feat: add node coverage and improve investigation presentation

tests/unit/test_investigation_diagram_status.py

@@ -37,6 +37,18 @@ def test_unknown_node_state_is_rejected():
         InvestigationDiagramNodeRef(node_id="A", label="查询", status="blocked")
 
 
+def test_class_attached_nodes_are_valid_declarations_without_accepting_partial_ids():
+    payload = {"request_id": uuid4(), "source_session_id": "session-1", "progress": {
+        "summary": "核查", "diagram": {"title": "路线", "mermaid": "flowchart TD\nQUERY:::running --> REVIEW:::pending",
+            "node_refs": [{"node_id": "QUERY", "label": "核查", "status": "running"},
+                          {"node_id": "REVIEW", "label": "复核", "status": "pending"}]},
+    }}
+    assert AgentArtifactsCommand.model_validate(payload).progress.diagram.node_refs[0].status == "running"
+    payload["progress"]["diagram"]["node_refs"][0]["node_id"] = "QUER"
+    with pytest.raises(ValidationError, match="QUER"):
+        AgentArtifactsCommand.model_validate(payload)
+
+
 @pytest.mark.parametrize("artifact", ["progress", "report"])
 def test_artifact_write_rejects_node_refs_missing_from_mermaid(artifact):
     diagram = {