feat(studio-3d): 历史回放里的三维面板 —— 由「重算」通道喂它，并标注来源

- What: `VIEW_SHOWS_3D` 加入 `replay`；`app_window` 新增 `_shows_3d()`（可见性与布局共用一个判据）
  与 `_splitter_sizes_for()`（预设表里的 3D 槽是"二维布局"的描述，面板打开时从最宽的面板借
  `DEFAULT_3D_PANE_WIDTH=340`）；`ThreeDPanel` 新增第三个来源标签（实时采集 / 回放：录像不含三维场 /
  重算通道：由录像重算，非记录值）与 `set_source_kind()`；`ThreeDCoordinator.show_rest()` 把参考模型
  放回屏幕并停止主张测量值（重算停止时调用，否则最后一帧会留在屏幕上）；`Mesh3dPanel` 转发这两者，
  并新增"加载中"状态的修正：切换传感器再切回来时若该包已加载，直接显示已就绪的画面而不是一条永远
  不会被替换的"正在加载"。
- Why: 录像里没有三维场（raw_*.mp4 是原始相机图像，`depth.stored=false`，CSV 只有力值），所以纯回放只能
  显示参考模型；但「从视频重算力值」本来就把同一个运行路径指向录像的原始视频，而采集线程上的三维 sink
  早已注册——因此重算一开始面板就会收到真实的形变帧。这两件事必须由界面区分：一个是"没有测量"，
  一个是"当前算法对这段录像会说什么"，把后者当成记录值展示就是另一种 `display_illustrative`。
- Verification: apps/studio 全量通过（test_scene3d_view.py 32 项，含"回放里面板可见且标注正确""重算时
  标注切换""停止重算后清回参考模型""实时视图标为实时"；test_scene3d_coordinator.py 15 项，含 show_rest
  与"停止时在飞的帧不会随后被显示"）；ui_check 570 项 0 失败（新增"已安装包必须被加载并标注来源"）；
  locale_check 0 缺失；仓库内工程包经 validate_scene 全部 ok。
- Not in this change: 逐帧保存展开场/深度（记录格式变更，设计文档明确否掉）；重算通道本身（已存在，本次
  只是把它的帧接到面板上）；示意位移（仍需 SDK lift + 已确认尺度）。

apps/studio/tests/test_scene3d_coordinator.py

@@ -312,3 +312,50 @@ def test_close_is_idempotent_and_stops_everything(scene, pool):
     presented = len(widget.frames)
     coordinator.tick()
     assert len(widget.frames) == presented
+
+
+# ------------------------------------------------- the reference model, on demand
+def test_show_rest_puts_the_model_back_and_stops_claiming_a_measurement(scene, pool):
+    """The replay view's case: a pass stops, so the last frame must go.
+
+    Without this the recomputed picture would stay on screen while nothing is
+    producing it — a measurement that is no longer being made.
+    """
+    widget = FakeWidget()
+    coordinator = ThreeDCoordinator(widget, SceneComposer(), pool)
+    coordinator.set_visible(True)
+    coordinator.activate(scene, "replay-A")
+    coordinator.submit(_frame(scene, source="replay-A"))
+    _drain(coordinator, ticks=10)
+    assert coordinator.state in ("live", "no_data")
+    assert widget.frames[-1].valid.any(), "the measurement never arrived"
+
+    coordinator.show_rest()
+    last = widget.frames[-1]
+    assert not last.valid.any(), "the old measurement is still on screen"
+    assert last.scalar_descriptor.quantity == "unavailable"
+    assert coordinator.state == "no_data"
+
+    # And it is a no-op when there is nothing to show or the view is off.
+    coordinator.set_visible(False)
+    before = len(widget.frames)
+    coordinator.show_rest()
+    assert len(widget.frames) == before
+    coordinator.close()
+    coordinator.show_rest()  # closed: still safe
+    assert coordinator.state == "disabled"
+
+
+def test_a_frame_already_queued_is_dropped_when_the_model_comes_back(scene, pool):
+    """The rest frame is not "the newest sample": a queued one must not follow it."""
+    widget = FakeWidget()
+    coordinator = ThreeDCoordinator(widget, CountingComposer(delay_s=0.02), pool)
+    coordinator.set_visible(True)
+    coordinator.activate(scene, "replay-A")
+    coordinator.submit(_frame(scene, source="replay-A", value=7.0))
+    coordinator.show_rest()
+    _drain(coordinator, ticks=4, sleep=0.01)
+    assert not widget.frames[-1].valid.any(), (
+        "a frame that was in flight when the pass stopped was presented anyway"
+    )
+    coordinator.close()

apps/studio/tests/test_scene3d_view.py

@@ -37,6 +37,7 @@ from orisys_app_shared.scene3d.contracts import (
     UNAVAILABLE_DESCRIPTOR,
 )
 from orisys_app_shared.scene3d.package import write_package
+from orisys_studio.app_window import MIN_PANEL_WIDTHS
 from orisys_studio.scene3d import prefs as scene3d_prefs
 from orisys_studio.scene3d.asset_source import (
     PACKAGE_SUFFIX,
@@ -45,7 +46,12 @@ from orisys_studio.scene3d.asset_source import (
     load_package,
     no_asset_diagnostic,
 )
-from tests.test_ui_smoke import _finish, _running_window
+from tests.test_ui_smoke import (  # noqa: F401  (fixtures are imported by name)
+    _finish,
+    _running_window,
+    record_root,
+    replay_recording,
+)
 
 #: Scratch root for the two-session comparison. One subdirectory per run, because
 #: the point of the test is that two recordings are identical, not that one file
@@ -112,9 +118,18 @@ def test_a_box_sensor_reports_that_it_has_no_3d_scene(qt_app):
         panel.deleteLater()
 
