claude-spawn

Open the Claude Code session you are in a second time, in another terminal. The new session starts with a copy of the conversation so far, then goes its own way: neither side sees what the other does next.

Useful when a session is about to take a turn you are not sure about. Spawn it, try the risky path in the new window, keep the original intact.

Claude Code already knows how to split a conversation: /branch moves you into the copy, /fork runs the copy as a background session in its own git worktree. Both leave you with one terminal in front of you. /spawn makes the same split, but the copy opens in a terminal of its own and you can type in either.

	Where the copy runs	Where you are left
/branch	in place of the original	in the copy
/fork	background session, own worktree	in the original
/spawn	a second terminal window	in the original, copy beside

One consequence to keep in mind: /spawn sets up no worktree. Both sessions work in the same directory, so keeping two Claude Codes off the same files is up to you.

Requirements

• Linux, with a terminal emulator or tmux
• Claude Code
• python3, for /spawns only

Installation

/plugin marketplace add https://github.com/nd-/claude-spawn.git
/plugin install claude-spawn@claude-spawn

From a local clone, with an absolute path or one starting with ./:

/plugin marketplace add ~/code/claude-spawn
/plugin install claude-spawn@claude-spawn

Commands

/spawn

Opens the second session. Where it lands depends on the machine, checked in this order:

1. $CLAUDE_SPAWN_TERMINAL, when you have set it
2. a tmux window, when the session runs under tmux, which is also what makes this work over SSH
3. $TERMINAL, then the first terminal emulator found in PATH

The window opens in the current working directory, detached, and with this session's CLAUDE_* variables cleared so the new Claude Code does not mistake itself for a child process. It prints one line naming the terminal it used and the session the copy was forked from, so a window that never came is not mistaken for a quiet success.

The copy replays the conversation up to and including the /spawn that opened it, which puts a fresh-looking invitation to run it again in front of you. Doing so forks the fork, and a handful of windows later nothing tells them apart. /spawns prints the tree if you need to untangle one after the fact.

Terminals it knows how to drive: ptyxis, gnome-terminal, kgx, konsole, kitty, ghostty, alacritty, wezterm, foot, xfce4-terminal, tilix, terminator, blackbox-terminal, x-terminal-emulator, xterm. Anything else is tried with the usual -e convention, so naming an unlisted one usually works:

export CLAUDE_SPAWN_TERMINAL=st

Set it to tmux to always open a tmux window instead of a new one.

/spawns

Lists what came out of what:

/home/you/code/project
  8f3c1a2b  refactor-payment-flow
  142 msg, last active 03 Mar 18:04, on main
     └─ b91d77e0  try-stripe-webhooks
        58 msg, last active 03 Mar 21:37, on webhooks

--all covers every project instead of the current one, --json prints the same data for a script to read.

Claude Code records no link between a session and the one it came from, so /spawns rebuilds it from the transcripts in ~/.claude/projects: messages copied into the new session keep the id of the session they were originally written in. Transcripts older than that field are matched on their shared opening messages instead, which shows that two sessions are related without saying which came first. Those appear as origin inferred.

A session shows up only once it has received a first message. A window you opened and never typed into was never recorded.

Troubleshooting

Print the command instead of running it:

CLAUDE_SPAWN_DRY_RUN=1 ./scripts/spawn.sh

No display and no tmux means nowhere to open a window: start Claude Code under tmux and /spawn will use a tmux window.

Two windows instead of one, on Ptyxis. Not the spawn: Ptyxis restores the windows of its previous session when it starts from cold, and /spawn is what wakes it up. The extra window holds a plain login shell, in whatever directory that earlier session was in. It never happens while a Ptyxis window is already open, which is what makes it look random.

gsettings get org.gnome.Ptyxis restore-session   # true means it will
gsettings set org.gnome.Ptyxis restore-session false

Other terminals with a session-restore setting behave the same way.

Credits

Inspired by claude-branch, which does the macOS side of the same idea.

License

MIT