diff --git a/cmd/internal-tools/campaign/campaign_test.go b/cmd/internal-tools/campaign/campaign_test.go
index bf64b31..dedf64e 100644
--- a/cmd/internal-tools/campaign/campaign_test.go
+++ b/cmd/internal-tools/campaign/campaign_test.go
@@ -138,14 +138,19 @@ func TestRunCampaign_RecordsDispatchedActionsNotSteps(t *testing.T) {
 }
 
 // A run that never produced a readable trace still has to carry the field, so
-// analysis can tell a zero-action run from a file written before the count.
-func TestRunRecord_AlwaysCarriesTheActionCount(t *testing.T) {
+// analysis can tell a zero-action run from a file written before the count. The
+// same holds for the unattributed count: a run whose every action named its
+// producer says so with a zero, and a file that says nothing is one recorded
+// before actions named one at all.
+func TestRunRecord_AlwaysCarriesTheActionCounts(t *testing.T) {
 	body, err := json.Marshal(runRecord{Seed: 7, TraceError: "no run directory with meta.json"})
 	if err != nil {
 		t.Fatal(err)
 	}
-	if !strings.Contains(string(body), `"actions":0`) {
-		t.Errorf("record %s omits the action count", body)
+	for _, field := range []string{`"actions":0`, `"unattributed_actions":0`} {
+		if !strings.Contains(string(body), field) {
+			t.Errorf("record %s omits %s", body, field)
+		}
 	}
 }
 
diff --git a/cmd/internal-tools/campaign/summary.go b/cmd/internal-tools/campaign/summary.go
index cbdf5aa..cd842a4 100644
--- a/cmd/internal-tools/campaign/summary.go
+++ b/cmd/internal-tools/campaign/summary.go
@@ -31,8 +31,11 @@ type traceSummary struct {
 	// UnattributedActions counts the dispatched steps whose action names no
 	// producer, which only a trace recorded before actions carried one can do.
 	// Such a run's Actions is the count it was already reported with rather than
-	// a setup-excluding one, and this is what says so.
-	UnattributedActions        int      `json:"unattributed_actions,omitempty"`
+	// a setup-excluding one, and this is what says so. It is written even when
+	// it is zero, because a record that omits it is one the analysis has to read
+	// as unattributable and a run where every action named a producer is the
+	// opposite of that.
+	UnattributedActions        int      `json:"unattributed_actions"`
 	FirstViolationOriginStep   *int     `json:"first_violation_origin_step"`
 	FirstViolationDetectedStep *int     `json:"first_violation_detected_step"`
 	FirstViolationProperties   []string `json:"first_violation_properties,omitempty"`