feat(scada): require complete authorized investigation evidence

tests/unit/test_mcp_query.py

@@ -774,6 +774,34 @@ def test_scada_catalog_default_100_paginates_without_changing_other_queries(runt
     assert TOOLS["list_elements"].model(context_handle=value.context_handle, element_type="pipe").limit == 20
 
 
+@pytest.mark.parametrize("complete", [False, True])
+def test_complete_scada_input_is_not_replaced_by_12kb_preview_but_details_stay_bounded(runtime, complete):
+    app, client, _, _ = runtime
+    value = binding()
+    data = {"devices": [{"device_id": f"D{index}", "node_id": f"J{index}", "description": "x" * 100}
+                        for index in range(168)],
+            "readings": [{"device_id": f"D{index}", "monitored_value": 20., "cleaned_value": 19.}
+                         for index in range(168)],
+            "coverage": {"mode": "all_scada", "query_complete": True, "queried_device_count": 168}}
+    assert len(json.dumps(data).encode()) > 12000
+    app.executor = AsyncMock(return_value=QueryResult(
+        source="query_scada_readings", source_ref="mcp:all-scada", queried_at=datetime.now(timezone.utc),
+        semantics="observed", data=data,
+    ))
+    arguments = {"context_handle": value.context_handle, "start": "2026-07-16T05:00:00+08:00",
+                 "end": "2026-07-16T08:00:00+08:00"}
+    if not complete:
+        arguments["device_ids"] = ["D1"]
+    response = request(client, "tools/call", {"name": "query_scada_readings", "arguments": arguments}).json()["result"]
+    if complete:
+        assert not response.get("isError"), response
+        assert response["structuredContent"]["data"] == data
+        assert response["structuredContent"]["truncated"] is False
+    else:
+        assert response["isError"] is True
+        assert response["structuredContent"]["error"]["code"] == "RESULT_TOO_LARGE"
+
+
 def test_business_skill_is_delivered_over_mcp_without_recording_event_evidence(runtime, monkeypatch):
     app, client, _, _ = runtime
     value = binding(task=True)