Present replay 3D with the cursor and open Analyze on a remembered video

Replay left the 3D pane on the rest mesh or a sparse overlay, and Analyze skipped the setup dialog unless the file was re-picked. Live Run no longer starts a chain on a video path. Verified with Studio tests for flush, overlay mask, Analyze open, live-video refusal, and locales.

apps/studio/tests/test_scene3d_overlays.py

@@ -2,6 +2,8 @@
 
 from __future__ import annotations
 
+from dataclasses import replace
+
 import numpy as np
 from orisys_app_shared.scene3d.composer import SceneComposer
 from orisys_app_shared.scene3d.contracts import (
@@ -152,3 +154,36 @@ def test_both_views_build_their_policy_from_the_same_settings() -> None:
     # Normalised, so a hand-edited preference cannot invert the hysteresis band.
     inverted = policy_for_settings(DisplaySettings(flow_on_px=0.1, flow_off_px=0.9))
     assert inverted.flow_on_px >= inverted.flow_off_px
+
+
+def test_a_sparse_recovered_field_still_draws_3d_arrows() -> None:
+    """A recovered analysis field is ``NaN`` off the stored grid; tips land there.
+
+    Handing ``isfinite(flow)`` as the overlay mask required the tip to sit on another
+    stored cell, so replay 3D kept a few rim dots while 2D drew the island grid.
+    """
+    assets = poc_scene()
+    h, w = assets.shape_hw
+    flow = np.full((h, w, 2), np.nan, dtype=np.float32)
+    flow[1, 1] = (0.9, 0.0)
+    settings = DisplaySettings(
+        flow_arrows_enabled=True,
+        contact_arrow_enabled=False,
+        flow_grid_spacing=1,
+        flow_on_px=0.4,
+        flow_off_px=0.3,
+        max_arrows=50,
+    )
+    dropped = SceneComposer().compose(
+        assets,
+        replace(
+            _depth_frame(assets, flow=flow),
+            flow_valid_mask=freeze(np.isfinite(flow[..., 0]), dtype=np.bool_),
+        ),
+        settings,
+    )
+    n_dropped = 0 if dropped.flow_arrows is None else int(dropped.flow_arrows.origins.shape[0])
+    drawn = SceneComposer().compose(assets, _depth_frame(assets, flow=flow), settings)
+    n_drawn = 0 if drawn.flow_arrows is None else int(drawn.flow_arrows.origins.shape[0])
+    assert n_drawn >= 1, "the island mask still produced no 3D arrows"
+    assert n_drawn > n_dropped, (n_drawn, n_dropped)