bring back z discontinuity speed changes

hardware-testing/hardware_testing/gravimetric/liquid_class/pipetting.py

@@ -2,9 +2,11 @@
 from dataclasses import dataclass
 from typing import Optional, Callable, Tuple
 
+from opentrons.config.defaults_ot3 import DEFAULT_MAX_SPEED_DISCONTINUITY
 from opentrons.protocol_api import InstrumentContext, ProtocolContext
 from opentrons.protocol_api.labware import Well
 
+from hardware_testing.opentrons_api.types import OT3AxisKind
 from hardware_testing.gravimetric import config
 from hardware_testing.gravimetric.workarounds import get_sync_hw_api
 from hardware_testing.gravimetric.liquid_height.height import LiquidTracker
@@ -127,10 +129,33 @@ def _retract(
     channel_offset: Point,
     mm_above_well_bottom: float,
     speed: float,
+    z_discontinuity: float,
 ) -> None:
+    # change discontinuity per the liquid-class settings
+    hw_api = ctx._core.get_hardware()
+    if pipette.channels == 96:
+        hw_api.config.motion_settings.max_speed_discontinuity.high_throughput[
+            OT3AxisKind.Z
+        ] = z_discontinuity
+    else:
+        hw_api.config.motion_settings.max_speed_discontinuity.low_throughput[
+            OT3AxisKind.Z
+        ] = z_discontinuity
+    # NOTE: re-setting the gantry-load will reset the move-manager's per-axis constraints
+    hw_api.set_gantry_load(hw_api.gantry_load)
     # retract out of the liquid (not out of the well)
     pipette.move_to(well.bottom(mm_above_well_bottom).move(channel_offset), speed=speed)
+    # reset discontinuity back to default
+    if pipette.channels == 96:
+        hw_api.config.motion_settings.max_speed_discontinuity.high_throughput[
+            OT3AxisKind.Z
+        ] = DEFAULT_MAX_SPEED_DISCONTINUITY.high_throughput[OT3AxisKind.Z]
+    else:
+        hw_api.config.motion_settings.max_speed_discontinuity.low_throughput[
+            OT3AxisKind.Z
+        ] = DEFAULT_MAX_SPEED_DISCONTINUITY.low_throughput[OT3AxisKind.Z]
     # NOTE: re-setting the gantry-load will reset the move-manager's per-axis constraints
+    hw_api.set_gantry_load(hw_api.gantry_load)
 
 
 def _pipette_with_liquid_settings(  # noqa: C901
@@ -186,9 +211,11 @@ def _get_max_blow_out_ul() -> float:
     if aspirate or mix:
         submerge_speed = config.TIP_SPEED_WHILE_SUBMERGING_ASPIRATE
         retract_speed = config.TIP_SPEED_WHILE_RETRACTING_ASPIRATE
+        _z_disc = liquid_class.aspirate.z_retract_discontinuity
     else:
         submerge_speed = config.TIP_SPEED_WHILE_SUBMERGING_DISPENSE
         retract_speed = config.TIP_SPEED_WHILE_RETRACTING_DISPENSE
+        _z_disc = liquid_class.dispense.z_retract_discontinuity
 
     # CREATE CALLBACKS FOR EACH PHASE
     def _aspirate_on_approach() -> None:
@@ -229,12 +256,7 @@ def _aspirate_on_mix() -> None:
             ctx.delay(liquid_class.dispense.delay)
         # don't go all the way up to retract position, but instead just above liquid
         _retract(
-            ctx,
-            pipette,
-            well,
-            channel_offset,
-            approach_mm,
-            retract_speed,
+            ctx, pipette, well, channel_offset, approach_mm, retract_speed, _z_disc
         )
         pipette.blow_out()
         pipette.prepare_to_aspirate()
@@ -306,7 +328,7 @@ def _dispense_on_retract() -> None:
 
         # PHASE 3: RETRACT
         callbacks.on_retracting()
-        _retract(ctx, pipette, well, channel_offset, retract_mm, retract_speed)
+        _retract(ctx, pipette, well, channel_offset, retract_mm, retract_speed, _z_disc)
         _aspirate_on_retract() if aspirate else _dispense_on_retract()
 
     # EXIT