整合求解器活动监控与步长回归证据

同步远端 PNL0003 诊断和大采样网格能力，语义合并活动感知的 60 秒真停滞判定与旧后端 15 分钟兼容兜底。

纳管热路径优化、15 单元运行证据、浏览器与 API 报告，并补充北京时间更新日志和遗留问题。

tests/test_generic_system_xml_simulation.py

@@ -26,7 +26,10 @@ from app.main import (
 )
 from app.simulation.components.experimental.flow.resistive_pipe import ResistivePipe
 from app.simulation.registry import get_component_model_spec
-from app.simulation.solvers.solver import SolveIVPConfig
+from app.simulation.solvers.solver import (
+    SolveIVPConfig,
+    SolverActivityTracker,
+)
 from app.simulation.systems.generic import (
     GenericFluidSystem,
     SimulationPreparationError,
@@ -259,7 +262,9 @@ class GenericSystemXmlSimulationTests(unittest.TestCase):
     def test_generic_chain_simulation_conserves_mass_and_moves_pressures(self) -> None:
         network = compile_reactflow_network(chain_project())
         progress: list[tuple[float, str]] = []
-        result = GenericFluidSystem(network).simulate(
+        activity_tracker = SolverActivityTracker()
+        system = GenericFluidSystem(network)
+        result = system.simulate(
             SolveIVPConfig(
                 t_start=0.0,
                 t_stop=0.01,
@@ -268,6 +273,7 @@ class GenericSystemXmlSimulationTests(unittest.TestCase):
             ),
             sample_step=0.005,
             progress_callback=lambda value, phase: progress.append((value, phase)),
+            activity_tracker=activity_tracker,
         )
 
         self.assertTrue(result.success)
@@ -281,6 +287,23 @@ class GenericSystemXmlSimulationTests(unittest.TestCase):
         )
         self.assertIn("integrating", {phase for _, phase in progress})
         self.assertIn("postprocessing", {phase for _, phase in progress})
+        activity = activity_tracker.snapshot()
+        self.assertEqual(activity.activity_kind, "complete")
+        self.assertGreater(activity.rhs_call_count, 0)
+        self.assertGreater(activity.accepted_step_sequence, 0)
+        self.assertEqual(activity.accepted_time, 0.01)
+        self.assertGreater(activity.thermofluid_closure_count, 0)
+        self.assertEqual(
+            result.diagnostics["activity"],
+            activity.as_dict(),
+        )
+        self.assertIsNone(system._activity_tracker)
+        self.assertEqual(
+            result.diagnostics["integration"][
+                "mechanicalAbsoluteTolerance"
+            ]["mode"],
+            "legacy",
+        )
         self.assertLess(result.series["cylinder_1.p"][-1], 500000.0)
         self.assertGreater(result.series["tank_1.p"][-1], 100000.0)
         total_mass = [
@@ -315,6 +338,33 @@ class GenericSystemXmlSimulationTests(unittest.TestCase):
             pressure_flow["optimizerEvaluationCount"],
         )
 
+    def test_activity_tracker_scope_is_restored_after_simulation_error(self) -> None:
+        system = GenericFluidSystem(compile_reactflow_network(chain_project()))
+        previous_tracker = SolverActivityTracker()
+        active_tracker = SolverActivityTracker()
+        system._activity_tracker = previous_tracker
+
+        with (
+            patch.object(
+                system,
+                "_simulate",
+                side_effect=RuntimeError("synthetic simulation failure"),
+            ),
+            self.assertRaisesRegex(RuntimeError, "synthetic simulation failure"),
+        ):
+            system.simulate(
+                SolveIVPConfig(
+                    t_start=0.0,
+                    t_stop=0.01,
+                    method="BDF",
+                    max_step=0.001,
+                ),
+                sample_step=0.005,
+                activity_tracker=active_tracker,
+            )
+
+        self.assertIs(system._activity_tracker, previous_tracker)
+
     def test_cancelled_simulation_returns_accepted_partial_samples(self) -> None:
         cancel_event = threading.Event()
 
@@ -569,10 +619,24 @@ class GenericSystemXmlSimulationTests(unittest.TestCase):
         self.assertEqual(snapshot["result"]["status"], "stopped")
 
     def test_streaming_endpoint_keeps_quiet_solver_connection_alive(self) -> None:
-        def delayed_simulation(_xml_bytes, progress_callback, _cancel_check=None):
+        def delayed_simulation(
+            _xml_bytes,
+            progress_callback,
+            _cancel_check=None,
+            activity_tracker=None,
+        ):
             progress_callback(49, "integrating", "正在进行时间积分与压力流量求解")
-            time.sleep(0.03)
-            return {"success": True}
+            self.assertIsNotNone(activity_tracker)
+            activity_tracker.start_integration(0.0)
+            for trial_time in (0.0487, 0.0488, 0.0489, 0.0490):
+                activity_tracker.record_rhs(trial_time)
+                time.sleep(0.008)
+            return {
+                "success": True,
+                "status": "completed",
+                "simulatedUntil": 0.2,
+                "requestedStopTime": 0.2,
+            }
 
         with (
             patch("app.main.SIMULATION_STREAM_HEARTBEAT_SECONDS", 0.005),
@@ -590,7 +654,21 @@ class GenericSystemXmlSimulationTests(unittest.TestCase):
         self.assertGreaterEqual(len(heartbeats), 1)
         self.assertTrue(all(event["progress"] == 49 for event in heartbeats))
         self.assertTrue(all(event["phase"] == "integrating" for event in heartbeats))
+        self.assertTrue(
+            all(event["acceptedStepSequence"] == 0 for event in heartbeats)
+        )
+        self.assertTrue(all(event["acceptedTime"] == 0.0 for event in heartbeats))
+        self.assertGreater(
+            len({event["activitySequence"] for event in heartbeats}),
+            1,
+        )
+        self.assertTrue(
+            all(event["activityKind"] == "rhs" for event in heartbeats)
+        )
         self.assertEqual(events[-1]["event"], "result")
+        self.assertEqual(events[-1]["activityKind"], "complete")
+        self.assertEqual(events[-1]["acceptedStepSequence"], 0)
+        self.assertEqual(events[-1]["rhsCallCount"], 4)
 
     def test_streaming_endpoint_returns_structured_validation_error(self) -> None:
         events = [