fix(isolation): distinguish accident links from same-numbered nodes

Prefer link endpoints for legacy accident IDs and allow explicit node selection. Read authoritative initial statuses and sources, verify source isolation, and separate direct isolation from newly disconnected supply nodes. Return validation errors as HTTP 422.

The node-first lookup misrouted adjacent Fengyang pipes 19025 and 19026 into unrelated regions. Regression cases fail against the previous algorithm and pass after this change.

app/algorithms/valve_isolation/topology_search.py

@@ -1,10 +1,11 @@
 """Topology-only valve isolation search."""
 
 from collections import defaultdict, deque
-from typing import Any, Iterable
+from typing import Any, Iterable, Literal
 
 
 VALVE_LINK_TYPE = "valve"
+AccidentElementType = Literal["auto", "link", "node"]
 
 
 def _parse_link_entry(link_entry: str) -> tuple[str, str, str, str]:
@@ -14,12 +15,37 @@ def _parse_link_entry(link_entry: str) -> tuple[str, str, str, str]:
     return parts[0], parts[1], parts[2], parts[3]
 
 
+def _reachable_nodes(
+    adjacency: dict[str, list[tuple[str, str]]],
+    start_nodes: Iterable[str],
+    blocked_links: set[str],
+) -> set[str]:
+    visited = set(start_nodes)
+    queue = deque(visited)
+    while queue:
+        for neighbor, link_id in adjacency.get(queue.popleft(), ()):
+            if link_id not in blocked_links and neighbor not in visited:
+                visited.add(neighbor)
+                queue.append(neighbor)
+    return visited
+
+
 def valve_isolation_analysis(
     link_entries: Iterable[str],
     accident_elements: str | list[str],
     disabled_valves: list[str] | None = None,
+    *,
+    accident_element_type: AccidentElementType = "auto",
+    water_source_nodes: Iterable[str] | None = None,
+    closed_links: Iterable[str] = (),
 ) -> dict[str, Any]:
-    """Determine boundary valves and affected nodes from a topology snapshot."""
+    """Find nearest valve boundaries, then check source connectivity.
+
+    Legacy untyped IDs prefer links; explicit node mode handles cross-type ID
+    collisions. Supply impact is a before/after connectivity difference, not
+    a hydraulic pressure or demand calculation. Without source metadata only
+    the provisional boundary search is available.
+    """
 
     disabled_valves_set = set(disabled_valves or [])
     target_elements = (
@@ -27,8 +53,13 @@ def valve_isolation_analysis(
         if isinstance(accident_elements, str)
         else accident_elements
     )
+    if not target_elements:
+        raise ValueError("At least one accident element is required")
+    if accident_element_type not in {"auto", "link", "node"}:
+        raise ValueError(f"Invalid accident element type: {accident_element_type}")
+    closed_links_set = set(closed_links)
 
-    pipe_adj: dict[str, set[str]] = defaultdict(set)
+    adjacency: dict[str, list[tuple[str, str]]] = defaultdict(list)
     all_valves: dict[str, tuple[str, str]] = {}
     link_lookup: dict[str, tuple[str, str, str]] = {}
     node_set: set[str] = set()
@@ -39,46 +70,31 @@ def valve_isolation_analysis(
         node_set.update((node1, node2))
         if link_type_name == VALVE_LINK_TYPE:
             all_valves[link_id] = (node1, node2)
-        else:
+        if link_id not in closed_links_set:
-            pipe_adj[node1].add(node2)
+            adjacency[node1].append((node2, link_id))
-            pipe_adj[node2].add(node1)
+            adjacency[node2].append((node1, link_id))
+
+    unknown_disabled = disabled_valves_set - all_valves.keys()
+    if unknown_disabled:
+        raise ValueError(f"Disabled valve was not found in topology: {sorted(unknown_disabled)}")
 
     start_nodes: set[str] = set()
     for element in target_elements:
-        if element in node_set:
+        if accident_element_type != "node" and element in link_lookup:
-            start_nodes.add(element)
-        elif element in link_lookup:
             node1, node2, _ = link_lookup[element]
             start_nodes.update((node1, node2))
+        elif accident_element_type != "link" and element in node_set:
+            start_nodes.add(element)
         else:
             raise ValueError(f"Accident element {element} was not found in topology")
 
