core/agent: surface openai responses stream error events

src/plyngent/agent/responses_dispatch.py

@@ -62,6 +62,12 @@ async def _stream_as_chat_chunks(
     final: ResponseModel | None = None
     async for event in stream:
         etype = event.type
+        if etype == "error":
+            code = event.code if event.code is not UNSET else ""
+            message = event.message if event.message is not UNSET else ""
+            detail = message.strip() or code
+            label = detail.strip() or etype
+            raise RuntimeError(f"openai responses stream error: {label}")  # noqa: TRY003 — transport failure
         if etype == "response.output_text.delta" and isinstance(event.delta, str) and event.delta:
             yield text_delta_chunk(model=model, content=event.delta)
             continue

src/plyngent/lmproto/openai/model.py

@@ -282,6 +282,9 @@ class ResponseStreamEvent(Struct, omit_defaults=True):
     name: str | Unset = UNSET
     arguments: str | Unset = UNSET
     call_id: str | Unset = UNSET
+    # error events (type == "error")
+    code: str | Unset = UNSET
+    message: str | Unset = UNSET
 
 
 # --- Helpers -----------------------------------------------------------------------

tests/test_agent/test_responses_dispatch.py

@@ -314,3 +314,17 @@ async def test_unknown_kind_not_implemented() -> None:
             stream=False,
         ):
             pass
+
+
+async def test_dispatch_stream_raises_on_error_event() -> None:
+    import pytest
+
+    events = [
+        ResponseStreamEvent(type="error", code="server_error", message="boom"),
+    ]
+    client = ScriptedResponsesClient(stream_events=[events])
+    param = ChatCompletionsParam(model="gpt-test", messages=[UserChatMessage(content="x")])
+    stream = await dispatch_responses(cast("Any", client), param, stream=True)
+    with pytest.raises(RuntimeError, match="boom"):
+        async for _ in cast("Any", stream):
+            pass