timing refactor

tests/VideoPlayoutSchedulerTests.cpp

@@ -70,6 +70,19 @@ void TestDefaultPolicyReportsLagWithoutSkippingScheduleTime()
 	Expect(scheduler.NextScheduleTime().streamTime == 1000, "default recovery keeps stream time continuous");
 }
 
+void TestScheduleCursorCanAlignToPlaybackClock()
+{
+	VideoPlayoutScheduler scheduler;
+	scheduler.Configure(1000, 50000);
+
+	(void)scheduler.NextScheduleTime();
+	scheduler.AlignNextScheduleTimeToPlayback(10000, 4);
+	Expect(scheduler.NextScheduleTime().streamTime == 14000, "schedule cursor skips stale stream time after underfeed");
+
+	scheduler.AlignNextScheduleTimeToPlayback(11000, 1);
+	Expect(scheduler.NextScheduleTime().streamTime == 15000, "schedule cursor does not move backward");
+}
+
 void TestMeasuredRecoveryIsCappedByPolicy()
 {
 	VideoPlayoutPolicy policy;
@@ -133,6 +146,7 @@ int main()
 	TestScheduleAdvancesFromZero();
 	TestLateAndDroppedRecoveryUsesMeasuredPressure();
 	TestDefaultPolicyReportsLagWithoutSkippingScheduleTime();
+	TestScheduleCursorCanAlignToPlaybackClock();
 	TestMeasuredRecoveryIsCappedByPolicy();
 	TestCleanCompletionTracksCompletedIndexAndClearsStreaks();
 	TestPolicyNormalization();