Use Jujutsu (jj) for ALL version-control operations in a repo that has a .jj/ directory. Assumes you already know jj mechanically; focuses on agent judgment — safe history surgery, splitting work into clean logical commits, recovering from mistakes, verifying rewrites, and operating within first- and second-order megamerges (multi-stream work). Load this whenever you will inspect history, commit, split, squash, rebase, reorder, work across multiple branches/PRs, or otherwise touch VCS state.
Load this skill for non-trivial work in a Cargo workspace. Covers what is genuinely peculiar to Cargo as an agent encounters it — keeping the build cache from exploding into tens of gigabytes, the workspace-deps feature-flag transit gotcha, and the architectural rule for keeping CLI-bearing crates testable. The general engineering-discipline rules (oracles, testing domains, evidence) live in `rigor`; the commit-shaping rules live in `jujutsu`.