src/evidence.js

export function addEvidence(history = [], action, metadata = {}, at = Date.now()) {
  return [...history, { at, action, ...metadata }].slice(-100);
}

export function evidenceSummary(history = []) {
  return history.reduce((summary, item) => {
    summary[item.action] = (summary[item.action] || 0) + 1;
    return summary;
  }, {});
}

export function buildEvidenceExport(project = {}, generatedAt = new Date().toISOString()) {
  return {
    schema: "ai-banner-lab-beta-evidence-v1",
    generatedAt,
    counts: evidenceSummary(project.history || []),
    selectedBanner: project.selectedBanner || null,
    pricingIntent: project.pricingIntent || null,
    shareIntent: project.shareIntent || null
  };
}