ADR suggestion: New code should be formatted using a linter

[rozyczko]

As discussed during the code camp (07/01/2025) we are trying to move towards proper code formatting with a linter.
ruff seems to be one solution, as it is very popular and allows not just checking but also automatic formatting.

We can start by requiring all the new code to be properly formatted but also spend time on the main body of the code.

[backmari]

ORNL gathers best practices like linting here: https://github.com/neutrons/python_project_template

[krzywon]

Do a single formatting PR that applies a linter to all code.

pre or post v6.1.0?

[krzywon]

For clarity, this is an action item discussed at todays meeting, assuming we move forward with this ADR. This would likely be post 6.1.0 release to ensure nothing breaks so close to a release.

[rozyczko]

With the new pyproject.toml based setup, adding a custom ruff section is easy.
We can

• disable checks for certain directories (docs, build_tools, installers, tests)
• modify default settings, e.g. increase the line length limit to 127 or so
• standardise on single quotes
• force single line imports
  etc.

[backmari]

A way to nudge developers into adopting some linting tool can be to add the app pre-commit ci in the repository. Pre-commit ci will add a "fix up" commit to PR:s that don't follow the linting rules.

[krzywon]

Comments from technical meeting

• CodeScene: need to discuss coverage and health rules
• pre-commit: Seems reasonable
• ruff vs. CodeScene: ruff is a lint tool, CodeScene is complexity checker
• More discussion for both tools and when to implement
• After 6.1.0 release - start to turn things on, slow steps forward - locally run ruff and once closer to clean, turn on pre-commit
• ruff: Not one PR to rule them all - Over time