Do not reload sample if it's already been loaded

src/mx_bluesky/hyperion/experiment_plans/robot_load_then_centre_plan.py

@@ -1,13 +1,15 @@
 from __future__ import annotations
 
 import dataclasses
+from collections.abc import Generator
 from datetime import datetime
 from pathlib import Path
 from typing import cast
 
 import bluesky.plan_stubs as bps
 import bluesky.preprocessors as bpp
 from blueapi.core import BlueskyContext, MsgGenerator
+from bluesky.utils import Msg
 from dodal.devices.aperturescatterguard import ApertureScatterguard, ApertureValue
 from dodal.devices.attenuator import Attenuator
 from dodal.devices.backlight import Backlight
@@ -185,11 +187,21 @@ def raise_exception_if_moved_out_of_cryojet(exception):
         )
 
 
+def pin_already_loaded(
+    robot: BartRobot, pin_to_load: int, puck_to_load: int
+) -> Generator[Msg, None, bool]:
+    current_puck = yield from bps.rd(robot.current_puck)
+    current_pin = yield from bps.rd(robot.current_pin)
+    return int(current_puck) == puck_to_load and int(current_pin) == pin_to_load
+
+
 def robot_load_then_centre_plan(
     composite: RobotLoadThenCentreComposite,
     params: RobotLoadThenCentre,
 ):
-    yield from prepare_for_robot_load(composite)
+    # TODO: get these from one source of truth #1347
+    assert params.sample_puck is not None
+    assert params.sample_pin is not None
 
     @bpp.run_decorator(
         md={
@@ -245,8 +257,17 @@ def robot_load_and_snapshots():
 
         yield from bps.wait("reset-lower_gonio")
 
-    yield from robot_load_and_snapshots()
-
+    if not (
+        yield from pin_already_loaded(
+            composite.robot, params.sample_pin, params.sample_puck
+        )
+    ):
+        yield from prepare_for_robot_load(composite)
+        yield from robot_load_and_snapshots()
+    else:
+        LOGGER.info(
+            f"Pin/puck {params.sample_pin}/{params.sample_puck} already loaded, will not reload."
+        )
     yield from pin_centre_then_xray_centre_plan(
         cast(GridDetectThenXRayCentreComposite, composite),
         params.pin_centre_then_xray_centre_params(),

tests/unit_tests/hyperion/experiment_plans/test_wait_for_robot_load_then_centre.py

@@ -17,6 +17,7 @@
     RobotLoadThenCentreComposite,
     prepare_for_robot_load,
     robot_load_then_centre,
+    robot_load_then_centre_plan,
     take_robot_snapshots,
 )
 from mx_bluesky.hyperion.external_interaction.callbacks.robot_load.ispyb_callback import (
@@ -491,3 +492,35 @@ def test_when_plan_run_then_thawing_turned_on_for_expected_time(
         and msg.obj.name == "thawer-thaw_for_time_s"
         and msg.args[0] == thaw_time,
     )
+
+
+@patch(
+    "mx_bluesky.hyperion.experiment_plans.robot_load_then_centre_plan.pin_centre_then_xray_centre_plan"
+)
+@patch("mx_bluesky.hyperion.experiment_plans.robot_load_then_centre_plan.do_robot_load")
+@patch(
+    "mx_bluesky.hyperion.experiment_plans.robot_load_then_centre_plan.prepare_for_robot_load"
+)
+def test_given_sample_already_loaded_when_plan_run_then_sample_not_loaded(
+    mock_prepare_robot: MagicMock,
+    mock_do_robot_load: MagicMock,
+    mock_centring_plan: MagicMock,
+    robot_load_composite: RobotLoadThenCentreComposite,
+    robot_load_then_centre_params_no_energy: RobotLoadThenCentre,
+    RE: RunEngine,
+):
+    set_mock_value(robot_load_composite.robot.current_pin, 1)
+    set_mock_value(robot_load_composite.robot.current_puck, 2)
+
+    robot_load_then_centre_params_no_energy.sample_pin = 1
+    robot_load_then_centre_params_no_energy.sample_puck = 2
+
+    RE(
+        robot_load_then_centre_plan(
+            robot_load_composite,
+            robot_load_then_centre_params_no_energy,
+        )
+    )
+    mock_prepare_robot.assert_not_called()
+    mock_do_robot_load.assert_not_called()
+    mock_centring_plan.assert_called()