fix(flomni): warn on invalid beamline states before manual xray-eye frame; fix sample-remove slot handling

xrayeye_update_frame() now checks all configured beamline states and, if any
are not valid, warns the user (the frame may be empty when the beam is down)
and asks before taking a frame. The automated alignment path is unaffected.

ftransfer_sample_change(): clarify the remove-only prompt to "sample currently
in the sample stage", and include tray slot 20 in the empty-slot scan
(range(1, 20) -> range(1, 21)) in both the remove and mount branches, matching
check_position_is_valid's 0-20 range.

csaxs_bec/bec_ipython_client/plugins/flomni/flomni.py

@@ -878,7 +878,7 @@ class FlomniSampleTransferMixin:
                 raise FlomniError("There is no sample in the sample stage to remove. Aborting.")
 
             empty_slots = []
-            for j in range(1, 20):
+            for j in range(1, 21):
                 if not dev.flomni_samples.is_sample_slot_used(j):
                     empty_slots.append(j)
             if not empty_slots:
@@ -887,7 +887,10 @@ class FlomniSampleTransferMixin:
             print(f"The following slots are empty: {empty_slots}.")
 
             while True:
-                user_input = input(f"Where shall I put the sample? Default: [{empty_slots[0]}] ")
+                user_input = input(
+                    "Where shall I put the sample currently in the sample stage? "
+                    f"Default: [{empty_slots[0]}] "
+                )
 
                 if user_input.strip() == "":
                     user_input = empty_slots[0]
@@ -934,7 +937,7 @@ class FlomniSampleTransferMixin:
             #                    continue
             #                if val.get("value") == 0:
             #                    empty_slots.append(int(name.split("flomni_samples_sample_placed_sample")[1]))
-            for j in range(1, 20):
+            for j in range(1, 21):
                 if not dev.flomni_samples.is_sample_slot_used(j):
                     empty_slots.append(j)
             if not empty_slots:
@@ -1801,7 +1804,45 @@ class Flomni(
                     umv(dev.fsamx, fsamx_in)
                 raise exc
 
+    def _check_beamline_states_valid(self):
+        """Return (all_valid, invalid_labels).
+
+        Reads every configured beamline state (bec.beamline_states) and
+        collects the ones whose status is not "valid" (i.e. "invalid",
+        "warning" or "unknown"). Used to warn before taking a manual X-ray
+        eye frame: if e.g. the beam is down, the frame would come back empty
+        and the user is left confused about why they see nothing.
+
+        Returns all_valid=True (with an empty list) if the beamline-state
+        machinery isn't available at all, so this never blocks on a setup
+        that doesn't use beamline states.
+        """
+        bec = builtins.__dict__.get("bec")
+        manager = getattr(bec, "beamline_states", None) if bec is not None else None
+        if manager is None:
+            return True, []
+
+        bad = []
+        for name in list(getattr(manager, "_states", {})):
+            try:
+                status = manager.get_status_by_name(name)
+            except Exception:  # pylint: disable=broad-except
+                continue
+            if status is not None and status != "valid":
+                bad.append(f"{name}: {status}")
+        return (len(bad) == 0), bad
+
     def xrayeye_update_frame(self, keep_shutter_open=False):
+        all_valid, bad_states = self._check_beamline_states_valid()
+        if not all_valid:
+            print(
+                "Attention: not all beamline states are valid:\n  "
+                + "\n  ".join(bad_states)
+                + "\nThe beam may be down, so the frame could come back empty."
+            )
+            if not self.OMNYTools.yesno("Take a frame anyway?", "n"):
+                print("Stopping.")
+                return
         self.align.update_frame(keep_shutter_open)
 
     def xrayeye_alignment_start(self, keep_shutter_open=False):