step 4

tests/HealthTelemetryTests.cpp

@@ -53,6 +53,29 @@ void TestRuntimeEventTryRecord()
 	Expect(metrics.queue.oldestEventAgeMilliseconds == 0.0, "queue age is clamped to non-negative values");
 	Expect(metrics.dispatch.lastDispatchDurationMilliseconds == 0.0, "dispatch duration is clamped to non-negative values");
 }
+
+void TestPersistenceWriteHealth()
+{
+	HealthTelemetry telemetry;
+	telemetry.RecordPersistenceWriteResult(false, "runtime-state", "runtime/runtime_state.json", "UpdateLayerParameter",
+		"disk full", true);
+
+	HealthTelemetry::PersistenceSnapshot persistence = telemetry.GetPersistenceSnapshot();
+	Expect(persistence.writeFailureCount == 1, "persistence health counts write failures");
+	Expect(!persistence.lastWriteSucceeded, "persistence health records failed write state");
+	Expect(persistence.unsavedChanges, "persistence health reports unsaved changes after failure");
+	Expect(persistence.newerRequestPending, "persistence health records pending newer request");
+	Expect(persistence.lastTargetKind == "runtime-state", "persistence health records target kind");
+	Expect(persistence.lastReason == "UpdateLayerParameter", "persistence health records reason");
+	Expect(persistence.lastErrorMessage == "disk full", "persistence health records error message");
+
+	Expect(telemetry.TryRecordPersistenceWriteResult(true, "runtime-state", "runtime/runtime_state.json", "flush", "", false),
+		"try persistence health succeeds when uncontended");
+	persistence = telemetry.GetPersistenceSnapshot();
+	Expect(persistence.writeSuccessCount == 1, "persistence health counts write successes");
+	Expect(persistence.lastWriteSucceeded, "persistence health records successful write state");
+	Expect(!persistence.unsavedChanges, "persistence health clears unsaved changes after latest successful write with no pending request");
+}
 }
 
 int main()
@@ -60,6 +83,7 @@ int main()
 	TestRuntimeEventQueueMetrics();
 	TestRuntimeEventDispatchStats();
 	TestRuntimeEventTryRecord();
+	TestPersistenceWriteHealth();
 
 	if (gFailures != 0)
 	{

tests/PersistenceWriterTests.cpp

@@ -94,12 +94,42 @@ void TestImmediateRequestsAreNotCoalesced()
 			"immediate snapshots preserve order");
 	}
 }
+
+void TestWriteFailureReportsStructuredResult()
+{
+	std::vector<PersistenceWriteResult> results;
+	PersistenceWriter writer(
+		std::chrono::milliseconds(1),
+		[](const PersistenceSnapshot&, std::string& error) {
+			error = "simulated failure";
+			return false;
+		});
+	writer.SetResultCallback([&results](const PersistenceWriteResult& result) {
+		results.push_back(result);
+	});
+
+	PersistenceSnapshot snapshot = MakeRuntimeSnapshot("payload");
+	snapshot.debounceAllowed = false;
+	snapshot.reason = "failure-test";
+
+	std::string error;
+	Expect(writer.EnqueueSnapshot(snapshot, error), "failing snapshot still enqueues");
+	writer.StopAndFlush();
+
+	Expect(results.size() == 1, "writer reports one failure result");
+	Expect(!results.empty() && !results[0].succeeded, "writer result records failure");
+	Expect(!results.empty() && results[0].reason == "failure-test", "writer result preserves reason");
+	Expect(!results.empty() && results[0].errorMessage == "simulated failure", "writer result preserves error message");
+	Expect(!results.empty() && !results[0].newerRequestPending, "writer result reports no newer pending request");
+	Expect(writer.GetMetrics().failedCount == 1, "writer metrics count failed writes");
+}
 }
 
 int main()
 {
 	TestDebouncedRequestsCoalesceToNewestSnapshot();
 	TestImmediateRequestsAreNotCoalesced();
+	TestWriteFailureReportsStructuredResult();
 
 	if (gFailures != 0)
 	{