidationChurnLimit;
const epochsForValidatorSetChurn = Math.floor(((SAFETY_DECAY * t) / (2 * delta * 100)) * EFFECTIVE_BALANCE_INCREMENT);

return minWithdrawabilityDelay + epochsForValidatorSetChurn;
}

export function getLatestBlockRoot(state: BeaconStateAllForks): Root {
const header = ssz.phase0.BeaconBlockHeader.clone(state.latestBlockHeader);
if (ssz.Root.equals(header.stateRoot, ZERO_HASH)) {
Expand Down
27 changes: 26 additions & 1 deletion packages/state-transition/test/unit/util/weakSubjectivity.test.ts
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Original file line number Diff line number Diff line change
@@ -1,8 +1,9 @@
import {describe, expect, it} from "vitest";
import {config} from "@lodestar/config/default";
import {getBalanceChurnLimit, getChurnLimit} from "../../../src/util/validator.js";
import {getBalanceChurnLimit, getChurnLimit, getGloasChurnLimits} from "../../../src/util/validator.js";
import {
computeWeakSubjectivityPeriodFromConstituentsElectra,
computeWeakSubjectivityPeriodFromConstituentsGloas,
computeWeakSubjectivityPeriodFromConstituentsPhase0,
} from "../../../src/util/weakSubjectivity.js";

Expand Down Expand Up @@ -66,4 +67,28 @@ describe("weak subjectivity tests", () => {
}
);
});
describe("computeWeakSubjectivityPeriodFromConstituentsGloas", () => {
const testValues = [
{totalBalanceIncrement: 1_048_576, wsPeriod: 620},
{totalBalanceIncrement: 2_097_152, wsPeriod: 911},
{totalBalanceIncrement: 4_194_304, wsPeriod: 1348},
{totalBalanceIncrement: 8_388_608, wsPeriod: 1348},
{totalBalanceIncrement: 16_777_216, wsPeriod: 1484},
{totalBalanceIncrement: 33_554_432, wsPeriod: 1566},
];
it.each(testValues)(
"should have wsPeriod: $wsPeriod with totalActiveBalance: $totalBalanceIncrement",
({totalBalanceIncrement, wsPeriod: expectedWsPeriod}) => {
const churn = getGloasChurnLimits(config, totalBalanceIncrement);
const wsPeriod = computeWeakSubjectivityPeriodFromConstituentsGloas(
totalBalanceIncrement,
churn.exit,
churn.activation,
churn.consolidation,
config.MIN_VALIDATOR_WITHDRAWABILITY_DELAY
);
expect(wsPeriod).toBe(expectedWsPeriod);
}
);
});
});
1 change: 0 additions & 1 deletion specrefs/.ethspecify.yml
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Expand Up @@ -401,7 +401,6 @@ exceptions:
- get_proposer_dependent_root#gloas

# gloas (new in alpha.3, not yet implemented)
- compute_weak_subjectivity_period#gloas
- block_to_light_client_header#gloas
- get_lc_execution_root#gloas
- is_valid_light_client_header#gloas
Expand Down
4 changes: 3 additions & 1 deletion specrefs/functions.yml
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Expand Up @@ -1707,7 +1707,9 @@
</spec>

- name: compute_weak_subjectivity_period#gloas
sources: []
sources:
- file: packages/state-transition/src/util/weakSubjectivity.ts
search: export function computeWeakSubjectivityPeriod(
spec: |
<spec fn="compute_weak_subjectivity_period" fork="gloas" hash="8b1ddc92">
def compute_weak_subjectivity_period(state: BeaconState) -> uint64:
Expand Down
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