Fix replay 2D black canvas and journey UX clarity

Stored analysis overlays now use the decoded frame; latch resets and draw failures surface. Verified with bare-video, replay-wiring, visual_policy, and analysis-progress tests.

apps/studio/tests/test_bare_video_analysis.py

@@ -42,6 +42,7 @@ from orisys_app_shared.acquisition.arrows import (
 )
 from orisys_app_shared.acquisition.image_backend import (
     ARROW_PURE,
+    ARROW_STITCHED,
     DEPTH,
     RECORDED,
     RESULT_FAILED,
@@ -395,6 +396,18 @@ def test_a_bare_video_is_analysed_and_scrubbed_in_both_directions(
         "the arrow view is the video's raw picture"
     )
 
+    # ---- overlay: arrows on the captured frame, not on the black placeholder -
+    set_mode(window, ARROW_STITCHED)
+    QApplication.processEvents()
+    overlay = panel_bgr(window)
+    assert painted(overlay, canvas) > 0, "the overlay painted no arrows"
+    assert float(np.mean(overlay)) > 8.0, (
+        "the overlay is still a near-black canvas; the captured frame was not under the arrows"
+    )
+    assert not np.array_equal(overlay, middle_shot), (
+        "the overlay view is the pure-colour canvas"
+    )
+
     # ---- the depth view, from the same stored frame -------------------------
     set_mode(window, DEPTH)
     QApplication.processEvents()