From 58e4b3577089dfb6915d193c93040e1ccb52822d Mon Sep 17 00:00:00 2001
From: huanghuoguoguo <1051233107@qq.com>
Date: Fri, 29 May 2026 21:05:20 +0800
Subject: [PATCH] fix(agent-runner): stabilize event context and streams

---
 .../pkg/agent/runner/context_builder.py       |  2 +-
 .../pkg/agent/runner/pipeline_adapter.py      | 65 +++++++++++++-----
 src/langbot/pkg/plugin/handler.py             |  2 +
 .../modelmgr/requesters/bailianchatcmpl.py    |  3 +-
 .../provider/modelmgr/requesters/chatcmpl.py  |  3 +-
 .../modelmgr/requesters/geminichatcmpl.py     |  3 +-
 .../modelmgr/requesters/jiekouaichatcmpl.py   |  5 +-
 .../modelmgr/requesters/modelscopechatcmpl.py |  3 +-
 .../modelmgr/requesters/ppiochatcmpl.py       |  5 +-
 .../agent/test_context_validation.py          | 67 ++++++++++++++++---
 .../agent/test_event_first_protocol.py        | 52 ++++++++------
 .../unit_tests/plugin/test_handler_actions.py | 47 +++++++++++++
 .../requesters/test_chatcmpl_errors_direct.py | 31 +++++++++
 13 files changed, 232 insertions(+), 56 deletions(-)

diff --git a/src/langbot/pkg/agent/runner/context_builder.py b/src/langbot/pkg/agent/runner/context_builder.py
index da7321e4..a6be6940 100644
--- a/src/langbot/pkg/agent/runner/context_builder.py
+++ b/src/langbot/pkg/agent/runner/context_builder.py
@@ -229,7 +229,7 @@ class AgentRunContextBuilder:
             subject_context = {
                 'subject_type': event.subject.subject_type,
                 'subject_id': event.subject.subject_id,
-                'subject_data': event.subject.data,
+                'data': event.subject.data,
             }
 
         # Build input from event
diff --git a/src/langbot/pkg/agent/runner/pipeline_adapter.py b/src/langbot/pkg/agent/runner/pipeline_adapter.py
index cbabebaa..ca0d67ae 100644
--- a/src/langbot/pkg/agent/runner/pipeline_adapter.py
+++ b/src/langbot/pkg/agent/runner/pipeline_adapter.py
@@ -5,8 +5,8 @@ Protocol v1 architecture.
 """
 from __future__ import annotations
 
+import hashlib
 import typing
-import time
 
 from langbot_plugin.api.entities.builtin.pipeline import query as pipeline_query
 from langbot_plugin.api.entities.builtin.platform import message as platform_message
@@ -19,7 +19,6 @@ from langbot_plugin.api.entities.builtin.agent_runner.event import (
 )
 from langbot_plugin.api.entities.builtin.agent_runner.input import AgentInput
 from langbot_plugin.api.entities.builtin.agent_runner.delivery import DeliveryContext
-from langbot_plugin.api.entities.builtin.agent_runner.trigger import AgentTrigger
 
 from .host_models import (
     AgentEventEnvelope,
@@ -305,8 +304,9 @@ class PipelineAdapter:
         if isinstance(event_time, (int, float)):
             event_time = int(event_time)
 
+        source_event_id = str(message_id or query.query_id)
         return AgentEventContext(
-            event_id=str(message_id or query.query_id),
+            event_id=cls._build_scoped_event_id(query, source_event_id, event_time),
             event_type=runner_events.MESSAGE_RECEIVED,
             event_time=event_time,
             source="pipeline_adapter",
@@ -314,20 +314,36 @@ class PipelineAdapter:
             data=event_data,
         )
 
