## Summary The long line of projects in `mypy_primer.yaml` is hard to work with when adding projects or checking whether they are currently run. Use a one-per-line text file instead. ## Test Plan Ecosystem check on this PR.
Markdown files within the mdtest/ subdirectory are tests of type inference and type checking;
executed by the tests/mdtest.rs integration test.
See crates/red_knot_test/README.md for documentation of this test format.