Function pickDraftModel

src/llm/speculative.ts:88–107

(targetModelId: string, availableModelIds: string[])

 * Returns null when nothing compatible is available.
 */
export function pickDraftModel(targetModelId: string, availableModelIds: string[]): string | null {
  const suggestion = suggestDraftFamily(targetModelId);
  if (!suggestion) return null;

  const lowerTarget = targetModelId.toLowerCase();
  // For each size hint (smallest first), find a same-family model that contains it.
  for (const hint of suggestion.draftHints) {
    for (const id of availableModelIds) {
      const lower = id.toLowerCase();
      if (lower === lowerTarget) continue; // never the target itself
      // Must share the family root and contain the size hint.
      const familyRule = FAMILY_RULES.find(r => r.family === suggestion.family)!;
      if (familyRule.match.test(id) && lower.includes(hint)) {
        logger.info('Auto-selected draft model', { target: targetModelId, draft: id, family: suggestion.family });
        return id;
      }
    }
  }
  return null;
}

/**
 * Recommended draft lookahead (number of speculative tokens per step) by task.