feat(v2): T7 网关扩展 + T9 token 计量与账单（/chat v2,/chat/legacy,/runs,/review,/metrics）

tests/test_trace.py

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+"""推理链轨迹存储 / 查询测试（T3：整体项目部分拆解·先行实现）。"""
+import pytest
+
+from router_system.router import build_router
+from router_system.trace import TraceStore
+
+
+def test_trace_store_put_get():
+    ts = TraceStore()
+    ts.put("abc", {"query": "q1", "route": ["a", "b"]})
+    t = ts.get("abc")
+    assert t["query"] == "q1"
+    assert ts.get("not-exist") is None
+
+
+def test_trace_store_ring_eviction():
+    ts = TraceStore(max_entries=3)
+    for i in range(5):
+        ts.put(f"id{i}", {"i": i})
+    assert ts.size() == 3
+    assert ts.get("id0") is None  # 最旧被淘汰
+    assert ts.get("id4") is not None
+
+
+def test_trace_store_overwrite():
+    ts = TraceStore()
+    ts.put("a", {"v": 1})
+    ts.put("a", {"v": 2})
+    assert ts.get("a")["v"] == 2
+    assert ts.size() == 1
+
+
+@pytest.mark.asyncio
+async def test_router_records_trace():
+    r = build_router()
+    res = await r.route("求解方程 x^2 - 5x + 6 = 0")
+    assert res.request_id
+    trace = r.trace_store.get(res.request_id)
+    assert trace is not None
+    assert trace["domain"] == "math"
+    assert trace["domain_group"] == "tech"
+    assert "plan:multi" in " ".join(trace["route"])
+    assert trace["quality_score"] > 0
+
+
+@pytest.mark.asyncio
+async def test_trace_cache_hit_roundtrip():
+    r = build_router()
+    q = "加班费怎么计算"
+    r1 = await r.route(q)
+    r2 = await r.route(q)  # 缓存命中
+    assert r2.cache_hit is True
+    trace = r.trace_store.get(r2.request_id)
+    assert trace["cache_hit"] is True
+    assert trace["cache_level"] == "exact"
+
+
+@pytest.mark.asyncio
+async def test_trace_subdomain_fields():
+    r = build_router()
+    res = await r.route("基金定投的收益率怎么计算")
+    trace = r.trace_store.get(res.request_id)
+    assert trace["subdomain"] == "investing"
+    assert trace["subdomain2"] == "investing"
+    assert trace["domain_group"] == "professional"
+
+
+def test_gateway_trace_endpoint():
+    from fastapi.testclient import TestClient
+    from gateway.api import app
+    c = TestClient(app, raise_server_exceptions=False)
+    chat = c.post("/chat/legacy", json={"query": "请用 Python 实现快速排序的迭代版本，并分析其时间与空间复杂度"})
+    rid = chat.json().get("request_id")
+    assert rid
+    t = c.get(f"/traces/{rid}")
+    assert t.status_code == 200
+    body = t.json()
+    assert body["domain"] == "code"
+    assert "subdomain:algorithm" in " ".join(body["route"])
+    miss = c.get("/traces/不存在的id")
+    assert miss.status_code == 404