Prove Notarius cache reuse end to end

internal/adapters/notarius/subprocess_test.go

@@ -766,6 +766,26 @@ func assertRedactedCredentialBytes(t *testing.T, data []byte, canary string) {
 	}
 }
 
+func TestValidateValidationSummariesAcceptsReusedProducerWithoutAttempts(t *testing.T) {
+	zero := 0
+	summaries, err := validateValidationSummaries([]validationSummaryDocument{{
+		Stage: "chunk", Status: "complete", ProducerAttemptCount: &zero, TerminalAction: "accepted",
+	}})
+	if err != nil {
+		t.Fatalf("validateValidationSummaries() error = %v", err)
+	}
+	if len(summaries) != 1 || summaries[0].ProducerAttemptCount != 0 {
+		t.Fatalf("summaries = %#v, want one reused producer with zero attempts", summaries)
+	}
+
+	negative := -1
+	if _, err := validateValidationSummaries([]validationSummaryDocument{{
+		Stage: "chunk", Status: "complete", ProducerAttemptCount: &negative, TerminalAction: "accepted",
+	}}); err == nil {
+		t.Fatal("validateValidationSummaries() negative producer attempts error = nil")
+	}
+}
+
 func writeValidBundleAndReceipt(t *testing.T, req RunRequest, includeUnknown bool) {
 	t.Helper()
 	bundle := filepath.Join(req.OutputRoot, "notarius-run-1")