fix(experiments): prevent NaN propagation and ACOS zero-value bug in experiment analysis

- Change ?? to || for salesAds/units/revenue in weekly aggregation to guard against NaN
- Add || 0 fallback to ads-only records in mergeSalesAndAdsData
- Fix parseCurrency to check isNaN on all EU-format return paths
- Handle ACOS edge case: cost > 0 with adRevenue = 0 now returns 100% instead of 0%
- Add diagnostic console logging to computeDiD for data flow tracing

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

components/ExperimentsView.tsx

@@ -812,8 +812,8 @@ const ExperimentDetailView: React.FC<{
                     <td className="px-4 py-2.5 text-slate-300 font-medium">{METRIC_LABELS[metric] || metric}</td>
                     <td className="px-4 py-2.5 text-right text-slate-400">{formatMetricValue(r.treatment_before, metric)}</td>
                     <td className="px-4 py-2.5 text-right text-white font-medium">{formatMetricValue(r.treatment_after, metric)}</td>
-                    <td className="px-4 py-2.5 text-right text-slate-400">{r.control_before ? formatMetricValue(r.control_before, metric) : '—'}</td>
+                    <td className="px-4 py-2.5 text-right text-slate-400">{typeof r.control_before === 'number' ? formatMetricValue(r.control_before, metric) : '—'}</td>
-                    <td className="px-4 py-2.5 text-right text-slate-400">{r.control_after ? formatMetricValue(r.control_after, metric) : '—'}</td>
+                    <td className="px-4 py-2.5 text-right text-slate-400">{typeof r.control_after === 'number' ? formatMetricValue(r.control_after, metric) : '—'}</td>
                     <td className={`px-4 py-2.5 text-right font-medium ${r.did_estimate >= 0 ? 'text-emerald-400' : 'text-red-400'}`}>
                       {r.did_estimate >= 0 ? '+' : ''}{formatMetricValue(r.did_estimate, metric)}
                     </td>

services/dataProcessor.ts

@@ -69,7 +69,8 @@ const parseCurrency = (value: string): number => {
         // Likely EU decimal without thousands or with thousands implicitly handled
         // e.g. "263,83" -> "263.83"
         clean = clean.replace(',', '.');
-        return parseFloat(clean);
+        const num = parseFloat(clean);
+        return isNaN(num) ? 0 : num;
     }
     else if (clean.includes(',') && clean.includes('.')) {
         // Mixed: 1.234,56 -> EU
@@ -79,7 +80,8 @@ const parseCurrency = (value: string): number => {
             // 1,234.56 -> US
             clean = clean.replace(/,/g, '');
         }
-        return parseFloat(clean);
+        const num = parseFloat(clean);
+        return isNaN(num) ? 0 : num;
     }
 
     // Case B: Standard/US Format or Clean Number (e.g. "277179.09" or "1000")
@@ -832,12 +834,12 @@ export const mergeSalesAndAdsData = (
                 sku: meta?.sku || '',
                 salesTotal: 0,
                 unitsTotal: 0,
-                salesAds: ad.attributedSales30d,
+                salesAds: ad.attributedSales30d || 0,
-                unitsAds: ad.attributedUnits30d,
+                unitsAds: ad.attributedUnits30d || 0,
-                cost: ad.cost,
+                cost: ad.cost || 0,
-                clicks: ad.clicks,
+                clicks: ad.clicks || 0,
-                impressions: ad.impressions,
+                impressions: ad.impressions || 0,
-                conversions: ad.conversions,
+                conversions: ad.conversions || 0,
                 salesOrganic: 0,
                 unitsOrganic: 0,
                 paidSalesShare: 0,

