Support new ACCESS-ESM1.6 raw output filenames

[rbeucher]

Closes #583

What this changes

ACCESS-ESM1.6 is moving towards storing one physical variable in each raw NetCDF file. This PR teaches ACCESS-MOPPy how to find those new files without removing support for existing runs.

In practical terms, MOPPy can now work with both:

• the current atmosphere files that bundle several variables together, plus the new access-esm1p6.um7p3... files;
• the current CICE files, plus the new access-esm1p6.cice5... files;
• the current ocean files, plus the new access-esm1p6.om2... files and the grouped ocean static file.

MOPPy also understands the date at the end of the new filenames. This keeps requests such as “only process 1850 to 1900” working as expected, and ensures that a request for one raw variable does not accidentally select another variable’s file.

Compatibility

This is additive. Existing file names and directory layouts remain supported, so older experiments do not need to be reorganised.

Checks

• pixi run -e dev python -m pytest tests/unit/test_file_discovery.py -q (91 passed)
• pixi run -e dev ruff check src/access_moppy/file_discovery.py tests/unit/test_file_discovery.py

@joshuatorrance @blimlim @rhaegar325 , could you please review the filename assumptions for UM, CICE, and ocean, and confirm that keeping both layouts covers the planned transition?

[rbeucher]

I guess we should not merge before it is tested against an actual experiment output dataset.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 75.1%. Comparing base (7d16a74) to head (4402e89).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@          Coverage Diff          @@
##            main    #584   +/-   ##
=====================================
  Coverage   75.0%   75.1%           
=====================================
  Files         38      38           
  Lines       7761    7774   +13     
  Branches    1451    1455    +4     
=====================================
+ Hits        5823    5836   +13     
  Misses      1638    1638           
  Partials     300     300           

Flag	Coverage Δ
unit	75.1% <100.0%> (+<0.1%)	⬆️

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[Copilot]

Pull request overview

Adds support for the new ACCESS-ESM1.6 “one variable per raw NetCDF” naming conventions (UM7.3/CICE5/OM2) while retaining legacy discovery behavior, including correct year/month parsing for end-of-filename datestamps.

Changes:

• Extend ACCESS-ESM1-6_mappings.json file-discovery patterns to include new access-esm1p6.{um7p3,cice5,om2}... filenames and additional subdirectory options.
• Teach filename parsing to extract year/month from dot-delimited ....YYYY(.nc) and ....YYYY-MM(.nc) suffixes.
• Expand unit tests to cover new filename patterns and mixed legacy + new-layout archives.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
tests/unit/test_file_discovery.py	Adds coverage for year parsing and discovery across legacy + new per-variable layouts.
src/access_moppy/mappings/ACCESS-ESM1-6_mappings.json	Adds new ACCESS-ESM1.6 per-variable filename globs and supports multiple subdirs per component.
src/access_moppy/file_discovery.py	Updates year/year-month extraction for dot-delimited datestamps and supports list-valued subdir.

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