Make the rail reset zero the sensor in live and the display in replay

The replay view disabled a control whose display reset is exactly what an
operator wants there, and the bare "Reset" hid that the live one zeroes the
sensor tracker; the label, tooltip and status line now name the target, and
Ctrl+R follows the view. Verified with the studio suite, ui_check (628
checks) and real-GL rail snapshots of both views.

apps/studio/tests/test_ui_smoke.py

@@ -1532,7 +1532,6 @@ def test_the_nav_items_switch_the_main_window_layout(make_window):
     assert not window.replay.is_loaded()
     assert window.force_plots.mode() == "follow", "browsing starts with no recording"
     assert window.toolbar.btn_replay_video.isVisible(), "no video picker in the replay"
-    live_sizes = tuple(window.content_splitter.sizes())
 
     window.brand_bar.btn_live.click()
     assert window.view_preset() == "live"
@@ -2050,7 +2049,8 @@ def test_the_replay_view_offers_a_stop_that_always_works(make_window, replay_rec
     wrong. So the rail's Stop button — the same one the live view uses to end a session
     — is an unconditional stop in this view, and it covers both things that can run
     there: plain playback and a recompute pass. The tracker reset owns no device here,
-    so it is disabled rather than repurposed.
+    so it is the *display* reset and says so (see
+    ``test_the_replay_reset_is_the_display_reset_and_never_the_device``).
     """
     from orisys_app_shared.i18n import t
     from PySide6.QtWidgets import QApplication
@@ -2061,10 +2061,10 @@ def test_the_replay_view_offers_a_stop_that_always_works(make_window, replay_rec
     assert window._load_recording(replay_recording)
     QApplication.processEvents()
 
-    assert not window.toolbar.btn_reset.isEnabled(), (
-        "the replay view offers to zero a device tracker it has not got"
+    assert window.toolbar.btn_reset.isEnabled(), (
+        "the replay view's display reset is unavailable"
     )
-    assert window.toolbar.btn_reset.text() == t("toolbar.reset")
+    assert window.toolbar.btn_reset.text() == t("toolbar.reset_display")
     assert window.toolbar.btn_stop.text() == t("toolbar.stop_label")
     assert not window.toolbar.btn_stop.isEnabled(), (
         "a stop is offered while nothing is running"
@@ -2136,12 +2136,131 @@ def test_the_live_view_keeps_the_tracker_reset(make_window):
     window = _show(make_window(), (1440, 880))
     window.brand_bar.btn_live.click()
     QApplication.processEvents()
-    assert window.toolbar.btn_reset.text() == t("toolbar.reset"), (
+    assert window.toolbar.reset_target() == "sensor", (
+        "the live view's reset is the sensor tracker's"
+    )
+    assert window.toolbar.btn_reset.text() == t("toolbar.reset_sensor"), (
         "the rail's reset slot is not the tracker reset in the live view"
     )
+    # Idle, the tip explains what is missing instead of leaving a dead button.
+    assert not window.toolbar.btn_reset.isEnabled()
+    assert window.toolbar.btn_reset.toolTip() == t("toolbar.reset_sensor_unavailable"), (
+        window.toolbar.btn_reset.toolTip()
+    )
     window.close()
 
