Add tag to avoid vernier CCE MPI bug

[Benjamin Went (MetBenjaminWent)]

Officiate the workaround so that Vernier can work out of the box at HoT without manual adjustments by users.

PR Summary

Sci/Tech Reviewer: Ed Hone (@EdHone)
Code Reviewer: Andrew Coughtrie (@andrewcoughtrie)

Code Quality Checklist

• I have performed a self-review of my own code
• My code follows the project's style guidelines
• Comments have been included that aid understanding and enhance the readability of the code
• My changes generate no new warnings
• All automated checks in the CI pipeline have completed successfully

Testing

• I have tested this change locally, using the LFRic Core rose-stem suite
• If required (e.g. API changes) I have also run the LFRic Apps test suite using this branch
• If any tests fail (rose-stem or CI) the reason is understood and acceptable (e.g. kgo changes)
• I have added tests to cover new functionality as appropriate (e.g. system tests, unit tests, etc.)
• Any new tests have been assigned an appropriate amount of compute resource and have been allocated to an appropriate testing group (i.e. the developer tests are for jobs which use a small amount of compute resource and complete in a matter of minutes)

trac.log

Test Suite Results - lfric_core - add_vernier_tag/run5

Suite Information

Item	Value
Suite Name	add_vernier_tag/run5
Suite User	benjamin.went
Workflow Start	2026-02-02T09:29:39
Groups Run	developer

Dependency	Reference	Main Like
lfric_core	MetBenjaminWent/lfric_core@add_vernier_tag	False
SimSys_Scripts	MetOffice/SimSys_Scripts@2025.12.1	True

Task Information

✅ succeeded tasks - 370

Test Suite Results - lfric_apps - hot_testing/run6

Suite Information

Item	Value
Suite Name	hot_testing/run6
Suite User	benjamin.went
Workflow Start	2026-01-30T13:28:35
Groups Run	ex1a_omp_C48_cce_full

Dependency	Reference	Main Like
casim	MetOffice/casim@2025.12.1	True
jules	MetOffice/jules@2025.12.1	True
lfric_apps	MetBenjaminWent/lfric_apps@9f301ea	True
lfric_core	MetBenjaminWent/lfric_core@4639446	True
moci	MetOffice/moci@2025.12.1	True
SimSys_Scripts	MetOffice/SimSys_Scripts@2025.12.1	True
socrates	MetOffice/socrates@2025.12.1	True
socrates-spectral	MetOffice/socrates-spectral@2025.12.1	True
ukca	MetOffice/ukca@2025.12.1	True

Task Information

❌ failed tasks - 3

Task	State
check_lfric_atm_nwp_gal9_1T-C48_MG_ex1a_cce_full-debug-32bit	failed
check_lfric_atm_nwp_gal9_4T-C48_MG_ex1a_cce_full-debug-32bit	failed
kgo_groups_checker	failed

✅ succeeded tasks - 10

• (KGOs were not added for 1T and 4T. Do note 2T remains unchanged.

Outputs produced:

Security Considerations

• I have reviewed my changes for potential security issues
• Sensitive data is properly handled (if applicable)
• Authentication and authorisation are properly implemented (if applicable)

Performance Impact

• Performance of the code has been considered and, if applicable, suitable performance measurements have been conducted

AI Assistance and Attribution

• Some of the content of this change has been produced with the assistance of Generative AI tool name (e.g., Met Office Github Copilot Enterprise, Github Copilot Personal, ChatGPT GPT-4, etc) and I have followed the Simulation Systems AI policy (including attribution labels)

Documentation

• Where appropriate I have updated documentation related to this change and confirmed that it builds correctly

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

Sci/Tech Review

• I understand this area of code and the changes being added
• The proposed changes correspond to the pull request description
• Documentation is sufficient (do documentation papers need updating)
• Sufficient testing has been completed

(Please alert the code reviewer via a tag when you have approved the SR)

Code Review

• All dependencies have been resolved
• Related Issues have been properly linked and addressed
• CLA compliance has been confirmed
• Code quality standards have been met
• Tests are adequate and have passed
• Documentation is complete and accurate
• Security considerations have been addressed
• Performance impact is acceptable

[Ed Hone (EdHone)]

Would it make more sense to pass the application_name through as the tag to vernier?

[Benjamin Went (MetBenjaminWent)]

It could do, though this was just to get the workaround on trunk quick as opposed to a perfect solution.

Ideally we wouldn't worry at all about the tags.

[Ed Hone (EdHone)]

I think changing 'lfric' to trim(application_name) would make sense for this fix, just in case we get stuck using a hard-coded name for the long term if we never get around to reverting it

[Benjamin Went (MetBenjaminWent)]

Given its right there in the timing_mod anyway, I don't mind adding it.

Andrew Coughtrie (@andrewcoughtrie), does this work as an alternative to 'lfric' ?

[Benjamin Went (MetBenjaminWent)]

Running the tests now

[Ed Hone (EdHone)]

Happy with the way this is implemented - passing on to CR Andrew Coughtrie (@andrewcoughtrie)

[Andrew Coughtrie (andrewcoughtrie)]

This all looks good to me.

[Andrew Coughtrie (andrewcoughtrie)]

All is good and the tests pass.