fix(api): use smaller of max pipette volume and max tip volume for splitting large transfer volumes (#17387)

# Overview

Found a bug in the logic that splits large volume transfers into smaller
volumes.
Bug is that we only check the transfer volume against max pipette
volume. So if you use a 50uL pipette with a 200uL tip, everything works
correctly, but if you use a 1000uL pipette with 50uL tip, it attempts to
pipette upto 1000uL, instead of clipping to the max tip volume of 50uL.

This PR fixes that by taking the smaller of pipette volume and tip
volume as the max volume a single transfer can take.

## Risk assessment

Low. A scope-limited bug fix

Author: sanni-t

api/src/opentrons/protocol_api/core/engine/instrument.py

@@ -1008,7 +1008,12 @@ def transfer_liquid(  # noqa: C901
         source_dest_per_volume_step = tx_commons.expand_for_volume_constraints(
             volumes=[volume for _ in range(len(source))],
             targets=zip(source, dest),
-            max_volume=self.get_max_volume(),
+            max_volume=min(
+                self.get_max_volume(),
+                tip_racks[0][1]
+                .get_well_core("A1")
+                .get_max_volume(),  # Assuming all tips in tiprack are of same volume
+            ),
         )
 
         def _drop_tip() -> None:
@@ -1175,10 +1180,11 @@ def aspirate_liquid_class(
         Return: List of liquid and air gap pairs in tip.
         """
         aspirate_props = transfer_properties.aspirate
+        # TODO (spp, 2025-01-30): check if check_valid_volume_parameters is necessary and is enough.
         tx_commons.check_valid_volume_parameters(
             disposal_volume=0,  # No disposal volume for 1-to-1 transfer
             air_gap=aspirate_props.retract.air_gap_by_volume.get_for_volume(volume),
-            max_volume=self.get_max_volume(),
+            max_volume=self.get_working_volume(),
         )
         source_loc, source_well = source
         aspirate_point = (

api/tests/opentrons/protocol_api/core/engine/test_instrument_core.py

@@ -1786,6 +1786,42 @@ def test_aspirate_liquid_class(
     assert result == [LiquidAndAirGapPair(air_gap=222, liquid=111)]
 
 
+def test_aspirate_liquid_class_raises_for_more_than_max_volume(
+    decoy: Decoy,
+    mock_engine_client: EngineClient,
+    subject: InstrumentCore,
+    minimal_liquid_class_def2: LiquidClassSchemaV1,
+    mock_transfer_components_executor: TransferComponentsExecutor,
+) -> None:
+    """It should call aspirate sub-steps execution based on liquid class."""
+    source_well = decoy.mock(cls=WellCore)
+    source_location = Location(Point(1, 2, 3), labware=None)
+    test_liquid_class = LiquidClass.create(minimal_liquid_class_def2)
+    test_transfer_properties = test_liquid_class.get_for(
+        "flex_1channel_50", "opentrons_flex_96_tiprack_50ul"
+    )
+    decoy.when(
+        mock_engine_client.state.pipettes.get_working_volume("abc123")
+    ).then_return(100)
+    decoy.when(
+        tx_commons.check_valid_volume_parameters(
+            disposal_volume=0,
+            air_gap=test_transfer_properties.aspirate.retract.air_gap_by_volume.get_for_volume(
+                123
+            ),
+            max_volume=100,
+        )
+    ).then_raise(ValueError("Oh oh!"))
+    with pytest.raises(ValueError, match="Oh oh!"):
+        subject.aspirate_liquid_class(
+            volume=123,
+            source=(source_location, source_well),
+            transfer_properties=test_transfer_properties,
+            transfer_type=TransferType.ONE_TO_ONE,
+            tip_contents=[],
+        )
+
+
 def test_dispense_liquid_class(
     decoy: Decoy,
     mock_engine_client: EngineClient,

api/tests/opentrons/protocol_api_integration/test_transfer_with_liquid_classes.py

@@ -27,8 +27,8 @@ def test_water_transfer_with_volume_more_than_tip_max(
     tiprack = simulated_protocol_context.load_labware(
         "opentrons_flex_96_tiprack_50ul", "D1"
     )
-    pipette_50 = simulated_protocol_context.load_instrument(
-        "flex_1channel_50", mount="left", tip_racks=[tiprack]
+    pipette_1k = simulated_protocol_context.load_instrument(
+        "flex_1channel_1000", mount="left", tip_racks=[tiprack]
     )
     nest_plate = simulated_protocol_context.load_labware(
         "nest_96_wellplate_200ul_flat", "C3"
@@ -47,7 +47,7 @@ def test_water_transfer_with_volume_more_than_tip_max(
         mock_manager = mock.Mock()
         mock_manager.attach_mock(patched_pick_up_tip, "pick_up_tip")
 
-        pipette_50.transfer_liquid(
+        pipette_1k.transfer_liquid(
             liquid_class=water,
             volume=60,
             source=nest_plate.rows()[0],
@@ -58,7 +58,7 @@ def test_water_transfer_with_volume_more_than_tip_max(
         assert patched_pick_up_tip.call_count == 24
         patched_pick_up_tip.reset_mock()
 
-        pipette_50.transfer_liquid(
+        pipette_1k.transfer_liquid(
             liquid_class=water,
             volume=100,
             source=nest_plate.rows()[0],
@@ -69,16 +69,16 @@ def test_water_transfer_with_volume_more_than_tip_max(
         assert patched_pick_up_tip.call_count == 12
         patched_pick_up_tip.reset_mock()
 
-        pipette_50.pick_up_tip()
-        pipette_50.transfer_liquid(
+        pipette_1k.pick_up_tip()
+        pipette_1k.transfer_liquid(
             liquid_class=water,
             volume=50,
             source=nest_plate.rows()[0],
             dest=arma_plate.rows()[0],
             new_tip="never",
             trash_location=trash,
         )
-        pipette_50.drop_tip()
+        pipette_1k.drop_tip()
         assert patched_pick_up_tip.call_count == 1