Deprecate copy field halo kernel

[Alistair Pirrie (mo-alistairp)]

PR Summary

Sci/Tech Reviewer:
Code Reviewer: Benjamin Went (@MetBenjaminWent)

This PR replaces copy_field_halo_kernel_mod.f90 with a temporary PSyKAl-lite script. This is documented in issue #334. The PSyKAl-lite script will search for the last clean halo and copy the field up to that point in a DoF-wise manner.

linked MetOffice/lfric_apps#471

is related to #334

Code Quality Checklist

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trac.log

Test Suite Results - lfric_core - deprecate_copy_field_halo_core/run1

Suite Information

Item	Value
Suite Name	deprecate_copy_field_halo_core/run1
Suite User	alistair.pirrie
Workflow Start	2026-04-30T12:54:16
Groups Run	developer

Dependency	Reference	Main Like
lfric_core	mo-alistairp/lfric_core@deprecate_copy_field_halo_kernel	False
SimSys_Scripts	MetOffice/SimSys_Scripts@cab3315	True

Task Information

✅ succeeded tasks - 390

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Documentation

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PSyclone Approval

• If you have edited any PSyclone-related code (e.g. PSyKAl-lite, Kernel interface, optimisation scripts, LFRic data structure code) then please contact the TCD Team

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[iboutle]

Should there not be a
call field_out_proxy%set_clean(clean_halo_depth)
included after this - otherwise the copying to a clean depth in the halo is entirely pointless, as it will just get halo exchanged anyway

[Alistair Pirrie (mo-alistairp)]

Yes, I think you're right.