Workshop harness. The participant's project is not this directory. just prepare builds it in develop/, and the sandbox can see only that directory.
nix develop # JDK, sbt, scalafmt, just, nono, Claude Code
just # recipes
just prepare # lesson names
just prepare refine-1 # empty project, then the prompt
just claude # Claude Code inside develop/just sandbox is the same boundary with a plain shell. The design is in docs/specs/SPEC.v1-onion-layering.md. The prompts are in workshop/JOURNEY.md.