Separate model checksum and finalise

[Steven Sandbach (ss421)]

PR Summary

Sci/Tech Reviewer: cjohnson-pi
Code Reviewer:

This is a small followup refactor that I suggested in: https://code.metoffice.gov.uk/trac/lfric/ticket/4351 (and copied to: #439). It separates the finalization and checksum of the model. The motivation here is for slightly cleaner interface as the checksum is only needed with running the full model and is not needed in the integration tests and JEDI.

The current solution is the inclusion of an optional that does the checksum if it is present. Here the checksum is explicitly called.

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 Apps rose-stem suite
• 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)

Tested via: cylc vip -z group=developer -S USE_MIRRORS=true -n gungho_finalise_model ./rose-stem and the trac.log is copied below.

trac.log

Test Suite Results - lfric_apps - gungho_finalise_model/run1

Suite Information

Item	Value
Suite Name	gungho_finalise_model/run1
Suite User	steven.sandbach
Workflow Start	2026-04-17T16:23:14
Groups Run	developer

Dependency	Reference	Main Like
casim	MetOffice/casim@2026.03.2	True
jules	MetOffice/jules@2026.03.2	True
lfric_apps	ss421/lfric_apps@gungho_finalise_model	False
lfric_core	MetOffice/lfric_core@2026.03.2	True
moci	MetOffice/moci@2026.03.2	True
SimSys_Scripts	MetOffice/SimSys_Scripts@2026.03.2	True
socrates	MetOffice/socrates@2026.03.2	True
socrates-spectral	MetOffice/socrates-spectral@2026.03.2	True
ukca	MetOffice/ukca@2026.03.2	True

Task Information

✅ succeeded tasks - 1164

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

[Steven Sandbach (ss421)]

To agree to the CLA, please add your details (GitHub username, Real Name, Affiliation, and Date) to the CONTRIBUTORS.md file (create one, if required) in the development branch for this PR. After signing the CLA, you won't need to do this again for future PRs.

Updated via: 3aa8f09

[cjohnson-pi]

Are diagnostic fields used?

[Steven Sandbach (ss421)]

They do not appear to be used. Removed via: 20c12fc

[cjohnson-pi]

Are fd_fields used?

[Steven Sandbach (ss421)]

They do not appear to be used. Removed via: 20c12fc

[cjohnson-pi]

Its curious that exner is listed here, but not actually used in the checksum. Ideally it should be added. But that would mean ALL the kgos would change. Its probably not necessary, given that we've used this code for a long time. Perhaps a comment can be added.

[Steven Sandbach (ss421)]

Added a comment in: 20c12fc. I could open an issue and reference it via the comment? I dont mind making that change but equally could assign the issue to someone - can you advise?

[cjohnson-pi]

I discussed with others in dynamics research and we agree that given that we've managed so far without exner in the checksum, its not a priority to add it in. And therefore best to just leave as is. But thanks for adding the comment to highlight that its not actually used in the checksum.

[cjohnson-pi]

As Sci/Tech reviewer, I've had a more thorough look and have added a few comments.

[Steven Sandbach (ss421)]

As Sci/Tech reviewer, I've had a more thorough look and have added a few comments.

Thanks for the review - apologies for adding you as Sci-Tech review before you agreed. I did that because you had reviewed the code and previously discussed the change I made the assumption...

I've updated as suggested and am rerunning the test suite via: cylc vip -z group=developer -S USE_MIRRORS=true -n gungho_finalise_model ./rose-stem - I don't expect any issues though.... The output will be here

[Steven Sandbach (ss421)]

I've updated as suggested and am rerunning the test suite via: cylc vip -z group=developer -S USE_MIRRORS=true -n gungho_finalise_model ./rose-stem - I don't expect any issues though.... The output will be here

All test are now running. I did need to make an extra commit: d986f6a because I left whitespace in the previous commit. Also note a number of tasks failed but on re-trigger they were successful. Let me know if there is anything else you would like me to do.