Claude Code installed and working, with the guidance file you wrote in 102.
A project with a test suite you can run locally, its test helper, and some git history. Code that calls a language model or another paid service makes Exercises 1 and 3 most useful. The sample repository in reference/sample-repo-spec.md works if you have no project.
No exercise calls a live model or spends money. Where a step needs model output, you record a response or write one by hand.
A shell. The examples use zsh, the shell the course's evidence comes from. Keep scratch files outside the repository, in a directory made once per shell: S=$(mktemp -d "${TMPDIR:-/tmp}/suite.XXXXXX").
