fix(simulation): export ACTIVE valves correctly for EPANET 2

The legacy online simulation path still exported internal ACTIVE states as STATUS keywords, which EPANET 2 rejects. Preserve numeric settings and EPANET 3 output while passing the format through both exporters. Surface the original engine error inside the model transaction so failed runs roll back before result storage.

Regression guard: six failures reproduced on the deployed baseline, including native input validation. All 34 focused export, service and endpoint checks pass after the fix; the real project also returns native node and link results.

tests/unit/test_analysis_simulation.py

@@ -277,3 +277,51 @@ def test_extended_simulation_marks_run_failed_when_result_storage_fails(monkeypa
         )
 
     assert [call[1]["status"] for call in lifecycle_calls] == ["failed"]
+
+
+@pytest.mark.parametrize("has_output", [False, True])
+def test_engine_failure_preserves_report_and_rolls_back_model_changes(monkeypatch, has_output):
+    from app.services import simulation
+
+    transaction_outcome = []
+
+    @contextmanager
+    def project_transaction(_name):
+        try:
+            yield
+        except Exception:
+            transaction_outcome.append("rollback")
+            raise
+        else:
+            transaction_outcome.append("commit")
+
+    monkeypatch.setattr(simulation, "project_transaction", project_transaction)
+    monkeypatch.setattr(simulation, "get_time", lambda _: {
+        "HYDRAULIC TIMESTEP": "0:15:00",
+        "DURATION": "0:00",
+        "PATTERN START": "0:00",
+    })
+    monkeypatch.setattr(simulation, "set_time", lambda *_: None)
+    result = {
+        "simulation_result": "failed",
+        "report": "EPANET report\n  Error 202: illegal numeric value ACTIVE in [STATUS] section:\n  V1 ACTIVE\n",
+    }
+    if has_output:
+        result["output"] = {"node_results": [], "link_results": [], "times": {"num_periods": 1}}
+    monkeypatch.setattr(simulation, "run_project", lambda _: json.dumps(result))
+    refresh = Mock()
+    store = Mock()
+    monkeypatch.setattr(simulation, "refresh_materialized_views_after_commit", refresh)
+    monkeypatch.setattr(simulation.TimescaleInternalStorage, "store_realtime_simulation", store)
+
+    with pytest.raises(RuntimeError, match="EPANET.*Error 202"):
+        simulation.run_simulation(
+            name="demo",
+            simulation_type="realtime",
+            modify_pattern_start_time="2026-07-30T04:30:00Z",
+            scada_mappings=_empty_scada_mappings(simulation),
+        )
+
+    assert transaction_outcome == ["rollback"]
+    refresh.assert_not_called()
+    store.assert_not_called()

tests/unit/test_epanet_status_export.py

@@ -0,0 +1,70 @@
+import ctypes
+import platform
+from pathlib import Path
+
+import pytest
+
+from app.native.wndb.model import status
+
+
+def test_epanet2_preserves_valve_setting_without_emitting_active(monkeypatch):
+    monkeypatch.setattr(status, "read_all", lambda *_: [
+        {"link": "V1", "status": "ACTIVE", "setting": None},
+        {"link": "V2", "status": "ACTIVE", "setting": 2.5},
+        {"link": "V3", "status": "CLOSED", "setting": None},
+        {"link": "P1", "status": "OPEN", "setting": 0},
+    ])
+    assert status.inp_out_status("model") == ["V2 2.5", "V3 CLOSED", "P1 OPEN", "P1 0"]
+
+
+def test_epanet3_retains_explicit_active_status(monkeypatch):
+    monkeypatch.setattr(status, "read_all", lambda *_: [
+        {"link": "V1", "status": "ACTIVE", "setting": 100},
+    ])
+    assert status.inp_out_status("model", version="3") == ["V1 ACTIVE", "V1 100"]
+
+
+@pytest.mark.parametrize("version", ["2", "3"])
+def test_file_and_text_exporters_forward_the_selected_format(monkeypatch, tmp_path, version):
+    from app.native.wndb.inp import exporter
+
+    monkeypatch.setattr(exporter, "have_project", lambda _: True)
+    monkeypatch.setattr(exporter, "section_name", [exporter.STATUS])
+    monkeypatch.setattr(exporter, "section_names_for_epanetv2", [exporter.STATUS])
+    monkeypatch.setattr(status, "read_all", lambda *_: [
+        {"link": "V1", "status": "ACTIVE", "setting": 100},
+    ])
+    path = tmp_path / "model.inp"
+    exporter.dump_inp("model", str(path), version)
+    text = exporter.export_inp("model", version).operations[0]["inp"]
+    assert "V1 100" in path.read_text() and "V1 100" in text
+    assert ("V1 ACTIVE" in path.read_text()) == (version == "3")
+    assert ("V1 ACTIVE" in text) == (version == "3")
+
+
+def test_exported_active_valve_passes_bundled_epanet2_input_validation(monkeypatch, tmp_path):
+    library = Path(__file__).resolve().parents[2] / "app/infra/epanet/linux/libepanet2.so"
+    if platform.system() != "Linux" or not library.exists():
+        pytest.skip("Bundled Linux EPANET library is unavailable")
+    monkeypatch.setattr(status, "read_all", lambda *_: [
+        {"link": "V1", "status": "ACTIVE", "setting": None},
+    ])
+    inp = tmp_path / "valve.inp"
+    inp.write_text(
+        "[JUNCTIONS]\nJ1 0 1\nJ2 0 1\n[RESERVOIRS]\nR1 100\n"
+        "[PIPES]\nP1 R1 J1 100 300 100 0 OPEN\n"
+        "[VALVES]\nV1 J1 J2 600 TCV 100 0\n[STATUS]\n"
+        + "\n".join(status.inp_out_status("model"))
+        + "\n[OPTIONS]\nUNITS LPS\n[END]\n"
+    )
+    lib = ctypes.CDLL(str(library))
+    lib.EN_createproject.argtypes = [ctypes.POINTER(ctypes.c_void_p)]
+    lib.EN_open.argtypes = [ctypes.c_void_p, ctypes.c_char_p, ctypes.c_char_p, ctypes.c_char_p]
+    lib.EN_deleteproject.argtypes = [ctypes.c_void_p]
+    handle = ctypes.c_void_p()
+    assert lib.EN_createproject(ctypes.byref(handle)) == 0
+    try:
+        code = lib.EN_open(handle, str(inp).encode(), str(tmp_path / "valve.rpt").encode(), b"")
+        assert code == 0
+    finally:
+        lib.EN_deleteproject(handle)