feat(review): 截屏前最大化绘图区 + 空瓦片过滤覆盖回退路径

新增 MCP 工具 set_drawing_area(mode="max"|"restore")：最大化主窗口 + CLEANSCREENON
（隐藏功能区/命令行/面板）。实测绘图区 2110x462 -> 3310x1084（面积 3.68x），
restore 精确回位（窗口矩形/最大化态/绘图区尺寸全部还原）。

坑：CLEANSCREENOFF 是异步命令，AutoCAD 会按「进入干净屏幕时的布局」重设窗口几何，
把同步的 SetWindowPlacement 覆盖掉（表现为窗口停在最大化）。解法是插件内
SetTimer 延迟 700ms 再压回；实测窗口在 0.5~1.0s 之间收敛，故调用方等待取 1.5s。

取证层：
- 新增 maximized_drawing_area(ctx) 上下文管理器，__main__ 用它包住整个取证循环
  （多图框只进出一次）；受 DRAWING_AREA_MAXIMIZE 控制，工具缺失/调用失败静默降级，
  restore 失败不掩盖业务异常。
- 内容过滤统一到规划与回退两条路径，共用同一谓词；过滤后为空则退回原集合。
- 判定改用「实体 bbox」而非「占用格」：格子量化会把跨界内容算进相邻格，反而更粗
  （实测实体 bbox 正好压象限边界时 4 个象限全判有内容）。heatmap.occupied_boxes 随之删除。

实测（真实图纸 A0/A1/A2 三图框）：截图张数 12/8/4 -> 8/5/4；pytest 296 passed。
新增 verify_drawing_area.py 作为该工具的验收脚本。

tests/test_config.py

@@ -101,6 +101,19 @@ def test_tiling_defaults_are_sane():
     assert config.HEATMAP_CELL_DIV > 0
 
 
+def test_drawing_area_constants_have_expected_types():
+    assert isinstance(config.DRAWING_AREA_MAXIMIZE, bool)
+    assert isinstance(config.DRAWING_AREA_ENTER_WAIT, float)
+    assert isinstance(config.DRAWING_AREA_RESTORE_WAIT, float)
+
+
+def test_drawing_area_defaults_are_sane():
+    # 默认开启绘图区最大化；还原等待须盖过插件内 700ms 的延迟还原（实测 1.0s 才收敛）
+    assert config.DRAWING_AREA_MAXIMIZE is True
+    assert config.DRAWING_AREA_ENTER_WAIT >= 0
+    assert config.DRAWING_AREA_RESTORE_WAIT >= 1.2
+
+
 def test_credibility_defaults_are_on():
     # 默认开启，保证默认拿到可信度收益
     assert config.DETERMINISTIC_CHECKS is True

tests/test_evidence.py

@@ -6,13 +6,25 @@ import io
 import pytest
 
 from dwg_review.phases.evidence import (
+    _apply_keep,
+    _content_predicate,
     _is_truncated,
     _plan_tiles,
     _text_boxes,
     bbox_to_window,
     collect_frame,
+    maximized_drawing_area,
+)
+from tests.fakes import (
+    STANDARD_TOOLS,
+    FakeMcpClient,
+    err,
+    frame,
+    make_ctx,
+    ok_image,
+    ok_text,
+    tool_schema,
 )
-from tests.fakes import FakeMcpClient, frame, make_ctx, ok_image, ok_text
 
 
 def test_bbox_to_window_mapping():
@@ -267,9 +279,25 @@ def test_capture_images_tiles_text_cluster_is_finer(tiling_env):
 
