Function isRedundantAssistantText

src/cli/modes/final-dedupe.ts:85–114

(prev: string, next: string)

 * earlier line does not).
 */
export function isRedundantAssistantText(prev: string, next: string): boolean {
  const a = normCompare(prev ?? '');
  const b = normCompare(next ?? '');
  if (!a || !b) return false;
  if (b.length < 40) return false; // don't suppress short acks
  if (a === b) return true;

  const [shorter, longer] = a.length <= b.length ? [a, b] : [b, a];

  // Fast path: exact containment (byte-identical re-emit, possibly with extra lines).
  if (longer.includes(shorter) && shorter.length >= 100 && shorter.length >= longer.length * 0.6) {
    return true;
  }

  // Tolerant path: a re-emitted answer is rarely byte-identical — the model
  // REGENERATES it with minor wording changes (or truncates it when it runs out
  // of budget), so exact containment misses it and the user sees the whole answer
  // twice. Mirror dedupeSelfRepeatedText: measure the shared LEADING word run. A
  // genuine re-emit shares a long identical opening; two genuinely different
  // assistant messages diverge almost immediately even when they reuse topic
  // vocabulary, so this stays conservative.
  const wa = a.split(' ');
  const wb = b.split(' ');
  const minLen = Math.min(wa.length, wb.length);
  if (minLen < 30) return false; // too short to be a duplicated full answer
  let common = 0;
  while (common < minLen && wa[common] === wb[common]) common++;
  const sharedRatio = common / minLen;
  return common >= 30 && sharedRatio >= 0.6;
}

/**
 * Collapse a block of text that contains its own answer twice. Some local models