VCS Detection Skill

Detect the version control system in use before running VCS commands.

Why This Matters

• jj and git have different CLIs and workflows.
• Running git commands in a jj repo (or vice versa) causes avoidable errors.
• Some repos are colocated (both .jj/ and .git/ exist).

Detection Logic

Priority order:

1. jj root succeeds -> jj
2. else git rev-parse --show-toplevel succeeds -> git
3. else -> none

Detection Command