 
-def test_a_missing_package_names_where_it_looked(tmp_path, qt_app):
+def test_a_missing_package_names_where_it_looked(tmp_path, qt_app, monkeypatch):
+    """With no package anywhere, the pane names the directory it looked in.
+
+    The search is stubbed rather than relied on: the repository may or may not carry
+    a compiled package (the application's own config directory is where one belongs),
+    and a test that only passes on a machine without one is a test that fails the
+    first time somebody installs the feature.
+    """
+    import orisys_studio.ui.mesh3d_panel as panel_module
     from orisys_studio.ui.mesh3d_panel import Mesh3dPanel
 
+    monkeypatch.setattr(panel_module, "find_package", lambda *a, **k: None)
     panel = Mesh3dPanel()
     try:
         panel.set_sensor("finger", package_override=tmp_path / "nope.oryscene")
@@ -164,17 +179,21 @@ def test_the_pane_fits_the_width_the_window_reserves_for_it(qt_app):
         view.close()
 
 
-def test_a_platform_without_a_context_says_so_instead_of_showing_an_empty_view(qt_app):
+def test_a_platform_without_a_context_says_so_instead_of_showing_an_empty_view(
+    write_poc, qt_app
+):
     """The offscreen plugin cannot create a context; that must not look like "no data".
 
     Qt reports this by never calling ``initializeGL``, so the widget asks Qt the one
-    question that has an answer — is there a context at all — on its first paint.
+    question that has an answer — is there a context at all — on its first paint. The
+    scene comes from a package written for this test, so the case does not depend on
+    whether the repository happens to carry a compiled one.
     """
     from orisys_studio.ui.mesh3d_panel import Mesh3dPanel
 
     panel = Mesh3dPanel()
     try:
-        panel.set_sensor("finger")
+        panel.set_sensor("finger", package_override=write_poc())
         view = panel.ensure_view()
         if view is None:
             pytest.skip("the pane did not build a view here")
@@ -184,7 +203,10 @@ def test_a_platform_without_a_context_says_so_instead_of_showing_an_empty_view(q
         panel.resize(240, 400)
         panel.show()
         view.show()
-        qt_app.processEvents()
+        panel.set_enabled(True)
+        assert _pump(qt_app, lambda: view.assets is not None, timeout_s=15.0), (
+            "the test package never loaded"
+        )
         widget = view.gl_widget
         for _ in range(5):
             widget.repaint()
@@ -584,6 +606,73 @@ def test_a_recording_says_what_the_3d_pane_was(
         window.close()
 
 
+def test_the_replay_view_shows_the_pane_and_says_where_the_field_comes_from(
+    make_window, replay_recording, qt_app
+):
+    """History browsing gets the pane, fed by the recompute pass — and says so.
+
+    A recording stores the raw camera image and the forces, not a per-frame
+    deformation field, so the pane in replay is either the surface model (no field) or
+    what a recompute pass produces from the video. Those are two different claims and
+    the label has to distinguish them.
+    """
+    from tests.test_ui_smoke import _show
+
+    window = _show(make_window(sensor_type="finger"), (1440, 880))
+    try:
+        assert window._load_recording(Path(replay_recording))
+        assert window._view_preset == "replay"
+        pane = window.mesh3d_panel
+        assert pane.isVisible(), "the 3D pane is hidden in the replay view"
+        assert pane.enabled(), "the pane is visible but not switched on"
+        assert window.content_splitter.sizes()[0] >= MIN_PANEL_WIDTHS["mesh3d"], (
+            "the replay layout left the pane at zero width"
+        )
+        view = pane.view
+        if view is None or view.panel is None:
+            pytest.skip("no 3D view on this platform")
+        # Wait for the scene to load, then read what the pane claims.
+        assert _pump(qt_app, lambda: view.assets is not None, timeout_s=15.0), (
+            "the scene never loaded: " + str(pane.last_diagnostic)
+        )
+        label = view.panel.source_label.text()
+        assert "回放" in label or "Replay" in label, label
+
+        # A running pass means the pixels are recomputed, and the label must say so.
+        window._recompute_running = True
+        window._apply_panel_visibility()
+        label = view.panel.source_label.text()
+        assert "重算" in label or "Recomputed" in label, label
+
+        # Stopping the pass must clear the picture, not leave the last frame up.
+        window._recompute_running = False
+        pane.show_reference_only()
+        qt_app.processEvents()
+        assert view.coordinator.state in ("no_data", "ready", "disabled")
+        assert "没有测量值" in view.panel.legend_label.text() or (
+            "No measurement" in view.panel.legend_label.text()
+        ), view.panel.legend_label.text()
+        window._apply_panel_visibility()
+        label = view.panel.source_label.text()
+        assert "回放" in label or "Replay" in label, label
+    finally:
+        window.close()
+
+
+def test_the_live_view_still_says_live(make_window, qt_app):
+    window = make_window(sensor_type="finger")
+    try:
+        window._apply_panel_visibility()
+        view = window.mesh3d_panel.view
+        if view is None or view.panel is None:
+            pytest.skip("no 3D view on this platform")
+        label = view.panel.source_label.text()
+        assert "实时" in label or "Live" in label, label
+        assert view.panel.source_label.toolTip()
+    finally:
+        window.close()
+
+
 def test_a_platform_locked_scene_is_refused_in_the_application(qt_app):
     """A lock violation is a *pane* failure: the view refuses the scene and says why."""
     from orisys_app_shared.scene3d.contracts import PlatformInfo, PlatformLock