-    extra_adj: dict[str, list[str]] = defaultdict(list)
+    closable_valves = set(all_valves) - disabled_valves_set - closed_links_set
-    boundary_valves: dict[str, tuple[str, str]] = {}
+    affected_nodes = _reachable_nodes(adjacency, start_nodes, closable_valves)
-    for valve_id, (node1, node2) in all_valves.items():
-        if valve_id in disabled_valves_set:
-            extra_adj[node1].append(node2)
-            extra_adj[node2].append(node1)
-        else:
-            boundary_valves[valve_id] = (node1, node2)
-
-    affected_nodes: set[str] = set()
-    queue = deque(start_nodes)
-    while queue:
-        node = queue.popleft()
-        if node in affected_nodes:
-            continue
-        affected_nodes.add(node)
-        queue.extend(pipe_adj.get(node, set()) - affected_nodes)
-        queue.extend(
-            neighbor
-            for neighbor in extra_adj.get(node, ())
-            if neighbor not in affected_nodes
-        )
 
     must_close_valves: list[str] = []
     optional_valves: list[str] = []
-    for valve_id, (node1, node2) in boundary_valves.items():
+    for valve_id in closable_valves:
+        node1, node2 = all_valves[valve_id]
         node1_affected = node1 in affected_nodes
         node2_affected = node2 in affected_nodes
         if node1_affected and node2_affected:
@@ -89,14 +105,37 @@ def valve_isolation_analysis(
     must_close_valves.sort()
     optional_valves.sort()
     isolatable = bool(must_close_valves)
+    failure_reason = None if isolatable else "no_boundary_valves"
+    sources = set(water_source_nodes or ())
+    source_check_performed = bool(sources)
+    supply_affected_nodes = None
+    if water_source_nodes is not None:
+        if not sources:
+            isolatable = False
+            failure_reason = "water_sources_unavailable"
+        else:
+            after_closure = _reachable_nodes(adjacency, sources, set(must_close_valves))
+            if affected_nodes & after_closure:
+                isolatable = False
+                failure_reason = "connected_to_water_source"
+            if isolatable:
+                before_closure = _reachable_nodes(adjacency, sources, set())
+                supply_affected_nodes = sorted(before_closure - after_closure)
     result: dict[str, Any] = {
         "accident_elements": target_elements,
+        "accident_element_type": accident_element_type,
         "disabled_valves": disabled_valves,
         "affected_nodes": sorted(affected_nodes) if isolatable else [],
         "affected_node_count": len(affected_nodes),
         "must_close_valves": must_close_valves,
         "optional_valves": optional_valves,
         "isolatable": isolatable,
+        "source_check_performed": source_check_performed,
+        "isolation_failure_reason": failure_reason,
+        "supply_affected_nodes": supply_affected_nodes,
+        "supply_affected_node_count": (
+            len(supply_affected_nodes) if supply_affected_nodes is not None else None
+        ),
     }
     if len(target_elements) == 1:
         result["accident_element"] = target_elements[0]

app/api/v1/endpoints/simulation.py

@@ -180,6 +180,9 @@ def valve_isolation_endpoint(
     network: str = Query(..., description="管网名称（或数据库名称）"),
     accident_element: List[str] = Query(..., description="发生事故的管段/节点ID列表"),
     disabled_valves: List[str] = Query(None, description="已故障的阀门ID列表（可选）"),
+    accident_element_type: Literal["auto", "link", "node"] = Query(
+        "auto", description="事故要素类型；auto优先管段再节点；分析同名节点须指定node，纯管段分析可指定link",
+    ),
 ):
     """
     阀门隔离分析
@@ -187,13 +190,19 @@ def valve_isolation_endpoint(
     - **network**: 管网名称（或数据库名称）
     - **accident_element**: 发生事故的管段/节点ID列表
     - **disabled_valves**: 已故障的阀门ID列表（可选）
+    - **accident_element_type**: auto优先管段；link仅匹配管段；node仅匹配节点
     
