test(review): 新增 pytest 离线回归网，锁定 dwg_review 既有行为

在改动审查流水线（确定性检查前置 / 结论结构化 / 证据交叉校验）之前，
先立一张离线、确定性、秒级的回归网。

- tests/fakes.py：假 LLM + 假 MCP 基座 + 响应构造器（ok_text/ok_image/err）
  + make_ctx/make_evidence，绝不触网、不读密钥
- 10 个模块共 134 用例：
  mcp_client / llm_client / cad_tools / checklist / config /
  planning / evidence / review / report / annotator
- pytest.ini（testpaths=tests）+ requirements-dev.txt + 根 conftest.py
  （sys.path + RENDER_WAIT=0 / REPORT_DIR=tmp fixture）

tests/test_evidence.py

@@ -0,0 +1,83 @@
+"""`dwg_review.phases.evidence` 单元测试。"""
+
+from dwg_review.phases.evidence import bbox_to_window, collect_frame
+from tests.fakes import FakeMcpClient, frame, make_ctx, ok_image, ok_text
+
+
+def test_bbox_to_window_mapping():
+    assert bbox_to_window([1, 2, 3, 4]) == {
+        "min_x": 1.0,
+        "min_y": 2.0,
+        "max_x": 3.0,
+        "max_y": 4.0,
+    }
+
+
+def test_collect_frame_returns_none_for_missing_bbox():
+    ctx = make_ctx(client=FakeMcpClient())
+    assert collect_frame(ctx, 1, {}) is None
+    assert collect_frame(ctx, 1, {"bbox": None}) is None
+
+
+def test_collect_frame_returns_none_for_bad_bbox_length():
+    ctx = make_ctx(client=FakeMcpClient())
+    assert collect_frame(ctx, 1, {"bbox": [0, 0, 10]}) is None
+
+
+def build_evidence_client(image=ok_image("QUJD")):
+    return FakeMcpClient(
+        responses={
+            "query_entities": ok_text({"total": 5, "items": [{"handle": "A"}]}),
+            "get_text_content": ok_text({"total": 1, "items": [{"text": "你好"}]}),
+            "get_dimensions": ok_text({"total": 2, "items": []}),
+            "get_block_references": ok_text({"total": 0, "items": []}),
+            "get_polylines_info": ok_text({"total": 3, "items": []}),
+            "get_viewport_screenshot": image,
+        }
+    )
+
+
+def test_collect_frame_assembles_evidence():
+    ctx = make_ctx(client=build_evidence_client())
+    ev = collect_frame(ctx, 2, frame([0, 0, 100, 50]))
+    assert ev["index"] == 2
+    assert ev["window"] == {"min_x": 0.0, "min_y": 0.0, "max_x": 100.0, "max_y": 50.0}
+    assert ev["entities"]["total"] == 5
+    assert ev["texts"]["total"] == 1
+    assert ev["dimensions"]["total"] == 2
+    assert ev["blocks"]["total"] == 0
+    assert ev["polylines"]["total"] == 3
+    assert ev["image_b64"] == "QUJD"
+    assert ev["image_mime"] == "image/png"
+
+
+def test_collect_frame_calls_expected_tools():
+    ctx = make_ctx(client=build_evidence_client(), frame_limit=99)
+    collect_frame(ctx, 1, frame([1, 2, 3, 4]))
+    client = ctx.client
+
+    win = {"min_x": 1.0, "min_y": 2.0, "max_x": 3.0, "max_y": 4.0}
+    assert client.arguments_of("zoom_to_window") == dict(win, margin=0.02)
+    for name in (
+        "query_entities",
+        "get_text_content",
+        "get_dimensions",
+        "get_block_references",
+        "get_polylines_info",
+    ):
+        assert client.arguments_of(name) == {"window": win, "limit": 99}
+    assert client.arguments_of("get_viewport_screenshot") == {}
+
+
+def test_collect_frame_without_image():
+    ctx = make_ctx(client=build_evidence_client(image=ok_text({})))
+    ev = collect_frame(ctx, 1, frame([0, 0, 10, 10]))
+    assert ev["image_b64"] is None
+    assert ev["image_mime"] is None
+
+
+def test_collect_frame_tolerates_empty_structured_data():
+    ctx = make_ctx(client=FakeMcpClient())  # 全部默认 ok_text({})
+    ev = collect_frame(ctx, 1, frame([0, 0, 10, 10]))
+    assert ev["entities"] == {}
+    assert ev["image_b64"] is None