Serialize chat resets with message generation

backend/src/alphapulse/api/chat.py

@@ -29,7 +29,7 @@ MAX_TOOL_ROUNDS = 8
 TOOL_PREVIEW_CHARS = 2000
 STOPPED_RESULT = json.dumps({"error": "用户已停止生成，未完成的工具结果尚未确认，请核对后再重试"}, ensure_ascii=False)
 
-# api 只有一个进程：同一时间只允许一轮生成，Reset 也要等生成结束
+# api 只有一个进程：生成与 Reset 共用互斥锁，不能同时修改当前会话。
 generating = asyncio.Lock()
 logger = logging.getLogger("alphapulse.api.chat")
 
@@ -127,7 +127,7 @@ async def get_chat_session(session: Annotated[AsyncSession, Depends(get_session)
 async def send_message(body: SendIn) -> AsyncIterator[ServerSentEvent]:
     """事件：prompt、thinking、delta、tool_call、tool_result、skill_draft、context_updated、usage、error、done"""
     if generating.locked():
-        yield event("error", {"message": "上一轮还在生成，请等待完成或先停止"})
+        yield event("error", {"message": "正在生成或重置会话，请等待完成"})
         return
     async with generating:
         async with SessionLocal() as session:
@@ -233,11 +233,12 @@ async def send_message(body: SendIn) -> AsyncIterator[ServerSentEvent]:
 async def reset(body: ResetIn, session: Annotated[AsyncSession, Depends(get_session)]) -> None:
     """结束当前会话（消息保留在库里，不再展示），可选同时清空 CONTEXT.md（写入空版本，可找回）"""
     if generating.locked():
-        raise HTTPException(status.HTTP_409_CONFLICT, "正在生成，请先停止")
-    await session.execute(update(ChatSession).where(ChatSession.ended_at.is_(None)).values(ended_at=datetime.now(UTC)))
-    if body.clear_context:
-        session.add(ContextVersion(content="", source="reset"))
-    await session.commit()
+        raise HTTPException(status.HTTP_409_CONFLICT, "正在生成或重置会话，请稍后重试")
+    async with generating:
+        await session.execute(update(ChatSession).where(ChatSession.ended_at.is_(None)).values(ended_at=datetime.now(UTC)))
+        if body.clear_context:
+            session.add(ContextVersion(content="", source="reset"))
+        await session.commit()
 
 
 @router.get("/context")

backend/tests/test_failure_paths.py

@@ -179,3 +179,54 @@ def test_skill_rename_rejects_whitespace_without_writing(trading):
         assert error.value.status_code == 400
         assert node.name == "原名称"
     asyncio.run(check())
+
+
+def test_chat_reset_blocks_new_generation_until_commit(trading, monkeypatch):
+    from alphapulse.api import chat
+
+    async def check():
+        monkeypatch.setattr(chat, "generating", asyncio.Lock())
+        entered, finish = asyncio.Event(), asyncio.Event()
+        monkeypatch.setattr(chat, "SessionLocal", lambda: pytest.fail("重置期间不能进入生成的数据库路径"))
+        saved = []
+        class Session:
+            async def execute(self, statement):
+                entered.set()
+                await finish.wait()
+            def add(self, row):
+                saved.append(row)
+            async def commit(self):
+                assert chat.generating.locked()
+        async def reset_and_send():
+            task = asyncio.create_task(chat.reset(chat.ResetIn(clear_context=True), Session()))
+            try:
+                await entered.wait()
+                events = [event async for event in chat.send_message(chat.SendIn(text="重置期间的新消息"))]
+                assert len(events) == 1 and events[0].event == "error"
+                assert not task.done()
+            finally:
+                finish.set()
+                await task
+        await asyncio.wait_for(reset_and_send(), timeout=2)
+        assert len(saved) == 1 and saved[0].content == "" and saved[0].source == "reset"
+        assert not chat.generating.locked()
+    asyncio.run(check())
+
+
+def test_chat_reset_rejects_busy_generation_and_releases_lock_on_failure(trading, monkeypatch):
+    from fastapi import HTTPException
+    from alphapulse.api import chat
+
+    async def check():
+        monkeypatch.setattr(chat, "generating", asyncio.Lock())
+        class Session:
+            async def execute(self, statement):
+                raise RuntimeError("重置写库失败")
+        async with chat.generating:
+            with pytest.raises(HTTPException) as error:
+                await chat.reset(chat.ResetIn(), Session())
+            assert error.value.status_code == 409
+        with pytest.raises(RuntimeError, match="重置写库失败"):
+            await chat.reset(chat.ResetIn(), Session())
+        assert not chat.generating.locked()
+    asyncio.run(check())