feat: add project-scoped operations

tests/unit/test_scada_repository.py

@@ -49,6 +49,32 @@ class _FakeConnection:
         return self.cursor_instance
 
 
+class _ReadingCursor:
+    def __init__(self, rows):
+        self.rows = rows
+        self.calls: list[tuple[str, tuple]] = []
+
+    async def __aenter__(self):
+        return self
+
+    async def __aexit__(self, exc_type, exc, tb):
+        return False
+
+    async def execute(self, query, params):
+        self.calls.append((str(query), params))
+
+    async def fetchall(self):
+        return self.rows
+
+
+class _ReadingConnection:
+    def __init__(self, rows):
+        self.cursor_instance = _ReadingCursor(rows)
+
+    def cursor(self):
+        return self.cursor_instance
+
+
 def test_update_scada_field_inserts_when_update_hits_no_rows():
     ScadaRepository = _load_scada_repository()
     conn = _FakeConnection(initial_rowcount=0)
@@ -114,3 +140,35 @@ def test_update_scada_field_batch_uses_one_set_based_statement():
         ["170490", "170491"],
         [26.5, 27.0],
     )
+
+
+def test_get_latest_scada_readings_uses_canonical_ids_and_one_bounded_query():
+    ScadaRepository = _load_scada_repository()
+    observed_at = datetime(2026, 10, 22, 1, 2, tzinfo=timezone.utc)
+    conn = _ReadingConnection([
+        {
+            "time": observed_at,
+            "device_id": "D-1",
+            "monitored_value": 0.31,
+            "cleaned_value": 0.3,
+        }
+    ])
+
+    result = asyncio.run(
+        ScadaRepository.get_latest_scada_readings(conn, ["D-1", "D-2"])
+    )
+
+    assert result["D-1"]["time"] == observed_at
+    assert len(conn.cursor_instance.calls) == 1
+    query, params = conn.cursor_instance.calls[0]
+    assert "DISTINCT ON (device_id)" in query
+    assert "ORDER BY device_id, time DESC" in query
+    assert params == (["D-1", "D-2"],)
+
+
+def test_get_latest_scada_readings_skips_database_for_empty_page():
+    ScadaRepository = _load_scada_repository()
+    conn = _ReadingConnection([])
+
+    assert asyncio.run(ScadaRepository.get_latest_scada_readings(conn, [])) == {}
+    assert conn.cursor_instance.calls == []