+    @classmethod
+    def _build_scoped_event_id(
+        cls,
+        query: pipeline_query.Query,
+        source_event_id: str,
+        event_time: int | None,
+    ) -> str:
+        """Build a globally unique host event id from pipeline-local ids."""
+        launcher_type = getattr(query, 'launcher_type', None)
+        launcher_type_value = getattr(launcher_type, 'value', launcher_type) if launcher_type is not None else None
+        scope_parts = [
+            'pipeline_adapter',
+            getattr(query, 'pipeline_uuid', None),
+            getattr(query, 'bot_uuid', None),
+            launcher_type_value,
+            getattr(query, 'launcher_id', None),
+            getattr(query, 'sender_id', None),
+            source_event_id,
+            event_time,
+        ]
+        scoped = '|'.join('' if part is None else str(part) for part in scope_parts)
+        digest = hashlib.sha256(scoped.encode('utf-8')).hexdigest()[:32]
+        return f'pipeline:{digest}'
+
     @classmethod
     def _build_conversation_context(
         cls,
         query: pipeline_query.Query,
     ) -> ConversationContext:
         """Build ConversationContext from Query."""
-        # Handle session and conversation_id
-        conversation_id = None
-        session = getattr(query, 'session', None)
-        if session:
-            conversation = getattr(session, 'using_conversation', None)
-            if conversation:
-                conversation_id = getattr(conversation, 'uuid', None)
-
         # Handle launcher_type safely
         launcher_type = getattr(query, 'launcher_type', None)
         launcher_type_value = None
@@ -337,6 +353,26 @@ class PipelineAdapter:
         # Handle launcher_id
         launcher_id = getattr(query, 'launcher_id', None)
 
+        # Build session_id from launcher info if available
+        session_id = None
+        if launcher_type_value and launcher_id:
+            session_id = f'{launcher_type_value}_{launcher_id}'
+
+        # Handle session and conversation_id
+        conversation_id = None
+        session = getattr(query, 'session', None)
+        if session:
+            conversation = getattr(session, 'using_conversation', None)
+            if conversation:
+                conversation_id = getattr(conversation, 'uuid', None)
+
+        if not conversation_id:
+            variables = getattr(query, 'variables', None) or {}
+            conversation_id = variables.get('conversation_id') or None
+
+        if not conversation_id:
+            conversation_id = session_id
+
         # Handle sender_id
         sender_id = getattr(query, 'sender_id', None)
         if sender_id is not None:
@@ -348,13 +384,8 @@ class PipelineAdapter:
         # Handle pipeline_uuid
         pipeline_uuid = getattr(query, 'pipeline_uuid', None)
 
-        # Build session_id from launcher info if available
-        session_id = None
-        if launcher_type_value and launcher_id:
-            session_id = f'{launcher_type_value}_{launcher_id}'
-
         return ConversationContext(
-            conversation_id=conversation_id,
+            conversation_id=str(conversation_id) if conversation_id is not None else None,
             thread_id=None,
             launcher_type=launcher_type_value,
             launcher_id=launcher_id,
diff --git a/src/langbot/pkg/plugin/handler.py b/src/langbot/pkg/plugin/handler.py
index d83726e4..312d2877 100644
--- a/src/langbot/pkg/plugin/handler.py
+++ b/src/langbot/pkg/plugin/handler.py
@@ -674,6 +674,8 @@ class RuntimeConnectionHandler(handler.Handler):
                 extra_args=effective_extra_args,
                 remove_think=remove_think,
             ):
+                if chunk is None:
+                    continue
                 yield handler.ActionResponse.success(
                     data={
                         'chunk': chunk.model_dump(),
diff --git a/src/langbot/pkg/provider/modelmgr/requesters/bailianchatcmpl.py b/src/langbot/pkg/provider/modelmgr/requesters/bailianchatcmpl.py
index 9da6e1b4..6b0da927 100644
--- a/src/langbot/pkg/provider/modelmgr/requesters/bailianchatcmpl.py
+++ b/src/langbot/pkg/provider/modelmgr/requesters/bailianchatcmpl.py
@@ -171,7 +171,8 @@ class BailianChatCompletions(modelscopechatcmpl.ModelScopeChatCompletions):
                 # 解析 chunk 数据
                 if hasattr(chunk, 'choices') and chunk.choices:
                     choice = chunk.choices[0]
-                    delta = choice.delta.model_dump() if hasattr(choice, 'delta') else {}
+                    delta_obj = getattr(choice, 'delta', None)
+                    delta = delta_obj.model_dump() if delta_obj is not None else {}
                     finish_reason = getattr(choice, 'finish_reason', None)
                 else:
                     delta = {}
diff --git a/src/langbot/pkg/provider/modelmgr/requesters/chatcmpl.py b/src/langbot/pkg/provider/modelmgr/requesters/chatcmpl.py
index e63e362b..ff5e6027 100644
--- a/src/langbot/pkg/provider/modelmgr/requesters/chatcmpl.py
+++ b/src/langbot/pkg/provider/modelmgr/requesters/chatcmpl.py
@@ -359,7 +359,8 @@ class OpenAIChatCompletions(requester.ProviderAPIRequester):
 
