ruvnet/ruflo · error · RangeError

lambda must be in (0, 1)

Error message

lambda must be in (0, 1)

What it means

RangeError guard on lambda, the per-win betting fraction in the anytime-valid e-value product. The e-process only converges when lambda is strictly between 0 and 1, so values at or outside those bounds are rejected before any pairs are folded.

Solutions

1. Choose lambda strictly between 0 and 1, e.g. 0.5

Example fix

Set lambda to a value strictly between 0 and 1 (e.g. 0.5).

When it happens

Trigger: Thrown at v3/@claude-flow/cli/src/services/flywheel-sequential-evidence.ts:97 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of ruvnet/ruflo@fa13ee4ad6 (2026-08-18). Data as JSON: /api/errors/76096b4f024ba6d9. Report an issue: GitHub.

Appendix: source

Thrown at v3/@claude-flow/cli/src/services/flywheel-sequential-evidence.ts:97

  if (!Number.isInteger(testIndex) || testIndex < 1) throw new RangeError('testIndex must be a positive integer');
  if (!(alphaTotal > 0 && alphaTotal < 1)) throw new RangeError('alphaTotal must be in (0, 1)');
  return (alphaTotal * 6) / (Math.PI * Math.PI * testIndex * testIndex);
}

/**
 * Fold paired outcomes into an anytime-valid e-value and judge it against the
 * k-th test's allocated alpha. Deterministic; order of outcomes does not
 * change the final e-value (the product commutes).
 */
export function sequentialEvidenceVerdict(
  outcomes: PairedTaskOutcome[],
  testIndex: number,
  config: SequentialEvidenceConfig = {},
): SequentialEvidenceVerdict {
  const alphaTotal = config.alphaTotal ?? DEFAULT_ALPHA_TOTAL;
  const lambda = config.lambda ?? DEFAULT_LAMBDA;
  const epsilon = config.epsilon ?? DEFAULT_SCORE_EPSILON;
  if (!(lambda > 0 && lambda < 1)) throw new RangeError('lambda must be in (0, 1)');
  const alphaAllocated = alphaForTest(testIndex, alphaTotal);
  const threshold = 1 / alphaAllocated;

  let eValue = 1;
  let informativePairs = 0;
  for (const o of outcomes) {
    const delta = o.candidateScore - o.baselineScore;
    if (Math.abs(delta) <= epsilon) continue; // concordant: no information
    informativePairs++;
    // Under the null a discordant pair favors either arm with probability 1/2,
    // so E[multiplier] = 1 and the running product is a martingale.
    eValue *= delta > 0 ? 1 + lambda : 1 - lambda;
  }

  return {
    significant: eValue >= threshold,
    eValue,
    threshold,

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