Add artifact provenance and stage skip outcomes

internal/manifest/manifest_test.go

@@ -110,3 +110,23 @@ func TestMarkStageSucceededClearsError(t *testing.T) {
 		t.Fatalf("error = %#v, want nil on success", stage.Error)
 	}
 }
+
+func TestMarkStageSkippedClearsEarlierOutputs(t *testing.T) {
+	m := New("2026-05-03", time.Date(2026, 5, 3, 10, 0, 0, 0, time.UTC))
+	m.MarkStageSucceeded("extract", time.Date(2026, 5, 3, 10, 1, 0, 0, time.UTC), []ArtifactRecord{
+		{Kind: "structured_data", SourceID: "narratio.example.characters", LocalPath: "artifacts/characters.json"},
+	})
+
+	m.MarkStageSkipped("extract", time.Date(2026, 5, 3, 10, 2, 0, 0, time.UTC), "integration_disabled")
+
+	stage := m.Stages["extract"]
+	if stage == nil {
+		t.Fatal("missing stage record")
+	}
+	if stage.Status != StatusSkipped {
+		t.Fatalf("status = %q, want %q", stage.Status, StatusSkipped)
+	}
+	if len(stage.Outputs) != 0 {
+		t.Fatalf("outputs = %#v, want cleared", stage.Outputs)
+	}
+}