refactor(tests): reorganize tests into unittest/ and e2e/ directories

- Move all unit tests from tests/ to tests/unittest/
- Add tests/e2e/ directory for end-to-end tests
- Update conftest.py for new test structure
- Add new tests for auth dependencies, policies, route injection
- Add new tests for run callbacks, create store, execution artifacts
- Remove obsolete tests for deleted persistence layer

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/tests/unittest/test_llm_error_handling_middleware.py

@@ -0,0 +1,136 @@
+from __future__ import annotations
+
+import asyncio
+from types import SimpleNamespace
+
+import pytest
+from langchain_core.messages import AIMessage
+from langgraph.errors import GraphBubbleUp
+
+from deerflow.agents.middlewares.llm_error_handling_middleware import (
+    LLMErrorHandlingMiddleware,
+)
+
+
+class FakeError(Exception):
+    def __init__(
+        self,
+        message: str,
+        *,
+        status_code: int | None = None,
+        code: str | None = None,
+        headers: dict[str, str] | None = None,
+        body: dict | None = None,
+    ) -> None:
+        super().__init__(message)
+        self.status_code = status_code
+        self.code = code
+        self.body = body
+        self.response = SimpleNamespace(status_code=status_code, headers=headers or {}) if status_code is not None or headers else None
+
+
+def _build_middleware(**attrs: int) -> LLMErrorHandlingMiddleware:
+    middleware = LLMErrorHandlingMiddleware()
+    for key, value in attrs.items():
+        setattr(middleware, key, value)
+    return middleware
+
+
+def test_async_model_call_retries_busy_provider_then_succeeds(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    middleware = _build_middleware(retry_max_attempts=3, retry_base_delay_ms=25, retry_cap_delay_ms=25)
+    attempts = 0
+    waits: list[float] = []
+    events: list[dict] = []
+
+    async def fake_sleep(delay: float) -> None:
+        waits.append(delay)
+
+    def fake_writer():
+        return events.append
+
+    async def handler(_request) -> AIMessage:
+        nonlocal attempts
+        attempts += 1
+        if attempts < 3:
+            raise FakeError("当前服务集群负载较高，请稍后重试，感谢您的耐心等待。 (2064)")
+        return AIMessage(content="ok")
+
+    monkeypatch.setattr("asyncio.sleep", fake_sleep)
+    monkeypatch.setattr(
+        "langgraph.config.get_stream_writer",
+        fake_writer,
+    )
+
+    result = asyncio.run(middleware.awrap_model_call(SimpleNamespace(), handler))
+
+    assert isinstance(result, AIMessage)
+    assert result.content == "ok"
+    assert attempts == 3
+    assert waits == [0.025, 0.025]
+    assert [event["type"] for event in events] == ["llm_retry", "llm_retry"]
+
+
+def test_async_model_call_returns_user_message_for_quota_errors() -> None:
+    middleware = _build_middleware(retry_max_attempts=3)
+
+    async def handler(_request) -> AIMessage:
+        raise FakeError(
+            "insufficient_quota: account balance is empty",
+            status_code=429,
+            code="insufficient_quota",
+        )
+
+    result = asyncio.run(middleware.awrap_model_call(SimpleNamespace(), handler))
+
+    assert isinstance(result, AIMessage)
+    assert "out of quota" in str(result.content)
+
+
+def test_sync_model_call_uses_retry_after_header(monkeypatch: pytest.MonkeyPatch) -> None:
+    middleware = _build_middleware(retry_max_attempts=2, retry_base_delay_ms=10, retry_cap_delay_ms=10)
+    waits: list[float] = []
+    attempts = 0
+
+    def fake_sleep(delay: float) -> None:
+        waits.append(delay)
+
+    def handler(_request) -> AIMessage:
+        nonlocal attempts
+        attempts += 1
+        if attempts == 1:
+            raise FakeError(
+                "server busy",
+                status_code=503,
+                headers={"Retry-After": "2"},
+            )
+        return AIMessage(content="ok")
+
+    monkeypatch.setattr("time.sleep", fake_sleep)
+
+    result = middleware.wrap_model_call(SimpleNamespace(), handler)
+
+    assert isinstance(result, AIMessage)
+    assert result.content == "ok"
+    assert waits == [2.0]
+
+
+def test_sync_model_call_propagates_graph_bubble_up() -> None:
+    middleware = _build_middleware()
+
+    def handler(_request) -> AIMessage:
+        raise GraphBubbleUp()
+
+    with pytest.raises(GraphBubbleUp):
+        middleware.wrap_model_call(SimpleNamespace(), handler)
+
+
+def test_async_model_call_propagates_graph_bubble_up() -> None:
+    middleware = _build_middleware()
+
+    async def handler(_request) -> AIMessage:
+        raise GraphBubbleUp()
+
+    with pytest.raises(GraphBubbleUp):
+        asyncio.run(middleware.awrap_model_call(SimpleNamespace(), handler))