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 git commands 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:

1. jj root succeeds → jj (handles colocated too)
2. git rev-parse succeeds → git
3. Both fail → no VCS