     返回隔离方案，包括：
     - must_close_valves: 必须关闭的阀门列表
     - optional_valves: 可选关闭的阀门列表
-    - affected_nodes: 受影响的节点列表；不可隔离时为空列表
+    - affected_nodes / affected_node_count: 最近阀门围成的直接隔离区；不可隔离时列表为空，计数保留
-    - affected_node_count: 受影响的节点总数
+    - supply_affected_nodes / supply_affected_node_count: 按建议关阀后新增失去水源连接的节点；未验证或不可隔离时为null
-    - isolatable: 是否可以有效隔离
+    - source_check_performed: 是否已执行水源连通检查
+    - isolation_failure_reason: 不可隔离原因；可隔离时为null
+    - isolatable: 存在关阀边界，且直接隔离区不再连通任何水源
+
+    使用模型初始开关状态进行无向拓扑分析，水池按潜在水源处理。
+    不包含时变控制、水池蓄水量或压力流量计算，不是现场停水范围的水力证明。
     """
     # result = {
     #     "accident_element": "P461309",
@@ -212,7 +221,13 @@ def valve_isolation_endpoint(
     #     "must_close_valves": ["210521658", "V12974", "V12986", "V12993"],
     #     "optional_valves": [],
     # }
-    result = analyze_valve_isolation(network, accident_element, disabled_valves)
+    try:
+        result = analyze_valve_isolation(
+            network, accident_element, disabled_valves,
+            accident_element_type=accident_element_type,
+        )
+    except ValueError as exc:
+        raise HTTPException(status_code=422, detail=str(exc)) from exc
     return result
 
 

app/native/wndb/gis/network_views.py

@@ -1,4 +1,4 @@
-"""Read-only projections backed by the GIS materialized-view query layer."""
+"""Read-only GIS projections and authoritative network topology snapshots."""
 
 from typing import Any
 
@@ -69,6 +69,46 @@ def get_network_link_nodes(name: str) -> list[str]:
     ]
 
 
+def get_valve_isolation_topology(name: str) -> tuple[list[str], list[str], list[str]]:
+    """Read links, closed statuses and sources from one consistent SQL snapshot.
+
+    Isolation must include model links without published geometries, and use
+    initial statuses rather than treating every link as open. UNION ALL keeps
+    source nodes in the same statement snapshot without repeating them for
+    every link or relying on materialized view refresh timing.
+    """
+    rows = read_all(
+        name,
+        """
+        SELECT l.id, l.link_type::text AS element_type,
+               l.start_node_id, l.end_node_id,
+               COALESCE(s.status::text, p.status::text) AS status
+        FROM network.links AS l
+        LEFT JOIN network.pipes AS p ON p.link_id = l.id
+        LEFT JOIN network.link_initial_settings AS s ON s.link_id = l.id
+        UNION ALL
+        SELECT n.id, n.node_type::text AS element_type,
+               NULL, NULL, NULL
+        FROM network.nodes AS n
+        WHERE n.node_type::text IN ('reservoir', 'tank')
+        """,
+    )
+    link_entries: list[str] = []
+    source_nodes: list[str] = []
+    closed_links: list[str] = []
+    for row in rows:
+        element_id = str(row["id"])
+        if row["element_type"] in {"reservoir", "tank"}:
+            source_nodes.append(element_id)
+        else:
+            link_entries.append(
+                f"{element_id}:{row['element_type']}:{row['start_node_id']}:{row['end_node_id']}"
+            )
+            if row["status"] == "CLOSED":
+                closed_links.append(element_id)
+    return link_entries, source_nodes, closed_links
+
+
 def get_major_pipe_nodes(name: str, diameter: int) -> list[str]:
     """Return large pipes in the established API wire format."""
     rows = read_all(

