Jj Agent Spawn

jj Agent Spawn

Create a new jj workspace (the equivalent of git worktree add) and open it ready for an agent to start work.

When to use

• User wants to run two or more agents on different tasks in parallel.
• User wants to try an alternative approach without contaminating the main working copy.
• User wants the agent's output isolated in its own @ for later review.

Prerequisites

• .jj/ exists in the repo root.
• $TMUX is set if --tmux mode is desired.
• $EDITOR is set (or an explicit editor is provided).

Steps

1. Pick a workspace name. Short, descriptive, kebab-case:

   • Good: fix-auth, review-pr-42, try-approach-b.
   • Bad: agent1, tmp, wip.

2. Pick the base revision — usually @ (current) or trunk().

3. Spawn. Prefer the plugin wrapper if available:

   # Preferred: with nwiizo/jujutsu.fish installed
   jj_agent <name> -r 'trunk()'
   jj_agent <name> --tmux           # opens a new tmux window
   jj_agent <name> -e 'claude'      # override editor
   
   # Fallback: plain jj
   jj workspace add --name <name> -r 'trunk()' ../<name>
   cd ../<name>
   $EDITOR .
   

4. Confirm the workspace registered:

   jj workspace list          # or `jj_agent_list` if the plugin is installed
   

   The new workspace should appear with an empty @.

Lifecycle follow-ups

Plugin-available shortcuts (otherwise run the underlying jj commands):

• Compare two agents' output: jj_agent_diff <A> <B> (or jj diff --from <A>@ --to <B>@).
• Close out a workspace: jj_agent_done <name> --push-pr --forget (or summarize + push + jj workspace forget <name>).
• Cleanup of empty abandoned workspaces: jj_agent_prune --dry-run then jj_agent_prune.

Notes for the invoking agent

• The spawned session is an independent jj workspace. Operations there record into the shared op log, so the main agent can see what the spawned agent did via jj op log from any workspace.
• Do not invoke this skill programmatically just to create a workspace — the skill exists so the user explicitly chooses the name, base, and mode.