fix: Unweighted Oracle Standard Deviation Inflates Reward Band

CHANGELOG.md

@@ -11,6 +11,7 @@
 
 ### Fixed
 
+- Compute the oracle ballot `StandardDeviation` as a stake-weighted variance (weight each squared deviation by the vote's power and divide by total voting power) instead of an unweighted average divided by the vote count, aligning the reward-band width with the stake-weighted median and preventing a group of low-stake validators from inflating the deviation to widen the accepted vote window
 - Close an oracle slashing bypass in the `EndBlocker` where validators were scored against the post-filtered `voteTargets` map: a denom that received votes but was pushed below the vote threshold (e.g. by a coordinated group abstaining) was dropped from the scoring denominator, letting the abstainers avoid miss penalties. Participation is now scored against the configured targets that received votes (passing targets plus below-threshold targets), crediting validators that voted on a below-threshold target while counting abstention on it as a miss; targets that received no votes at all are still excluded so a legitimately unpriceable denom cannot mass-slash the validator set
 - Allow EIP-7702 delegated EOAs to send direct EVM transactions by exempting delegation-designator code from the externally-owned-account-only check in `VerifyIfAccountExists`, so accounts that delegate via `SetCodeTx` can still manage (and revoke) their own delegation without a sponsored transaction
 - Remove the forced minimum 1-unit-per-block reward release in `CalculateReward` and skip (instead of deactivating) sub-unit blocks in the rewards `BeginBlocker`, so the proportional share accumulates and the pool follows the configured schedule independent of block time (previously a 10-year, 1M-unit schedule drained in ~12 days at the 1s target block time and ~28 days at the current ~2.4s rate, regardless of the configured duration)

x/oracle/types/ballot.go

@@ -173,20 +173,26 @@ func (ex ExchangeRateBallot) StandardDeviation(median sdkMath.LegacyDec) (standa
 		}
 	}()
 
+	// Get the total voting power to weight the variance
+	totalPower := ex.Power()
+	if totalPower == 0 {
+		return sdkMath.LegacyZeroDec()
+	}
+
 	sum := sdkMath.LegacyZeroDec()
 	for _, votes := range ex {
-		deviation := votes.ExchangeRate.Sub(median) // calculate the ex - median
-		sum = sum.Add(deviation.Mul(deviation))     // Calculate sum += (ex - median)^2
+		deviation := votes.ExchangeRate.Sub(median)                   // calculate the ex - median
+		sum = sum.Add(deviation.Mul(deviation).MulInt64(votes.Power)) // Calculate sum += power * (ex - median)^2
 	}
 
-	// Divide the result by the number of ex
-	variance := sum.QuoInt64(int64(len(ex)))
+	// Divide the result by the total voting power
+	variance := sum.QuoInt64(totalPower)
 
 	// Finally get the square root of variance
 	standardDeviation, err := variance.ApproxSqrt()
 	if err != nil {
 		return sdkMath.LegacyZeroDec()
 	}
 
-	return
+	return standardDeviation
 }

x/oracle/types/ballot_test.go

@@ -180,7 +180,7 @@ func TestStandardDeviation(t *testing.T) {
 	median := ballot.WeightedMedianWithAssertion()
 	deviation := ballot.StandardDeviation(median)
 
-	expected := sdkMath.LegacyNewDecWithPrec(1224745, 6)
+	expected := sdkMath.LegacyOneDec()
 	// 2e-7 tolerance
 	delta := sdkMath.LegacyNewDecWithPrec(2, 7)