             if hasattr(chunk, 'choices') and chunk.choices:
                 choice = chunk.choices[0]
-                delta = choice.delta.model_dump() if hasattr(choice, 'delta') else {}
+                delta_obj = getattr(choice, 'delta', None)
+                delta = delta_obj.model_dump() if delta_obj is not None else {}
 
                 finish_reason = getattr(choice, 'finish_reason', None)
             else:
diff --git a/src/langbot/pkg/provider/modelmgr/requesters/geminichatcmpl.py b/src/langbot/pkg/provider/modelmgr/requesters/geminichatcmpl.py
index 956b49f6..149a7356 100644
--- a/src/langbot/pkg/provider/modelmgr/requesters/geminichatcmpl.py
+++ b/src/langbot/pkg/provider/modelmgr/requesters/geminichatcmpl.py
@@ -132,7 +132,8 @@ class GeminiChatCompletions(chatcmpl.OpenAIChatCompletions):
 
             if hasattr(chunk, 'choices') and chunk.choices:
                 choice = chunk.choices[0]
-                delta = choice.delta.model_dump() if hasattr(choice, 'delta') else {}
+                delta_obj = getattr(choice, 'delta', None)
+                delta = delta_obj.model_dump() if delta_obj is not None else {}
 
                 finish_reason = getattr(choice, 'finish_reason', None)
             else:
diff --git a/src/langbot/pkg/provider/modelmgr/requesters/jiekouaichatcmpl.py b/src/langbot/pkg/provider/modelmgr/requesters/jiekouaichatcmpl.py
index 305ae21f..67a45651 100644
--- a/src/langbot/pkg/provider/modelmgr/requesters/jiekouaichatcmpl.py
+++ b/src/langbot/pkg/provider/modelmgr/requesters/jiekouaichatcmpl.py
@@ -144,7 +144,8 @@ class JieKouAIChatCompletions(chatcmpl.OpenAIChatCompletions):
             # 解析 chunk 数据
             if hasattr(chunk, 'choices') and chunk.choices:
                 choice = chunk.choices[0]
-                delta = choice.delta.model_dump() if hasattr(choice, 'delta') else {}
+                delta_obj = getattr(choice, 'delta', None)
+                delta = delta_obj.model_dump() if delta_obj is not None else {}
                 finish_reason = getattr(choice, 'finish_reason', None)
             else:
                 delta = {}
@@ -159,7 +160,7 @@ class JieKouAIChatCompletions(chatcmpl.OpenAIChatCompletions):
             # reasoning_content = delta.get('reasoning_content', '')
 
             if remove_think:
-                if delta['content'] is not None:
+                if delta.get('content') is not None:
                     if '<think>' in delta['content'] and not thinking_started and not thinking_ended:
                         thinking_started = True
                         continue
diff --git a/src/langbot/pkg/provider/modelmgr/requesters/modelscopechatcmpl.py b/src/langbot/pkg/provider/modelmgr/requesters/modelscopechatcmpl.py
index c98a71d7..479e6775 100644
--- a/src/langbot/pkg/provider/modelmgr/requesters/modelscopechatcmpl.py
+++ b/src/langbot/pkg/provider/modelmgr/requesters/modelscopechatcmpl.py
@@ -391,7 +391,8 @@ class ModelScopeChatCompletions(requester.ProviderAPIRequester):
             # 解析 chunk 数据
             if hasattr(chunk, 'choices') and chunk.choices:
                 choice = chunk.choices[0]
-                delta = choice.delta.model_dump() if hasattr(choice, 'delta') else {}
+                delta_obj = getattr(choice, 'delta', None)
+                delta = delta_obj.model_dump() if delta_obj is not None else {}
                 finish_reason = getattr(choice, 'finish_reason', None)
             else:
                 delta = {}
diff --git a/src/langbot/pkg/provider/modelmgr/requesters/ppiochatcmpl.py b/src/langbot/pkg/provider/modelmgr/requesters/ppiochatcmpl.py
index 1836bd62..594cb841 100644
--- a/src/langbot/pkg/provider/modelmgr/requesters/ppiochatcmpl.py
+++ b/src/langbot/pkg/provider/modelmgr/requesters/ppiochatcmpl.py
@@ -144,7 +144,8 @@ class PPIOChatCompletions(chatcmpl.OpenAIChatCompletions):
             # 解析 chunk 数据
             if hasattr(chunk, 'choices') and chunk.choices:
                 choice = chunk.choices[0]
-                delta = choice.delta.model_dump() if hasattr(choice, 'delta') else {}
+                delta_obj = getattr(choice, 'delta', None)
+                delta = delta_obj.model_dump() if delta_obj is not None else {}
                 finish_reason = getattr(choice, 'finish_reason', None)
             else:
                 delta = {}
@@ -159,7 +160,7 @@ class PPIOChatCompletions(chatcmpl.OpenAIChatCompletions):
             # reasoning_content = delta.get('reasoning_content', '')
 
