Merge system-optimization IR contracts and retire legacy engine adapter

tests/test_generic_system_xml_simulation.py

@@ -423,6 +423,8 @@ class GenericSystemXmlSimulationTests(unittest.TestCase):
         self.assertEqual(snapshot["result"]["status"], "stopped")
 
     def test_streaming_endpoint_keeps_quiet_solver_connection_alive(self) -> None:
+        heartbeat_observed = threading.Event()
+
         def delayed_simulation(
             _xml_bytes,
             progress_callback,
@@ -433,8 +435,10 @@ class GenericSystemXmlSimulationTests(unittest.TestCase):
             self.assertIsNotNone(activity_tracker)
             activity_tracker.start_integration(0.0)
             for trial_time in (0.0487, 0.0488, 0.0489, 0.0490):
+                heartbeat_observed.clear()
                 activity_tracker.record_rhs(trial_time)
-                time.sleep(0.008)
+                # Wait for the consumer, independent of machine scheduling.
+                self.assertTrue(heartbeat_observed.wait(timeout=2.0))
             return {
                 "success": True,
                 "status": "completed",
@@ -449,10 +453,12 @@ class GenericSystemXmlSimulationTests(unittest.TestCase):
                 side_effect=delayed_simulation,
             ),
         ):
-            events = [
-                json.loads(line)
-                for line in simulation_event_stream(b"<System />")
-            ]
+            events = []
+            for line in simulation_event_stream(b"<System />"):
+                event = json.loads(line)
+                events.append(event)
+                if event.get("heartbeat"):
+                    heartbeat_observed.set()
 
         heartbeats = [event for event in events if event.get("heartbeat") is True]
         self.assertGreaterEqual(len(heartbeats), 1)