feat(csaxs): csaxs.aerotech.plot() title shows the plotted scan number

The history plot uses the given scan number; the live plot the last scan at
start and then the number of each followed aerotech_cont_grid scan. The title
is set in the redraw thread, only when the scan changes.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017NrH3poJsYBCTVq2Y9fuHZ

csaxs_bec/bec_ipython_client/plugins/cSAXS/aerotech.py

@@ -53,8 +53,9 @@ class cSAXSAerotech:
         waveform, curves = self._setup_plot()
         if scan_number is not None:
             _draw(curves, self._history_lines(scan_number))
+            waveform.title = _title(scan_number)
             return waveform
-        self._live = _LivePositions(self, curves)
+        self._live = _LivePositions(self, waveform, curves)
         self._live.start()
         return waveform
 
@@ -74,7 +75,7 @@ class cSAXSAerotech:
         if waveform is None:
             waveform = window.new("Waveform", object_name=self.PLOT, timeout=self.GUI_RPC_TIMEOUT)
         waveform.clear_all()
-        waveform.title = "aerotech_cont_grid: exposure centres"
+        waveform.title = _title(None)
         waveform.x_label = "X centre (aerox)"
         waveform.y_label = "Y centre (aeroy)"
         waveform.lock_aspect_ratio = True
@@ -96,6 +97,13 @@ class cSAXSAerotech:
         return _lines_from_file(scan._msg.file_path)
 
 
+def _title(scan_number: int | None) -> str:
+    """Plot title with the number of the plotted scan."""
+    if scan_number is None:
+        return "aerotech_cont_grid: exposure centres"
+    return f"aerotech_cont_grid scan {scan_number}: exposure centres"
+
+
 def _lines_from_file(file_path: str) -> list[tuple[np.ndarray, np.ndarray]]:
     """Exposure centres per line from an aerotech_cont_grid data file."""
     with h5py.File(file_path, "r") as f:
@@ -150,12 +158,15 @@ def _markers_only(x: np.ndarray, y: np.ndarray) -> tuple[np.ndarray, np.ndarray]
 class _LivePositions:
     """Follows aerotech_cont_grid scans and redraws the exposure centres per line."""
 
-    def __init__(self, parent: cSAXSAerotech, curves: dict):
+    def __init__(self, parent: cSAXSAerotech, waveform, curves: dict):
         self.parent = parent
         self.connector = parent.client.connector
+        self.waveform = waveform
         self.curves = curves
         self._lock = threading.Lock()
         self._lines: list[tuple[np.ndarray, np.ndarray]] = []
+        self._scan_number: int | None = None
+        self._shown_scan_number: int | None = None
         self._scan_id = None
         self._stream_topic = None
         self._dirty = threading.Event()
@@ -177,7 +188,8 @@ class _LivePositions:
 
     def _show_last_scan(self) -> None:
         try:
-            self._set_lines(_lines_from_file(self.parent.client.history[-1]._msg.file_path))
+            msg = self.parent.client.history[-1]._msg
+            self._set_lines(_lines_from_file(msg.file_path), scan_number=msg.scan_number)
         except Exception:  # no scan yet, or the last one is not an aerotech_cont_grid
             pass
 
@@ -191,7 +203,7 @@ class _LivePositions:
             return
         self._unfollow()
         self._scan_id = status.scan_id
-        self._set_lines([])
+        self._set_lines([], scan_number=status.scan_number)
         self._stream_topic = MessageEndpoints.device_async_signal(
             scan_id=status.scan_id,
             device=self.parent.CAPTURE_DEVICE,
@@ -216,9 +228,10 @@ class _LivePositions:
             self._lines.append((x, y))
         self._dirty.set()
 
-    def _set_lines(self, lines) -> None:
+    def _set_lines(self, lines, scan_number: int | None = None) -> None:
         with self._lock:
             self._lines = list(lines)
+            self._scan_number = scan_number
         self._dirty.set()
 
     def _redraw_loop(self) -> None:
@@ -229,8 +242,12 @@ class _LivePositions:
                 self._dirty.clear()
                 with self._lock:
                     lines = list(self._lines)
+                    scan_number = self._scan_number
                 try:
                     _draw(self.curves, lines)
+                    if scan_number != self._shown_scan_number:
+                        self.waveform.title = _title(scan_number)
+                        self._shown_scan_number = scan_number
                 except Exception as exc:  # window or plot closed, GUI restarted
                     # stop following instead of failing on every line of every scan
                     logger.warning(

tests/tests_bec_ipython_client/test_cSAXS_aerotech.py

@@ -76,6 +76,7 @@ def test_plot_history_draws_forward_and_backward_curves():
         "Waveform", object_name="aerotech_positions", timeout=20
     )
     assert waveform.lock_aspect_ratio is True
+    assert waveform.title == "aerotech_cont_grid scan 8494: exposure centres"
     for curve in (forward, backward):
         x, y = curve.set_data.call_args.args
         # markers only: a NaN after every point, X finite and increasing
@@ -132,9 +133,31 @@ def test_live_follows_an_aerotech_scan_line_by_line():
 
     x, _ = backward.set_data.call_args.args
     assert len(x) == 2 * 5
+    assert waveform.title == "aerotech_cont_grid scan 1: exposure centres"
     client.connector.unregister.assert_called()
 
 
+def test_live_title_shows_the_last_scan():
+    client = _client()
+    waveform = _waveform(client)
+    forward, backward = mock.MagicMock(), mock.MagicMock()
+    waveform.plot.side_effect = [forward, backward]
+    client.history.__getitem__.return_value._msg = SimpleNamespace(
+        file_path="scan.h5", scan_number=4897
+    )
+    tool = cSAXSAerotech(client)
+    with mock.patch(
+        "csaxs_bec.bec_ipython_client.plugins.cSAXS.aerotech._lines_from_file",
+        return_value=_snake(),
+    ):
+        tool.plot()
+    deadline = time.time() + 3
+    while time.time() < deadline and "4897" not in str(waveform.title):
+        time.sleep(0.05)
+    tool.stop_plot()
+    assert waveform.title == "aerotech_cont_grid scan 4897: exposure centres"
+
+
 def test_live_ignores_other_scans():
     client = _client()
     client.history.__getitem__.side_effect = IndexError