             if remove_think:
-                if delta['content'] is not None:
+                if delta.get('content') is not None:
                     if '<think>' in delta['content'] and not thinking_started and not thinking_ended:
                         thinking_started = True
                         continue
diff --git a/tests/unit_tests/agent/test_context_validation.py b/tests/unit_tests/agent/test_context_validation.py
index 480b64b3..0ea003a8 100644
--- a/tests/unit_tests/agent/test_context_validation.py
+++ b/tests/unit_tests/agent/test_context_validation.py
@@ -3,28 +3,20 @@ from __future__ import annotations
 
 import pytest
 from unittest.mock import MagicMock, AsyncMock, patch
-import uuid
 
 # SDK imports for validation
 from langbot_plugin.api.entities.builtin.agent_runner.context import AgentRunContext
 from langbot_plugin.api.entities.builtin.agent_runner.event import AgentEventContext
 from langbot_plugin.api.entities.builtin.agent_runner.delivery import DeliveryContext
 from langbot_plugin.api.entities.builtin.agent_runner.context_access import ContextAccess
-from langbot_plugin.api.entities.builtin.agent_runner.trigger import AgentTrigger
 from langbot_plugin.api.entities.builtin.agent_runner.input import AgentInput
 from langbot_plugin.api.entities.builtin.agent_runner.resources import AgentResources
 from langbot_plugin.api.entities.builtin.agent_runner.runtime import AgentRuntimeContext
-from langbot_plugin.api.entities.builtin.agent_runner.state import AgentRunState
 
 # LangBot imports
 from langbot.pkg.agent.runner.context_builder import (
     AgentRunContextBuilder,
-    AgentTrigger as BuilderTrigger,
-    ConversationContext as BuilderConversation,
-    AgentInput as BuilderInput,
-    AgentRunState as BuilderState,
     AgentResources as BuilderResources,
-    AgentRuntimeContext as BuilderRuntime,
 )
 from langbot.pkg.agent.runner.host_models import AgentEventEnvelope, AgentBinding, BindingScope
 from langbot.pkg.core import app
@@ -171,6 +163,65 @@ class TestContextValidation:
         # Verify input
         assert validated.input.text == "Hello world"
 
+    @pytest.mark.asyncio
+    async def test_build_context_preserves_subject_data_for_non_message_events(self):
+        """Non-message EBA events keep subject.data instead of relying on message text."""
+        from langbot_plugin.api.entities.builtin.agent_runner.event import ActorContext, SubjectContext
+        from langbot_plugin.api.entities.builtin.agent_runner.input import AgentInput as EventInput
+        from langbot_plugin.api.entities.builtin.agent_runner.delivery import DeliveryContext
+
+        mock_app = self._make_mock_app()
+        builder = AgentRunContextBuilder(mock_app)
+        event = AgentEventEnvelope(
+            event_id="evt_recall_1",
+            event_type="message.recalled",
+            event_time=1700000001,
+            source="platform",
+            source_event_type="platform.message.recall",
+            bot_id="bot_1",
+            workspace_id="workspace_1",
+            conversation_id="conv_1",
+            actor=ActorContext(actor_type="user", actor_id="user_1"),
+            subject=SubjectContext(
+                subject_type="message",
+                subject_id="message_1",
+                data={"recalled_message_id": "message_1", "reason": "user_recall"},
+            ),
+            input=EventInput(text=None),
+            delivery=DeliveryContext(surface="test"),
+            data={"source_event_id": "source_recall_1"},
+        )
+        binding = self._make_binding()
+        binding.event_types = ["message.recalled"]
+        resources = self._make_resources()
+        descriptor = self._make_descriptor()
+
+        with patch('langbot.pkg.agent.runner.context_builder.get_persistent_state_store') as mock_get_store:
+            mock_store = AsyncMock()
+            mock_store.build_snapshot_from_event = AsyncMock(return_value={
+                'conversation': {},
+                'actor': {},
+                'subject': {},
+                'runner': {},
+            })
+            mock_get_store.return_value = mock_store
+
+            context_dict = await builder.build_context_from_event(
+                event=event,
+                binding=binding,
+                descriptor=descriptor,
+                resources=resources,
+            )
+
+        validated = AgentRunContext.model_validate(context_dict)
+
+        assert validated.event.event_type == "message.recalled"
+        assert validated.input.text is None
+        assert validated.subject is not None
+        assert validated.subject.subject_type == "message"
+        assert validated.subject.subject_id == "message_1"
+        assert validated.subject.data == {"recalled_message_id": "message_1", "reason": "user_recall"}
+
     @pytest.mark.asyncio
     async def test_build_context_from_event_has_no_legacy_top_level_fields(self):
         """Test that build_context_from_event does NOT have top-level messages/prompt/params."""
diff --git a/tests/unit_tests/agent/test_event_first_protocol.py b/tests/unit_tests/agent/test_event_first_protocol.py
index 6dee9c30..a58c1848 100644
--- a/tests/unit_tests/agent/test_event_first_protocol.py
+++ b/tests/unit_tests/agent/test_event_first_protocol.py
@@ -10,15 +10,11 @@ Tests cover:
 from __future__ import annotations
 
