From 53b87052e4bfb3d0f3090f593709de0e863d593e Mon Sep 17 00:00:00 2001
From: Alise Au <20424172+ahiuchingau@users.noreply.github.com>
Date: Thu, 25 Jan 2024 14:14:41 -0500
Subject: [PATCH] fix(api): fix left mount being disengaged when moving to
 maintenance position (#14341)

* RQA-2235 if z_L is disengaged before moving to maintenance pos, home z_l
---
 api/src/opentrons/hardware_control/ot3api.py              | 6 ++++++
 api/src/opentrons/hardware_control/protocols/__init__.py  | 8 ++++++++
 .../commands/calibration/move_to_maintenance_position.py  | 6 ++++++
 3 files changed, 20 insertions(+)

diff --git a/api/src/opentrons/hardware_control/ot3api.py b/api/src/opentrons/hardware_control/ot3api.py
index a795d12f270..5da50e41c55 100644
--- a/api/src/opentrons/hardware_control/ot3api.py
+++ b/api/src/opentrons/hardware_control/ot3api.py
@@ -1001,6 +1001,12 @@ def _assert_encoder_ok(self, axes: Sequence[Axis]) -> None:
                 detail={"axes": axes_str},
             )
 
+    def motor_status_ok(self, axis: Axis) -> bool:
+        return self._backend.check_motor_status([axis])
+
+    def encoder_status_ok(self, axis: Axis) -> bool:
+        return self._backend.check_encoder_status([axis])
+
     async def encoder_current_position(
         self,
         mount: Union[top_types.Mount, OT3Mount],
diff --git a/api/src/opentrons/hardware_control/protocols/__init__.py b/api/src/opentrons/hardware_control/protocols/__init__.py
index 4b85140f9ba..e47b54dba2c 100644
--- a/api/src/opentrons/hardware_control/protocols/__init__.py
+++ b/api/src/opentrons/hardware_control/protocols/__init__.py
@@ -1,6 +1,8 @@
 """Typing protocols describing a hardware controller."""
 from typing_extensions import Protocol, Type
 
+from opentrons.hardware_control.types import Axis
+
 from .module_provider import ModuleProvider
 from .hardware_manager import HardwareManager
 from .chassis_accessory_manager import ChassisAccessoryManager
@@ -82,6 +84,12 @@ class FlexHardwareControlInterface(
     def get_robot_type(self) -> Type[FlexRobotType]:
         return FlexRobotType
 
+    def motor_status_ok(self, axis: Axis) -> bool:
+        ...
+
+    def encoder_status_ok(self, axis: Axis) -> bool:
+        ...
+
 
 __all__ = [
     "HardwareControlAPI",
diff --git a/api/src/opentrons/protocol_engine/commands/calibration/move_to_maintenance_position.py b/api/src/opentrons/protocol_engine/commands/calibration/move_to_maintenance_position.py
index 464b177e980..b610eefe86c 100644
--- a/api/src/opentrons/protocol_engine/commands/calibration/move_to_maintenance_position.py
+++ b/api/src/opentrons/protocol_engine/commands/calibration/move_to_maintenance_position.py
@@ -80,6 +80,12 @@ async def execute(
         ot3_api = ensure_ot3_hardware(
             self._hardware_api,
         )
+        # the 96-channel mount is disengaged during gripper calibration and
+        #  must be homed before the gantry position can be called
+        if ot3_api.encoder_status_ok(Axis.Z_L) and not ot3_api.motor_status_ok(
+            Axis.Z_L
+        ):
+            await ot3_api.home([Axis.Z_L])
         current_position_mount = await ot3_api.gantry_position(
             Mount.LEFT, critical_point=CriticalPoint.MOUNT
         )