app/services/valve_isolation.py

@@ -1,13 +1,22 @@
 from typing import Any
 
-from app.algorithms.valve_isolation.topology_search import valve_isolation_analysis
+from app.algorithms.valve_isolation.topology_search import (
-from app.native.wndb.gis.network_views import get_network_link_nodes
+    AccidentElementType,
+    valve_isolation_analysis,
+)
+from app.native.wndb.gis.network_views import get_valve_isolation_topology
 
 
 def analyze_valve_isolation(
     network: str,
     accident_element: str | list[str],
-    disabled_valves: list[str] = None,
+    disabled_valves: list[str] | None = None,
+    accident_element_type: AccidentElementType = "auto",
 ) -> dict[str, Any]:
-    link_entries = get_network_link_nodes(network)
+    link_entries, source_nodes, closed_links = get_valve_isolation_topology(network)
-    return valve_isolation_analysis(link_entries, accident_element, disabled_valves)
+    return valve_isolation_analysis(
+        link_entries, accident_element, disabled_valves,
+        accident_element_type=accident_element_type,
+        water_source_nodes=source_nodes,
+        closed_links=closed_links,
+    )

contracts/manifest.json

@@ -3,7 +3,7 @@
   "contracts": {
     "server": {
       "file": "server-v1.openapi.json",
-      "sha256": "b565d841061c9091f48ff3118bcc0cbb1b918b0cb8c2316d177570e8b2d8ba29"
+      "sha256": "5b8ec0b469f1194e72214003a9cf427489f48de19ae31ee6492821cf64916b6d"
     }
   }
 }

contracts/server-v1.openapi.json

@@ -35969,6 +35969,23 @@
               "type": "array"
             }
           },
+          {
+            "description": "事故要素类型；auto优先管段再节点；分析同名节点须指定node，纯管段分析可指定link",
+            "in": "query",
+            "name": "accident_element_type",
+            "required": false,
+            "schema": {
+              "default": "auto",
+              "description": "事故要素类型；auto优先管段再节点；分析同名节点须指定node，纯管段分析可指定link",
+              "enum": [
+                "auto",
+                "link",
+                "node"
+              ],
+              "title": "Accident Element Type",
+              "type": "string"
+            }
+          },
           {
             "in": "header",
             "name": "X-Project-Id",

tests/api/test_openapi_contract.py

@@ -254,14 +254,16 @@ def test_committed_write_refresh_failure_has_explicit_http_contract() -> None:
     assert response.json()["code"] == "materialized_view_refresh_failed_after_commit"
 
 
-def test_valve_isolation_runtime_accepts_frontend_query(monkeypatch) -> None:
+@pytest.mark.parametrize("element_type", ["auto", "link", "node"])
+def test_valve_isolation_runtime_accepts_frontend_query(monkeypatch, element_type) -> None:
     captured: dict[str, object] = {}
 
-    def fake_analyze_valve_isolation(network, accident_element, disabled_valves):
+    def fake_analyze_valve_isolation(network, accident_element, disabled_valves, accident_element_type):
         captured.update(
             network=network,
             accident_element=accident_element,
             disabled_valves=disabled_valves,
+            accident_element_type=accident_element_type,
             business_dsn=get_project_pgconn_string(network),
             timescale_dsn=get_project_timescale_pgconn_string(network),
         )
@@ -288,6 +290,7 @@ def test_valve_isolation_runtime_accepts_frontend_query(monkeypatch) -> None:
             ("accident_element", "P-1"),
             ("accident_element", "P-2"),
             ("disabled_valves", "V-9"),
+            *([] if element_type == "auto" else [("accident_element_type", element_type)]),
         ],
     )
 
