test: cover agent api base url suffix handling

README.md

@@ -148,7 +148,7 @@ Matrix бот подключается к `platform-agent` по service name, а
 На `2026-04-21` локальный compose runtime использует vendored upstream-версии платформы без локальных патчей:
 
 - `platform-agent`: `5e7c2df954cc3cd2f5bf8ae688e10a20038dde61`
-- `platform-agent_api`: `aa480bbec5bbf8e006284dd03aed1c2754e9bbee`
+- `platform-agent_api`: `8a4f4db6d36786fe8af7feefffe506d4a54ac6bd`
 
 ### 4. Staged attachments в Matrix
 

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"