 import pytest
-from unittest.mock import Mock, MagicMock, patch
-import typing
+from unittest.mock import Mock
 
 # Import SDK entities
 from langbot_plugin.api.entities.builtin.agent_runner.event import (
     AgentEventContext,
-    ConversationContext,
-    ActorContext,
-    SubjectContext,
 )
 from langbot_plugin.api.entities.builtin.agent_runner.input import AgentInput
 from langbot_plugin.api.entities.builtin.agent_runner.trigger import AgentTrigger
@@ -33,22 +29,8 @@ from langbot_plugin.api.entities.builtin.agent_runner.capabilities import (
 from langbot_plugin.api.entities.builtin.agent_runner.permissions import (
     AgentRunnerPermissions,
 )
-from langbot_plugin.api.entities.builtin.agent_runner.context_policy import (
-    AgentRunnerContextPolicy,
-)
-from langbot_plugin.api.entities.builtin.agent_runner.manifest import (
-    AgentRunnerManifest,
-)
 
 # Import LangBot host models
-from langbot.pkg.agent.runner.host_models import (
-    AgentEventEnvelope,
-    AgentBinding,
-    BindingScope,
-    ResourcePolicy,
-    StatePolicy,
-    DeliveryPolicy,
-)
 from langbot.pkg.agent.runner.pipeline_adapter import PipelineAdapter
 
 
@@ -76,9 +58,24 @@ class TestPipelineQueryToEventEnvelope:
         """Test conversation context extraction."""
         event = PipelineAdapter.query_to_event(mock_query)
 
-        # Conversation may be None if no session
-        if event.conversation_id:
-            assert event.conversation_id is not None
+        assert event.conversation_id == "conv-uuid-123"
+
+    def test_query_to_event_prefers_variable_conversation_id_when_conversation_uuid_missing(self, mock_query):
+        """Pipeline variables can provide the conversation identity for state scope."""
+        mock_query.session.using_conversation.uuid = None
+        mock_query.variables["conversation_id"] = "conv-from-vars"
+
+        event = PipelineAdapter.query_to_event(mock_query)
+
+        assert event.conversation_id == "conv-from-vars"
+
+    def test_query_to_event_falls_back_to_launcher_session_for_state_scope(self, mock_query):
+        """Debug Chat and legacy pipeline runs may not have a conversation UUID."""
+        mock_query.session.using_conversation.uuid = None
+
+        event = PipelineAdapter.query_to_event(mock_query)
+
+        assert event.conversation_id == "person_launcher-123"
 
     def test_query_to_event_delivery_context(self, mock_query):
         """Test delivery context extraction."""
@@ -118,6 +115,17 @@ class TestPipelineQueryToEventEnvelope:
 
         assert event.delivery.reply_target == {"message_id": None}
 
+    def test_query_to_event_scopes_pipeline_local_event_ids(self, mock_query):
+        """Pipeline-local message IDs must not become global audit IDs."""
+        first = PipelineAdapter.query_to_event(mock_query)
+
+        mock_query.launcher_id = "launcher-456"
+        second = PipelineAdapter.query_to_event(mock_query)
+
+        assert first.event_id.startswith("pipeline:")
+        assert first.event_id != "789"
+        assert second.event_id != first.event_id
+
 
 class TestPipelineConfigToBinding:
     """Test Pipeline config -> AgentBinding conversion."""
diff --git a/tests/unit_tests/plugin/test_handler_actions.py b/tests/unit_tests/plugin/test_handler_actions.py
index 29e6a0cb..60b52552 100644
--- a/tests/unit_tests/plugin/test_handler_actions.py
+++ b/tests/unit_tests/plugin/test_handler_actions.py
@@ -511,6 +511,53 @@ class TestAgentRunProxyActions:
         assert provider.kwargs['remove_think'] is True
         assert provider.kwargs['funcs'] == []
 