@@ -297,11 +300,39 @@ def test_valve_isolation_runtime_accepts_frontend_query(monkeypatch) -> None:
         "network": "fengyang",
         "accident_element": ["P-1", "P-2"],
         "disabled_valves": ["V-9"],
+        "accident_element_type": element_type,
         "business_dsn": "postgresql://user:password@biz/fengyang",
         "timescale_dsn": "postgresql://user:password@timescale/fengyang",
     }
 
 
+@pytest.mark.parametrize(
+    "target,disabled,detail",
+    [("P", "typo", "Disabled valve"), ("missing", "V", "Accident element")],
+)
+def test_valve_isolation_invalid_ids_return_validation_error(monkeypatch, target, disabled, detail):
+    from app.services import valve_isolation as service
+
+    monkeypatch.setattr(
+        service, "get_valve_isolation_topology",
+        lambda _network: (["P:pipe:A:B", "V:valve:B:R"], ["R"], []),
+    )
+    monkeypatch.setattr(simulation_endpoint, "analyze_valve_isolation", service.analyze_valve_isolation)
+    app = FastAPI()
+    app.include_router(api_router, prefix="/api/v1")
+    _override_project_routing(app, ProjectContext(
+        project_id=uuid4(), project_code="project", user_id=uuid4(), project_role="member",
+    ))
+
+    response = TestClient(app, raise_server_exceptions=False).post(
+        "/api/v1/valve-isolation-analyses",
+        params={"accident_element": target, "disabled_valves": disabled},
+    )
+
+    assert response.status_code == 422
+    assert detail in response.json()["detail"]
+
+
 def test_scada_cleaning_runs_are_post() -> None:
     methods_by_path = {
         route.path: route.methods

tests/unit/test_valve_isolation.py

@@ -1,3 +1,5 @@
+import pytest
+
 from app.algorithms.valve_isolation import topology_search as valve
 
 
@@ -23,6 +25,183 @@ def test_isolatable_keeps_affected_node_ids_and_count():
     assert result["must_close_valves"] == ["V-close"]
 
