VCS Detection Skill
Detect the version control system in use before running any VCS commands.
Why This Matters
- jj (Jujutsu) and git have different CLIs and workflows
- Running
gitcommands in a jj repo (or vice versa) causes errors - Some repos use jj with git colocated (both
.jj/and.git/exist)
Detection Logic
Both jj root and git rev-parse --show-toplevel walk up the filesystem to find repo root.
Priority order:
jj rootsucceeds → jj (handles colocated too)git rev-parsesucceeds → git- Both fail → no VCS
Detection Command
if jj root &>/dev/null; then echo "jj"
elif git rev-parse --show-toplevel &>/dev/null; then echo "git"
else echo "none"
fi
Command Mappings
| Operation | git | jj |
|---|---|---|
| Status | git status | jj status |
| Log | git log | jj log |
| Diff | git diff | jj diff |
| Commit | git commit | jj commit / jj describe |
| Branch list | git branch | jj branch list |
| New branch | git checkout -b <name> | jj branch create <name> |
| Push | git push | jj git push |
| Pull/Fetch | git pull / git fetch | jj git fetch |
| Rebase | git rebase | jj rebase |
Usage
Before any VCS operation:
- Run detection command
- Use appropriate CLI based on result
- If
none, warn user directory is not version controlled
Example Integration
User: Show me the git log
Agent: [Runs detection] -> Result: jj
Agent: [Runs `jj log` instead of `git log`]
Colocated Repos
When both .jj/ and .git/ exist, the repo is "colocated":
- jj manages the working copy
- git is available for compatibility (GitHub, etc.)
- Always prefer jj commands in colocated repos