Jj Agent Spawn

jj Agent Spawn

Create a new jj workspace (the equivalent of git worktree add) and open it in an editor or tmux window, 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 via jj_agent_diff.

Prerequisites

• jj_agent function is available (this plugin is installed).
• $TMUX is set if --tmux mode is desired.
• $EDITOR is set (or override with -e).

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:

   jj_agent <name>                      # based on current @
   jj_agent <name> -r 'trunk()'         # based on trunk
   jj_agent <name> -r <change-id>       # based on a specific revision
   

3. Pick the launch mode:

   • --tmux — opens a new tmux window inside the current session. Preferred when running multiple agents side by side.
   • (default) — opens $EDITOR inside the new workspace directory.
   • -e '<command>' — override editor, e.g. -e 'claude', -e 'codex'.

4. Confirm the workspace registered:

   jj_agent_list
   

   The new workspace should appear with state clean (no edits yet).

Lifecycle follow-ups

• Compare two agents' output: jj_agent_diff <A> <B>.
• Close out the winning workspace: jj_agent_done <name> --push-pr --forget.
• Bulk cleanup of empty abandoned workspaces: jj_agent_prune --dry-run then jj_agent_prune.

See README.md "End-to-end agent loop" for the full cycle walkthrough.

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 call jj_agent programmatically to reproduce this skill — the skill exists so the user explicitly chooses the name, base, and mode.