 
+def test_the_replay_reset_is_the_display_reset_and_never_the_device(
+    make_window, replay_recording
+):
+    """The reported defect: "the reset button cannot be used in replay mode".
+
+    The replay view owns no device, so the tracker reset is meaningless there — but the
+    display reset is exactly what an operator wants. The control is the same one, and
+    these are the facts that have to hold together: it is available, it puts the display
+    back (curves redrawn at their default framing, playhead at the start), and it never
+    asks a device worker to zero anything — the window is armed with one, and its request
+    counter stays at zero.
+    """
+    from orisys_app_shared.i18n import t
+    from PySide6.QtWidgets import QApplication
+
+    window = _show(make_window(), (1440, 880))
+    stuck = ui_check._StuckWorker()
+    window._ensure_workers = lambda: None
+    window._box_worker = stuck
+    window._finger_worker = stuck
+    window.brand_bar.btn_playback.click()
+    QApplication.processEvents()
+    assert window._load_recording(replay_recording)
+    QApplication.processEvents()
+
+    assert window.toolbar.reset_target() == "display"
+    assert window.toolbar.btn_reset.isEnabled(), (
+        "the replay view must offer the display reset"
+    )
+    assert window.toolbar.btn_reset.text() == t("toolbar.reset_display")
+    assert window.toolbar.btn_reset.toolTip() == t("toolbar.reset_display_tip")
+    assert window.act_reset.text() == t("menu.reset_display"), (
+        "Ctrl+R is the same control and must be named the same way"
+    )
+    assert window.act_reset.isEnabled()
+
+    # What the reset has to undo: a moved playhead and a browsed window.
+    window.replay.set_position(0.9)
+    window.force_plots.set_window(0.4, 1.1)
+    QApplication.processEvents()
+    assert window.force_plots.mode() == "browse"
+    assert window.replay.position() > 0.5
+
+    window.toolbar.btn_reset.click()
+    QApplication.processEvents()
+    assert stuck.reset_requests == 0, (
+        "the replay's reset asked a device worker to zero the tracker"
+    )
+    assert window.replay.position() == 0.0, (
+        f"the reset did not start the replay over: {window.replay.position()}"
+    )
+    assert window.force_plots.cursor_time() == 0.0
+    assert window.force_plots.mode() == "browse", (
+        "the reset left the charts out of the replay's own mode"
+    )
+    sizes = [
+        0 if curve.getData()[0] is None else int(curve.getData()[0].size)
+        for curve in window.force_plots.curves
+    ]
+    assert all(size > 0 for size in sizes), (
+        f"the reset left the replay with blank charts: {sizes}"
+    )
+    assert window.statusBar().currentMessage() == t("status.reset_display"), (
+        window.statusBar().currentMessage()
+    )
+    window.close()
+
+
+def test_the_live_reset_zeroes_the_device_and_restarts_the_display_baseline(make_window):
+    """The live half of the same control: the device is asked, and the tip's side
+    effect (the display baseline restarting) really happens."""
+    from orisys_app_shared.i18n import t
+    from PySide6.QtWidgets import QApplication
+
+    window = _show(make_window(sensor_type="box", source_mode="camera"), (1440, 880))
+    stuck = ui_check._StuckWorker()
+    window._ensure_workers = lambda: None
+    window._box_worker = stuck
+    window._finger_worker = stuck
+    window._start_run()
+    window._run_timer.stop()
+    try:
+        # The first frame is the application's own path to ``running`` — and the moment
+        # the rail recomputes what a session can do (see ``_update_run_enabled``), which
+        # is why the state is reached through it rather than stated directly.
+        stuck.emit(ui_check._fake_packet(1))
+        window._on_run_tick()
+        QApplication.processEvents()
+        assert window._session_phase == "running"
+        assert window.toolbar.btn_reset.isEnabled()
+        assert window.toolbar.btn_reset.text() == t("toolbar.reset_sensor")
+        assert window.toolbar.btn_reset.toolTip() == t("toolbar.reset_sensor_tip")
+        restarts: list = []
+        window.force_plots.request_presentation_reestimate = lambda: restarts.append(True)
+
+        window.toolbar.btn_reset.click()
+        assert stuck.reset_requests == 1, "the live reset did not reach the device"
+        assert restarts == [True], (
+            "the display baseline was not restarted with the zero (the tooltip's side effect)"
+        )
+        assert window.statusBar().currentMessage() == t("status.reset_pending"), (
+            window.statusBar().currentMessage()
+        )
+        assert window.act_reset.text() == t("menu.reset"), (
+            "Ctrl+R must be named as the sensor reset in the live view"
+        )
+    finally:
+        window._stop_run(reason="user_stop")
+        stuck.release()
+
+
 def test_the_tracker_reset_follows_the_session_across_a_view_switch(make_window):
     """Zeroing the tracker is a *device* action: which panel is on screen is not a fact
     about the session, so switching live → calibration → live must not take the reset
@@ -2171,7 +2290,7 @@ def test_the_tracker_reset_follows_the_session_across_a_view_switch(make_window)
         assert window.toolbar.btn_reset.isEnabled() and window.act_reset.isEnabled(), (
             "a running session must offer the tracker reset before any view switch"
         )
-        assert window.toolbar.btn_reset.text() == t("toolbar.reset")
+        assert window.toolbar.btn_reset.text() == t("toolbar.reset_sensor")
 
         window.brand_bar.btn_calibration.click()
         QApplication.processEvents()