Tools live under tools/<role>/<domain> (checks, generate, release, ci, dev), every tool is a workspace named @open-pencil/<domain>-tools, a shared tools/tsconfig.json backs the new check:tools gate that fixed 55 latent type errors, test:tools runs through bun --filter, the placement check is its own checks/test-homes package, and every tool resolves the repository through resolveWorkspaceRoot. Bun, Node, and mdast types live in a tools-root workspace so they never reach the app program.