Changes To ISIS CI/CD Policy

[Kelvinrr]

As part of making ISIS adhere to NASA's Class C software standards, ISIS will use test coverage checks for new PRs going forward. The specifics about its implementation are tentative. This post can act as a discussion board for these changes.

What this means:

• Only impacts PR authors; if you do not write code for ISIS, it won't affect you.
• PRs can now be rejected based on whether tests pass or fail, as well as how it affects ISIS test coverage.

Starting 1/26/26, the following tentative rules will be adopted. These are up for discussion as we work out the details with community members. Feel free to open a discussion here, on your PRs, or on ISIS issues.

1. PRs that drop overage more than 2% will not be merged. Maintainers should request changes.
2. Large PRs are still subject to our "one changelog entry per PR" rule. If a PR has thousands of line changes while staying within the one changelog entry limit, it can drop coverage more than 2% as long as critical paths are being tested.
3. Coverage will not drop below 70% (ISIS test coverage is 78% at the time of writing).
4. Coverage is reported at the end of CI reports that are linked in PRs.
5. Static checks for code correctness were added, PRs can be denied for undefined behavior, data leaks, etc.