fix(agent): preserve string blocks in visualization routing context

apps/agent/src/visualization_router.py

@@ -81,9 +81,9 @@ def message_text(message) -> str:
         return content
     if isinstance(content, list):
         return "\n".join(
-            b.get("text", "")
+            b if isinstance(b, str) else b["text"]
             for b in content
-            if isinstance(b, dict) and isinstance(b.get("text"), str)
+            if isinstance(b, str) or (isinstance(b, dict) and isinstance(b.get("text"), str))
         )
     return ""
 

apps/agent/tests/test_router_text_blocks_regression.py

@@ -0,0 +1,19 @@
+from langchain_core.messages import AIMessage, HumanMessage
+
+from src.visualization_router import message_text, routing_input
+
+
+def test_plain_text_blocks_keep_the_latest_user_request():
+    message = HumanMessage(content=["Compare these cities", {"type": "text", "text": "using a table"}])
+    assert message_text(message) == "Compare these cities\nusing a table"
+    _, context = routing_input({"messages": [message]})
+    assert context == [{"role": "human", "content": "Compare these cities\nusing a table"}]
+
+
+def test_nontext_blocks_remain_excluded_and_text_order_is_preserved():
+    message = AIMessage(content=[
+        {"type": "text", "text": "First"},
+        {"type": "image_url", "image_url": {"url": "https://example.test/image.png"}},
+        "Last",
+    ])
+    assert message_text(message) == "First\nLast"