[Anthony Sligar (sligara7)]

Adds move_slits(slits, horizontal_center, vertical_center, horizontal_gap, vertical_gap, relative=False) and a Slits tab next to Motors in the GUI.

• Slits move as a pair by their center line and gap (Jakub). Only the values given move; a center move keeps the gap, and a gap move is symmetric about the center.
• relative=True uses bps.mvr. Gaps move before centers, because both drive the same blades.
• No kinematics redone in the plan: it uses the existing Slits gap/center signals.

Root cause behind Jakub's review comment:

• Slits built its derived gap/center signals from each motor's user_readback.
• A derived signal is only locatable when its raw inputs are, and readback signals are not. So bps.rd and bps.mvr raised TypeError, which is why the first version read the blades by hand.
• The signals are now built from the Motor devices, which ophyd-async supports by design; the transform still receives readback values.
• A new test, test_slits_gap_and_center_work_with_locating_plan_stubs, pins bps.rd/bps.mvr on both axes. I observed it fail before the fix.
• Note: bps.mvr moves relative to the motors' setpoints, as for any motor.

Verification: mock tests only; not run on the beamline.

• move_slits: absolute, relative and gap-before-center moves, and an empty call refused. The existing slit kinematics and watcher tests still pass.
• The GUI form (offscreen) builds the Slits device field, four optional floats and a relative checkbox.
• move_slits is in the profile namespace.
• ty adds no diagnostics.
• Full suite on the first commit: 474 passed. The one failure, test_detector_viewer_axes, also fails on main in my dev env (older ntnda-qt-viewer than the lock).

[Copilot]

🟢 Approval recommended

The motion sequencing, exports, GUI integration, and regression coverage have no identified blocking issues.

No open issues 🎉

What changed in this PR

Adds a move_slits plan and a Slits GUI tab, making center and gap adjustments available through the existing plan interface.

Changes:

• Supports selective absolute or relative adjustments, moving gaps before centers.
• Exports the plan and adds it to the GUI.
• Adds motion, GUI-field, and namespace tests, plus CLI documentation.

File	Description
tests/​test_profile_namespace.py	Checks that move_slits is exposed in the profile namespace.
tests/​photon_delivery_system/​test_slits.py	Tests selective moves, sequencing, relative moves, and missing input.
tests/​gui/​test_plan_widget_slits.py	Checks device selection and scalar fields in the Slits form.
src/​hextools/​photon_delivery_system/​slits.py	Implements the move_slits plan.
src/​hextools/​photon_delivery_system/​__init__.py	Exports move_slits publicly.
src/​hextools/​gui/​__main__.py	Adds the Slits plan tab.
docs/​profile.md	Lists the newly available plan.
docs/​cli.md	Adds slit movement examples.

_{Review effort: Balanced}

[Copilot]

🟢 Approval recommended

The focused implementation, integration, and test coverage are consistent, with no blocking issues identified; tests were not executed.

No open issues 🎉

_{Review effort: Balanced}