fix(sensor-placement): enforce project write boundaries

Bind every scheme request to ProjectContext, keep viewer access read-only, reject concurrent optimization jobs without blocking worker threads, and cap export/update payload sizes. Run optimization and workbook work off the event loop.

tests/api/test_sensor_placement_endpoints.py

@@ -81,8 +81,9 @@ def _load_module(monkeypatch):
     )
 
     class ProjectContext:
-        def __init__(self, project_code: str):
+        def __init__(self, project_code: str, project_role: str = "member"):
             self.project_code = project_code
+            self.project_role = project_role
 
     async def project_context():
         return ProjectContext("tjwater")
@@ -127,7 +128,7 @@ def _load_module(monkeypatch):
     )
 
 
-def _client(module, user=None):
+def _client(module, user=None, project_role="member"):
     app = build_test_app(module.router, "/api/v1")
     if user is None:
         user = SimpleNamespace(
@@ -137,7 +138,7 @@ def _client(module, user=None):
         )
     app.dependency_overrides[module.get_current_metadata_user] = lambda: user
     app.dependency_overrides[module.get_project_context] = lambda: (
-        module.ProjectContext("tjwater")
+        module.ProjectContext("tjwater", project_role)
     )
     return TestClient(app)
 
@@ -236,6 +237,73 @@ def test_optimize_rejects_unbounded_sensor_count(monkeypatch):
     assert response.status_code == 422
 
 
+def test_optimize_rejects_viewer_project_role(monkeypatch):
+    module = _load_module(monkeypatch)
+    response = _client(module, project_role="viewer").post(
+        "/api/v1/sensor-placement-schemes/optimize",
+        json={
+            "network": "tjwater",
+            "scheme_name": "只读成员方案",
+            "sensor_type": "pressure",
+            "method": "kmeans",
+            "sensor_count": 2,
+            "min_diameter": 300,
+        },
+    )
+
+    assert response.status_code == 403
+
+
+def test_project_owner_and_admin_can_optimize(monkeypatch):
+    module = _load_module(monkeypatch)
+    for project_role in ("owner", "admin"):
+        response = _client(module, project_role=project_role).post(
+            "/api/v1/sensor-placement-schemes/optimize",
+            json={
+                "network": "tjwater",
+                "scheme_name": f"{project_role}方案",
+                "sensor_type": "pressure",
+                "method": "kmeans",
+                "sensor_count": 2,
+                "min_diameter": 300,
+            },
+        )
+        assert response.status_code == 200
+
+
+def test_optimize_maps_running_project_job_to_409(monkeypatch):
+    module = _load_module(monkeypatch)
+
+    def conflict(**kwargs):
+        raise ConflictError("当前项目已有监测点优化任务正在运行，请稍后重试")
+
+    monkeypatch.setattr(module, "pressure_sensor_placement_kmeans", conflict)
+    response = _client(module).post(
+        "/api/v1/sensor-placement-schemes/optimize",
+        json={
+            "network": "tjwater",
+            "scheme_name": "并发方案",
+            "sensor_type": "pressure",
+            "method": "kmeans",
+            "sensor_count": 2,
+            "min_diameter": 300,
+        },
+    )
+
+    assert response.status_code == 409
+
+
+def test_viewer_reads_scheme_as_non_editable(monkeypatch):
+    module = _load_module(monkeypatch)
+    response = _client(module, project_role="viewer").get(
+        "/api/v1/sensor-placement-schemes/7",
+        params={"network": "tjwater"},
+    )
+
+    assert response.status_code == 200
+    assert response.json()["can_edit"] is False
+
+
 def test_update_rejects_non_owner(monkeypatch):
     module = _load_module(monkeypatch)
     response = _client(
@@ -253,6 +321,20 @@ def test_update_rejects_non_owner(monkeypatch):
     assert response.status_code == 403
 
 
+def test_update_rejects_owner_with_viewer_project_role(monkeypatch):
+    module = _load_module(monkeypatch)
+    response = _client(module, project_role="viewer").put(
+        "/api/v1/sensor-placement-schemes/7",
+        params={"network": "tjwater"},
+        json={
+            "expected_sensor_location": ["J1", "J2"],
+            "sensor_location": ["J1", "J3"],
+        },
+    )
+
+    assert response.status_code == 403
+
+
 def test_admin_can_overwrite_scheme(monkeypatch):
     module = _load_module(monkeypatch)
     response = _client(