services/experimentAnalysis.ts

@@ -83,9 +83,9 @@ function aggregateWeeklyMetrics(
     }
 
     const w = weeklyMap.get(key)!;
-    w.units += r.unitsTotal ?? (r as any).units ?? 0;
+    w.units += r.unitsTotal || (r as any).units || 0;
-    w.revenue += r.salesTotal ?? (r as any).sellOut ?? 0;
+    w.revenue += r.salesTotal || (r as any).sellOut || 0;
-    w.adRevenue += r.salesAds ?? 0;
+    w.adRevenue += r.salesAds || 0;
     w.sessions += r.glanceViews || 0;
     w.cost += r.cost || 0;
     w.clicks += r.clicks || 0;
@@ -110,7 +110,7 @@ function getMetricValue(w: ComputedWeeklyMetrics, metric: string): number {
     case 'ctr': return w.ctr;
     case 'roas': return w.roas;
     case 'revenue': return w.revenue;
-    case 'acos': return w.cost > 0 && w.adRevenue > 0 ? (w.cost / w.adRevenue) * 100 : 0;
+    case 'acos': return w.cost > 0 ? (w.adRevenue > 0 ? (w.cost / w.adRevenue) * 100 : 100) : 0;
     default: return w.units;
   }
 }
@@ -173,7 +173,8 @@ function avgMetric(data: ComputedWeeklyMetrics[], metric: string, durationWeeks:
   if (metric === 'acos') {
     const totalAdRevenue = data.reduce((s, w) => s + w.adRevenue, 0);
     const totalCost = data.reduce((s, w) => s + w.cost, 0);
-    return totalAdRevenue > 0 ? (totalCost / totalAdRevenue) * 100 : 0;
+    if (totalCost === 0) return 0; // No ad spend → ACOS is 0
+    return totalAdRevenue > 0 ? (totalCost / totalAdRevenue) * 100 : 100; // Cost but no ad revenue → 100% ACOS
   }
 
   // For absolute quantities (units, revenue, sessions), we sum them and divide by the duration
@@ -293,6 +294,24 @@ export function computeDiD(
   const treatmentDurationWeeks = Math.max(1, Math.round((endTs - startTs) / (7 * 86400000)));
   const baselineDurationWeeks = Math.max(1, Math.round((beforeEndTs - beforeStartTs) / (7 * 86400000)));
 
+  // Debug: log data flow for ACOS diagnosis
+  const afterTotalCost = tSplit.after.reduce((s, w) => s + w.cost, 0);
+  const afterTotalAdRev = tSplit.after.reduce((s, w) => s + w.adRevenue, 0);
+  const beforeTotalCost = tSplit.before.reduce((s, w) => s + w.cost, 0);
+  const beforeTotalAdRev = tSplit.before.reduce((s, w) => s + w.adRevenue, 0);
+  console.log(`[computeDiD DEBUG] Experiment: ${experiment.name} | Mkt: ${experiment.marketplace}`);
+  console.log(`  Treatment ASINs: ${treatmentAsinSet.size} | Weekly buckets: ${treatmentWeekly.length}`);
+  console.log(`  Period: ${new Date(startTs).toISOString().split('T')[0]} → ${new Date(endTs).toISOString().split('T')[0]}`);
+  console.log(`  Baseline: ${new Date(beforeStartTs).toISOString().split('T')[0]} → ${new Date(beforeEndTs).toISOString().split('T')[0]}`);
+  console.log(`  After split: ${tSplit.after.length} weeks [cost=${afterTotalCost.toFixed(2)}, adRev=${afterTotalAdRev.toFixed(2)}]`);
+  console.log(`  Before split: ${tSplit.before.length} weeks [cost=${beforeTotalCost.toFixed(2)}, adRev=${beforeTotalAdRev.toFixed(2)}]`);
+  if (tSplit.after.length > 0) {
+    console.log(`  After weeks: ${tSplit.after.map(w => w.week).join(', ')}`);
+  }
+  if (tSplit.before.length > 0) {
+    console.log(`  Before weeks: ${tSplit.before.map(w => w.week).join(', ')}`);
+  }
+
   const metrics: Record<string, DiDMetricResult> = {};
   for (const metric of METRICS) {
     metrics[metric] = computeMetricDiD(