+    @pytest.mark.asyncio
+    async def test_invoke_llm_stream_skips_none_chunks(self, app):
+        """INVOKE_LLM_STREAM tolerates provider heartbeat/no-op chunks."""
+        from langbot.pkg.agent.runner.session_registry import get_session_registry
+
+        class StreamProvider:
+            async def invoke_llm_stream(self, **kwargs):
+                yield provider_message.MessageChunk(role='assistant', content='ok')
+                yield None
+                yield provider_message.MessageChunk(role='assistant', content=' done', is_final=True)
+
+        run_id = 'run_proxy_invoke_llm_stream_none_chunks'
+        query = self.query()
+        app.query_pool.cached_queries[904] = query
+
+        registry = get_session_registry()
+        await registry.unregister(run_id)
+        await registry.register(
+            run_id=run_id,
+            runner_id='plugin:test/runner/default',
+            query_id=904,
+            plugin_identity='test/runner',
+            resources=make_agent_resources(models=[{'model_id': 'llm_stream_002'}]),
+        )
+
+        model = SimpleNamespace(
+            model_entity=SimpleNamespace(abilities=[], extra_args={}),
+            provider=StreamProvider(),
+        )
+        app.model_mgr.get_model_by_uuid.return_value = model
+        runtime_handler = make_handler(app)
+
+        responses = []
+        try:
+            stream = runtime_handler.actions[PluginToRuntimeAction.INVOKE_LLM_STREAM.value]({
+                'run_id': run_id,
+                'llm_model_uuid': 'llm_stream_002',
+                'messages': [{'role': 'user', 'content': 'hello'}],
+            })
+            async for response in stream:
+                responses.append(response)
+        finally:
+            await registry.unregister(run_id)
+
+        assert [response.code for response in responses] == [0, 0]
+        assert [response.data['chunk']['content'] for response in responses] == ['ok', ' done']
+
     @pytest.mark.asyncio
     async def test_call_tool_passes_current_query(self, app):
         """CALL_TOOL passes the current Query back into tool execution."""
diff --git a/tests/unit_tests/provider/requesters/test_chatcmpl_errors_direct.py b/tests/unit_tests/provider/requesters/test_chatcmpl_errors_direct.py
index c51476c2..946c32a4 100644
--- a/tests/unit_tests/provider/requesters/test_chatcmpl_errors_direct.py
+++ b/tests/unit_tests/provider/requesters/test_chatcmpl_errors_direct.py
@@ -7,6 +7,7 @@ only the necessary dependencies.
 from __future__ import annotations
 
 import asyncio
+from types import SimpleNamespace
 from unittest.mock import AsyncMock, MagicMock
 import pytest
 import openai  # Import real openai package
@@ -140,6 +141,36 @@ class TestInvokeLLMErrorHandling:
 
         assert '频繁' in str(exc.value) or '余额' in str(exc.value)
 
+    @pytest.mark.asyncio
+    async def test_stream_skips_choice_with_none_delta(self, requester_with_mocked_client, mock_model):
+        """OpenAI-compatible streams may include choice frames with delta=None."""
+
+        async def fake_req_stream(args, extra_body=None):
+            yield SimpleNamespace(choices=[SimpleNamespace(delta=None, finish_reason=None)])
+            yield SimpleNamespace(
+                choices=[
+                    SimpleNamespace(
+                        delta=SimpleNamespace(model_dump=lambda: {'role': 'assistant', 'content': 'OK'}),
+                        finish_reason='stop',
+                    )
+                ]
+            )
+
+        requester_with_mocked_client._req_stream = fake_req_stream
+
+        chunks = [
+            chunk
+            async for chunk in requester_with_mocked_client._closure_stream(
+                query=None,
+                req_messages=[{'role': 'user', 'content': 'hello'}],
+                use_model=mock_model,
+            )
+        ]
+
+        assert len(chunks) == 1
+        assert chunks[0].content == 'OK'
+        assert chunks[0].is_final is True
+
 
 class TestInvokeEmbeddingErrorHandling:
     """Tests for invoke_embedding error handling."""