 
 def test_capture_images_falls_back_without_scale(tiling_env):
-    """缺 sheet_size/sheet_scale → 退回固定 2x2 象限。"""
+    """缺 sheet_size/sheet_scale → 退回固定 2x2 象限，并按内容过滤空白象限。"""
     pytest.importorskip("PIL")
-    ctx = make_ctx(client=_tiling_client(_png_b64()))
+    client = _tiling_client(_png_b64())
+    # 实体完全落在**左下**象限内（不贴边界）
+    client.responses["query_entities"] = ok_text(
+        {"total": 1, "items": [{"handle": "A", "type": "LINE",
+                                "bbox": [0, 0, 50000, 15000]}]}
+    )
+    ctx = make_ctx(client=client)
+    ev = collect_frame(ctx, 1, frame([0, 0, 120000, 40000], sheet_size="ZZ"))
+    assert [i["label"] for i in ev["images"]] == ["overall", "tile-1"]
+
+
+def test_capture_images_fallback_keeps_all_when_no_boxes(tiling_env):
+    """拿不到实体 bbox（无法判断内容）→ 回退路径不过滤，四象限全拍。"""
+    pytest.importorskip("PIL")
+    client = _tiling_client(_png_b64())
+    client.responses["query_entities"] = ok_text({"total": 0, "items": []})
+    ctx = make_ctx(client=client)
     ev = collect_frame(ctx, 1, frame([0, 0, 120000, 40000], sheet_size="ZZ"))
     assert [i["label"] for i in ev["images"]] == [
         "overall", "tile-1", "tile-2", "tile-3", "tile-4",
@@ -291,3 +319,110 @@ def test_capture_images_falls_back_when_truncated(tiling_env):
     assert [i["label"] for i in ev["images"]] == [
         "overall", "tile-1", "tile-2", "tile-3", "tile-4",
     ]
+
+
+# ---------------------------------------------------------------------------
+#  内容过滤 / 绘图区最大化
+# ---------------------------------------------------------------------------
+def test_apply_keep_filters_and_falls_back():
+    regions = [
+        {"min_x": 0.0, "min_y": 0.0, "max_x": 1.0, "max_y": 1.0},
+        {"min_x": 1.0, "min_y": 1.0, "max_x": 2.0, "max_y": 2.0},
+    ]
+    keep_first = lambda w: w["min_x"] == 0.0  # noqa: E731
+    assert _apply_keep(regions, keep_first) == regions[:1]
+    assert _apply_keep(regions, None) == regions            # 无谓词 → 原样
+    assert _apply_keep(regions, lambda w: False) == regions  # 全被滤掉 → 退回原集合
+    assert _apply_keep([], keep_first) == []
+
+
+def test_content_predicate_none_without_boxes():
+    assert _content_predicate([]) is None
+    assert _content_predicate(None) is None
+
+
+def test_content_predicate_detects_intersection():
+    keep = _content_predicate([(0.0, 0.0, 5.0, 5.0)])
+    assert keep({"min_x": 4.0, "min_y": 4.0, "max_x": 9.0, "max_y": 9.0}) is True
+    assert keep({"min_x": 6.0, "min_y": 6.0, "max_x": 9.0, "max_y": 9.0}) is False
+
+
+@pytest.fixture
+def drawing_area_env(monkeypatch):
+    """打开绘图区最大化，并把等待时间归零（用例不真的 sleep）。"""
+    from dwg_review import config
+
+    monkeypatch.setattr(config, "DRAWING_AREA_MAXIMIZE", True)
+    monkeypatch.setattr(config, "DRAWING_AREA_ENTER_WAIT", 0.0)
+    monkeypatch.setattr(config, "DRAWING_AREA_RESTORE_WAIT", 0.0)
+    return config
+
+
+def _area_client(responses=None):
+    """带 set_drawing_area 工具的假客户端。"""
+    return FakeMcpClient(
+        tools=STANDARD_TOOLS + [tool_schema("set_drawing_area", "绘图区最大化")],
+        responses=responses,
+    )
+
+
+def test_maximized_drawing_area_calls_max_then_restore(drawing_area_env):
+    client = _area_client()
+    ctx = make_ctx(client=client)
+    with maximized_drawing_area(ctx):
+        assert client.called_names() == ["set_drawing_area"]  # 进入时只 max
+    assert [c["arguments"] for c in client.called("set_drawing_area")] == [
+        {"mode": "max"}, {"mode": "restore"},
+    ]
+
+
+def test_maximized_drawing_area_degrades_without_tool(drawing_area_env):
+    """旧版插件没有该工具 → 静默降级，一次调用都不发。"""
+    client = FakeMcpClient()
+    ctx = make_ctx(client=client)
+    with maximized_drawing_area(ctx):
+        pass
+    assert client.calls == []
+
+
+def test_maximized_drawing_area_disabled_by_config(drawing_area_env):
+    drawing_area_env.DRAWING_AREA_MAXIMIZE = False
+    client = _area_client()
+    ctx = make_ctx(client=client)
+    with maximized_drawing_area(ctx):
+        pass
+    assert client.calls == []
+
+
+def test_maximized_drawing_area_restores_even_if_body_raises(drawing_area_env):
+    client = _area_client()
+    ctx = make_ctx(client=client)
+    with pytest.raises(RuntimeError):
+        with maximized_drawing_area(ctx):
+            raise RuntimeError("boom")
+    assert client.arguments_of("set_drawing_area") == {"mode": "restore"}
+
+
+def test_maximized_drawing_area_degrades_when_max_fails(drawing_area_env):
+    """max 调用失败 → 视为没进入最大化，不再发 restore，也不抛异常。"""
+    client = _area_client(responses={"set_drawing_area": err("no window")})
+    ctx = make_ctx(client=client)
+    with maximized_drawing_area(ctx):
+        pass
+    assert [c["arguments"] for c in client.called("set_drawing_area")] == [{"mode": "max"}]
+
+
+def test_maximized_drawing_area_restore_failure_does_not_mask_body(drawing_area_env):
+    """restore 失败不应掩盖业务异常。"""
+    client = _area_client()
+    ctx = make_ctx(client=client)
+
+    def boom(args):
+        if args.get("mode") == "restore":
+            raise RuntimeError("restore failed")
+        return ok_text({})
+
+    client.responses["set_drawing_area"] = boom
+    with pytest.raises(ValueError):
+        with maximized_drawing_area(ctx):
+            raise ValueError("business error")

tests/test_heatmap.py

@@ -171,12 +171,3 @@ def test_grid_stats_without_clusters():
     st = hm.grid_stats(_grid([]))
     assert st["occupied"] == 0
     assert "clusters" not in st
-
-
-def test_occupied_boxes_returns_cell_world_boxes():
-    # 左下角格（row 1 / col 0）→ 世界 (0,0)-(50,50)
-    assert hm.occupied_boxes(_grid([(0, 0, 50, 50)])) == [(0.0, 0.0, 50.0, 50.0)]
-
-
-def test_occupied_boxes_empty():
-    assert hm.occupied_boxes(_grid([])) == []