test: cover agent api base url suffix handling

tests/platform/test_agent_session.py

@@ -9,6 +9,18 @@ def test_lambda_agent_api_module_is_importable():
     assert AgentApi is not None
 
 
+def test_lambda_agent_api_preserves_base_url_path_suffix():
+    from sdk.upstream_agent_api import AgentApi
+
+    api = AgentApi(
+        agent_id="matrix-bot",
+        base_url="http://platform-agent:8000/proxy/",
+        chat_id="chat-7",
+    )
+
+    assert api.url == "http://platform-agent:8000/proxy/v1/agent_ws/chat-7/"
+
+
 def test_agent_session_module_is_intentionally_stubbed():
     contents = Path(__file__).resolve().parents[2] / "sdk" / "agent_session.py"