 
+@pytest.fixture
+def colliding_topology():
+    # The reported adjacent pipes and their same-numbered nodes are in
+    # different valve-bounded regions. Keep this fixture independent of a DB.
+    return [
+        "19025:pipe:17038:17037",
+        "19026:pipe:17038:17039",
+        "AUTO_TCV_4:valve:17037:D",
+        "AUTO_TCV_5:valve:17039:E",
+        "AUTO_TCV_546:valve:17038:R",
+        "32252:pipe:19025:X",
+        "15383:pipe:19026:Y",
+        "V-wrong-25:valve:X:R",
+        "V-wrong-26:valve:Y:R",
+    ]
+
+
+@pytest.mark.parametrize("target", ["19025", "19026", ["19025", "19026"]])
+def test_adjacent_pipes_take_priority_over_same_numbered_nodes(colliding_topology, target):
+    result = valve.valve_isolation_analysis(colliding_topology, target)
+
+    assert result["affected_nodes"] == ["17037", "17038", "17039"]
+    assert result["must_close_valves"] == ["AUTO_TCV_4", "AUTO_TCV_5", "AUTO_TCV_546"]
+    assert result["optional_valves"] == []
+
+
+def test_explicit_node_type_resolves_the_other_side_of_an_id_collision(colliding_topology):
+    result = valve.valve_isolation_analysis(
+        colliding_topology, "19025", accident_element_type="node",
+    )
+
+    assert result["affected_nodes"] == ["19025", "X"]
+    assert result["must_close_valves"] == ["V-wrong-25"]
+
+
+def test_unambiguous_legacy_node_input_still_works():
+    result = valve.valve_isolation_analysis(["P:pipe:A:B", "V:valve:B:R"], "A")
+    assert result["affected_nodes"] == ["A", "B"]
+
+
+def test_explicit_link_type_does_not_fall_back_to_a_node():
+    with pytest.raises(ValueError, match="not found"):
+        valve.valve_isolation_analysis(
+            ["P:pipe:A:B"], "A", accident_element_type="link",
+        )
+
+
+def test_a_boundary_valve_does_not_prove_source_isolation():
+    result = valve.valve_isolation_analysis(
+        ["P:pipe:R:A", "V:valve:A:B"], "P", water_source_nodes=["R"],
+    )
+
+    assert result["isolatable"] is False
+    assert result["source_check_performed"] is True
+    assert result["isolation_failure_reason"] == "connected_to_water_source"
+    assert result["affected_nodes"] == []
+    assert result["affected_node_count"] == 2
+    assert result["supply_affected_nodes"] is None
+
+
+def test_supply_impact_includes_downstream_regions_but_not_preexisting_outages():
+    links = [
+        "P:pipe:A:B", "V-source:valve:A:R", "V-downstream:valve:B:C",
+        "P-downstream:pipe:C:D", "P-already-off:pipe:X:Y",
+    ]
+    result = valve.valve_isolation_analysis(links, "P", water_source_nodes=["R"])
+
+    assert result["isolatable"] is True
+    assert result["source_check_performed"] is True
+    assert result["affected_nodes"] == ["A", "B"]
+    assert result["affected_node_count"] == 2
+    assert result["supply_affected_nodes"] == ["A", "B", "C", "D"]
+    assert result["supply_affected_node_count"] == 4
+
+
+def test_closed_links_are_not_traversed_or_recommended_for_closure():
+    result = valve.valve_isolation_analysis(
+        ["P:pipe:A:B", "P-closed:pipe:B:R", "V:valve:A:R", "V-closed:valve:B:C"],
+        "P", water_source_nodes=["R"], closed_links=["P-closed", "V-closed"],
+    )
+
+    assert result["isolatable"] is True
+    assert result["affected_nodes"] == ["A", "B"]
+    assert result["must_close_valves"] == ["V"]
+    assert result["supply_affected_nodes"] == ["A", "B"]
+
+
+def test_disabled_valve_cannot_cut_the_source_path():
+    result = valve.valve_isolation_analysis(
+        ["P:pipe:A:B", "V-disabled:valve:A:R", "V-other:valve:B:C"],
+        "P", disabled_valves=["V-disabled"], water_source_nodes=["R"],
+    )
+
+    assert result["isolatable"] is False
+    assert result["isolation_failure_reason"] == "connected_to_water_source"
+
+
+def test_joint_accidents_fail_if_any_region_remains_connected_to_a_source():
+    result = valve.valve_isolation_analysis(
+        ["P1:pipe:A:B", "V1:valve:B:R", "P2:pipe:R:C", "V2:valve:C:D"],
+        ["P1", "P2"], water_source_nodes=["R"],
+    )
+    assert result["isolatable"] is False
+
+
+def test_missing_sources_do_not_claim_verified_isolation():
+    result = valve.valve_isolation_analysis(
+        ["P:pipe:A:B", "V:valve:B:C"], "P", water_source_nodes=[],
+    )
+    assert result["isolatable"] is False
+    assert result["source_check_performed"] is False
+    assert result["isolation_failure_reason"] == "water_sources_unavailable"
+    assert result["supply_affected_node_count"] is None
+
+
+@pytest.mark.parametrize("sources", [["R1"], ["R1", "R2"]])
+def test_all_water_sources_are_considered(sources):
+    result = valve.valve_isolation_analysis(
+        ["P:pipe:A:B", "V:valve:A:R1", "P2:pipe:B:R2"],
+        "P", water_source_nodes=sources,
+    )
+    assert result["isolatable"] is (len(sources) == 1)
+
+
+def test_empty_targets_are_rejected():
+    with pytest.raises(ValueError, match="At least one"):
+        valve.valve_isolation_analysis(["P:pipe:A:B"], [])
+
+
+def test_unknown_disabled_valve_is_rejected():
+    with pytest.raises(ValueError, match="Disabled valve"):
+        valve.valve_isolation_analysis(["P:pipe:A:B"], "P", disabled_valves=["typo"])
+
+
+def test_service_passes_authoritative_sources_statuses_and_element_type(monkeypatch):
+    from app.services import valve_isolation as service
+
+    projects = []
+
+    def snapshot(network):
+        projects.append(network)
+        return (
+            ["P:pipe:A:B", "P-closed:pipe:B:R", "V:valve:A:R"],
+            ["R"], ["P-closed"],
+        )
+
+    monkeypatch.setattr(service, "get_valve_isolation_topology", snapshot)
+    result = service.analyze_valve_isolation(
+        "trusted-project", ["A"], accident_element_type="node",
+    )
+
+    assert projects == ["trusted-project"]
+    assert result["isolatable"] is True
+    assert result["source_check_performed"] is True
+    assert result["must_close_valves"] == ["V"]
+    assert result["supply_affected_nodes"] == ["A", "B"]
+
+
+def test_parallel_links_preserve_an_open_bypass():
+    result = valve.valve_isolation_analysis(
+        ["P:pipe:A:B", "V:valve:B:R", "P-bypass:pipe:B:R"],
+        "P", water_source_nodes=["R"],
+    )
+    assert result["isolatable"] is False
+    assert result["isolation_failure_reason"] == "connected_to_water_source"
+
+
+def test_closed_disabled_valve_does_not_reopen_a_known_closed_link():
+    result = valve.valve_isolation_analysis(
+        ["P:pipe:A:B", "V:valve:B:R", "V-disabled:valve:A:R"],
+        "P", disabled_valves=["V-disabled"], closed_links=["V-disabled"],
+        water_source_nodes=["R"],
+    )
+    assert result["isolatable"] is True
+    assert result["must_close_valves"] == ["V"]
+
+
 def test_disabled_valve_expands_affected_area_before_counting():
     links = [
         "P-1:pipe:A:B",

