fix: prevent incorrect zero inference for empty, null, or boolean numeric facts

src/features/dashboard/DashboardPanel.tsx

@@ -577,12 +577,23 @@ function observationFact(snapshot: EnvironmentSnapshot | undefined, property: st
   return observation ? factText(displayValue(observation)) : UNKNOWN_FACT;
 }
 
+/**
+ * Parst einen Faktwert, ohne eine Null zu erfinden: leere Zeichenketten,
+ * ausdrueckliches null und Wahrheitswerte bleiben unbekannt statt zu 0 zu
+ * werden. `Number('')`, `Number(null)` und `Number(false)` ergeben sonst
+ * jeweils die endliche 0 und faelschten den em-dash zu einer "0".
+ */
+function finiteFactNumber(value: unknown): number | undefined {
+  const numeric = typeof value === 'number' ? value
+    : typeof value === 'string' && value.trim() !== '' ? Number(value)
+      : NaN;
+  return Number.isFinite(numeric) ? numeric : undefined;
+}
+
 function optionalObservationNumber(snapshot: EnvironmentSnapshot | undefined, property: string, label?: string, sectionKey?: string): number | undefined {
   const observation = observationFor(snapshot, property, label, sectionKey);
   if (!observation) return undefined;
-  const value = observation.normalizedValue ?? observation.originalValue;
-  const numeric = typeof value === 'number' ? value : Number(value);
-  return Number.isFinite(numeric) ? numeric : undefined;
+  return finiteFactNumber(observation.normalizedValue ?? observation.originalValue);
 }
 
 function numberFact(value: number | undefined): string {
@@ -887,9 +898,7 @@ function dashboardFieldValue(record: FindingRecord, pattern: RegExp): string | u
 
 function dashboardObservationNumber(snapshot: EnvironmentSnapshot | undefined, property: string): number | undefined {
   const observation = snapshot?.observations.find(item => item.property === property && item.state === 'observed');
-  const value = observation?.normalizedValue ?? observation?.originalValue;
-  const number = typeof value === 'number' ? value : Number(value);
-  return Number.isFinite(number) ? number : undefined;
+  return finiteFactNumber(observation?.normalizedValue ?? observation?.originalValue);
 }
 
 function dashboardEnvironmentTableNumber(snapshot: EnvironmentSnapshot | undefined, sectionKey: string, header: RegExp): number | undefined {
@@ -899,8 +908,8 @@ function dashboardEnvironmentTableNumber(snapshot: EnvironmentSnapshot | undefin
       const column = table.headers.findIndex(value => header.test(value.trim()));
       if (column < 0) return [];
       return table.rows.flatMap(row => {
-        const numeric = Number(row[column]);
-        return Number.isFinite(numeric) ? [numeric] : [];
+        const numeric = finiteFactNumber(row[column]);
+        return numeric === undefined ? [] : [numeric];
       });
     })) ?? [];
   return values.length ? values.reduce((sum, value) => sum + value, 0) : undefined;

tests/features/dashboard-environment-detail.test.ts

@@ -94,6 +94,35 @@ describe('client info environment detail', () => {
     expect(fact(dashboardEnvironmentDetail(snapshot).inventory, 'Trusts')).toBe('—');
   });
 
+  it('does not infer a zero for present numeric facts that are empty, null, or boolean', () => {
+    const blank = {
+      version: 1, projectId: 'project-1', scanRunIds: ['run-1'], generatedAt: '2026-08-25T00:00:00.000Z',
+      coverage: { observed: 4, explicitlyAbsent: 0, empty: 0, restricted: 0, incomplete: 0 },
+      sections: [
+        section('sectionUserInformation', 'User information', [{
+          name: 'Account analysis',
+          headers: ['Nb User Accounts', 'Nb Enabled', 'Nb Disabled'],
+          rows: [['', '', '']]
+        }])
+      ],
+      observations: [
+        observation('benchmark.score', 'Benchmark score', '' as unknown as number),
+        observation('purple_knight.ad.ioes_found', 'IOEs found', null as unknown as number),
+        observation('purple_knight.ad.security_posture_score', 'security posture score', false)
+      ]
+    } satisfies EnvironmentSnapshot;
+
+    const detail = dashboardEnvironmentDetail(blank);
+
+    // A present observation whose value is an empty string, explicit null, or
+    // boolean must stay an em dash: Number('')/Number(null)/Number(false) are all 0.
+    expect(fact(detail.toolContext, 'CIS-CAT score')).toBe('—');
+    expect(fact(detail.toolContext, 'Purple Knight IOEs')).toBe('—');
+    expect(fact(detail.toolContext, 'Purple Knight posture')).toBe('—');
+    // A table column whose cells are all blank must not sum to a fabricated 0.
+    expect(fact(detail.inventory, 'User accounts')).toBe('—');
+  });
+
   it('reads the password policy and PKI counts from their own report tables', () => {
     const detail = dashboardEnvironmentDetail(snapshot);