diff --git a/packages/core/src/scoring/index.test.ts b/packages/core/src/scoring/index.test.ts
index 1c8c73a..2489741 100644
--- a/packages/core/src/scoring/index.test.ts
+++ b/packages/core/src/scoring/index.test.ts
@@ -38,6 +38,13 @@ function withHashChain(events: CanonicalEvent[], withSignature: boolean): Canoni
 // computeProvenanceIntegrity via computeRiskScore
 // ---------------------------------------------------------------------------
 
+describe('computeRiskScore — trace_completeness scoring', () => {
+  it('returns zero trace completeness when the trace has no events', async () => {
+    const score = await computeRiskScore([], 'empty-run');
+    expect(score.components.trace_completeness).toBe(0);
+  });
+});
+
 describe('computeRiskScore — provenance_integrity scoring', () => {
   it('returns 100 when all events have ed25519 signatures (no AEP provenance)', async () => {
     const events = withHashChain([makeToolCall('e1'), makeToolCall('e2')], true);
diff --git a/packages/core/src/scoring/index.ts b/packages/core/src/scoring/index.ts
index a3af03d..1270bc2 100644
--- a/packages/core/src/scoring/index.ts
+++ b/packages/core/src/scoring/index.ts
@@ -19,7 +19,7 @@ function toGrade(score: number): Grade {
 }
 
 function computeTraceCompleteness(events: CanonicalEvent[]): number {
-  if (events.length === 0) return 100;
+  if (events.length === 0) return 0;
 
   let score = 100;