tests/unit/test_wndb_network_views.py

@@ -52,6 +52,36 @@ def test_network_link_nodes_use_one_unified_view_query(monkeypatch) -> None:
     assert "FROM gis.network_links" in calls[0][1]
 
 
+def test_isolation_snapshot_reads_authoritative_links_statuses_and_sources_once(monkeypatch):
+    calls = []
+
+    def fake_read_all(name, statement, params=None):
+        calls.append((name, statement, params))
+        return [
+            {"id": "P", "element_type": "pipe", "start_node_id": "A", "end_node_id": "B", "status": None},
+            {"id": "P-closed", "element_type": "pipe", "start_node_id": "A", "end_node_id": "R", "status": "CLOSED"},
+            {"id": "V", "element_type": "valve", "start_node_id": "B", "end_node_id": "R", "status": "CLOSED"},
+            {"id": "PU", "element_type": "pump", "start_node_id": "T", "end_node_id": "A", "status": "CLOSED"},
+            {"id": "R", "element_type": "reservoir", "start_node_id": None, "end_node_id": None, "status": None},
+            {"id": "T", "element_type": "tank", "start_node_id": None, "end_node_id": None, "status": None},
+        ]
+
+    monkeypatch.setattr(network_views, "read_all", fake_read_all)
+
+    assert network_views.get_valve_isolation_topology("project_a") == (
+        ["P:pipe:A:B", "P-closed:pipe:A:R", "V:valve:B:R", "PU:pump:T:A"],
+        ["R", "T"], ["P-closed", "V", "PU"],
+    )
+    assert len(calls) == 1
+    name, statement, _params = calls[0]
+    assert name == "project_a"
+    assert "FROM network.links" in statement
+    assert "network.link_initial_settings" in statement
+    assert "COALESCE(s.status::text, p.status::text)" in statement
+    assert "FROM network.nodes" in statement
+    assert "UNION ALL" in statement
+
+
 def test_topology_rows_are_loaded_in_two_batch_queries(monkeypatch) -> None:
     calls = []
     responses = [