v1 STAR heads: move_to_xy_position follow-ups

pylabrobot/hamilton/star/driver/features/head.py

@@ -1156,13 +1156,20 @@ async def move_to_xy_position(
     if minimum_traverse_height_start is None:
       await self.move_to_safe_z(speed=z_speed, acceleration=z_acceleration)
     else:
+      tips = await self.request_tip_presence()
       stop_disc = minimum_traverse_height_start
-      if await self.request_tip_presence():
+      if tips:
         stop_disc += await self.request_tip_overhang()
       if await self.request_z_position() < stop_disc:
-        await self.move_stop_disc_to_z_position(
-          stop_disc, speed=z_speed, acceleration=z_acceleration
-        )
+        # With tips, the move names the tip bottom, so a refusal says what the caller asked for.
+        if tips:
+          await self.move_tool_bottom_to_z_position(
+            minimum_traverse_height_start, speed=z_speed, acceleration=z_acceleration
+          )
+        else:
+          await self.move_stop_disc_to_z_position(
+            stop_disc, speed=z_speed, acceleration=z_acceleration
+          )
     if self.arm is not None and self.arm.pipettes is not None:
       await self.arm.pipettes.move_to_safe_z()
     await asyncio.gather(

pylabrobot/hamilton/star/driver/features/head96.py

@@ -2891,7 +2891,7 @@ def get_following(height: float) -> float:
     if not await self.request_tip_presence():
       raise RuntimeError("the head reports no tips; pick up tips first")
     await self.move_to_xy_position(
-      a1.x, a1.y, minimum_traverse_height_start=minimum_traverse_height_start, z_speed=descent_speed
+      a1.x, a1.y, minimum_traverse_height_start=minimum_traverse_height_start
     )
 
     async def strokes() -> None:

pylabrobot/hamilton/star/driver/features/head_tests.py

@@ -713,6 +713,16 @@ async def test_every_drive_setting_reaches_its_move(self):
       a1.y, speed=100.0, acceleration=200.0, current_limit=10
     )
 
+  async def test_an_unreachable_traverse_height_is_refused_as_a_tip_bottom(self):
+    a1 = self.head._get_target(self.plate, None)[1]
+    with self.assertRaisesRegex(ValueError, "the tool bottom reaches .* not 1000.0"):
+      await self.head.move_to_xy_position(a1.x, a1.y, minimum_traverse_height_start=1000.0)
+
+  async def test_mix_rises_at_the_drive_default_not_its_descent_speed(self):
+    with patch.object(self.head, "move_to_safe_z", AsyncMock()) as raised:
+      await self.head.mix(self.plate, Mix(volume=50.0, repetitions=1, flow_rate=100.0))
+    self.assertEqual(raised.await_args_list[0].kwargs, {"speed": None, "acceleration": None})
+
   async def test_an_unreachable_y_is_refused_before_the_head_is_raised(self):
     a1 = self.head._get_target(self.plate, None)[1]
     top = self.head.configuration.z_range[1] - await self.head.request_tip_overhang()